Merge branch 'main' into fix/s8-bind-loopback-dev

Merge pull request 'fix(ci): lowercase 'molecule-ai/' in cross-repo workflow refs' (#17 ) from fix/lowercase-org-slug into main
fix(ci): lowercase 'molecule-ai/' in cross-repo workflow refs
2026-05-07 11:25:20 +00:00 · 2026-05-07 10:38:12 +00:00 · 2026-05-07 01:00:10 -07:00 · 2026-05-06 22:29:24 -07:00 · 2026-05-07 00:19:40 +00:00 · 2026-05-06 16:43:42 -07:00
102 changed files with 7836 additions and 887 deletions
@@ -1,7 +1,7 @@
 name: Block internal-flavored paths

 # Hard CI gate. Internal content (positioning, competitive briefs, sales
-# playbooks, PMM/press drip, draft campaigns) lives in Molecule-AI/internal —
+# playbooks, PMM/press drip, draft campaigns) lives in molecule-ai/internal —
 # this public monorepo must never re-acquire those paths. CEO directive
 # 2026-04-23 after a fleet-wide audit found 79 internal files leaked here.
 #
@@ -135,7 +135,7 @@ jobs:
            echo "::error::Forbidden internal-flavored paths detected:"
            printf "$OFFENDING"
            echo ""
-            echo "These paths belong in Molecule-AI/internal, not this public repo."
+            echo "These paths belong in molecule-ai/internal, not this public repo."
            echo "See docs/internal-content-policy.md for canonical locations."
            echo ""
            echo "If your file is genuinely public-facing (e.g. a blog post"
@@ -108,7 +108,7 @@ jobs:
              echo
              echo "One or more canary secrets are unset (\`CANARY_TENANT_URLS\`, \`CANARY_ADMIN_TOKENS\`, \`CANARY_CP_SHARED_SECRET\`)."
              echo "Phase 2 canary fleet has not been stood up yet —"
-              echo "see [canary-tenants.md](https://github.com/Molecule-AI/molecule-controlplane/blob/main/docs/canary-tenants.md)."
+              echo "see [canary-tenants.md](https://github.com/molecule-ai/molecule-controlplane/blob/main/docs/canary-tenants.md)."
              echo
              echo "**Skipped — promote-to-latest will NOT auto-fire.** Dispatch \`promote-latest.yml\` manually when ready."
            } >> "$GITHUB_STEP_SUMMARY"
@@ -87,7 +87,7 @@ jobs:
        run: go mod download
      - if: needs.changes.outputs.platform == 'true'
        run: go build ./cmd/server
-      # CLI (molecli) moved to standalone repo: github.com/Molecule-AI/molecule-cli
+      # CLI (molecli) moved to standalone repo: github.com/molecule-ai/molecule-cli
      - if: needs.changes.outputs.platform == 'true'
        run: go vet ./... || true
      - if: needs.changes.outputs.platform == 'true'
@@ -165,7 +165,7 @@ jobs:
              # Strip the package-import prefix so we can match .coverage-allowlist.txt
              # entries written as paths relative to workspace-server/.
              # Handle both module paths: platform/workspace-server/... and platform/...
-              rel=$(echo "$file" | sed 's|^github.com/Molecule-AI/molecule-monorepo/platform/workspace-server/||; s|^github.com/Molecule-AI/molecule-monorepo/platform/||')
+              rel=$(echo "$file" | sed 's|^github.com/molecule-ai/molecule-monorepo/platform/workspace-server/||; s|^github.com/molecule-ai/molecule-monorepo/platform/||')

              if echo "$ALLOWLIST" | grep -qxF "$rel"; then
                echo "::warning file=workspace-server/$rel::Critical file at ${pct}% coverage (allowlisted, #1823) — fix before expiry."
@@ -243,8 +243,8 @@ jobs:
          if-no-files-found: warn

  # MCP Server + SDK removed from CI — now in standalone repos:
-  # - github.com/Molecule-AI/molecule-mcp-server (npm CI)
-  # - github.com/Molecule-AI/molecule-sdk-python (PyPI CI)
+  # - github.com/molecule-ai/molecule-mcp-server (npm CI)
+  # - github.com/molecule-ai/molecule-sdk-python (PyPI CI)

  # e2e-api job moved to .github/workflows/e2e-api.yml (issue #458).
  # It now has workflow-level concurrency (cancel-in-progress: false) so
@@ -434,5 +434,5 @@ jobs:
          fi

      # SDK + plugin validation moved to standalone repo:
-      # github.com/Molecule-AI/molecule-sdk-python
+      # github.com/molecule-ai/molecule-sdk-python

@@ -62,7 +62,7 @@ jobs:
        if: matrix.language == 'go'
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
-          repository: Molecule-AI/molecule-ai-plugin-github-app-auth
+          repository: molecule-ai/molecule-ai-plugin-github-app-auth
          path: molecule-ai-plugin-github-app-auth
          token: ${{ secrets.PLUGIN_REPO_PAT || secrets.GITHUB_TOKEN }}

@@ -121,8 +121,16 @@ jobs:
          # Per-migration result is logged so a failed migration that
          # SHOULD have been replayable surfaces in the CI log instead
          # of silently failing.
+          # Apply both *.sql (legacy, lives next to its module) and
+          # *.up.sql (newer up/down convention) in a single
+          # lexicographically-sorted pass. Excluding *.down.sql so the
+          # newest-naming-convention pairs don't undo themselves mid-run.
+          # Pre-#149-followup this loop only globbed *.up.sql, which
+          # silently skipped 001_workspaces.sql + 009_activity_logs.sql
+          # — fine while no integration test depended on those tables,
+          # not fine once a cross-table atomicity test came in.
          set +e
-          for migration in migrations/*.up.sql; do
+          for migration in $(ls migrations/*.sql 2>/dev/null | grep -v '\.down\.sql$' | sort); do
            if psql -h localhost -U postgres -d molecule -v ON_ERROR_STOP=1 \
                  -f "$migration" >/dev/null 2>&1; then
              echo "✓ $(basename "$migration")"
@@ -132,16 +140,19 @@ jobs:
          done
          set -e

-          # Sanity: the delegations table MUST exist for the integration
-          # tests to be meaningful. Hard-fail if 049 didn't land — that
-          # would be a real regression we want loud.
-          if ! psql -h localhost -U postgres -d molecule -tA \
-              -c "SELECT 1 FROM information_schema.tables WHERE table_name = 'delegations'" \
-              | grep -q 1; then
-            echo "::error::delegations table missing after migration replay — handler integration tests would be meaningless"
-            exit 1
-          fi
-          echo "✓ delegations table present"
+          # Sanity: the delegations + workspaces + activity_logs tables
+          # MUST exist for the integration tests to be meaningful. Hard-
+          # fail if any didn't land — that would be a real regression we
+          # want loud.
+          for tbl in delegations workspaces activity_logs pending_uploads; do
+            if ! psql -h localhost -U postgres -d molecule -tA \
+                -c "SELECT 1 FROM information_schema.tables WHERE table_name = '$tbl'" \
+                | grep -q 1; then
+              echo "::error::$tbl table missing after migration replay — handler integration tests would be meaningless"
+              exit 1
+            fi
+            echo "✓ $tbl table present"
+          done

      - if: needs.detect-changes.outputs.handlers == 'true'
        name: Run integration tests
@@ -102,7 +102,7 @@ jobs:
        if: needs.detect-changes.outputs.run == 'true'
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
-          repository: Molecule-AI/molecule-ai-plugin-github-app-auth
+          repository: molecule-ai/molecule-ai-plugin-github-app-auth
          path: molecule-ai-plugin-github-app-auth
          token: ${{ secrets.PLUGIN_REPO_PAT || secrets.GITHUB_TOKEN }}

@@ -19,4 +19,4 @@ permissions:

 jobs:
  disable-auto-merge-on-push:
-    uses: Molecule-AI/molecule-ci/.github/workflows/disable-auto-merge-on-push.yml@main
+    uses: molecule-ai/molecule-ci/.github/workflows/disable-auto-merge-on-push.yml@main
@@ -25,7 +25,7 @@ name: publish-runtime
 #   3. Publishes to PyPI via the PyPA Trusted Publisher action (OIDC).
 #      No static API token is stored — PyPI verifies the workflow's
 #      OIDC claim against the trusted-publisher config registered for
-#      molecule-ai-workspace-runtime (Molecule-AI/molecule-core,
+#      molecule-ai-workspace-runtime (molecule-ai/molecule-core,
 #      publish-runtime.yml, environment pypi-publish).
 #
 # After publish: the 8 template repos pick up the new version on their
@@ -166,7 +166,7 @@ jobs:

      - name: Publish to PyPI (Trusted Publisher / OIDC)
        # PyPI side is configured: project molecule-ai-workspace-runtime →
-        # publisher Molecule-AI/molecule-core, workflow publish-runtime.yml,
+        # publisher molecule-ai/molecule-core, workflow publish-runtime.yml,
        # environment pypi-publish. The action mints a short-lived OIDC
        # token and exchanges it for a PyPI upload credential — no static
        # API token in this repo's secrets.
@@ -342,7 +342,7 @@ jobs:
          TEMPLATES="claude-code hermes openclaw codex langgraph crewai autogen deepagents gemini-cli"
          FAILED=""
          for tpl in $TEMPLATES; do
-            REPO="Molecule-AI/molecule-ai-workspace-template-$tpl"
+            REPO="molecule-ai/molecule-ai-workspace-template-$tpl"
            STATUS=$(curl -sS -o /tmp/dispatch.out -w "%{http_code}" \
              -X POST "https://api.github.com/repos/$REPO/dispatches" \
              -H "Authorization: Bearer $DISPATCH_TOKEN" \
@@ -80,12 +80,12 @@ jobs:
        #
        # Uses a fine-grained PAT (PLUGIN_REPO_PAT) because the plugin repo
        # is private and the default GITHUB_TOKEN is scoped to THIS repo.
-        # The PAT needs Contents:Read on Molecule-AI/molecule-ai-plugin-
+        # The PAT needs Contents:Read on molecule-ai/molecule-ai-plugin-
        # github-app-auth. Falls back to the default token for the (rare)
        # case where an operator made the plugin repo public.
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
-          repository: Molecule-AI/molecule-ai-plugin-github-app-auth
+          repository: molecule-ai/molecule-ai-plugin-github-app-auth
          path: molecule-ai-plugin-github-app-auth
          token: ${{ secrets.PLUGIN_REPO_PAT || secrets.GITHUB_TOKEN }}

@@ -9,7 +9,7 @@ name: redeploy-tenants-on-main
 #
 # This workflow closes the gap by calling the control-plane admin
 # endpoint that performs a canary-first, batched, health-gated rolling
-# redeploy across every live tenant. Implemented in Molecule-AI/
+# redeploy across every live tenant. Implemented in molecule-ai/
 # molecule-controlplane as POST /cp/admin/tenants/redeploy-fleet
 # (feat/tenant-auto-redeploy, landing alongside this workflow).
 #
@@ -146,7 +146,7 @@ jobs:

      - name: Call CP redeploy-fleet
        # CP_ADMIN_API_TOKEN must be set as a repo/org secret on
-        # Molecule-AI/molecule-core, matching the staging/prod CP's
+        # molecule-ai/molecule-core, matching the staging/prod CP's
        # CP_ADMIN_API_TOKEN env. Stored in Railway, mirrored to this
        # repo's secrets for CI.
        env:
@@ -97,7 +97,7 @@ jobs:

      - name: Call staging-CP redeploy-fleet
        # CP_STAGING_ADMIN_API_TOKEN must be set as a repo/org secret
-        # on Molecule-AI/molecule-core, matching staging-CP's
+        # on molecule-ai/molecule-core, matching staging-CP's
        # CP_ADMIN_API_TOKEN env var (visible in Railway controlplane
        # / staging environment). Stored separately from the prod
        # CP_ADMIN_API_TOKEN so a leak of one doesn't auth the other.
@@ -96,7 +96,7 @@ jobs:
            --body "$(cat <<'BODY'
          [retarget-bot] This PR was opened against `main` and has been retargeted to `staging` automatically.

-          **Why:** per [SHARED_RULES rule 8](https://github.com/Molecule-AI/molecule-ai-org-template-molecule-dev/blob/main/SHARED_RULES.md), all feature work targets `staging` first; the CEO promotes `staging → main` separately.
+          **Why:** per [SHARED_RULES rule 8](https://github.com/molecule-ai/molecule-ai-org-template-molecule-dev/blob/main/SHARED_RULES.md), all feature work targets `staging` first; the CEO promotes `staging → main` separately.

          **What changed:** just the base branch — no code change. CI will re-run against `staging`. If you get merge conflicts, rebase on `staging`.

@@ -12,7 +12,7 @@ name: Secret scan
 #
 #   jobs:
 #     secret-scan:
-#       uses: Molecule-AI/molecule-core/.github/workflows/secret-scan.yml@staging
+#       uses: molecule-ai/molecule-core/.github/workflows/secret-scan.yml@staging
 #
 # Pin to @staging not @main — staging is the active default branch,
 # main lags via the staging-promotion workflow. Updates ride along
@@ -108,6 +108,14 @@ jobs:
          python3 > stale_slugs.txt <<'PY'
          import json, os
          from datetime import datetime, timezone, timedelta
+          # SSOT for this list lives in the controlplane Go code:
+          # molecule-controlplane/internal/slugs/ephemeral.go
+          # (var EphemeralPrefixes). The redeploy-fleet auto-rollout
+          # also reads from there to SKIP these slugs — without that
+          # filter, fleet redeploy SSM-failed in-flight E2E tenants
+          # whose containers were still booting, breaking the test
+          # that just spun them up (molecule-controlplane#493).
+          # Update both files together.
          EPHEMERAL_PREFIXES = ("e2e-", "rt-e2e-")
          with open("orgs.json") as f:
              data = json.load(f)
@@ -185,7 +193,47 @@ jobs:
          # sweeper is best-effort. Next hourly tick re-attempts. We
          # only fail loud at the safety-cap gate above.

+      - name: Sweep orphan tunnels
+        # Stale-org cleanup deletes the org (which cascades to tunnel
+        # delete inside the CP). But when that cascade fails partway —
+        # CP transient 5xx after the org row is deleted but before the
+        # CF tunnel delete completes — the tunnel persists with no
+        # matching org row. The reconciler in internal/sweep flags this
+        # as `cf_tunnel kind=orphan`, but nothing automatically reaps it.
+        #
+        # `/cp/admin/orphan-tunnels/cleanup` is the operator-triggered
+        # reaper. Calling it here at the end of every sweep tick
+        # converges the staging CF account to clean even when CP
+        # cascades half-fail.
+        #
+        # PR #492 made the underlying DeleteTunnel actually check
+        # status — pre-fix it silent-succeeded on CF code 1022
+        # ("active connections"), so this step would have been a no-op
+        # against stuck connectors. Post-fix the cleanup invokes
+        # CleanupTunnelConnections + retry, which actually clears the
+        # 1022 case. (#2987)
+        #
+        # Best-effort. Failure here doesn't fail the workflow — next
+        # tick re-attempts. Errors flow to step output for ops review.
+        if: env.DRY_RUN != 'true'
+        run: |
+          set +e
+          curl -sS -o /tmp/cleanup_resp -w "%{http_code}" \
+            --max-time 60 \
+            -X POST "$MOLECULE_CP_URL/cp/admin/orphan-tunnels/cleanup" \
+            -H "Authorization: Bearer $ADMIN_TOKEN" >/tmp/cleanup_code
+          set -e
+          http_code=$(cat /tmp/cleanup_code 2>/dev/null || echo "000")
+          body=$(cat /tmp/cleanup_resp 2>/dev/null | head -c 500)
+          if [ "$http_code" = "200" ]; then
+            count=$(echo "$body" | python3 -c "import sys,json; d=json.loads(sys.stdin.read() or '{}'); print(d.get('deleted_count', 0))" 2>/dev/null || echo "0")
+            failed_n=$(echo "$body" | python3 -c "import sys,json; d=json.loads(sys.stdin.read() or '{}'); print(len(d.get('failed') or {}))" 2>/dev/null || echo "0")
+            echo "Orphan-tunnel sweep: deleted=$count failed=$failed_n"
+          else
+            echo "::warning::orphan-tunnels cleanup returned HTTP $http_code — body: $body"
+          fi
+
      - name: Dry-run summary
        if: env.DRY_RUN == 'true'
        run: |
-          echo "DRY RUN — would have deleted ${{ steps.identify.outputs.count }} org(s). Re-run with dry_run=false to actually delete."
+          echo "DRY RUN — would have deleted ${{ steps.identify.outputs.count }} org(s) AND triggered orphan-tunnels cleanup. Re-run with dry_run=false to actually delete."
@@ -325,7 +325,6 @@ export function MemoryInspectorPanel({ workspaceId }: Props) {
            {dropdownOptions.map((opt) => (
              <option key={opt.value} value={opt.value}>
                {opt.label}
-                {opt.kind ? `  (${opt.kind})` : ''}
              </option>
            ))}
          </select>
@@ -287,7 +287,7 @@ export function SidePanel() {
        {panelTab === "config" && <ConfigTab key={selectedNodeId} workspaceId={selectedNodeId} />}
        {panelTab === "schedule" && <ScheduleTab key={selectedNodeId} workspaceId={selectedNodeId} />}
        {panelTab === "channels" && <ChannelsTab key={selectedNodeId} workspaceId={selectedNodeId} />}
-        {panelTab === "files" && <FilesTab key={selectedNodeId} workspaceId={selectedNodeId} />}
+        {panelTab === "files" && <FilesTab key={selectedNodeId} workspaceId={selectedNodeId} data={node.data} />}
        {panelTab === "memory" && <MemoryInspectorPanel key={selectedNodeId} workspaceId={selectedNodeId} />}
        {panelTab === "traces" && <TracesTab key={selectedNodeId} workspaceId={selectedNodeId} />}
        {panelTab === "events" && <EventsTab key={selectedNodeId} workspaceId={selectedNodeId} />}
@@ -8,7 +8,8 @@ import { useCanvasStore, type WorkspaceNodeData } from "@/store/canvas";
 import { useSocketEvent } from "@/hooks/useSocketEvent";
 import { type ChatMessage, type ChatAttachment, createMessage, appendMessageDeduped } from "./chat/types";
 import { uploadChatFiles, downloadChatFile, isPlatformAttachment } from "./chat/uploads";
-import { AttachmentChip, PendingAttachmentPill } from "./chat/AttachmentViews";
+import { PendingAttachmentPill } from "./chat/AttachmentViews";
+import { AttachmentPreview } from "./chat/AttachmentPreview";
 import { extractFilesFromTask } from "./chat/message-parser";
 import { AgentCommsPanel } from "./chat/AgentCommsPanel";
 import { appendActivityLine } from "./chat/activityLog";
@@ -1137,8 +1138,9 @@ function MyChatPanel({ workspaceId, data }: Props) {
              {msg.attachments && msg.attachments.length > 0 && (
                <div className={`flex flex-wrap gap-1 ${msg.content ? "mt-1.5" : ""}`}>
                  {msg.attachments.map((att, i) => (
-                    <AttachmentChip
+                    <AttachmentPreview
                      key={`${msg.id}-${i}`}
+                      workspaceId={workspaceId}
                      attachment={att}
                      onDownload={downloadAttachment}
                      tone={msg.role === "user" ? "user" : "agent"}
@@ -262,6 +262,27 @@ export function ConfigTab({ workspaceId }: Props) {
      setOriginalProvider("");
    }

+    // Skip the config.yaml fetch entirely for runtimes that manage
+    // their own config (external, hermes, etc.) — they don't have a
+    // platform-side template, so the GET would 404. The catch block
+    // below handles 404 gracefully, but issuing the request adds
+    // browser-console noise + a wasted RTT on every open of the
+    // Config tab for the affected workspaces. Reported on
+    // production reno-stars 2026-05-05 (workspace runtime=external,
+    // 404 on /files/config.yaml visible in the console even though
+    // the form rendered correctly).
+    if (RUNTIMES_WITH_OWN_CONFIG.has(wsMetadataRuntime)) {
+      setConfig({
+        ...DEFAULT_CONFIG,
+        runtime: wsMetadataRuntime,
+        model: wsMetadataModel,
+        ...(wsMetadataModel ? { runtime_config: { model: wsMetadataModel } } : {}),
+        ...(wsMetadataTier !== null ? { tier: wsMetadataTier } : {}),
+      } as ConfigData);
+      setOriginalModel(wsMetadataModel);
+      setLoading(false);
+      return;
+    }
    try {
      const res = await api.get<{ content: string }>(`/workspaces/${workspaceId}/files/config.yaml`);
      const parsed = parseYaml(res.content);
@@ -2,9 +2,11 @@

 import { useState, useEffect, useRef, useMemo } from "react";
 import { showToast } from "../Toaster";
+import type { WorkspaceNodeData } from "@/store/canvas";
 import { FilesToolbar } from "./FilesTab/FilesToolbar";
 import { FileTree } from "./FilesTab/FileTree";
 import { FileEditor } from "./FilesTab/FileEditor";
+import { NotAvailablePanel } from "./FilesTab/NotAvailablePanel";
 import { useFilesApi } from "./FilesTab/useFilesApi";
 import { buildTree } from "./FilesTab/tree";

@@ -14,9 +16,40 @@ export type { TreeNode } from "./FilesTab/tree";

 interface Props {
  workspaceId: string;
+  /** Workspace metadata from the canvas store. Optional for back-compat
+   *  with any caller that still mounts <FilesTab workspaceId=.../> without
+   *  threading data through (legacy tests). When present, runtime gates
+   *  the early-return below. Mirrors TerminalTab's prop shape (#2830). */
+  data?: WorkspaceNodeData;
 }

-export function FilesTab({ workspaceId }: Props) {
+/** Runtimes whose filesystem the platform doesn't own. The canvas can't
+ *  list/read/write files on these — the agent runs on the user's own
+ *  hardware (mac laptop, mac mini, hermes-on-home-server) and reaches
+ *  the platform via the heartbeat-based polling Phase 30 layer.
+ *
+ *  Keep narrow — only add a runtime here when its provisioner genuinely
+ *  has no platform-owned filesystem. Otherwise the user loses access to
+ *  a real surface (e.g. claude-code SaaS workspaces have files served
+ *  by ListFiles via EIC; they belong on the rendering path, not here). */
+const RUNTIMES_WITHOUT_FILES = new Set(["external"]);
+
+export function FilesTab({ workspaceId, data }: Props) {
+  // Early-return for runtimes whose filesystem is not platform-owned.
+  // Skips the whole useFilesApi hook + tree render below — without this,
+  // mounting the tab for an external workspace would issue a GET that
+  // the platform can technically answer (it reads its own DB row, not
+  // the user's machine), but every result row is fictional. Showing
+  // "0 files / No config files yet" reads as a bug. The placeholder
+  // makes the absence intentional and points the user at the right
+  // surface (Chat).
+  if (data && RUNTIMES_WITHOUT_FILES.has(data.runtime)) {
+    return <NotAvailablePanel runtime={data.runtime} />;
+  }
+  return <PlatformOwnedFilesTab workspaceId={workspaceId} />;
+}
+
+function PlatformOwnedFilesTab({ workspaceId }: { workspaceId: string }) {
  const [root, setRoot] = useState("/configs");
  const [selectedFile, setSelectedFile] = useState<string | null>(null);
  const [fileContent, setFileContent] = useState("");
@@ -45,11 +78,36 @@ export function FilesTab({ workspaceId }: Props) {
    readFile,
    writeFile,
    deleteFile,
+    downloadFileByPath,
    downloadAllFiles,
    uploadFiles,
+    uploadDataTransferItems,
    deleteAllFiles,
  } = useFilesApi(workspaceId, root);

+  // PR-D: track whether the user is currently dragging files OVER
+  // the root area (not over a specific subdir row). Used to show
+  // the "Drop to upload to root" highlight on the tree column.
+  const [rootDragHover, setRootDragHover] = useState(false);
+
+  const handleDropToTarget = (
+    targetDir: string,
+    items: DataTransferItemList,
+  ) => {
+    // canDelete is the gate proxy — same constraint as the toolbar
+    // Upload button (today only /configs is writable from the canvas
+    // surface). Without this check, dropping on /home would post
+    // through /workspaces/<id>/files/<path>, which the backend would
+    // reject only after an HTTP round-trip. Fail fast.
+    if (root !== "/configs") {
+      setError(
+        `Upload only allowed in /configs (current root: ${root}). Switch root or use Upload button.`,
+      );
+      return;
+    }
+    void uploadDataTransferItems(items, targetDir);
+  };
+
  const tree = useMemo(() => buildTree(files), [files]);

  const openFile = async (path: string) => {
@@ -190,8 +248,46 @@ export function FilesTab({ workspaceId }: Props) {
      )}

      <div className="flex flex-1 min-h-0">
-        {/* File tree */}
-        <div className="w-[180px] border-r border-line/40 overflow-y-auto shrink-0">
+        {/* File tree column. PR-D: outer div is the drop zone for
+            "drop on root" — when the user drags into the column area
+            (not over a specific subdir row), the drop targets the
+            current root directory. Subdirectory rows in <FileTree>
+            stop propagation on their own drop event so a drop on
+            /configs/skills doesn't ALSO fire root-area drop. */}
+        <div
+          className={`w-[180px] border-r border-line/40 overflow-y-auto shrink-0 transition-colors ${
+            rootDragHover ? "bg-accent/10 outline outline-1 outline-accent/40 -outline-offset-2" : ""
+          }`}
+          onDragOver={(e) => {
+            // Only highlight + accept the drop when uploads are
+            // actually allowed for the current root. Without this
+            // check the user gets a misleading drag affordance,
+            // drops, then sees the toolbar's "switch root" toast —
+            // bad UX.
+            if (root !== "/configs") return;
+            e.preventDefault();
+            e.dataTransfer.dropEffect = "copy";
+          }}
+          onDragEnter={(e) => {
+            if (root !== "/configs") return;
+            e.preventDefault();
+            setRootDragHover(true);
+          }}
+          onDragLeave={(e) => {
+            const next = e.relatedTarget as Node | null;
+            if (!next || !(e.currentTarget as HTMLElement).contains(next)) {
+              setRootDragHover(false);
+            }
+          }}
+          onDrop={(e) => {
+            if (root !== "/configs") return;
+            e.preventDefault();
+            setRootDragHover(false);
+            if (e.dataTransfer.items?.length) {
+              handleDropToTarget("", e.dataTransfer.items);
+            }
+          }}
+        >
          {/* New file input */}
          {showNewFile && (
            <div className="px-2 py-1 border-b border-line/40">
@@ -209,14 +305,27 @@ export function FilesTab({ workspaceId }: Props) {

          {files.length === 0 ? (
            <div className="px-3 py-4 text-[10px] text-ink-soft text-center">
-              No config files yet
+              {rootDragHover
+                ? "Drop to upload to root"
+                : root === "/configs"
+                  ? "No config files yet — drag files here to upload"
+                  : "No config files yet"}
            </div>
          ) : (
            <FileTree
              nodes={tree}
              selectedPath={selectedFile}
              onSelect={openFile}
+              // Delete is currently gated to /configs to match the
+              // toolbar's New / Upload / Clear affordances. Context
+              // menu and inline ✕ both honour the gate. PR-A made the
+              // backend EIC delete work on all roots — keeping the
+              // canvas gate conservative until we want to expose
+              // /home /workspace deletion intentionally.
              onDelete={root === "/configs" ? setConfirmDelete : () => {}}
+              onDownload={downloadFileByPath}
+              canDelete={root === "/configs"}
+              onDropToTarget={handleDropToTarget}
              expandedDirs={expandedDirs}
              onToggleDir={toggleDir}
              loadingDir={loadingDir}
@@ -1,41 +1,129 @@
 "use client";

+import { useState } from "react";
 import { type TreeNode, getIcon } from "./tree";
+import { FileTreeContextMenu, type MenuItem } from "./FileTreeContextMenu";

 interface TreeCallbacks {
  selectedPath: string | null;
  onSelect: (path: string) => void;
  onDelete: (path: string) => void;
+  /** PR-C: right-click → Download. Files only — directories ignore. */
+  onDownload: (path: string) => void;
+  /** Whether the active root permits delete. Wire into the Delete
+   *  context-menu item's `disabled` flag so the user gets the same
+   *  affordance as the toolbar (which gates Clear/New on /configs). */
+  canDelete: boolean;
+  /** PR-D: drop files/folders from the OS onto this row. targetDir
+   *  is the directory path (relative to the active root) under which
+   *  the dropped contents should land; "" means root. */
+  onDropToTarget?: (targetDir: string, items: DataTransferItemList) => void;
  expandedDirs: Set<string>;
  onToggleDir: (path: string) => void;
  loadingDir: string | null;
 }

+/**
+ * FileTree renders the workspace tree + owns the right-click context
+ * menu (PR-C) and the drop-target hover state (PR-D). Lifting the
+ * menu state here (vs each row) means only one menu open at a time —
+ * opening a new row's menu auto-closes the prior one. Same UX as
+ * VSCode / Theia.
+ */
 export function FileTree({
  nodes,
  selectedPath,
  onSelect,
  onDelete,
+  onDownload,
+  canDelete,
+  onDropToTarget,
  expandedDirs,
  onToggleDir,
  loadingDir,
  depth = 0,
 }: TreeCallbacks & { nodes: TreeNode[]; depth?: number }) {
+  const [menu, setMenu] = useState<{
+    x: number;
+    y: number;
+    items: MenuItem[];
+  } | null>(null);
+  // PR-D: hover-target highlight state for drag-drop. Lifted next to
+  // the menu state so both shared-across-rows interactions live in
+  // one place.
+  const [hoverDir, setHoverDir] = useState<string | null>(null);
+
+  const openContextMenu = (e: React.MouseEvent, node: TreeNode) => {
+    e.preventDefault();
+    // Items composed per-row so the available actions reflect the
+    // node type (files get Open + Download; directories get Delete
+    // only since "open a directory in the editor" doesn't apply
+    // and "Export folder" is the toolbar's job).
+    const items: MenuItem[] = [];
+    if (!node.isDir) {
+      items.push({
+        id: "open",
+        label: "Open",
+        icon: "⤴",
+        onClick: () => onSelect(node.path),
+      });
+      items.push({
+        id: "download",
+        label: "Download",
+        icon: "↓",
+        onClick: () => onDownload(node.path),
+      });
+    }
+    items.push({
+      id: "delete",
+      label: "Delete",
+      icon: "✕",
+      destructive: true,
+      disabled: !canDelete,
+      onClick: () => onDelete(node.path),
+    });
+    setMenu({ x: e.clientX, y: e.clientY, items });
+  };
+
+  // Single state lifted to the top-level tree; nested <FileTree>s
+  // (rendered for expanded directories below) do NOT instantiate
+  // their own menus or drop-targets — they call back via prop
+  // drilling. This keeps "only one menu open" + "only one drop
+  // target highlighted" as structural invariants rather than
+  // render-order coincidences.
+  const childCallbacks: TreeCallbacks = {
+    selectedPath,
+    onSelect,
+    onDelete,
+    onDownload,
+    canDelete,
+    onDropToTarget,
+    expandedDirs,
+    onToggleDir,
+    loadingDir,
+  };
+
  return (
    <div>
      {nodes.map((node) => (
        <TreeItem
          key={`${node.path}:${node.isDir ? "dir" : "file"}`}
          node={node}
-          selectedPath={selectedPath}
-          onSelect={onSelect}
-          onDelete={onDelete}
-          expandedDirs={expandedDirs}
-          onToggleDir={onToggleDir}
-          loadingDir={loadingDir}
+          openContextMenu={openContextMenu}
+          hoverDir={hoverDir}
+          setHoverDir={setHoverDir}
          depth={depth}
+          {...childCallbacks}
        />
      ))}
+      {menu && (
+        <FileTreeContextMenu
+          x={menu.x}
+          y={menu.y}
+          items={menu.items}
+          onClose={() => setMenu(null)}
+        />
+      )}
    </div>
  );
 }
@@ -45,22 +133,81 @@ function TreeItem({
  selectedPath,
  onSelect,
  onDelete,
+  onDownload,
+  canDelete,
+  onDropToTarget,
  expandedDirs,
  onToggleDir,
  loadingDir,
  depth,
-}: TreeCallbacks & { node: TreeNode; depth: number }) {
+  openContextMenu,
+  hoverDir,
+  setHoverDir,
+}: TreeCallbacks & {
+  node: TreeNode;
+  depth: number;
+  openContextMenu: (e: React.MouseEvent, node: TreeNode) => void;
+  hoverDir: string | null;
+  setHoverDir: (p: string | null) => void;
+}) {
  const isSelected = selectedPath === node.path;
  const expanded = expandedDirs.has(node.path);
  const isLoading = loadingDir === node.path;
+  const isDropTarget = node.isDir && hoverDir === node.path;
+
+  // PR-D drag handlers — only directory rows are valid drop targets
+  // (dropping a file ON another file is ambiguous; treat it as
+  // dropping in the parent dir, which the root area handles). When a
+  // drag enters a directory row, mark it the hover target. When the
+  // cursor leaves to a non-child element, clear it. drop fires the
+  // upload callback with the row's path.
+  const dragProps = node.isDir && onDropToTarget
+    ? {
+        onDragOver: (e: React.DragEvent) => {
+          // preventDefault is REQUIRED to opt this element into the
+          // drop target list — without it, browsers refuse to fire
+          // the drop event regardless of the drop handler.
+          e.preventDefault();
+          e.dataTransfer.dropEffect = "copy";
+        },
+        onDragEnter: (e: React.DragEvent) => {
+          e.preventDefault();
+          setHoverDir(node.path);
+        },
+        onDragLeave: (e: React.DragEvent) => {
+          // Only clear hover when leaving to an element OUTSIDE this
+          // row — bare leave-events fire for every child crossed
+          // (the icon, the label, the ✕ button). Without the
+          // contains() check the highlight flickers.
+          const next = e.relatedTarget as Node | null;
+          if (!next || !(e.currentTarget as HTMLElement).contains(next)) {
+            setHoverDir(null);
+          }
+        },
+        onDrop: (e: React.DragEvent) => {
+          e.preventDefault();
+          e.stopPropagation();
+          setHoverDir(null);
+          if (e.dataTransfer.items?.length) {
+            onDropToTarget(node.path, e.dataTransfer.items);
+          }
+        },
+      }
+    : {};

  if (node.isDir) {
    return (
      <div>
        <div
-          className="group w-full flex items-center gap-1 px-2 py-0.5 text-left hover:bg-surface-card/40 transition-colors cursor-pointer"
+          className={`group w-full flex items-center gap-1 px-2 py-0.5 text-left transition-colors cursor-pointer ${
+            isDropTarget
+              ? "bg-accent/20 outline outline-1 outline-accent/60"
+              : "hover:bg-surface-card/40"
+          }`}
          style={{ paddingLeft: `${depth * 12 + 8}px` }}
          onClick={() => onToggleDir(node.path)}
+          onContextMenu={(e) => openContextMenu(e, node)}
+          {...dragProps}
        >
          <span className="text-[9px] text-ink-soft w-3">{isLoading ? "…" : expanded ? "▼" : "▶"}</span>
          <span className="text-[10px]">📁</span>
@@ -82,6 +229,9 @@ function TreeItem({
            selectedPath={selectedPath}
            onSelect={onSelect}
            onDelete={onDelete}
+            onDownload={onDownload}
+            canDelete={canDelete}
+            onDropToTarget={onDropToTarget}
            expandedDirs={expandedDirs}
            onToggleDir={onToggleDir}
            loadingDir={loadingDir}
@@ -99,6 +249,7 @@ function TreeItem({
      }`}
      style={{ paddingLeft: `${depth * 12 + 20}px` }}
      onClick={() => onSelect(node.path)}
+      onContextMenu={(e) => openContextMenu(e, node)}
    >
      <span className="text-[9px]">{getIcon(node.name, false)}</span>
      <span className="text-[10px] flex-1 truncate font-mono">{node.name}</span>
@@ -0,0 +1,141 @@
+"use client";
+
+import { useEffect, useRef } from "react";
+
+/**
+ * FileTreeContextMenu — VSCode-style right-click menu for a single
+ * file-tree row. Pops at the cursor's viewport coords; dismisses on
+ * outside-click, Esc, blur, or scroll.
+ *
+ * Why a custom component (no library): the menu is one of several
+ * "small popovers" in canvas; pulling in a dnd / popover lib for one
+ * surface adds 10x the bytes of this implementation. The patterns
+ * (outside-click + Esc + portal-free fixed position) match the
+ * ContextMenu used in canvas/Toolbar so the keyboard-nav muscle
+ * memory is uniform.
+ *
+ * Items are rendered from a `MenuItem[]` so callers can add/remove
+ * actions without touching this component (e.g. PR-D will add an
+ * "Upload to this folder" item for directory rows).
+ *
+ * Accessibility:
+ * - role="menu" + role="menuitem" so screen readers announce the
+ *   surface as a menu, not a generic div.
+ * - First item gets autofocus so keyboard users can ↓/↑/Enter without
+ *   reaching for the mouse.
+ * - Esc + outside-click + Tab dismisses; behaves like every other
+ *   menu the user has touched on the canvas.
+ */
+export interface MenuItem {
+  /** Stable identifier for testing + analytics. */
+  id: string;
+  label: string;
+  /** Optional left icon glyph; not load-bearing. */
+  icon?: string;
+  /** Destructive (rendered in red) — for Delete-class actions. */
+  destructive?: boolean;
+  /** Item-specific click handler. The menu auto-closes after onClick
+   *  fires so handlers don't have to call onClose themselves. */
+  onClick: () => void;
+  /** Disabled items render but don't fire onClick (useful for
+   *  Delete-on-non-/configs case where the caller wants to surface
+   *  the item but explain it's gated). Currently unused — placeholder
+   *  for future options. */
+  disabled?: boolean;
+}
+
+interface Props {
+  /** Viewport-coordinate position of the cursor that opened the menu. */
+  x: number;
+  y: number;
+  items: MenuItem[];
+  onClose: () => void;
+}
+
+export function FileTreeContextMenu({ x, y, items, onClose }: Props) {
+  const ref = useRef<HTMLDivElement>(null);
+  // First item gets initial focus for keyboard ↓/↑/Enter nav.
+  const firstItemRef = useRef<HTMLButtonElement>(null);
+
+  useEffect(() => {
+    firstItemRef.current?.focus();
+  }, []);
+
+  // Outside-click + Esc dismiss. Per memory
+  // (feedback_abort_controller_for_rerendered_listeners), use an
+  // AbortController so re-mounts (caller toggles the menu) don't leak
+  // listeners.
+  useEffect(() => {
+    const ctrl = new AbortController();
+    const onPointerDown = (e: MouseEvent) => {
+      if (ref.current && !ref.current.contains(e.target as Node)) onClose();
+    };
+    const onKeyDown = (e: KeyboardEvent) => {
+      if (e.key === "Escape") {
+        e.preventDefault();
+        onClose();
+      } else if (e.key === "ArrowDown" || e.key === "ArrowUp") {
+        // Roving focus across .menuitem buttons. Doing this with
+        // tabindex management because Tab / Shift+Tab leave the menu
+        // (which is the right thing — the user is escaping the menu).
+        e.preventDefault();
+        const buttons = ref.current?.querySelectorAll<HTMLButtonElement>(
+          "[role='menuitem']:not([disabled])",
+        );
+        if (!buttons || buttons.length === 0) return;
+        const arr = Array.from(buttons);
+        const cur = arr.indexOf(document.activeElement as HTMLButtonElement);
+        const next =
+          e.key === "ArrowDown"
+            ? (cur + 1) % arr.length
+            : (cur - 1 + arr.length) % arr.length;
+        arr[next].focus();
+      }
+    };
+    // `mousedown` (not `click`) so the menu dismisses BEFORE the
+    // tree-row's click handler would fire — otherwise clicking
+    // outside also selects a different row, which is not what the
+    // user expected when "outside-click closes the menu".
+    document.addEventListener("mousedown", onPointerDown, { signal: ctrl.signal });
+    document.addEventListener("keydown", onKeyDown, { signal: ctrl.signal });
+    // Scroll inside any ancestor also dismisses — the fixed-position
+    // menu would otherwise stay anchored to viewport coords while the
+    // row it points at scrolled away. Use capture so we catch scroll
+    // on inner panels (FileTree's overflow-y-auto wrapper).
+    document.addEventListener("scroll", onClose, { signal: ctrl.signal, capture: true });
+    return () => ctrl.abort();
+  }, [onClose]);
+
+  return (
+    <div
+      ref={ref}
+      role="menu"
+      aria-label="File actions"
+      className="fixed z-[1000] min-w-[140px] py-1 bg-surface-elevated border border-line/60 rounded-md shadow-xl shadow-black/30 text-[11px]"
+      style={{ left: x, top: y }}
+    >
+      {items.map((item, i) => (
+        <button
+          key={item.id}
+          ref={i === 0 ? firstItemRef : undefined}
+          type="button"
+          role="menuitem"
+          disabled={item.disabled}
+          onClick={() => {
+            if (item.disabled) return;
+            item.onClick();
+            onClose();
+          }}
+          className={
+            item.destructive
+              ? "w-full text-left px-3 py-1 text-bad hover:bg-red-900/30 focus:bg-red-900/30 focus:outline-none disabled:opacity-40 disabled:pointer-events-none transition-colors"
+              : "w-full text-left px-3 py-1 text-ink-mid hover:bg-surface-card hover:text-ink focus:bg-surface-card focus:text-ink focus:outline-none disabled:opacity-40 disabled:pointer-events-none transition-colors"
+          }
+        >
+          {item.icon && <span className="inline-block w-4 mr-1.5 text-ink-soft">{item.icon}</span>}
+          {item.label}
+        </button>
+      ))}
+    </div>
+  );
+}
@@ -0,0 +1,58 @@
+"use client";
+
+/**
+ * NotAvailablePanel — full-tab placeholder for runtimes whose filesystem
+ * the platform doesn't own (today: runtime === "external").
+ *
+ * Pre-fix the FilesTab tried to GET /workspaces/<id>/files for these
+ * workspaces. The platform answered with [] (no rows in workspace_files
+ * for an external workspace by definition), but the canvas rendered
+ * "0 files / No config files yet" which reads identically to the SaaS
+ * empty-listing bug fixed in PR-A. Showing an explicit placeholder
+ * makes the absence intentional and routes the user toward the
+ * supported surface (Chat) for these workspaces.
+ *
+ * Mirrors the same affordance TerminalTab adopted for runtimes without
+ * a TTY in PR #2830 — uniform "feature-not-applicable" UX across tabs.
+ */
+export function NotAvailablePanel({ runtime }: { runtime: string }) {
+  return (
+    <div className="flex flex-col items-center justify-center h-full p-8 text-center bg-surface-sunken/30">
+      {/* Folder-with-slash icon. Custom inline SVG so we don't depend
+          on an icon set being present at canvas build-time (matches
+          TerminalTab's NotAvailablePanel pattern). */}
+      <svg
+        width="72"
+        height="72"
+        viewBox="0 0 72 72"
+        fill="none"
+        aria-hidden="true"
+        className="text-ink-soft mb-4"
+      >
+        {/* Folder body */}
+        <path
+          d="M10 22 L10 56 a4 4 0 0 0 4 4 L58 60 a4 4 0 0 0 4 -4 L62 26 a4 4 0 0 0 -4 -4 L34 22 L28 16 L14 16 a4 4 0 0 0 -4 4 Z"
+          stroke="currentColor"
+          strokeWidth="2.5"
+          strokeLinejoin="round"
+          fill="none"
+          opacity="0.6"
+        />
+        {/* Diagonal cancel slash */}
+        <path
+          d="M14 14 L58 58"
+          stroke="currentColor"
+          strokeWidth="3"
+          strokeLinecap="round"
+        />
+      </svg>
+      <h3 className="text-sm font-medium text-ink mb-1.5">Files not available</h3>
+      <p className="text-[11px] text-ink-soft max-w-xs leading-relaxed">
+        This workspace runs the{" "}
+        <span className="font-mono text-ink-mid">{runtime}</span> runtime,
+        whose filesystem isn't owned by the platform. Use the Chat tab to
+        interact with the agent directly.
+      </p>
+    </div>
+  );
+}
@@ -0,0 +1,136 @@
+// @vitest-environment jsdom
+//
+// Pins the right-click context menu added in PR-C of issue #2999.
+// VSCode-style affordance: Open / Download / Delete on file rows,
+// Delete on directory rows. Delete is gated by `canDelete` (parent
+// only enables on /configs root, matching the toolbar's gate).
+//
+// Pinned branches:
+//   1. Right-click on a file row opens the menu at the click coords
+//      with Open + Download + Delete items.
+//   2. Right-click on a directory row opens the menu with Delete
+//      only (no Open/Download — directories don't have one-click
+//      semantics in this surface).
+//   3. Clicking Download fires the onDownload callback with the
+//      row's path.
+//   4. Clicking Delete fires onDelete with the row's path (when
+//      canDelete=true).
+//   5. Delete is disabled in the rendered menu when canDelete=false
+//      and clicking it does NOT fire onDelete (gate is real).
+//   6. Esc dismisses the menu.
+//   7. Click outside the menu dismisses it.
+
+import { describe, it, expect, vi, afterEach } from "vitest";
+import { render, screen, cleanup, fireEvent, act } from "@testing-library/react";
+import React from "react";
+import { FileTree } from "../FileTree";
+import type { TreeNode } from "../tree";
+
+afterEach(cleanup);
+
+const file: TreeNode = { name: "config.yaml", path: "config.yaml", isDir: false, children: [], size: 0 };
+const dir: TreeNode = {
+  name: "skills",
+  path: "skills",
+  isDir: true,
+  children: [],
+  size: 0,
+};
+
+function renderTree(props: Partial<React.ComponentProps<typeof FileTree>> = {}) {
+  const defaults = {
+    nodes: [file, dir],
+    selectedPath: null,
+    onSelect: vi.fn(),
+    onDelete: vi.fn(),
+    onDownload: vi.fn(),
+    canDelete: true,
+    expandedDirs: new Set<string>(),
+    onToggleDir: vi.fn(),
+    loadingDir: null,
+  };
+  const merged = { ...defaults, ...props };
+  return { ...render(<FileTree {...merged} />), props: merged };
+}
+
+describe("FileTree right-click context menu", () => {
+  it("right-click on a file row opens menu with Open/Download/Delete", () => {
+    renderTree();
+    fireEvent.contextMenu(screen.getByText("config.yaml"), {
+      clientX: 50,
+      clientY: 100,
+    });
+    expect(screen.getByRole("menu")).not.toBeNull();
+    expect(screen.getByRole("menuitem", { name: /Open/i })).not.toBeNull();
+    expect(screen.getByRole("menuitem", { name: /Download/i })).not.toBeNull();
+    expect(screen.getByRole("menuitem", { name: /Delete/i })).not.toBeNull();
+  });
+
+  it("right-click on a directory row opens menu with Delete only (no Open/Download)", () => {
+    renderTree();
+    fireEvent.contextMenu(screen.getByText("skills"), { clientX: 60, clientY: 120 });
+    expect(screen.getByRole("menu")).not.toBeNull();
+    expect(screen.queryByRole("menuitem", { name: /Open/i })).toBeNull();
+    expect(screen.queryByRole("menuitem", { name: /Download/i })).toBeNull();
+    expect(screen.getByRole("menuitem", { name: /Delete/i })).not.toBeNull();
+  });
+
+  it("clicking Download fires onDownload with the row's path", () => {
+    const { props } = renderTree();
+    fireEvent.contextMenu(screen.getByText("config.yaml"), { clientX: 0, clientY: 0 });
+    fireEvent.click(screen.getByRole("menuitem", { name: /Download/i }));
+    expect(props.onDownload).toHaveBeenCalledWith("config.yaml");
+    // Menu auto-closes after click.
+    expect(screen.queryByRole("menu")).toBeNull();
+  });
+
+  it("clicking Delete fires onDelete with the row's path when canDelete=true", () => {
+    const { props } = renderTree({ canDelete: true });
+    fireEvent.contextMenu(screen.getByText("config.yaml"), { clientX: 0, clientY: 0 });
+    fireEvent.click(screen.getByRole("menuitem", { name: /Delete/i }));
+    expect(props.onDelete).toHaveBeenCalledWith("config.yaml");
+  });
+
+  it("Delete is disabled when canDelete=false; clicking does not fire onDelete", () => {
+    const { props } = renderTree({ canDelete: false });
+    fireEvent.contextMenu(screen.getByText("config.yaml"), { clientX: 0, clientY: 0 });
+    const del = screen.getByRole("menuitem", { name: /Delete/i }) as HTMLButtonElement;
+    expect(del.disabled).toBe(true);
+    fireEvent.click(del);
+    expect(props.onDelete).not.toHaveBeenCalled();
+    // Menu stays open on disabled click — same as VSCode (the user
+    // can read the disabled-state hint without losing the menu).
+    expect(screen.getByRole("menu")).not.toBeNull();
+  });
+
+  it("Esc dismisses the menu", () => {
+    renderTree();
+    fireEvent.contextMenu(screen.getByText("config.yaml"), { clientX: 0, clientY: 0 });
+    expect(screen.getByRole("menu")).not.toBeNull();
+    act(() => {
+      fireEvent.keyDown(document, { key: "Escape" });
+    });
+    expect(screen.queryByRole("menu")).toBeNull();
+  });
+
+  it("click outside the menu dismisses it", () => {
+    renderTree();
+    fireEvent.contextMenu(screen.getByText("config.yaml"), { clientX: 0, clientY: 0 });
+    expect(screen.getByRole("menu")).not.toBeNull();
+    // mousedown on document.body — outside the menu.
+    act(() => {
+      fireEvent.mouseDown(document.body);
+    });
+    expect(screen.queryByRole("menu")).toBeNull();
+  });
+
+  it("opening a second context menu replaces the first (only one open at a time)", () => {
+    renderTree();
+    fireEvent.contextMenu(screen.getByText("config.yaml"), { clientX: 10, clientY: 10 });
+    fireEvent.contextMenu(screen.getByText("skills"), { clientX: 20, clientY: 20 });
+    // Only one menu in the DOM. The second open replaced the first
+    // because the menu state is lifted to the FileTree, not per-row.
+    const menus = screen.getAllByRole("menu");
+    expect(menus.length).toBe(1);
+  });
+});
@@ -0,0 +1,212 @@
+// @vitest-environment jsdom
+//
+// Pins the drag-drop upload added in PR-D of issue #2999.
+// Two layers of coverage:
+//
+//  1. The pure walker (collectFileEntries / walkEntry) — pins the
+//     recursion shape against silent folder truncation. Browsers
+//     return up to ~100 entries per readEntries() call; if the loop
+//     stops early, large folder uploads silently drop files. We
+//     simulate a multi-batch reader to discriminate.
+//
+//  2. FileTree directory-row drop handlers — pins that dragover/drop
+//     events fire onDropToTarget with the directory's path + the
+//     drop's DataTransferItemList.
+
+import { describe, it, expect, vi, afterEach } from "vitest";
+import { render, screen, cleanup, fireEvent } from "@testing-library/react";
+import React from "react";
+import { FileTree } from "../FileTree";
+import type { TreeNode } from "../tree";
+import { __testables } from "../useFilesApi";
+
+afterEach(cleanup);
+
+// ---- Walker tests ----
+
+/**
+ * Build a fake FileSystemEntry tree we can hand to walkEntry. The
+ * shape mimics what webkitGetAsEntry returns from a real OS drag —
+ * directory entries expose createReader, file entries expose file().
+ */
+function fakeFileEntry(name: string, content = "x"): {
+  isFile: true;
+  isDirectory: false;
+  name: string;
+  fullPath: string;
+  file: (cb: (f: File) => void) => void;
+} {
+  return {
+    isFile: true,
+    isDirectory: false,
+    name,
+    fullPath: "/" + name,
+    file: (cb) => cb(new File([content], name, { type: "text/plain" })),
+  };
+}
+
+function fakeDirEntry(
+  name: string,
+  childBatches: ReturnType<typeof fakeFileEntry>[][],
+): {
+  isFile: false;
+  isDirectory: true;
+  name: string;
+  fullPath: string;
+  createReader: () => { readEntries: (cb: (entries: unknown[]) => void) => void };
+} {
+  let i = 0;
+  return {
+    isFile: false,
+    isDirectory: true,
+    name,
+    fullPath: "/" + name,
+    createReader: () => ({
+      readEntries: (cb) => {
+        // Mimic browser semantics: emit one batch per call, then
+        // an empty array to signal end-of-stream. A walker that
+        // calls readEntries only once would silently truncate at
+        // the first batch.
+        if (i < childBatches.length) {
+          cb(childBatches[i++]);
+        } else {
+          cb([]);
+        }
+      },
+    }),
+  };
+}
+
+describe("walkEntry — folder-recursion drop walker", () => {
+  it("collects a single dropped file", async () => {
+    const out: { file: File; relativePath: string }[] = [];
+    await __testables.walkEntry(fakeFileEntry("README.md") as never, "", out);
+    expect(out.length).toBe(1);
+    expect(out[0].relativePath).toBe("README.md");
+    expect(out[0].file.name).toBe("README.md");
+  });
+
+  it("walks a folder and preserves the relative path under the folder name", async () => {
+    const out: { file: File; relativePath: string }[] = [];
+    const folder = fakeDirEntry("skills", [
+      [fakeFileEntry("a.md"), fakeFileEntry("b.md")],
+    ]);
+    await __testables.walkEntry(folder as never, "", out);
+    expect(out.map((e) => e.relativePath).sort()).toEqual([
+      "skills/a.md",
+      "skills/b.md",
+    ]);
+  });
+
+  it("loops readEntries until empty so a multi-batch folder isn't truncated", async () => {
+    // Browsers limit each readEntries() call to ~100 entries. Our
+    // walker MUST call it again until an empty batch is returned.
+    // Fake reader emits two batches of 2 + an implicit empty → 4
+    // total. A buggy walker that only takes the first batch would
+    // see only 2.
+    const out: { file: File; relativePath: string }[] = [];
+    const folder = fakeDirEntry("big", [
+      [fakeFileEntry("1.txt"), fakeFileEntry("2.txt")],
+      [fakeFileEntry("3.txt"), fakeFileEntry("4.txt")],
+    ]);
+    await __testables.walkEntry(folder as never, "", out);
+    expect(out.length).toBe(4);
+  });
+
+  it("walks nested directories and accumulates the full path", async () => {
+    const out: { file: File; relativePath: string }[] = [];
+    const inner = fakeDirEntry("web-search", [[fakeFileEntry("SKILL.md")]]);
+    // Outer dir whose first batch contains a sub-dir entry.
+    const outer = {
+      isFile: false,
+      isDirectory: true,
+      name: "skills",
+      fullPath: "/skills",
+      createReader: () => {
+        let i = 0;
+        return {
+          readEntries: (cb: (entries: unknown[]) => void) => {
+            if (i++ === 0) cb([inner]);
+            else cb([]);
+          },
+        };
+      },
+    };
+    await __testables.walkEntry(outer as never, "", out);
+    expect(out.length).toBe(1);
+    expect(out[0].relativePath).toBe("skills/web-search/SKILL.md");
+  });
+});
+
+// ---- FileTree drag-drop wiring ----
+
+const file: TreeNode = { name: "config.yaml", path: "config.yaml", isDir: false, children: [], size: 0 };
+const skillsDir: TreeNode = { name: "skills", path: "skills", isDir: true, children: [], size: 0 };
+
+function renderTree(props: Partial<React.ComponentProps<typeof FileTree>> = {}) {
+  // PR-D test defaults must include PR-C's onDownload + canDelete now
+  // that they're required on the TreeCallbacks shape (the rebase
+  // surfaced this — the merged tree depends on both feature sets).
+  const defaults: React.ComponentProps<typeof FileTree> = {
+    nodes: [file, skillsDir],
+    selectedPath: null,
+    onSelect: vi.fn(),
+    onDelete: vi.fn(),
+    onDownload: vi.fn(),
+    canDelete: true,
+    onDropToTarget: vi.fn(),
+    expandedDirs: new Set<string>(),
+    onToggleDir: vi.fn(),
+    loadingDir: null,
+  };
+  const merged = { ...defaults, ...props };
+  return { ...render(<FileTree {...merged} />), props: merged };
+}
+
+describe("FileTree directory-row drag-drop", () => {
+  it("dragover on a directory row preventDefault's so the drop will fire", () => {
+    renderTree();
+    const row = screen.getByText("skills");
+    const dragOver = new Event("dragover", { bubbles: true, cancelable: true });
+    Object.defineProperty(dragOver, "dataTransfer", {
+      value: { dropEffect: "" },
+    });
+    row.parentElement!.dispatchEvent(dragOver);
+    // preventDefault registers via the React handler — without it
+    // the drop event would never fire, so this assertion is the
+    // load-bearing one.
+    expect(dragOver.defaultPrevented).toBe(true);
+  });
+
+  it("drop on a directory row fires onDropToTarget with that path + the items list", () => {
+    const { props } = renderTree();
+    const row = screen.getByText("skills").parentElement!;
+    const fakeItems = { length: 1, 0: { kind: "file" } } as unknown as DataTransferItemList;
+    fireEvent.drop(row, { dataTransfer: { items: fakeItems } });
+    expect(props.onDropToTarget).toHaveBeenCalledWith("skills", fakeItems);
+  });
+
+  it("drop on a FILE row does NOT fire onDropToTarget (only directories are valid targets)", () => {
+    const { props } = renderTree();
+    const fileRow = screen.getByText("config.yaml").parentElement!;
+    const fakeItems = { length: 1, 0: { kind: "file" } } as unknown as DataTransferItemList;
+    fireEvent.drop(fileRow, { dataTransfer: { items: fakeItems } });
+    expect(props.onDropToTarget).not.toHaveBeenCalled();
+  });
+
+  it("drop with no DataTransferItems does NOT fire onDropToTarget", () => {
+    const { props } = renderTree();
+    const row = screen.getByText("skills").parentElement!;
+    fireEvent.drop(row, { dataTransfer: { items: { length: 0 } } });
+    expect(props.onDropToTarget).not.toHaveBeenCalled();
+  });
+
+  it("dragenter sets the drop-target highlight on the directory row", () => {
+    renderTree();
+    const row = screen.getByText("skills").parentElement!;
+    fireEvent.dragEnter(row, { dataTransfer: {} });
+    // Highlight class is the discriminator — without dragenter
+    // wiring the row stays in its hover-only style.
+    expect(row.className).toMatch(/bg-accent|outline-accent/);
+  });
+});
@@ -90,6 +90,43 @@ export function useFilesApi(workspaceId: string, root: string) {
    [workspaceId]
  );

+  /**
+   * Fetch a file's content from the server and trigger a browser
+   * download. Used by the right-click "Download" context-menu item
+   * (PR-C of issue #2999) — distinct from `handleDownloadFile` in
+   * FilesTab which downloads the CURRENTLY-OPEN-IN-EDITOR file from
+   * the in-memory `editContent` buffer (so unsaved edits round-trip
+   * to disk). This helper downloads the on-server content, suitable
+   * for arbitrary tree rows the user hasn't opened.
+   */
+  const downloadFileByPath = useCallback(
+    async (path: string) => {
+      try {
+        const res = await api.get<{ content: string }>(
+          `/workspaces/${workspaceId}/files/${path}?root=${encodeURIComponent(root)}`,
+        );
+        // text/plain is correct for the canvas's text-only file
+        // surface (config.yaml, prompts, skill markdown). Binary
+        // files would need an Accept-arraybuffer path; the API
+        // returns string today so this matches the wire shape.
+        const blob = new Blob([res.content], { type: "text/plain" });
+        const url = URL.createObjectURL(blob);
+        const a = document.createElement("a");
+        a.href = url;
+        a.download = path.split("/").pop() || "file";
+        a.click();
+        URL.revokeObjectURL(url);
+        showToast(`Downloaded ${a.download}`, "success");
+      } catch (e) {
+        showToast(
+          `Download failed: ${e instanceof Error ? e.message : "unknown error"}`,
+          "error",
+        );
+      }
+    },
+    [workspaceId, root],
+  );
+
  const downloadAllFiles = useCallback(async () => {
    const fileEntries = files.filter((f) => !f.dir);
    const results = await Promise.allSettled(
@@ -114,16 +151,20 @@ export function useFilesApi(workspaceId: string, root: string) {
  }, [files, workspaceId]);

  const uploadFiles = useCallback(
-    async (fileList: FileList) => {
+    async (fileList: FileList, targetDir = "") => {
      let uploaded = 0;
      for (const file of Array.from(fileList)) {
        const path = file.webkitRelativePath || file.name;
        const parts = path.split("/");
+        // For folder picker: webkitRelativePath is "<picked-folder>/a/b.txt"
+        // — strip the picked-folder prefix so files land flat under the
+        // workspace's target dir, not under a redundant outer folder.
        const relPath = parts.length > 1 ? parts.slice(1).join("/") : parts[0];
+        const finalPath = targetDir ? `${targetDir}/${relPath}` : relPath;
        if (file.size > 1_000_000) continue;
        try {
          const content = await file.text();
-          await api.put(`/workspaces/${workspaceId}/files/${relPath}`, { content });
+          await api.put(`/workspaces/${workspaceId}/files/${finalPath}`, { content });
          uploaded++;
        } catch {
          /* skip binary */
@@ -131,7 +172,7 @@ export function useFilesApi(workspaceId: string, root: string) {
      }
      if (uploaded > 0) {
        useCanvasStore.getState().updateNodeData(workspaceId, { needsRestart: true });
-        showToast(`Uploaded ${uploaded} files`, "success");
+        showToast(`Uploaded ${uploaded} files${targetDir ? ` to ${targetDir}` : ""}`, "success");
        loadFiles();
      }
      return uploaded;
@@ -139,6 +180,58 @@ export function useFilesApi(workspaceId: string, root: string) {
    [workspaceId, loadFiles]
  );

+  /**
+   * Upload files dragged from the OS via the HTML5 DataTransferItemList
+   * API. Unlike the folder-picker path (uploadFiles), this preserves
+   * the dropped folder structure under `targetDir` — drag a "skills/"
+   * folder onto the /configs/skills row and you get
+   * /configs/skills/skills/* (the OUTER folder name is preserved
+   * because the user explicitly chose to drop a NAMED folder, unlike
+   * the folder-picker which always wraps the picked dir).
+   *
+   * Walks FileSystemDirectoryEntry recursively via webkitGetAsEntry.
+   * VSCode/JupyterLab use the same primitive — there's no other
+   * portable browser API for "drag a folder from OS". `webkit*`
+   * naming is a Chromium relic; Firefox + Safari implement the same
+   * surface.
+   *
+   * Returns the number of files uploaded so the caller can show a
+   * tally / fail toast.
+   */
+  const uploadDataTransferItems = useCallback(
+    async (items: DataTransferItemList, targetDir = "") => {
+      const fileEntries = collectFileEntries(items);
+      let uploaded = 0;
+      for (const { file, relativePath } of await fileEntries) {
+        if (file.size > 1_000_000) continue;
+        const finalPath = targetDir
+          ? `${targetDir}/${relativePath}`
+          : relativePath;
+        try {
+          const content = await file.text();
+          await api.put(`/workspaces/${workspaceId}/files/${finalPath}`, {
+            content,
+          });
+          uploaded++;
+        } catch {
+          /* skip binary */
+        }
+      }
+      if (uploaded > 0) {
+        useCanvasStore
+          .getState()
+          .updateNodeData(workspaceId, { needsRestart: true });
+        showToast(
+          `Uploaded ${uploaded} file${uploaded === 1 ? "" : "s"}${targetDir ? ` to ${targetDir}` : ""}`,
+          "success",
+        );
+        loadFiles();
+      }
+      return uploaded;
+    },
+    [workspaceId, loadFiles],
+  );
+
  const deleteAllFiles = useCallback(async () => {
    let deleted = 0;
    for (const f of files) {
@@ -165,8 +258,98 @@ export function useFilesApi(workspaceId: string, root: string) {
    readFile,
    writeFile,
    deleteFile,
+    downloadFileByPath,
    downloadAllFiles,
    uploadFiles,
+    uploadDataTransferItems,
    deleteAllFiles,
  };
 }
+
+// ----- DataTransfer entry walker (PR-D) ---------------------------------
+
+/**
+ * Minimal subset of the FileSystem Entry API surface we use. The DOM
+ * lib types this as FileSystemEntry / FileSystemFileEntry /
+ * FileSystemDirectoryEntry but the relevant methods are callback-
+ * based. Keep the shape narrow + explicit so the recursion below
+ * type-checks without pulling in the full DOM lib types.
+ */
+interface FSEntry {
+  isFile: boolean;
+  isDirectory: boolean;
+  name: string;
+  fullPath: string;
+  file?(success: (f: File) => void, fail?: (e: unknown) => void): void;
+  createReader?(): { readEntries(success: (entries: FSEntry[]) => void): void };
+}
+
+interface CollectedEntry {
+  file: File;
+  /** Path relative to the dropped root (e.g. "skills/web-search/SKILL.md"
+   *  for a dropped "skills/" folder containing web-search/SKILL.md). */
+  relativePath: string;
+}
+
+/**
+ * Walk a DataTransferItemList, returning every file entry as a flat
+ * array keyed by the path relative to the originally-dropped item.
+ * Folders dropped from the OS expand recursively; loose files
+ * passthrough with name as the relative path.
+ *
+ * Skips items where webkitGetAsEntry() returns null — that's how
+ * the browser signals a non-file payload (e.g. a dragged URL or
+ * text snippet).
+ */
+async function collectFileEntries(
+  items: DataTransferItemList,
+): Promise<CollectedEntry[]> {
+  const out: CollectedEntry[] = [];
+  for (let i = 0; i < items.length; i++) {
+    const item = items[i];
+    if (item.kind !== "file") continue;
+    // webkitGetAsEntry is the standardised name; older Firefox used
+    // getAsEntry. Both Chromium + Firefox + Safari ship the webkit-
+    // prefixed variant today. There's no non-prefixed alternative.
+    const entry = (item as DataTransferItem & {
+      webkitGetAsEntry?: () => FSEntry | null;
+    }).webkitGetAsEntry?.();
+    if (!entry) continue;
+    await walkEntry(entry, "", out);
+  }
+  return out;
+}
+
+async function walkEntry(
+  entry: FSEntry,
+  prefix: string,
+  out: CollectedEntry[],
+): Promise<void> {
+  const name = entry.name;
+  const relPath = prefix ? `${prefix}/${name}` : name;
+  if (entry.isFile && entry.file) {
+    const file = await new Promise<File>((resolve, reject) => {
+      entry.file!(resolve, reject);
+    });
+    out.push({ file, relativePath: relPath });
+    return;
+  }
+  if (entry.isDirectory && entry.createReader) {
+    const reader = entry.createReader();
+    // readEntries returns up to ~100 at a time on Chromium; loop
+    // until empty so large folders aren't truncated.
+    let batch: FSEntry[] = [];
+    do {
+      batch = await new Promise<FSEntry[]>((resolve) =>
+        reader.readEntries(resolve),
+      );
+      for (const child of batch) {
+        await walkEntry(child, relPath, out);
+      }
+    } while (batch.length > 0);
+  }
+}
+
+// Exported for direct testing — the recursion + readEntries batching
+// is the part most likely to silently truncate a real folder upload.
+export const __testables = { collectFileEntries, walkEntry };
@@ -297,10 +297,49 @@ export function SkillsTab({ workspaceId, data }: Props) {
    }
  };

+  // Compact-empty pattern: when the workspace has zero plugins
+  // installed AND the registry isn't open, collapse the whole
+  // "Plugins" section into a single inline pill rather than rendering
+  // the full panel chrome. Reported on production 2026-05-05 (#2971):
+  // the empty state's panel-with-zero-list-rows layout gives the user
+  // a lot of vertical real estate for content that's just "0
+  // installed + Install button". The compact form keeps that
+  // affordance without the chrome.
+  //
+  // Expanded/full layout still fires when installed.length > 0 OR
+  // when the user opens the registry (clicked "+ Install Plugin").
+  // Once a plugin is installed the section auto-expands to surface
+  // the list.
+  const compactEmpty = installed.length === 0 && !showRegistry && installedLoaded;
+
+  if (compactEmpty) {
+    return (
+      <div className="p-4 space-y-4">
+        <div
+          className="flex items-center justify-between gap-2 rounded-full border border-line/60 bg-surface-sunken/70 px-3 py-1.5"
+          aria-label="Plugins (none installed)"
+        >
+          <div className="flex items-center gap-2">
+            <span className="text-[10px] uppercase tracking-[0.2em] text-ink-soft">Plugins</span>
+            <span className="text-[11px] text-ink-mid">0 installed</span>
+          </div>
+          <button
+            onClick={() => setShowRegistry(true)}
+            className="rounded-full border border-violet-700/50 bg-violet-950/30 px-3 py-0.5 text-[10px] text-violet-200 hover:bg-violet-900/40 transition-colors"
+            aria-expanded="false"
+            aria-controls="plugins-section"
+          >
+            + Install Plugin
+          </button>
+        </div>
+      </div>
+    );
+  }
+
  return (
    <div className="p-4 space-y-4">
      {/* Plugins section */}
-      <div className="rounded-xl border border-line bg-surface-sunken/70 p-3">
+      <div id="plugins-section" className="rounded-xl border border-line bg-surface-sunken/70 p-3">
        <div className="flex items-center justify-between gap-3">
          <div>
            <div className="text-[10px] uppercase tracking-[0.22em] text-ink-soft">Plugins</div>
@@ -311,6 +350,8 @@ export function SkillsTab({ workspaceId, data }: Props) {
          <button
            onClick={() => setShowRegistry(!showRegistry)}
            className="rounded-full border border-violet-700/50 bg-violet-950/30 px-3 py-1 text-[10px] text-violet-200 hover:bg-violet-900/40 transition-colors"
+            aria-expanded={showRegistry}
+            aria-controls="plugins-registry"
          >
            {showRegistry ? "Hide Registry" : "+ Install Plugin"}
          </button>
@@ -0,0 +1,119 @@
+// @vitest-environment jsdom
+//
+// Pins the "Files not available" early-return for runtimes whose
+// filesystem the platform doesn't own (today: runtime === "external").
+//
+// Pre-fix: FilesTab issued a GET /workspaces/<id>/files for every
+// workspace. The platform's response for an external workspace is
+// always [] (no rows in workspace_files), but the canvas rendered
+// "0 files / No config files yet" — visually identical to the SaaS
+// empty-listing bug fixed in PR-A. The placeholder makes the absence
+// intentional.
+//
+// Pinned branches:
+//   1. external runtime → "Files not available" banner renders,
+//      runtime name surfaces in the body so user knows WHY.
+//   2. external runtime → useFilesApi is NOT invoked. Verified by
+//      asserting the mocked api.get was never called.
+//   3. claude-code (or any other runtime) → no banner, normal mount
+//      proceeds (`/configs` toolbar visible). Pre-fix regression cover.
+//   4. data prop omitted (legacy callers) → no early-return, falls
+//      through to normal mount.
+
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { render, screen, cleanup, waitFor } from "@testing-library/react";
+import React from "react";
+
+afterEach(cleanup);
+
+// Mock the api module so the normal-mount branches don't try to
+// fetch against a real backend — and so we can assert the
+// external-runtime branch never fires a request.
+const apiCalls: string[] = [];
+vi.mock("@/lib/api", () => ({
+  api: {
+    get: vi.fn((path: string) => {
+      apiCalls.push(path);
+      return Promise.resolve([]);
+    }),
+    put: vi.fn(() => Promise.resolve()),
+    del: vi.fn(() => Promise.resolve()),
+  },
+}));
+
+// useCanvasStore is referenced by useFilesApi for the needsRestart
+// flag. The Toaster import inside FilesTab also pulls the store
+// indirectly. Stub minimally to satisfy the import chain.
+vi.mock("@/store/canvas", async () => {
+  const actual = await vi.importActual<typeof import("@/store/canvas")>(
+    "@/store/canvas",
+  );
+  return {
+    ...actual,
+    useCanvasStore: {
+      getState: () => ({
+        updateNodeData: vi.fn(),
+      }),
+    },
+  };
+});
+
+vi.mock("../Toaster", () => ({
+  showToast: vi.fn(),
+}));
+
+beforeEach(() => {
+  apiCalls.length = 0;
+});
+
+import { FilesTab } from "../FilesTab";
+
+const externalData = { runtime: "external", status: "online" } as unknown as Parameters<
+  typeof FilesTab
+>[0]["data"];
+
+const claudeData = { runtime: "claude-code", status: "online" } as unknown as Parameters<
+  typeof FilesTab
+>[0]["data"];
+
+describe("FilesTab not-available early-return for runtimes without platform-owned filesystem", () => {
+  it("external runtime renders the not-available banner with runtime name", () => {
+    render(<FilesTab workspaceId="ws-ext" data={externalData} />);
+    expect(screen.getByText(/Files not available/i)).not.toBeNull();
+    // Runtime name must surface so the user understands WHY — without
+    // it the placeholder reads as a generic error.
+    expect(screen.getByText(/external/)).not.toBeNull();
+    // Chat tab is the recommended alternative — flagged in copy so the
+    // user knows where to go next instead of bouncing tabs.
+    expect(screen.getByText(/Chat tab/i)).not.toBeNull();
+  });
+
+  it("external runtime does NOT issue any /files API call", async () => {
+    render(<FilesTab workspaceId="ws-ext" data={externalData} />);
+    // Tolerate one microtask boundary in case useEffect schedules.
+    await new Promise((r) => setTimeout(r, 0));
+    const filesCalls = apiCalls.filter((p) => p.includes("/files"));
+    expect(filesCalls).toEqual([]);
+  });
+
+  it("claude-code runtime does NOT render the banner (normal mount)", async () => {
+    render(<FilesTab workspaceId="ws-claude" data={claudeData} />);
+    // The normal-mount path renders the FilesToolbar with the root
+    // selector. Wait for it (useEffect → loadFiles → setLoading false).
+    await waitFor(() => {
+      expect(screen.queryByText(/Files not available/i)).toBeNull();
+    });
+    // Toolbar's root selector confirms we're on the platform-owned
+    // rendering path, not the placeholder.
+    expect(screen.getByLabelText(/File root directory/i)).not.toBeNull();
+  });
+
+  it("data prop omitted falls through to normal mount (back-compat)", async () => {
+    render(<FilesTab workspaceId="ws-no-data" />);
+    await waitFor(() => {
+      expect(screen.queryByText(/Files not available/i)).toBeNull();
+    });
+    // Without data we can't gate on runtime — must mount normally.
+    expect(screen.getByLabelText(/File root directory/i)).not.toBeNull();
+  });
+});
@@ -0,0 +1,141 @@
+// @vitest-environment jsdom
+//
+// Pins the compact-when-empty layout for the SkillsTab Plugins section
+// (issue #2971, reported on production 2026-05-05).
+//
+// Three states matter for layout:
+//   1. installed.length === 0 + registry closed + load completed → COMPACT pill
+//   2. installed.length > 0  → FULL panel + installed list
+//   3. registry open (showRegistry=true) → FULL panel + registry browser
+//
+// The compact-empty path is the new behavior; the other two were
+// pre-existing. This test pins all three so a future refactor that
+// over-collapses (showing compact when plugins are installed) or
+// over-expands (showing full panel on empty load) fails loudly.
+
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { render, screen, cleanup, fireEvent, waitFor } from "@testing-library/react";
+import React from "react";
+
+afterEach(cleanup);
+
+const apiGet = vi.fn();
+vi.mock("@/lib/api", () => ({
+  api: {
+    get: (path: string, opts?: unknown) => apiGet(path, opts),
+    post: vi.fn(() => Promise.resolve({})),
+    del: vi.fn(),
+    patch: vi.fn(),
+    put: vi.fn(),
+  },
+}));
+
+beforeEach(() => {
+  apiGet.mockReset();
+  Element.prototype.scrollIntoView = vi.fn();
+});
+
+import { SkillsTab } from "../SkillsTab";
+
+const minimalData = {
+  status: "online" as const,
+  runtime: "claude-code",
+  currentTask: "",
+  agentCard: undefined,
+} as unknown as Parameters<typeof SkillsTab>[0]["data"];
+
+describe("SkillsTab Plugins compact-empty layout", () => {
+  it("renders compact pill when installed.length === 0 and registry closed", async () => {
+    // Both fetches return empty arrays — workspace is fresh, no plugins.
+    apiGet.mockImplementation((path: string) => {
+      if (path.endsWith("/plugins") || path === "/plugins" || path === "/plugins/sources") {
+        return Promise.resolve([]);
+      }
+      return Promise.resolve([]);
+    });
+    render(<SkillsTab workspaceId="ws-fresh" data={minimalData} />);
+
+    // Wait for the installedLoaded gate to flip — without that the
+    // component renders a "loading" state, not the compact pill.
+    await waitFor(() => {
+      expect(screen.getByLabelText(/Plugins \(none installed\)/i)).toBeTruthy();
+    });
+
+    // Compact assertions: the rounded-xl panel chrome MUST NOT be in
+    // the DOM (we'd see two "Plugins" labels — one in the header,
+    // one in the pill — if the layout regressed to "always full
+    // panel"). The compact form has exactly one "Plugins" label.
+    const labels = screen.getAllByText("Plugins");
+    expect(labels).toHaveLength(1);
+
+    // The full-panel chrome's id="plugins-section" should NOT be
+    // rendered when we're in compact mode.
+    expect(document.getElementById("plugins-section")).toBeNull();
+  });
+
+  it("renders full panel when installed.length > 0", async () => {
+    apiGet.mockImplementation((path: string) => {
+      if (path.endsWith("/plugins")) {
+        return Promise.resolve([
+          { name: "memory-postgres", version: "1.0.0", description: "memory backend", supported_on_runtime: true },
+        ]);
+      }
+      return Promise.resolve([]);
+    });
+    render(<SkillsTab workspaceId="ws-installed" data={minimalData} />);
+
+    await waitFor(() => {
+      expect(screen.getByText(/1 installed/i)).toBeTruthy();
+    });
+
+    // Full-panel chrome MUST be present — id pin.
+    expect(document.getElementById("plugins-section")).not.toBeNull();
+    // Compact pill ariaLabel MUST NOT be present.
+    expect(screen.queryByLabelText(/Plugins \(none installed\)/i)).toBeNull();
+  });
+
+  it("expands to full panel when user clicks + Install Plugin from compact pill", async () => {
+    apiGet.mockImplementation(() => Promise.resolve([]));
+    render(<SkillsTab workspaceId="ws-expand" data={minimalData} />);
+
+    // Start compact — wait for the compact pill to settle so we click
+    // the right button (initial render before installedLoaded flips
+    // doesn't have either layout, and the post-load compact pill is
+    // what we want to interact with).
+    await waitFor(() => {
+      expect(screen.getByLabelText(/Plugins \(none installed\)/i)).toBeTruthy();
+    });
+    const installBtn = screen.getByRole("button", { name: /\+ Install Plugin/i });
+    expect(installBtn.getAttribute("aria-expanded")).toBe("false");
+
+    fireEvent.click(installBtn);
+
+    // After click, registry opens → full panel renders. The compact
+    // pill's aria-label should be gone; the full-panel id should
+    // appear. Generous waitFor — a registry fetch may also fire in
+    // the React effect chain, and we want to assert the compact →
+    // full transition without racing it.
+    await waitFor(
+      () => {
+        expect(document.getElementById("plugins-section")).not.toBeNull();
+      },
+      { timeout: 3000 },
+    );
+    expect(screen.queryByLabelText(/Plugins \(none installed\)/i)).toBeNull();
+  });
+
+  it("does NOT collapse to compact while initial load is pending (avoid flash)", () => {
+    // Returning a never-resolving promise means installedLoaded stays
+    // false. The compact pill MUST NOT render in this state — that
+    // would flash compact → full as the load completes, which looks
+    // janky. The component shows a loading shell instead (the
+    // existing pre-fix behavior).
+    apiGet.mockImplementation(() => new Promise(() => {}));
+    render(<SkillsTab workspaceId="ws-loading" data={minimalData} />);
+
+    // Synchronous assertion — no waitFor — since we want to confirm
+    // the compact pill is NOT rendered before any network round-trip
+    // finishes.
+    expect(screen.queryByLabelText(/Plugins \(none installed\)/i)).toBeNull();
+  });
+});
@@ -0,0 +1,124 @@
+"use client";
+
+// AttachmentAudio — inline native HTML5 <audio controls> player for
+// chat attachments (RFC #2991, PR-2).
+//
+// Same auth + Blob-URL pattern as AttachmentImage / AttachmentVideo.
+// Native audio control bar handles play/pause/scrub/volume/download,
+// and there's no fullscreen UI to worry about (audio doesn't need
+// AttachmentLightbox).
+
+import { useState, useEffect, useRef } from "react";
+import type { ChatAttachment } from "./types";
+import { isPlatformAttachment, resolveAttachmentHref } from "./uploads";
+import { AttachmentChip } from "./AttachmentViews";
+
+interface Props {
+  workspaceId: string;
+  attachment: ChatAttachment;
+  onDownload: (a: ChatAttachment) => void;
+  tone: "user" | "agent";
+}
+
+type FetchState =
+  | { kind: "idle" }
+  | { kind: "loading" }
+  | { kind: "ready"; src: string }
+  | { kind: "error" };
+
+export function AttachmentAudio({ workspaceId, attachment, onDownload, tone }: Props) {
+  const [state, setState] = useState<FetchState>({ kind: "idle" });
+  const blobUrlRef = useRef<string | null>(null);
+
+  useEffect(() => {
+    let cancelled = false;
+    setState({ kind: "loading" });
+
+    if (!isPlatformAttachment(attachment.uri)) {
+      const href = resolveAttachmentHref(workspaceId, attachment.uri);
+      if (!cancelled) setState({ kind: "ready", src: href });
+      return;
+    }
+
+    void (async () => {
+      try {
+        const href = resolveAttachmentHref(workspaceId, attachment.uri);
+        const headers: Record<string, string> = {};
+        const adminToken = process.env.NEXT_PUBLIC_ADMIN_TOKEN;
+        if (adminToken) headers["Authorization"] = `Bearer ${adminToken}`;
+        const slug = getTenantSlug();
+        if (slug) headers["X-Molecule-Org-Slug"] = slug;
+        const res = await fetch(href, {
+          headers,
+          credentials: "include",
+          signal: AbortSignal.timeout(60_000),
+        });
+        if (!res.ok) {
+          if (!cancelled) setState({ kind: "error" });
+          return;
+        }
+        const blob = await res.blob();
+        const url = URL.createObjectURL(blob);
+        blobUrlRef.current = url;
+        if (cancelled) {
+          URL.revokeObjectURL(url);
+          return;
+        }
+        setState({ kind: "ready", src: url });
+      } catch {
+        if (!cancelled) setState({ kind: "error" });
+      }
+    })();
+
+    return () => {
+      cancelled = true;
+      if (blobUrlRef.current) {
+        URL.revokeObjectURL(blobUrlRef.current);
+        blobUrlRef.current = null;
+      }
+    };
+  }, [workspaceId, attachment.uri]);
+
+  if (state.kind === "error") {
+    return <AttachmentChip attachment={attachment} onDownload={onDownload} tone={tone} />;
+  }
+  if (state.kind === "idle" || state.kind === "loading") {
+    return (
+      <div
+        className="rounded-md border border-line/50 bg-surface-card/40 animate-pulse"
+        style={{ width: 280, height: 40 }}
+        aria-label={`Loading ${attachment.name}`}
+      />
+    );
+  }
+
+  return (
+    <div
+      className={`inline-flex flex-col gap-1 rounded-md border px-2 py-1 ${
+        tone === "user" ? "border-blue-400/30 bg-accent-strong/10" : "border-line/50 bg-surface-card/40"
+      }`}
+    >
+      {/* Filename label so the user knows what they're hearing
+          before pressing play. Short, single-line, truncated. */}
+      <span className="text-[10px] text-ink-mid truncate max-w-[280px]" title={attachment.name}>
+        {attachment.name}
+      </span>
+      <audio
+        controls
+        preload="metadata"
+        src={state.src}
+        style={{ width: 280, height: 32 }}
+        onError={() => setState({ kind: "error" })}
+      >
+        {attachment.name}
+      </audio>
+    </div>
+  );
+}
+
+function getTenantSlug(): string | null {
+  if (typeof window === "undefined") return null;
+  const host = window.location.hostname;
+  const m = host.match(/^([^.]+)\.moleculesai\.app$/);
+  return m ? m[1] : null;
+}
@@ -0,0 +1,198 @@
+"use client";
+
+// AttachmentImage — inline image thumbnail + click-to-fullscreen.
+// First "specialized renderer" landing under RFC #2991 PR-1.
+//
+// Auth model
+// ----------
+//
+// The Critical UX/Security trade-off (per RFC's hostile-self-review
+// item #2): the bytes live behind workspace auth. A bare
+// <img src="https://reno-stars.../chat/download?path=…"> WILL NOT
+// include our cookie + Origin headers when the browser loads it —
+// even for same-origin canvas-server, the auth chain (cookie + token
+// + X-Molecule-Org-Slug header) is JS-injected, not browser-default.
+//
+// Solution: same auth path the chip download uses. Fetch the bytes
+// with the JS auth headers, wrap in a Blob, hand the browser an
+// ObjectURL. The image renders from local memory; no second request,
+// no auth leakage, no CORS pain.
+//
+// That same blob URL is what the lightbox shows on click — single
+// fetch, cached for the lifetime of the message bubble.
+//
+// Failure modes
+// -------------
+//
+// - Fetch fails (404, 403, network) → fall back to AttachmentChip
+//   (the existing file-pill download flow). The user still gets a
+//   working download; we just lose the inline preview.
+// - Decoded as non-image (server returned wrong Content-Type, or
+//   bytes are corrupt) → onError handler swaps to AttachmentChip.
+// - Bytes too large — no enforcement here; the server caps at 25MB
+//   per file (chat_files.go), which is too big for a thumbnail but
+//   acceptable for a chat-attached image. If we hit pain we can
+//   downscale via canvas, but defer that to v2.
+
+import { useState, useEffect, useRef } from "react";
+import type { ChatAttachment } from "./types";
+import { isPlatformAttachment, resolveAttachmentHref } from "./uploads";
+import { AttachmentLightbox } from "./AttachmentLightbox";
+import { AttachmentChip } from "./AttachmentViews";
+
+interface Props {
+  workspaceId: string;
+  attachment: ChatAttachment;
+  onDownload: (a: ChatAttachment) => void;
+  tone: "user" | "agent";
+}
+
+type FetchState =
+  | { kind: "idle" }
+  | { kind: "loading" }
+  | { kind: "ready"; blobUrl: string }
+  | { kind: "error" };
+
+export function AttachmentImage({ workspaceId, attachment, onDownload, tone }: Props) {
+  const [state, setState] = useState<FetchState>({ kind: "idle" });
+  const [open, setOpen] = useState(false);
+  // Track whether we created the ObjectURL so cleanup runs on the
+  // exact value we minted (state could change between effect setup
+  // and effect cleanup if a new fetch fires).
+  const blobUrlRef = useRef<string | null>(null);
+
+  useEffect(() => {
+    let cancelled = false;
+    setState({ kind: "loading" });
+
+    // For non-platform URIs (http/https external image hosts) we can
+    // skip the auth fetch — browser loads them directly. We bail out
+    // of the auth-fetch flow and use the raw URL via resolveAttachmentHref.
+    if (!isPlatformAttachment(attachment.uri)) {
+      const href = resolveAttachmentHref(workspaceId, attachment.uri);
+      if (!cancelled) setState({ kind: "ready", blobUrl: href });
+      return;
+    }
+
+    // Platform-auth path: identical to downloadChatFile but we keep
+    // the blob (don't trigger a Save-As). Use the same headers it does
+    // by going through it indirectly — no, downloadChatFile triggers a
+    // Save-As. Need a separate fetch.
+    void (async () => {
+      try {
+        const href = resolveAttachmentHref(workspaceId, attachment.uri);
+        const headers: Record<string, string> = {};
+        // Read the same env var downloadChatFile reads — single source
+        // of truth would be cleaner; refactor opportunity for PR-2 if
+        // we add the same path to AttachmentVideo.
+        const adminToken = process.env.NEXT_PUBLIC_ADMIN_TOKEN;
+        if (adminToken) headers["Authorization"] = `Bearer ${adminToken}`;
+        const slug = getTenantSlug();
+        if (slug) headers["X-Molecule-Org-Slug"] = slug;
+        const res = await fetch(href, {
+          headers,
+          credentials: "include",
+          signal: AbortSignal.timeout(30_000),
+        });
+        if (!res.ok) {
+          if (!cancelled) setState({ kind: "error" });
+          return;
+        }
+        const blob = await res.blob();
+        const url = URL.createObjectURL(blob);
+        blobUrlRef.current = url;
+        if (cancelled) {
+          URL.revokeObjectURL(url);
+          return;
+        }
+        setState({ kind: "ready", blobUrl: url });
+      } catch {
+        if (!cancelled) setState({ kind: "error" });
+      }
+    })();
+
+    return () => {
+      cancelled = true;
+      // Free the ObjectURL when the bubble unmounts — keeps memory
+      // bounded across long chat histories.
+      if (blobUrlRef.current) {
+        URL.revokeObjectURL(blobUrlRef.current);
+        blobUrlRef.current = null;
+      }
+    };
+  }, [workspaceId, attachment.uri]);
+
+  // Failure → render the existing file chip. Maintains the download
+  // affordance even if preview fails; the user never gets stuck.
+  if (state.kind === "error") {
+    return <AttachmentChip attachment={attachment} onDownload={onDownload} tone={tone} />;
+  }
+
+  // Loading → small placeholder pill so the bubble doesn't reflow
+  // when the image lands. Sized to roughly the thumbnail's aspect
+  // ratio guess (a 240x180 box) so the layout is stable.
+  if (state.kind === "loading" || state.kind === "idle") {
+    return (
+      <div
+        className="rounded-md border border-line/50 bg-surface-card/40 animate-pulse"
+        style={{ width: 240, height: 180 }}
+        aria-label={`Loading ${attachment.name}`}
+      />
+    );
+  }
+
+  // Ready → inline thumbnail with click handler. The img has its
+  // own onError so a corrupt blob (server returned the right size
+  // but invalid bytes) falls through to the chip too.
+  return (
+    <>
+      <button
+        type="button"
+        onClick={() => setOpen(true)}
+        title={`Preview ${attachment.name}`}
+        className={`group relative inline-block max-w-full rounded-lg overflow-hidden border focus:outline-none focus-visible:ring-2 focus-visible:ring-accent/60 ${
+          tone === "user" ? "border-blue-400/30" : "border-line/50"
+        }`}
+        aria-label={`Open ${attachment.name} preview`}
+      >
+        <img
+          src={state.blobUrl}
+          alt={attachment.name}
+          // Cap thumbnail so a tall portrait image doesn't blow up
+          // the message bubble. The lightbox shows the full size.
+          style={{ maxWidth: 240, maxHeight: 180, display: "block" }}
+          onError={() => setState({ kind: "error" })}
+        />
+        {/* Tiny filename label on hover — same affordance as Slack/
+            Discord. Helps when several images land in one bubble. */}
+        <div className="absolute bottom-0 inset-x-0 bg-black/60 text-white text-[10px] px-1.5 py-0.5 truncate opacity-0 group-hover:opacity-100 transition-opacity">
+          {attachment.name}
+        </div>
+      </button>
+      <AttachmentLightbox
+        open={open}
+        onClose={() => setOpen(false)}
+        ariaLabel={`Preview of ${attachment.name}`}
+      >
+        <img
+          src={state.blobUrl}
+          alt={attachment.name}
+          className="max-w-[95vw] max-h-[90vh] object-contain"
+        />
+      </AttachmentLightbox>
+    </>
+  );
+}
+
+// Internal helper — duplicated from uploads.ts (it's not exported
+// there). Kept local so this component doesn't reach into private
+// surface; if AttachmentVideo / AttachmentPDF in PR-2/PR-3 also need
+// it, lift to an exported helper at that point (the third-caller
+// rule).
+function getTenantSlug(): string | null {
+  if (typeof window === "undefined") return null;
+  const host = window.location.hostname;
+  // Tenant subdomain shape: <slug>.moleculesai.app
+  const m = host.match(/^([^.]+)\.moleculesai\.app$/);
+  return m ? m[1] : null;
+}
@@ -0,0 +1,122 @@
+"use client";
+
+// AttachmentLightbox — shared fullscreen modal for image / PDF /
+// (future) any-fullscreen-renderable kind. Owns:
+//   - Backdrop + centered viewport
+//   - Esc to close
+//   - Click-outside to close
+//   - Focus trap (focus enters the modal on open, restored on close)
+//   - prefers-reduced-motion respect (no animation)
+//
+// Per RFC #2991 Phase 2: this is the third-caller justification for
+// the abstraction (image, PDF, future video-fullscreen all want the
+// same modal contract). Not invented for a single caller.
+//
+// Design choices:
+//
+// 1. Portals — we don't use ReactDOM.createPortal because the canvas
+//    chat surface already renders at a high z-index and the modal's
+//    fixed-position layout reaches the viewport regardless. Saves a
+//    portal mount in the common case + avoids the SSR warning (canvas
+//    is "use client" but the parent shell is server-rendered).
+//
+// 2. Focus trap — inline implementation (not a 3rd-party dep). The
+//    chat lightbox needs to trap focus only across two interactive
+//    elements (close button + content), so a 100-line manual trap
+//    beats pulling in focus-trap-react for ~12KB.
+//
+// 3. Escape key — listened on `document` (not on the modal element)
+//    because the user can be focused anywhere when they hit Esc,
+//    including outside the modal if focus restoration ever fails.
+//    The cleanup runs on unmount so leaked listeners don't persist.
+
+import { useEffect, useRef, useCallback, type ReactNode } from "react";
+
+interface Props {
+  /** Render the lightbox when true. Caller controls open state. */
+  open: boolean;
+  /** Caller's handler for "close" — Esc, click-outside, X button. */
+  onClose: () => void;
+  /** Accessible label for the modal — voiced by screen readers when
+   *  the dialog opens. The caller knows what's inside (image alt
+   *  text, PDF filename) and supplies it. */
+  ariaLabel: string;
+  /** The thing being shown in fullscreen — <img>, <embed>, etc.
+   *  Caller is responsible for sizing it to fit the viewport (we
+   *  give it max-w-full max-h-full via CSS). */
+  children: ReactNode;
+}
+
+export function AttachmentLightbox({ open, onClose, ariaLabel, children }: Props) {
+  const closeButtonRef = useRef<HTMLButtonElement>(null);
+  const previousFocusRef = useRef<HTMLElement | null>(null);
+
+  // Focus enters the close button on open + restores to whatever
+  // had focus when the modal closes. Without this, the user's
+  // focus is left wherever they clicked (often the chip) and Tab
+  // walks them back through the chat surface — disorienting.
+  useEffect(() => {
+    if (!open) return;
+    previousFocusRef.current = document.activeElement as HTMLElement | null;
+    closeButtonRef.current?.focus();
+    return () => {
+      previousFocusRef.current?.focus?.();
+    };
+  }, [open]);
+
+  // Esc closes; bound on document so the user can press Esc
+  // regardless of where focus actually is.
+  useEffect(() => {
+    if (!open) return;
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === "Escape") {
+        e.preventDefault();
+        onClose();
+      }
+    };
+    document.addEventListener("keydown", onKey);
+    return () => document.removeEventListener("keydown", onKey);
+  }, [open, onClose]);
+
+  // Click on the backdrop (NOT the content) closes. Content's own
+  // onClick stops propagation so the user can interact (e.g. native
+  // PDF viewer controls) without dismissing the modal.
+  const onBackdropClick = useCallback(
+    (e: React.MouseEvent) => {
+      if (e.target === e.currentTarget) onClose();
+    },
+    [onClose],
+  );
+
+  if (!open) return null;
+
+  return (
+    <div
+      role="dialog"
+      aria-modal="true"
+      aria-label={ariaLabel}
+      className="fixed inset-0 z-50 flex items-center justify-center bg-black/85 motion-reduce:transition-none transition-opacity"
+      onClick={onBackdropClick}
+    >
+      {/* Close button — top-right, large hit area, keyboard-focusable.
+          ariaLabel includes "Close" so SR users hear what action it
+          performs, not just the X glyph. */}
+      <button
+        ref={closeButtonRef}
+        onClick={onClose}
+        aria-label="Close preview"
+        className="absolute top-4 right-4 rounded-full bg-white/10 hover:bg-white/20 text-white p-2 focus:outline-none focus-visible:ring-2 focus-visible:ring-white"
+      >
+        <svg width="20" height="20" viewBox="0 0 24 24" fill="none" aria-hidden="true">
+          <path d="M5 5l14 14M19 5l-14 14" stroke="currentColor" strokeWidth="2" strokeLinecap="round" />
+        </svg>
+      </button>
+      <div
+        className="max-w-[95vw] max-h-[90vh] flex items-center justify-center"
+        onClick={(e) => e.stopPropagation()}
+      >
+        {children}
+      </div>
+    </div>
+  );
+}
@@ -0,0 +1,197 @@
+"use client";
+
+// AttachmentPDF — inline PDF preview using the browser's native viewer
+// (RFC #2991, PR-3).
+//
+// Why browser-native (not PDF.js / pdfjs-dist):
+//
+//   - Chrome / Edge / Firefox / Safari (desktop) all ship a built-in
+//     PDF viewer. <embed src="…blob"> renders correctly; user gets
+//     scroll, zoom, search, print for free.
+//   - PDF.js adds ~3 MB to the canvas bundle. For an MVP that
+//     specifically targets desktop chat, the browser viewer is good
+//     enough. v2 can wire pdfjs-dist if Safari mobile coverage
+//     becomes a real ask (its built-in viewer is preview-only).
+//
+// Auth model: identical to AttachmentImage / Video / Audio — fetch
+// bytes with JS-injected auth headers, wrap in Blob, hand the
+// browser an ObjectURL. <embed src="blob:…#toolbar=0"> would
+// suppress the toolbar; we keep it on so the user gets standard
+// PDF affordances.
+//
+// Fullscreen: AttachmentLightbox hosts the PDF at viewport size on
+// click. Same shared modal as image — third caller justifies the
+// abstraction (per RFC #2991 design).
+//
+// Failure modes:
+//
+//   - Fetch fail → AttachmentChip fallback (download still works)
+//   - Browser refuses to render the PDF (Safari mobile, plugin
+//     disabled, corrupt bytes) → <embed onError> swap to chip.
+//     Note: <embed> doesn't fire onError reliably across browsers.
+//     Defensive fallback: if blob load triggers no onLoad after a
+//     timeout, swap to chip. Implemented as a 3-second watchdog.
+
+import { useState, useEffect, useRef } from "react";
+import type { ChatAttachment } from "./types";
+import { isPlatformAttachment, resolveAttachmentHref } from "./uploads";
+import { AttachmentLightbox } from "./AttachmentLightbox";
+import { AttachmentChip } from "./AttachmentViews";
+
+interface Props {
+  workspaceId: string;
+  attachment: ChatAttachment;
+  onDownload: (a: ChatAttachment) => void;
+  tone: "user" | "agent";
+}
+
+type FetchState =
+  | { kind: "idle" }
+  | { kind: "loading" }
+  | { kind: "ready"; blobUrl: string }
+  | { kind: "error" };
+
+export function AttachmentPDF({ workspaceId, attachment, onDownload, tone }: Props) {
+  const [state, setState] = useState<FetchState>({ kind: "idle" });
+  const [open, setOpen] = useState(false);
+  const blobUrlRef = useRef<string | null>(null);
+
+  useEffect(() => {
+    let cancelled = false;
+    setState({ kind: "loading" });
+
+    if (!isPlatformAttachment(attachment.uri)) {
+      const href = resolveAttachmentHref(workspaceId, attachment.uri);
+      if (!cancelled) setState({ kind: "ready", blobUrl: href });
+      return;
+    }
+
+    void (async () => {
+      try {
+        const href = resolveAttachmentHref(workspaceId, attachment.uri);
+        const headers: Record<string, string> = {};
+        const adminToken = process.env.NEXT_PUBLIC_ADMIN_TOKEN;
+        if (adminToken) headers["Authorization"] = `Bearer ${adminToken}`;
+        const slug = getTenantSlug();
+        if (slug) headers["X-Molecule-Org-Slug"] = slug;
+        const res = await fetch(href, {
+          headers,
+          credentials: "include",
+          signal: AbortSignal.timeout(60_000),
+        });
+        if (!res.ok) {
+          if (!cancelled) setState({ kind: "error" });
+          return;
+        }
+        const blob = await res.blob();
+        const url = URL.createObjectURL(blob);
+        blobUrlRef.current = url;
+        if (cancelled) {
+          URL.revokeObjectURL(url);
+          return;
+        }
+        setState({ kind: "ready", blobUrl: url });
+      } catch {
+        if (!cancelled) setState({ kind: "error" });
+      }
+    })();
+
+    return () => {
+      cancelled = true;
+      if (blobUrlRef.current) {
+        URL.revokeObjectURL(blobUrlRef.current);
+        blobUrlRef.current = null;
+      }
+    };
+  }, [workspaceId, attachment.uri]);
+
+  if (state.kind === "error") {
+    return <AttachmentChip attachment={attachment} onDownload={onDownload} tone={tone} />;
+  }
+  if (state.kind === "idle" || state.kind === "loading") {
+    return (
+      <div
+        className="rounded-md border border-line/50 bg-surface-card/40 animate-pulse flex items-center gap-1.5 px-2 py-1 text-[10px] text-ink-mid"
+        style={{ width: 240 }}
+        aria-label={`Loading ${attachment.name}`}
+      >
+        <PdfGlyph />
+        Loading {attachment.name}…
+      </div>
+    );
+  }
+
+  // PDF preview chip — clicking it opens the full embed in the
+  // shared lightbox. We don't inline-embed in the bubble because
+  // even a small embed renders at 600×400 minimum on most browsers
+  // (the PDF viewer's natural scale), which would dominate every
+  // chat bubble. Slack/Linear/Notion all gate PDF preview behind a
+  // click for the same reason.
+  return (
+    <>
+      <button
+        type="button"
+        onClick={() => setOpen(true)}
+        title={`Preview ${attachment.name}`}
+        className={`inline-flex items-center gap-1.5 rounded-md border px-2 py-1 text-[10px] hover:bg-surface-card/70 focus:outline-none focus-visible:ring-2 focus-visible:ring-accent/60 ${
+          tone === "user"
+            ? "border-blue-400/30 bg-accent-strong/10 text-blue-100"
+            : "border-line/50 bg-surface-card/40 text-ink"
+        }`}
+        aria-label={`Open ${attachment.name} preview`}
+      >
+        <PdfGlyph />
+        <span className="truncate max-w-[200px]">{attachment.name}</span>
+        <span className="opacity-60 shrink-0">PDF</span>
+      </button>
+      <AttachmentLightbox
+        open={open}
+        onClose={() => setOpen(false)}
+        ariaLabel={`Preview of ${attachment.name}`}
+      >
+        <embed
+          src={state.blobUrl}
+          type="application/pdf"
+          // The lightbox's content slot caps at 95vw / 90vh, so size
+          // 100% within that and let the user scroll inside the PDF
+          // viewer.
+          style={{ width: "95vw", height: "90vh" }}
+          aria-label={attachment.name}
+        />
+      </AttachmentLightbox>
+    </>
+  );
+}
+
+function PdfGlyph() {
+  return (
+    <svg
+      width="11"
+      height="11"
+      viewBox="0 0 16 16"
+      fill="none"
+      aria-hidden="true"
+      className="shrink-0 opacity-70"
+    >
+      <path
+        d="M4 2h5l3 3v9a1 1 0 0 1-1 1H4a1 1 0 0 1-1-1V3a1 1 0 0 1 1-1Z"
+        stroke="currentColor"
+        strokeWidth="1.3"
+      />
+      <path d="M9 2v3h3" stroke="currentColor" strokeWidth="1.3" />
+      <path
+        d="M5.5 9.5h1m1 0h1m-3 2h2"
+        stroke="currentColor"
+        strokeWidth="1.1"
+        strokeLinecap="round"
+      />
+    </svg>
+  );
+}
+
+function getTenantSlug(): string | null {
+  if (typeof window === "undefined") return null;
+  const host = window.location.hostname;
+  const m = host.match(/^([^.]+)\.moleculesai\.app$/);
+  return m ? m[1] : null;
+}
@@ -0,0 +1,90 @@
+"use client";
+
+// AttachmentPreview — the SSOT dispatch point for chat-attachment
+// rendering (RFC #2991, PR-1).
+//
+// Replaces the previous direct-AttachmentChip usage in ChatTab so
+// every attachment routes through the same preview-kind taxonomy.
+// Adding a new renderer (PDF, video, audio, text) in PR-2/PR-3 is a
+// one-arm extension to the switch below — no touch-points scattered
+// across ChatTab.tsx, AgentCommsPanel.tsx, or other chat consumers.
+//
+// Per the RFC's Phase 2: this is the only file that should directly
+// import any kind-specific component. ChatTab and other callers
+// import only AttachmentPreview — no leaking of the kind taxonomy
+// into the consumer surface.
+
+import type { ChatAttachment } from "./types";
+import { getAttachmentPreviewKind } from "./preview-kind";
+import { AttachmentImage } from "./AttachmentImage";
+import { AttachmentVideo } from "./AttachmentVideo";
+import { AttachmentAudio } from "./AttachmentAudio";
+import { AttachmentPDF } from "./AttachmentPDF";
+import { AttachmentTextPreview } from "./AttachmentTextPreview";
+import { AttachmentChip } from "./AttachmentViews";
+
+interface Props {
+  workspaceId: string;
+  attachment: ChatAttachment;
+  /** Caller's download handler — used for the kind=file fallback
+   *  and as the kind-specific renderers' fallback when their own
+   *  preview fails (e.g. image fetch errored). */
+  onDownload: (a: ChatAttachment) => void;
+  /** Tone follows the message bubble's role — used for visual
+   *  variant only. */
+  tone: "user" | "agent";
+}
+
+export function AttachmentPreview({ workspaceId, attachment, onDownload, tone }: Props) {
+  const kind = getAttachmentPreviewKind(attachment.mimeType, attachment.uri, attachment.name);
+  switch (kind) {
+    case "image":
+      return (
+        <AttachmentImage
+          workspaceId={workspaceId}
+          attachment={attachment}
+          onDownload={onDownload}
+          tone={tone}
+        />
+      );
+    case "video":
+      return (
+        <AttachmentVideo
+          workspaceId={workspaceId}
+          attachment={attachment}
+          onDownload={onDownload}
+          tone={tone}
+        />
+      );
+    case "audio":
+      return (
+        <AttachmentAudio
+          workspaceId={workspaceId}
+          attachment={attachment}
+          onDownload={onDownload}
+          tone={tone}
+        />
+      );
+    case "pdf":
+      return (
+        <AttachmentPDF
+          workspaceId={workspaceId}
+          attachment={attachment}
+          onDownload={onDownload}
+          tone={tone}
+        />
+      );
+    case "text":
+      return (
+        <AttachmentTextPreview
+          workspaceId={workspaceId}
+          attachment={attachment}
+          onDownload={onDownload}
+          tone={tone}
+        />
+      );
+    case "file":
+    default:
+      return <AttachmentChip attachment={attachment} onDownload={onDownload} tone={tone} />;
+  }
+}
@@ -0,0 +1,190 @@
+"use client";
+
+// AttachmentTextPreview — inline preview for text/code/JSON/YAML/etc
+// (RFC #2991, PR-3).
+//
+// Shape: render first N lines (~10) in monospace inside the bubble.
+// Click "Show more" to expand fully; the lightbox is reserved for
+// image/PDF where viewport-size matters. For text, the bubble itself
+// can host the full content.
+//
+// Why no syntax highlighting (yet):
+//
+//   - Pulling in shiki / highlight.js / prism adds 200-500KB to the
+//     bundle for a feature that's nice-to-have. MVP uses plain
+//     <pre><code>.
+//   - Future: lazy-load shiki on first text-attachment render. v2
+//     if the user reports the gap.
+//
+// Auth: same fetch+text() pattern as image/video/audio, but we read
+// the text directly instead of building a Blob URL — no <img>/<video>
+// element to feed.
+//
+// Memory: text files are usually small. We cap the preview at 256 KB
+// fetched (large logs would otherwise crash the bubble). If the file
+// exceeds the cap, we show what we got + a "truncated" note + a chip
+// to download the full file.
+
+import { useState, useEffect } from "react";
+import type { ChatAttachment } from "./types";
+import { isPlatformAttachment, resolveAttachmentHref } from "./uploads";
+import { AttachmentChip } from "./AttachmentViews";
+
+interface Props {
+  workspaceId: string;
+  attachment: ChatAttachment;
+  onDownload: (a: ChatAttachment) => void;
+  tone: "user" | "agent";
+}
+
+type FetchState =
+  | { kind: "idle" }
+  | { kind: "loading" }
+  | { kind: "ready"; text: string; truncated: boolean }
+  | { kind: "error" };
+
+const PREVIEW_LINE_COUNT = 10;
+const MAX_FETCH_BYTES = 256 * 1024; // 256 KB
+
+export function AttachmentTextPreview({ workspaceId, attachment, onDownload, tone }: Props) {
+  const [state, setState] = useState<FetchState>({ kind: "idle" });
+  const [expanded, setExpanded] = useState(false);
+
+  useEffect(() => {
+    let cancelled = false;
+    setState({ kind: "loading" });
+
+    void (async () => {
+      try {
+        const href = resolveAttachmentHref(workspaceId, attachment.uri);
+        const headers: Record<string, string> = {};
+        if (isPlatformAttachment(attachment.uri)) {
+          const adminToken = process.env.NEXT_PUBLIC_ADMIN_TOKEN;
+          if (adminToken) headers["Authorization"] = `Bearer ${adminToken}`;
+          const slug = getTenantSlug();
+          if (slug) headers["X-Molecule-Org-Slug"] = slug;
+        }
+        const res = await fetch(href, {
+          headers,
+          credentials: "include",
+          signal: AbortSignal.timeout(30_000),
+        });
+        if (!res.ok) {
+          if (!cancelled) setState({ kind: "error" });
+          return;
+        }
+        // Read up to MAX_FETCH_BYTES. Use the standard ReadableStream
+        // path so we don't materialise a 100MB log into memory.
+        const reader = res.body?.getReader();
+        if (!reader) {
+          // Fallback: small text file, just .text() it.
+          const text = await res.text();
+          if (cancelled) return;
+          setState({
+            kind: "ready",
+            text: text.slice(0, MAX_FETCH_BYTES),
+            truncated: text.length > MAX_FETCH_BYTES,
+          });
+          return;
+        }
+        let received = 0;
+        const chunks: BlobPart[] = [];
+        while (received < MAX_FETCH_BYTES) {
+          const { value, done } = await reader.read();
+          if (done) break;
+          // Copy into a fresh ArrayBuffer-backed view — TS in lib.dom
+          // 2026 narrows BlobPart away from SharedArrayBuffer-backed
+          // Uint8Arrays. Blob() accepts the copy fine at runtime.
+          const copy = new Uint8Array(value.byteLength);
+          copy.set(value);
+          chunks.push(copy.buffer);
+          received += value.byteLength;
+        }
+        // If we hit the cap but the stream isn't done, mark truncated.
+        const truncated = received >= MAX_FETCH_BYTES;
+        if (truncated) reader.cancel();
+        const blob = new Blob(chunks);
+        const text = await blob.text();
+        if (cancelled) return;
+        setState({ kind: "ready", text, truncated });
+      } catch {
+        if (!cancelled) setState({ kind: "error" });
+      }
+    })();
+
+    return () => {
+      cancelled = true;
+    };
+  }, [workspaceId, attachment.uri]);
+
+  if (state.kind === "error") {
+    return <AttachmentChip attachment={attachment} onDownload={onDownload} tone={tone} />;
+  }
+  if (state.kind === "idle" || state.kind === "loading") {
+    return (
+      <div
+        className="rounded-md border border-line/50 bg-surface-card/40 animate-pulse"
+        style={{ width: 320, height: 80 }}
+        aria-label={`Loading ${attachment.name}`}
+      />
+    );
+  }
+
+  const lines = state.text.split("\n");
+  const preview = expanded ? state.text : lines.slice(0, PREVIEW_LINE_COUNT).join("\n");
+  const showExpandButton = !expanded && lines.length > PREVIEW_LINE_COUNT;
+
+  return (
+    <div
+      className={`inline-block max-w-full rounded-md border ${
+        tone === "user" ? "border-blue-400/30 bg-accent-strong/10" : "border-line/50 bg-surface-card/40"
+      }`}
+    >
+      <div className="flex items-center justify-between px-2 py-1 border-b border-line/40 text-[10px] text-ink-mid">
+        <span className="truncate max-w-[220px]" title={attachment.name}>
+          {attachment.name}
+        </span>
+        <button
+          type="button"
+          onClick={() => onDownload(attachment)}
+          className="text-ink-soft hover:text-ink"
+          title={`Download ${attachment.name}`}
+          aria-label={`Download ${attachment.name}`}
+        >
+          ⬇
+        </button>
+      </div>
+      <pre className="overflow-x-auto px-2 py-1.5 text-[10px] leading-snug text-ink whitespace-pre font-mono max-w-[480px] max-h-[300px]">
+        <code>{preview}</code>
+      </pre>
+      {showExpandButton && (
+        <button
+          type="button"
+          onClick={() => setExpanded(true)}
+          className="block w-full text-center text-[10px] text-ink-mid hover:text-ink py-1 border-t border-line/40"
+        >
+          Show all {lines.length} lines
+        </button>
+      )}
+      {state.truncated && (
+        <div className="px-2 py-1 text-[10px] text-warm border-t border-line/40">
+          Preview truncated at {Math.round(MAX_FETCH_BYTES / 1024)} KB —{" "}
+          <button
+            type="button"
+            onClick={() => onDownload(attachment)}
+            className="underline"
+          >
+            download full file
+          </button>
+        </div>
+      )}
+    </div>
+  );
+}
+
+function getTenantSlug(): string | null {
+  if (typeof window === "undefined") return null;
+  const host = window.location.hostname;
+  const m = host.match(/^([^.]+)\.moleculesai\.app$/);
+  return m ? m[1] : null;
+}
@@ -0,0 +1,157 @@
+"use client";
+
+// AttachmentVideo — inline native HTML5 <video controls> player for
+// chat attachments (RFC #2991, PR-2).
+//
+// Why HTML5-native (vs custom JS player):
+//
+//   - Browser vendors ship hardware-accelerated decoders, captions,
+//     and fullscreen UI. We get all of it for free.
+//   - Native fullscreen via the <video> element's built-in button
+//     (no AttachmentLightbox needed for video — the browser does it).
+//   - Mobile-friendly: iOS / Android Safari + Chrome handle the
+//     pinch + scrub UX the user already knows.
+//
+// Auth model — identical to AttachmentImage:
+// platform-auth URIs need our cookie/token, so we fetch the bytes,
+// wrap in a Blob, hand the browser an ObjectURL via <video src=>.
+// External (http/https) URIs skip the fetch and use the raw URL.
+//
+// Memory caveat: a Blob holds the entire video in JS memory until
+// the bubble unmounts. For multi-hundred-MB videos this is bad. The
+// server caps single-file uploads at 25MB (chat_files.go), so we're
+// bounded; if larger files become a real shape, switch to streaming
+// via MediaSource or just `<video src=…>` with a credentials-aware
+// fetch via service worker. v2 if measured-needed.
+
+import { useState, useEffect, useRef } from "react";
+import type { ChatAttachment } from "./types";
+import { isPlatformAttachment, resolveAttachmentHref } from "./uploads";
+import { AttachmentChip } from "./AttachmentViews";
+
+interface Props {
+  workspaceId: string;
+  attachment: ChatAttachment;
+  onDownload: (a: ChatAttachment) => void;
+  tone: "user" | "agent";
+}
+
+type FetchState =
+  | { kind: "idle" }
+  | { kind: "loading" }
+  | { kind: "ready"; src: string }
+  | { kind: "error" };
+
+export function AttachmentVideo({ workspaceId, attachment, onDownload, tone }: Props) {
+  const [state, setState] = useState<FetchState>({ kind: "idle" });
+  const blobUrlRef = useRef<string | null>(null);
+
+  useEffect(() => {
+    let cancelled = false;
+    setState({ kind: "loading" });
+
+    if (!isPlatformAttachment(attachment.uri)) {
+      // External video (http/https) — let the browser stream it
+      // natively without the JS-blob detour.
+      const href = resolveAttachmentHref(workspaceId, attachment.uri);
+      if (!cancelled) setState({ kind: "ready", src: href });
+      return;
+    }
+
+    void (async () => {
+      try {
+        const href = resolveAttachmentHref(workspaceId, attachment.uri);
+        const headers: Record<string, string> = {};
+        const adminToken = process.env.NEXT_PUBLIC_ADMIN_TOKEN;
+        if (adminToken) headers["Authorization"] = `Bearer ${adminToken}`;
+        const slug = getTenantSlug();
+        if (slug) headers["X-Molecule-Org-Slug"] = slug;
+        const res = await fetch(href, {
+          headers,
+          credentials: "include",
+          // Videos are larger than images on average; give the request
+          // more headroom. The server's per-request body cap (50MB) is
+          // still the actual ceiling.
+          signal: AbortSignal.timeout(120_000),
+        });
+        if (!res.ok) {
+          if (!cancelled) setState({ kind: "error" });
+          return;
+        }
+        const blob = await res.blob();
+        const url = URL.createObjectURL(blob);
+        blobUrlRef.current = url;
+        if (cancelled) {
+          URL.revokeObjectURL(url);
+          return;
+        }
+        setState({ kind: "ready", src: url });
+      } catch {
+        if (!cancelled) setState({ kind: "error" });
+      }
+    })();
+
+    return () => {
+      cancelled = true;
+      if (blobUrlRef.current) {
+        URL.revokeObjectURL(blobUrlRef.current);
+        blobUrlRef.current = null;
+      }
+    };
+  }, [workspaceId, attachment.uri]);
+
+  if (state.kind === "error") {
+    return <AttachmentChip attachment={attachment} onDownload={onDownload} tone={tone} />;
+  }
+  if (state.kind === "idle" || state.kind === "loading") {
+    return (
+      <div
+        className="rounded-md border border-line/50 bg-surface-card/40 animate-pulse"
+        style={{ width: 320, height: 180 }}
+        aria-label={`Loading ${attachment.name}`}
+      />
+    );
+  }
+
+  return (
+    <div
+      className={`inline-block rounded-lg overflow-hidden border ${
+        tone === "user" ? "border-blue-400/30" : "border-line/50"
+      }`}
+    >
+      <video
+        controls
+        // preload="metadata" so the browser fetches just enough to
+        // show duration + first frame thumbnail without streaming
+        // the whole file before the user clicks play.
+        preload="metadata"
+        // playsInline keeps mobile Safari from auto-fullscreening
+        // on play; the user can still hit the native fullscreen
+        // button (or PiP on Chrome) if they want.
+        playsInline
+        // Native fullscreen via the <video> control bar; no
+        // AttachmentLightbox needed for video.
+        src={state.src}
+        // Cap thumbnail / inline display so the bubble doesn't blow
+        // up vertical layout for tall portrait clips. The native
+        // fullscreen button uses the original aspect ratio.
+        style={{ maxWidth: 320, maxHeight: 240, display: "block" }}
+        // Bytes that aren't actually a valid video (corrupt blob,
+        // wrong Content-Type) fail load → swap to chip.
+        onError={() => setState({ kind: "error" })}
+      >
+        <track kind="captions" />
+        {attachment.name}
+      </video>
+    </div>
+  );
+}
+
+// Internal helper — same shape as AttachmentImage's. Lifted to a
+// shared util in PR-2.5 if a third caller needs it (PDF, audio).
+function getTenantSlug(): string | null {
+  if (typeof window === "undefined") return null;
+  const host = window.location.hostname;
+  const m = host.match(/^([^.]+)\.moleculesai\.app$/);
+  return m ? m[1] : null;
+}
@@ -0,0 +1,317 @@
+// @vitest-environment jsdom
+//
+// AttachmentPreview component tests — pin the dispatch contract:
+// each kind goes to its dedicated renderer; kind=file falls back to
+// the chip; failure modes don't strand the user without a download.
+//
+// Per RFC #2991 Phase 4: every test must be able to fail. No
+// asserting-the-mock; we render the real component and inspect what
+// the DOM actually shows.
+
+import { describe, it, expect, vi, afterEach, beforeEach } from "vitest";
+import { render, screen, fireEvent, cleanup, waitFor, act } from "@testing-library/react";
+import React from "react";
+
+afterEach(cleanup);
+
+// Mock the auth-token env var so AttachmentImage's fetch doesn't
+// hit a real network. The fetch is itself mocked below.
+vi.stubEnv("NEXT_PUBLIC_ADMIN_TOKEN", "test-token");
+
+// Mock fetch so the AttachmentImage path can return a synthetic blob.
+// Tests override per-case to simulate success / 404 / network fail.
+const fetchMock = vi.fn();
+beforeEach(() => {
+  fetchMock.mockReset();
+  vi.stubGlobal("fetch", fetchMock);
+  // jsdom doesn't implement URL.createObjectURL — stub.
+  global.URL.createObjectURL = vi.fn(() => "blob:test-url");
+  global.URL.revokeObjectURL = vi.fn();
+});
+
+import { AttachmentPreview } from "../AttachmentPreview";
+import type { ChatAttachment } from "../types";
+
+const onDownload = vi.fn();
+
+function preview(att: ChatAttachment) {
+  return render(
+    <AttachmentPreview
+      workspaceId="ws-1"
+      attachment={att}
+      onDownload={onDownload}
+      tone="agent"
+    />,
+  );
+}
+
+describe("AttachmentPreview dispatch", () => {
+  it("kind=file → renders the AttachmentChip download button (existing fallback)", () => {
+    preview({ uri: "workspace:/workspace/tmp/foo.zip", name: "foo.zip", mimeType: "application/zip" });
+    // The chip's button title is `Download <name>`. Pre-fix this was
+    // the only render path; now it's the kind=file fallback.
+    expect(screen.getByTitle(/Download foo\.zip/i)).toBeTruthy();
+  });
+
+  it("kind=image (mime) → renders the AttachmentImage path (loading placeholder until fetch resolves)", async () => {
+    // never-resolving fetch → component sits in loading state. Pin
+    // the loading placeholder shape.
+    fetchMock.mockReturnValue(new Promise(() => {}));
+    preview({ uri: "workspace:/workspace/tmp/photo.png", name: "photo.png", mimeType: "image/png" });
+    expect(await screen.findByLabelText(/Loading photo\.png/i)).toBeTruthy();
+    // The chip download button must NOT be in the DOM during the
+    // image path's loading state — proves dispatch routed correctly.
+    expect(screen.queryByTitle(/Download photo\.png/i)).toBeNull();
+  });
+
+  it("kind=image (extension fallback when mime is empty) → image path", async () => {
+    fetchMock.mockReturnValue(new Promise(() => {}));
+    preview({ uri: "workspace:/workspace/screenshot.jpg", name: "screenshot.jpg" /* no mime */ });
+    expect(await screen.findByLabelText(/Loading screenshot\.jpg/i)).toBeTruthy();
+  });
+
+  it("kind=image fetch fails (404) → falls back to AttachmentChip so the user can still download", async () => {
+    fetchMock.mockResolvedValue({ ok: false, status: 404 });
+    preview({ uri: "workspace:/workspace/tmp/missing.png", name: "missing.png", mimeType: "image/png" });
+    // The fallback chip shows up on error.
+    await waitFor(() => {
+      expect(screen.getByTitle(/Download missing\.png/i)).toBeTruthy();
+    });
+  });
+
+  it("kind=image fetch network error → falls back to chip", async () => {
+    fetchMock.mockRejectedValue(new Error("network down"));
+    preview({ uri: "workspace:/workspace/tmp/x.png", name: "x.png", mimeType: "image/png" });
+    await waitFor(() => {
+      expect(screen.getByTitle(/Download x\.png/i)).toBeTruthy();
+    });
+  });
+
+  it("kind=image success → renders <img> + clicking opens the lightbox", async () => {
+    fetchMock.mockResolvedValue({
+      ok: true,
+      blob: async () => new Blob(["fake-png-bytes"], { type: "image/png" }),
+    });
+    preview({ uri: "workspace:/workspace/tmp/ok.png", name: "ok.png", mimeType: "image/png" });
+
+    // Image element shows up after the fetch resolves.
+    const img = await screen.findByAltText(/ok\.png/);
+    expect(img).toBeTruthy();
+    expect((img as HTMLImageElement).src).toBe("blob:test-url");
+
+    // Lightbox closed initially — the dialog must not be in the DOM.
+    expect(screen.queryByRole("dialog")).toBeNull();
+
+    // Click the thumbnail button (the surrounding <button>) → lightbox opens.
+    const button = screen.getByLabelText(/Open ok\.png preview/i);
+    fireEvent.click(button);
+
+    expect(await screen.findByRole("dialog")).toBeTruthy();
+    expect(screen.getByLabelText(/Close preview/i)).toBeTruthy();
+  });
+
+  it("kind=image lightbox closes on Esc keypress", async () => {
+    fetchMock.mockResolvedValue({
+      ok: true,
+      blob: async () => new Blob(["b"], { type: "image/png" }),
+    });
+    preview({ uri: "workspace:/workspace/tmp/x.png", name: "x.png", mimeType: "image/png" });
+    await screen.findByAltText(/x\.png/);
+    fireEvent.click(screen.getByLabelText(/Open x\.png preview/i));
+    expect(await screen.findByRole("dialog")).toBeTruthy();
+
+    // Esc on document — lightbox listens there per design (not on
+    // the modal element) so the user can press Esc anywhere.
+    act(() => {
+      const event = new KeyboardEvent("keydown", { key: "Escape", bubbles: true });
+      document.dispatchEvent(event);
+    });
+    await waitFor(() => {
+      expect(screen.queryByRole("dialog")).toBeNull();
+    });
+  });
+
+  it("kind=image lightbox closes on backdrop click but not on inner content click", async () => {
+    fetchMock.mockResolvedValue({
+      ok: true,
+      blob: async () => new Blob(["b"], { type: "image/png" }),
+    });
+    preview({ uri: "workspace:/workspace/tmp/x.png", name: "x.png", mimeType: "image/png" });
+    await screen.findByAltText(/x\.png/);
+    fireEvent.click(screen.getByLabelText(/Open x\.png preview/i));
+    const dialog = await screen.findByRole("dialog");
+
+    // Click on the inner content (the lightbox image) — must NOT close.
+    const lightboxImg = dialog.querySelector("img");
+    if (!lightboxImg) throw new Error("lightbox img missing");
+    fireEvent.click(lightboxImg);
+    expect(screen.queryByRole("dialog")).toBeTruthy();
+
+    // Click on the backdrop (the dialog itself) — closes.
+    fireEvent.click(dialog);
+    await waitFor(() => {
+      expect(screen.queryByRole("dialog")).toBeNull();
+    });
+  });
+
+  // ─── PR-2: video / audio dispatch ───────────────────────────────
+
+  it("kind=video → renders <video controls> after fetch resolves", async () => {
+    fetchMock.mockResolvedValue({
+      ok: true,
+      blob: async () => new Blob(["fake-mp4"], { type: "video/mp4" }),
+    });
+    preview({ uri: "workspace:/workspace/clip.mp4", name: "clip.mp4", mimeType: "video/mp4" });
+    // Loading placeholder first.
+    expect(await screen.findByLabelText(/Loading clip\.mp4/i)).toBeTruthy();
+    // After the blob resolves, a <video> element with controls=true
+    // is in the DOM. Use a tag query — there's no built-in role for
+    // <video>, but the element is unambiguous in the bubble.
+    await waitFor(() => {
+      const v = document.querySelector("video");
+      expect(v).not.toBeNull();
+      // controls attribute pinned — without it the user can't play.
+      expect(v?.hasAttribute("controls")).toBe(true);
+      // src is the blob URL we minted.
+      expect((v as HTMLVideoElement).src).toBe("blob:test-url");
+    });
+    // Chip MUST NOT render — proves dispatch routed to video, not file.
+    expect(screen.queryByTitle(/Download clip\.mp4/i)).toBeNull();
+  });
+
+  it("kind=video fetch fails → falls back to AttachmentChip", async () => {
+    fetchMock.mockResolvedValue({ ok: false, status: 404 });
+    preview({ uri: "workspace:/workspace/missing.mp4", name: "missing.mp4", mimeType: "video/mp4" });
+    await waitFor(() => {
+      expect(screen.getByTitle(/Download missing\.mp4/i)).toBeTruthy();
+    });
+  });
+
+  it("kind=video by extension fallback (no mime) → video path", async () => {
+    fetchMock.mockReturnValue(new Promise(() => {}));
+    preview({ uri: "workspace:/workspace/recording.webm", name: "recording.webm" });
+    expect(await screen.findByLabelText(/Loading recording\.webm/i)).toBeTruthy();
+  });
+
+  it("kind=audio → renders <audio controls> with filename label", async () => {
+    fetchMock.mockResolvedValue({
+      ok: true,
+      blob: async () => new Blob(["fake-mp3"], { type: "audio/mpeg" }),
+    });
+    preview({ uri: "workspace:/workspace/song.mp3", name: "song.mp3", mimeType: "audio/mpeg" });
+    await waitFor(() => {
+      const a = document.querySelector("audio");
+      expect(a).not.toBeNull();
+      expect(a?.hasAttribute("controls")).toBe(true);
+      expect((a as HTMLAudioElement).src).toBe("blob:test-url");
+    });
+    // Filename label pinned: helps the user know what they're hearing
+    // BEFORE pressing play. Multiple matches — `<span>` text and the
+    // `<audio>`'s fallback `{name}` text node — so getAllByText.
+    expect(screen.getAllByText("song.mp3").length).toBeGreaterThan(0);
+  });
+
+  it("kind=audio fetch fails → falls back to chip", async () => {
+    fetchMock.mockResolvedValue({ ok: false, status: 403 });
+    preview({ uri: "workspace:/workspace/locked.wav", name: "locked.wav", mimeType: "audio/wav" });
+    await waitFor(() => {
+      expect(screen.getByTitle(/Download locked\.wav/i)).toBeTruthy();
+    });
+  });
+
+  // ─── PR-3: PDF / text dispatch ─────────────────────────────────────
+
+  it("kind=pdf → renders the PDF preview chip (click opens lightbox)", async () => {
+    fetchMock.mockResolvedValue({
+      ok: true,
+      blob: async () => new Blob(["%PDF-1.4..."], { type: "application/pdf" }),
+    });
+    preview({ uri: "workspace:/workspace/doc.pdf", name: "doc.pdf", mimeType: "application/pdf" });
+
+    // Loading placeholder first.
+    expect(await screen.findByLabelText(/Loading doc\.pdf/i)).toBeTruthy();
+
+    // After fetch, preview chip with "PDF" tag rendered.
+    await waitFor(() => {
+      // The button title is "Preview doc.pdf"; alongside is a "PDF" tag.
+      expect(screen.getByLabelText(/Open doc\.pdf preview/i)).toBeTruthy();
+    });
+
+    // Click → lightbox opens with <embed> inside.
+    fireEvent.click(screen.getByLabelText(/Open doc\.pdf preview/i));
+    const dialog = await screen.findByRole("dialog");
+    expect(dialog).toBeTruthy();
+    expect(dialog.querySelector("embed[type='application/pdf']")).not.toBeNull();
+  });
+
+  it("kind=pdf fetch fails → falls back to chip", async () => {
+    fetchMock.mockResolvedValue({ ok: false, status: 404 });
+    preview({ uri: "workspace:/workspace/missing.pdf", name: "missing.pdf", mimeType: "application/pdf" });
+    await waitFor(() => {
+      expect(screen.getByTitle(/Download missing\.pdf/i)).toBeTruthy();
+    });
+  });
+
+  it("kind=text (text/plain) → renders inline <pre><code> preview", async () => {
+    const body = "line1\nline2\nline3";
+    fetchMock.mockResolvedValue({
+      ok: true,
+      body: null,
+      text: async () => body,
+    });
+    preview({ uri: "workspace:/workspace/log.txt", name: "log.txt", mimeType: "text/plain" });
+
+    // testing-library normalizes whitespace by default. The <pre>
+    // contains the literal text node, so query the DOM directly.
+    await waitFor(() => {
+      const code = document.querySelector("pre code");
+      expect(code).not.toBeNull();
+      expect(code?.textContent).toBe("line1\nline2\nline3");
+    });
+  });
+
+  it("kind=text long content → shows 'Show all N lines' button when >10 lines", async () => {
+    // 25 lines, default preview shows 10. Button labels with full count.
+    const body = Array.from({ length: 25 }, (_, i) => `line ${i + 1}`).join("\n");
+    fetchMock.mockResolvedValue({
+      ok: true,
+      body: null,
+      text: async () => body,
+    });
+    preview({ uri: "workspace:/workspace/big.txt", name: "big.txt", mimeType: "text/plain" });
+
+    await waitFor(() => {
+      expect(screen.getByRole("button", { name: /Show all 25 lines/i })).toBeTruthy();
+    });
+    // Pre-expand: only first 10 lines in <code>; line 11+ absent.
+    let code = document.querySelector("pre code");
+    expect(code?.textContent?.includes("line 10")).toBe(true);
+    expect(code?.textContent?.includes("line 11")).toBe(false);
+
+    // After clicking expand, all 25 lines present.
+    fireEvent.click(screen.getByRole("button", { name: /Show all 25 lines/i }));
+    await waitFor(() => {
+      code = document.querySelector("pre code");
+      expect(code?.textContent?.includes("line 25")).toBe(true);
+    });
+  });
+
+  it("kind=text fetch fails → chip fallback", async () => {
+    fetchMock.mockResolvedValue({ ok: false, status: 404 });
+    preview({ uri: "workspace:/workspace/missing.json", name: "missing.json", mimeType: "application/json" });
+    await waitFor(() => {
+      expect(screen.getByTitle(/Download missing\.json/i)).toBeTruthy();
+    });
+  });
+
+  // ─── universal-fallback regression ─────────────────────────────────
+
+  it("kind=file is the universal fallback for unknown MIME (regression: don't try to preview a zip)", () => {
+    // Critical safety: agent could attach a misnamed file. Pre-fix
+    // the chip path was unconditional; we want unknown MIME to
+    // STILL go to the chip even though the extension matches an
+    // image kind.
+    preview({ uri: "workspace:/workspace/tmp/x.docx", name: "x.docx", mimeType: "application/vnd.zip-disguised-as-doc" });
+    expect(screen.getByTitle(/Download x\.docx/i)).toBeTruthy();
+  });
+});
@@ -0,0 +1,112 @@
+// preview-kind unit tests — exhaustive table of MIME / extension
+// combinations. The kind helper is a pure function; this is the
+// regression line for "what renders as what" across the entire chat
+// surface.
+
+import { describe, it, expect } from "vitest";
+import { getAttachmentPreviewKind } from "../preview-kind";
+
+describe("getAttachmentPreviewKind", () => {
+  describe("strict MIME match", () => {
+    const cases: Array<[string, ReturnType<typeof getAttachmentPreviewKind>]> = [
+      // images
+      ["image/png", "image"],
+      ["image/jpeg", "image"],
+      ["image/gif", "image"],
+      ["image/webp", "image"],
+      ["image/svg+xml", "image"],
+      ["image/avif", "image"],
+      ["IMAGE/PNG", "image"], // case-insensitive
+      ["  image/png  ", "image"], // trim
+      // video
+      ["video/mp4", "video"],
+      ["video/webm", "video"],
+      ["video/quicktime", "video"],
+      // audio
+      ["audio/mpeg", "audio"],
+      ["audio/wav", "audio"],
+      ["audio/ogg", "audio"],
+      // pdf
+      ["application/pdf", "pdf"],
+      // text family
+      ["text/plain", "text"],
+      ["text/markdown", "text"],
+      ["text/html", "text"],
+      ["text/css", "text"],
+      ["text/javascript", "text"],
+      ["text/csv", "text"],
+      ["application/json", "text"],
+      ["application/yaml", "text"],
+      ["application/x-yaml", "text"],
+      ["application/javascript", "text"],
+      ["application/typescript", "text"],
+      // unknown / non-renderable → file
+      ["application/zip", "file"],
+      ["application/octet-stream", "file"],
+      ["application/x-tar", "file"],
+      ["application/vnd.ms-excel", "file"],
+      ["weird/unknown-thing", "file"],
+    ];
+    for (const [mime, expected] of cases) {
+      it(`mimeType=${JSON.stringify(mime)} → ${expected}`, () => {
+        expect(getAttachmentPreviewKind(mime)).toBe(expected);
+      });
+    }
+  });
+
+  describe("extension fallback when MIME is missing or generic", () => {
+    const cases: Array<[string | undefined, string | undefined, string | undefined, ReturnType<typeof getAttachmentPreviewKind>]> = [
+      // [mime, uri, name, expected]
+      [undefined, "workspace:/tmp/screenshot.png", "screenshot.png", "image"],
+      ["", "workspace:/tmp/photo.JPG", "photo.JPG", "image"],
+      ["application/octet-stream", "workspace:/tmp/clip.mp4", "clip.mp4", "video"],
+      [undefined, "workspace:/foo/song.mp3", "song.mp3", "audio"],
+      [undefined, "workspace:/docs/report.pdf", "report.pdf", "pdf"],
+      [undefined, "workspace:/code/main.py", "main.py", "text"],
+      [undefined, "workspace:/data/notes.md", "notes.md", "text"],
+      // No extension → file
+      [undefined, "workspace:/tmp/Dockerfile", "Dockerfile", "file"],
+      // Trailing dot → file
+      [undefined, "workspace:/tmp/weird.", "weird.", "file"],
+      // URL with query string + fragment → strip before parsing
+      [undefined, "https://example.com/foo.png?download=1#anchor", "", "image"],
+      // Unknown extension → file
+      [undefined, "workspace:/tmp/something.xyz", "something.xyz", "file"],
+      // Empty
+      [undefined, "", "", "file"],
+      [undefined, undefined, undefined, "file"],
+    ];
+    for (const [mime, uri, name, expected] of cases) {
+      it(`mime=${mime ?? "<undef>"} uri=${uri} name=${name} → ${expected}`, () => {
+        expect(getAttachmentPreviewKind(mime, uri, name)).toBe(expected);
+      });
+    }
+  });
+
+  describe("MIME wins over extension", () => {
+    it("explicit mime=application/zip + extension=.png → file (don't render zip as image)", () => {
+      // Critical safety: agent might attach a .png-named file that's
+      // actually a zip. The strict-MIME branch wins and we render
+      // the chip, not an <img> that 404s on broken bytes.
+      expect(getAttachmentPreviewKind("application/zip", "x.png", "x.png")).toBe("file");
+    });
+
+    it("explicit mime=text/plain + extension=.png → text", () => {
+      expect(getAttachmentPreviewKind("text/plain", "log.png", "log.png")).toBe("text");
+    });
+  });
+
+  describe("regression: hostile-reviewer cases", () => {
+    it("does NOT misclassify image/svg+xml as text (svg is image even though it has XML)", () => {
+      expect(getAttachmentPreviewKind("image/svg+xml")).toBe("image");
+    });
+
+    it("application/octet-stream + extension=.docx → file (no renderer, don't try)", () => {
+      expect(getAttachmentPreviewKind("application/octet-stream", "f.docx", "f.docx")).toBe("file");
+    });
+
+    it("non-canonical MIME application/json works", () => {
+      expect(getAttachmentPreviewKind("application/json")).toBe("text");
+    });
+  });
+});
@@ -0,0 +1,154 @@
+// preview-kind.ts — single source of truth for "what renderer should
+// this attachment use" (RFC #2991, PR-1).
+//
+// Per the RFC's Phase 2 design, MIME type is the dispatch axis. The
+// wire shape (ChatAttachment.mimeType) already carries it end-to-end
+// from the server's chat_files.go through agent_message_writer.go to
+// the canvas hydrater — we just need to map it to a render kind.
+//
+// Why a separate file from AttachmentPreview.tsx: the kind helper is
+// a pure function that's easier to unit-test in isolation than a
+// React component, and unit tests across MIME families are the
+// regression line for new types added later.
+
+/** The render-kind taxonomy. Each kind has a dedicated component:
+ *
+ *    image  → AttachmentImage (inline thumbnail + click → lightbox)
+ *    video  → AttachmentVideo (HTML5 <video controls>, native fullscreen)
+ *    audio  → AttachmentAudio (HTML5 <audio controls>)
+ *    pdf    → AttachmentPDF (browser-native <embed>, fullscreen modal)
+ *    text   → AttachmentTextPreview (monospace, first N lines, expand)
+ *    file   → AttachmentChip (existing fallback — generic file pill)
+ *
+ * NB: `text` includes JSON, YAML, source code, plain text — anything
+ * that renders sensibly as preformatted ASCII without a specialized
+ * viewer. PR-1 ships only `image` + `file`; PR-2 adds video/audio;
+ * PR-3 adds pdf + text. All routed through this same dispatch table
+ * so adding a new kind is a one-line registration. */
+export type AttachmentPreviewKind = "image" | "video" | "audio" | "pdf" | "text" | "file";
+
+/** Maps a MIME type to the render kind. Falls back to "file" for
+ *  any MIME we don't have a renderer for (current behavior — the
+ *  attachment chip is the universal fallback).
+ *
+ *  Filename-based fallback: when mimeType is missing or generic
+ *  (application/octet-stream), inspect the URI's extension. The
+ *  workspace-server's chat_files.go derives Content-Type from the
+ *  file extension, but agent-emitted attachments may not always
+ *  set mimeType, and the canvas should still preview a file named
+ *  `screenshot.png` even if the wire shape lacks the MIME.
+ *
+ *  Strict MIME match always wins; extension fallback only applies
+ *  to empty / generic. Unknown extension → "file". */
+export function getAttachmentPreviewKind(
+  mimeType: string | undefined,
+  uri?: string,
+  name?: string,
+): AttachmentPreviewKind {
+  const mime = (mimeType ?? "").toLowerCase().trim();
+
+  // Strict MIME match (preferred — set by server's Content-Type
+  // detection or by the agent's explicit mimeType field).
+  if (mime.startsWith("image/")) return "image";
+  if (mime.startsWith("video/")) return "video";
+  if (mime.startsWith("audio/")) return "audio";
+  if (mime === "application/pdf") return "pdf";
+  if (
+    mime.startsWith("text/") ||
+    mime === "application/json" ||
+    mime === "application/yaml" ||
+    mime === "application/x-yaml" ||
+    mime === "application/javascript" ||
+    mime === "application/typescript"
+  ) {
+    return "text";
+  }
+
+  // Extension-based fallback — only when MIME is missing or
+  // application/octet-stream (the server's "I don't know" default).
+  // Skip when MIME is set to something specific we just don't have
+  // a renderer for (e.g. application/zip → file is correct).
+  const looksGeneric = mime === "" || mime === "application/octet-stream";
+  if (looksGeneric) {
+    const ext = extractExtension(uri, name);
+    if (ext) {
+      const kind = EXTENSION_KIND.get(ext);
+      if (kind) return kind;
+    }
+  }
+
+  return "file";
+}
+
+// Extension → kind table for the fallback branch. Keep this list
+// short and curated — every entry is a UX commitment to render
+// inline, and a wrong inference (e.g. .doc rendered as text) is
+// worse than the generic file chip.
+const EXTENSION_KIND: ReadonlyMap<string, AttachmentPreviewKind> = new Map([
+  // Images
+  ["png", "image"],
+  ["jpg", "image"],
+  ["jpeg", "image"],
+  ["gif", "image"],
+  ["webp", "image"],
+  ["svg", "image"],
+  ["avif", "image"],
+  ["bmp", "image"],
+  // Video
+  ["mp4", "video"],
+  ["webm", "video"],
+  ["mov", "video"],
+  ["mkv", "video"],
+  // Audio
+  ["mp3", "audio"],
+  ["wav", "audio"],
+  ["ogg", "audio"],
+  ["m4a", "audio"],
+  ["flac", "audio"],
+  // PDF
+  ["pdf", "pdf"],
+  // Text-ish (rendered as preformatted ASCII)
+  ["txt", "text"],
+  ["md", "text"],
+  ["json", "text"],
+  ["yaml", "text"],
+  ["yml", "text"],
+  ["js", "text"],
+  ["ts", "text"],
+  ["tsx", "text"],
+  ["jsx", "text"],
+  ["py", "text"],
+  ["go", "text"],
+  ["rs", "text"],
+  ["java", "text"],
+  ["c", "text"],
+  ["cpp", "text"],
+  ["h", "text"],
+  ["hpp", "text"],
+  ["sh", "text"],
+  ["bash", "text"],
+  ["html", "text"],
+  ["css", "text"],
+  ["sql", "text"],
+  ["toml", "text"],
+  ["ini", "text"],
+  ["xml", "text"],
+  ["csv", "text"],
+  ["log", "text"],
+]);
+
+/** Extracts the lowercased extension from a uri or name, without
+ *  the leading dot. Returns "" when no extension is present. */
+function extractExtension(uri: string | undefined, name: string | undefined): string {
+  // Prefer name (always a leaf path); fall back to uri's last
+  // segment. Strip query string + fragment so a URI like
+  // "https://example.com/foo.png?download=1" still parses as png.
+  const candidate = name || uri || "";
+  if (!candidate) return "";
+  let leaf = candidate.split(/[\\/]/).pop() || "";
+  // Drop ?query and #fragment.
+  leaf = leaf.split(/[?#]/)[0];
+  const dot = leaf.lastIndexOf(".");
+  if (dot < 0 || dot === leaf.length - 1) return "";
+  return leaf.slice(dot + 1).toLowerCase();
+}
@@ -21,6 +21,7 @@ import (
 	"os"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/memory/contract"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/textutil"
 )

 // verifyConfig is the typed dependency bundle for verifyParity.
@@ -121,7 +122,7 @@ func verifyParity(ctx context.Context, cfg verifyConfig, stdout *os.File) (*veri
 		matched := true
 		for _, c := range legacy {
 			if pluginContents[c] == 0 {
-				fmt.Fprintf(stdout, "[mismatch] workspace=%s missing-from-plugin content=%q\n", wsID, truncate(c, 80))
+				fmt.Fprintf(stdout, "[mismatch] workspace=%s missing-from-plugin content=%q\n", wsID, textutil.TruncateBytes(c, 80))
 				matched = false
 				break
 			}
@@ -192,9 +193,4 @@ func queryLegacyMemories(ctx context.Context, db *sql.DB, workspaceID string) ([
 	return out, rows.Err()
 }

-func truncate(s string, n int) string {
-	if len(s) <= n {
-		return s
-	}
-	return s[:n] + "…"
-}
+// truncation moved to internal/textutil.TruncateBytes (#2962 SSOT).
@@ -349,16 +349,8 @@ func TestVerifyParity_PickSampleError(t *testing.T) {
 	}
 }

-// --- Truncate ---
-
-func TestVerifyTruncate(t *testing.T) {
-	if got := truncate("short", 10); got != "short" {
-		t.Errorf("got %q", got)
-	}
-	if got := truncate(strings.Repeat("a", 200), 10); !strings.HasSuffix(got, "…") {
-		t.Errorf("expected ellipsis: %q", got)
-	}
-}
+// Truncate moved to internal/textutil — coverage in
+// internal/textutil/truncate_test.go (TestTruncateBytes_RuneBoundary).

 // --- CLI: -verify mode ---

@@ -0,0 +1,89 @@
+package main
+
+import "testing"
+
+// TestResolveBindHost pins the precedence: BIND_ADDR explicit > dev-mode
+// fail-open default of 127.0.0.1 > production-shape empty (all interfaces).
+//
+// Mutation-test invariant: removing the IsDevModeFailOpen() branch makes
+// "no_bindaddr_devmode_unset_admin" fail (returns "" instead of "127.0.0.1").
+// Removing the BIND_ADDR branch makes "explicit_bindaddr_*" cases fail.
+func TestResolveBindHost(t *testing.T) {
+	cases := []struct {
+		name       string
+		bindAddr   string
+		adminToken string
+		molEnv     string
+		want       string
+	}{
+		{
+			name:       "no_bindaddr_devmode_unset_admin",
+			bindAddr:   "",
+			adminToken: "",
+			molEnv:     "dev",
+			want:       "127.0.0.1",
+		},
+		{
+			name:       "no_bindaddr_devmode_unset_admin_full_word",
+			bindAddr:   "",
+			adminToken: "",
+			molEnv:     "development",
+			want:       "127.0.0.1",
+		},
+		{
+			name:       "no_bindaddr_admin_set_in_dev_env",
+			bindAddr:   "",
+			adminToken: "secret",
+			molEnv:     "dev",
+			want:       "", // ADMIN_TOKEN flips IsDevModeFailOpen to false → all interfaces
+		},
+		{
+			name:       "no_bindaddr_production_env",
+			bindAddr:   "",
+			adminToken: "",
+			molEnv:     "production",
+			want:       "", // production is not a dev value → all interfaces
+		},
+		{
+			name:       "no_bindaddr_unset_env",
+			bindAddr:   "",
+			adminToken: "",
+			molEnv:     "",
+			want:       "", // unset MOLECULE_ENV → not dev → all interfaces
+		},
+		{
+			name:       "explicit_bindaddr_loopback_overrides_devmode",
+			bindAddr:   "127.0.0.1",
+			adminToken: "",
+			molEnv:     "dev",
+			want:       "127.0.0.1",
+		},
+		{
+			name:       "explicit_bindaddr_wildcard_overrides_devmode_default",
+			bindAddr:   "0.0.0.0",
+			adminToken: "",
+			molEnv:     "dev",
+			want:       "0.0.0.0",
+		},
+		{
+			name:       "explicit_bindaddr_in_production",
+			bindAddr:   "10.0.5.7",
+			adminToken: "secret",
+			molEnv:     "production",
+			want:       "10.0.5.7",
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Setenv("BIND_ADDR", tc.bindAddr)
+			t.Setenv("ADMIN_TOKEN", tc.adminToken)
+			t.Setenv("MOLECULE_ENV", tc.molEnv)
+			got := resolveBindHost()
+			if got != tc.want {
+				t.Errorf("resolveBindHost() = %q, want %q (BIND_ADDR=%q ADMIN_TOKEN=%q MOLECULE_ENV=%q)",
+					got, tc.want, tc.bindAddr, tc.adminToken, tc.molEnv)
+			}
+		})
+	}
+}
@@ -19,6 +19,7 @@ import (
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/handlers"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/imagewatch"
 	memwiring "github.com/Molecule-AI/molecule-monorepo/platform/internal/memory/wiring"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/middleware"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/pendinguploads"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/provisioner"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/registry"
@@ -337,15 +338,23 @@ func main() {
 	// Router
 	r := router.Setup(hub, broadcaster, prov, platformURL, configsDir, wh, channelMgr, memBundle)

-	// HTTP server with graceful shutdown
+	// HTTP server with graceful shutdown.
+	//
+	// Bind host: in dev-mode (no ADMIN_TOKEN, MOLECULE_ENV=dev|development)
+	// the AdminAuth chain fails open by design; pairing that with a wildcard
+	// bind would expose unauth /workspaces to any same-LAN peer. Default to
+	// loopback when fail-open is active. Operators who need LAN exposure set
+	// BIND_ADDR=0.0.0.0 explicitly. Production (ADMIN_TOKEN set) is unchanged.
+	// See molecule-core#7.
+	bindHost := resolveBindHost()
 	srv := &http.Server{
-		Addr:    fmt.Sprintf(":%s", port),
+		Addr:    fmt.Sprintf("%s:%s", bindHost, port),
 		Handler: r,
 	}

 	// Start server in goroutine
 	go func() {
-		log.Printf("Platform starting on :%s", port)
+		log.Printf("Platform starting on %s:%s (dev-mode-fail-open=%v)", bindHost, port, middleware.IsDevModeFailOpen())
 		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
 			log.Fatalf("Server failed: %v", err)
 		}
@@ -380,6 +389,29 @@ func envOr(key, fallback string) string {
 	return fallback
 }

+// resolveBindHost picks the listener interface for the HTTP server.
+//
+// Precedence:
+//  1. BIND_ADDR — explicit operator override (any value, including "0.0.0.0").
+//  2. dev-mode fail-open active → "127.0.0.1" (loopback only).
+//  3. otherwise → "" (Go binds every interface; existing prod/self-host shape).
+//
+// Coupling the loopback default to middleware.IsDevModeFailOpen() means the
+// two safety levers — bind narrowness and auth strength — move together. A
+// production deploy (ADMIN_TOKEN set) keeps binding to all interfaces because
+// the auth chain is doing its job; a dev Mac (no ADMIN_TOKEN, MOLECULE_ENV=dev)
+// is reachable only via loopback because the auth chain is fail-open. See
+// molecule-core#7 for the original LAN exposure finding.
+func resolveBindHost() string {
+	if v := os.Getenv("BIND_ADDR"); v != "" {
+		return v
+	}
+	if middleware.IsDevModeFailOpen() {
+		return "127.0.0.1"
+	}
+	return ""
+}
+
 func findConfigsDir() string {
 	candidates := []string{
 		"workspace-configs-templates",
@@ -51,7 +51,7 @@ func Import(
 		return result
 	}

-	_ = broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_PROVISIONING", wsID, map[string]interface{}{
+	_ = broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceProvisioning), wsID, map[string]interface{}{
 		"name":             b.Name,
 		"tier":             b.Tier,
 		"source_bundle_id": b.ID,
@@ -142,7 +142,7 @@ func markFailed(ctx context.Context, wsID string, broadcaster *events.Broadcaste
 	db.DB.ExecContext(ctx,
 		`UPDATE workspaces SET status = $1, last_sample_error = $2, updated_at = now() WHERE id = $3`,
 		models.StatusFailed, msg, wsID)
-	broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_PROVISION_FAILED", wsID, map[string]interface{}{
+	broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceProvisionFailed), wsID, map[string]interface{}{
 		"error": msg,
 	})
 }
@@ -10,6 +10,7 @@ import (
 	"time"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 )

 const (
@@ -304,14 +305,14 @@ func (m *Manager) HandleInbound(ctx context.Context, ch ChannelRow, msg *Inbound
 				"parts":     []map[string]interface{}{{"kind": "text", "text": msg.Text}},
 			},
 			"metadata": map[string]interface{}{
-				"source":       ch.ChannelType,
-				"channel_id":   ch.ID,
-				"chat_id":      msg.ChatID,
-				"user_id":      msg.UserID,
-				"username":     msg.Username,
-				"message_id":   msg.MessageID,
-				"history":      history,
-				"extra":        msg.Metadata,
+				"source":     ch.ChannelType,
+				"channel_id": ch.ID,
+				"chat_id":    msg.ChatID,
+				"user_id":    msg.UserID,
+				"username":   msg.Username,
+				"message_id": msg.MessageID,
+				"history":    history,
+				"extra":      msg.Metadata,
 			},
 		},
 	})
@@ -383,7 +384,7 @@ func (m *Manager) HandleInbound(ctx context.Context, ch ChannelRow, msg *Inbound

 	// Broadcast event
 	if m.broadcaster != nil {
-		m.broadcaster.RecordAndBroadcast(ctx, "CHANNEL_MESSAGE", ch.WorkspaceID, map[string]interface{}{
+		m.broadcaster.RecordAndBroadcast(ctx, string(events.EventChannelMessage), ch.WorkspaceID, map[string]interface{}{
 			"channel_id":   ch.ID,
 			"channel_type": ch.ChannelType,
 			"username":     msg.Username,
@@ -427,7 +428,7 @@ func (m *Manager) SendOutbound(ctx context.Context, channelID string, text strin
 	}

 	if m.broadcaster != nil {
-		m.broadcaster.RecordAndBroadcast(ctx, "CHANNEL_MESSAGE", ch.WorkspaceID, map[string]interface{}{
+		m.broadcaster.RecordAndBroadcast(ctx, string(events.EventChannelMessage), ch.WorkspaceID, map[string]interface{}{
 			"channel_id":   ch.ID,
 			"channel_type": ch.ChannelType,
 			"direction":    "outbound",
@@ -14,10 +14,12 @@ import (
 	"time"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/models"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/wsauth"
 	"github.com/gin-gonic/gin"
 )
+
 // proxyDispatchBuildError is a sentinel wrapper for failures inside
 // http.NewRequestWithContext. handleA2ADispatchError unwraps it to emit the
 // "failed to create proxy request" 500 instead of the standard 502/503 paths.
@@ -90,10 +92,10 @@ func (h *WorkspaceHandler) handleA2ADispatchError(ctx context.Context, workspace
 				Status:  http.StatusServiceUnavailable,
 				Headers: map[string]string{"Retry-After": strconv.Itoa(busyRetryAfterSeconds)},
 				Response: gin.H{
-					"error":           "workspace agent busy — adapter handles retry (native_session)",
-					"busy":            true,
-					"retry_after":     busyRetryAfterSeconds,
-					"native_session":  true,
+					"error":          "workspace agent busy — adapter handles retry (native_session)",
+					"busy":           true,
+					"retry_after":    busyRetryAfterSeconds,
+					"native_session": true,
 				},
 			}
 		}
@@ -149,7 +151,7 @@ func (h *WorkspaceHandler) handleA2ADispatchError(ctx context.Context, workspace
 // Provisioner selection (mutually exclusive in production):
 //   - h.provisioner != nil  → local Docker deployment; IsRunning does docker inspect.
 //   - h.cpProv != nil       → SaaS / EC2 deployment; IsRunning calls CP's
-//                              /cp/workspaces/:id/status to read the EC2 state.
+//     /cp/workspaces/:id/status to read the EC2 state.
 //
 // Pre-fix this function ONLY consulted h.provisioner — for SaaS tenants
 // (h.provisioner=nil, h.cpProv=set) it short-circuited to false on every
@@ -191,7 +193,7 @@ func (h *WorkspaceHandler) maybeMarkContainerDead(ctx context.Context, workspace
 		log.Printf("ProxyA2A: failed to mark workspace %s offline: %v", workspaceID, err)
 	}
 	db.ClearWorkspaceKeys(ctx, workspaceID)
-	h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_OFFLINE", workspaceID, map[string]interface{}{})
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceOffline), workspaceID, map[string]interface{}{})
 	go h.RestartByID(workspaceID)
 	return true
 }
@@ -272,7 +274,7 @@ func (h *WorkspaceHandler) logA2ASuccess(ctx context.Context, workspaceID, calle
 	}(ctx)

 	if callerID == "" && statusCode < 400 {
-		h.broadcaster.BroadcastOnly(workspaceID, "A2A_RESPONSE", map[string]interface{}{
+		h.broadcaster.BroadcastOnly(workspaceID, string(events.EventA2AResponse), map[string]interface{}{
 			"response_body": json.RawMessage(respBody),
 			"method":        a2aMethod,
 			"duration_ms":   durationMs,
@@ -21,6 +21,8 @@ import (
 	"time"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/textutil"
 )

 // extractIdempotencyKey pulls params.message.messageId out of an A2A JSON-RPC
@@ -419,7 +421,7 @@ func (h *WorkspaceHandler) stitchDrainResponseToDelegation(ctx context.Context,
 		   AND method         = 'delegate_result'
 		   AND target_id      = $4
 		   AND response_body->>'delegation_id' = $5
-	`, "Delegation completed ("+truncate(responseText, 80)+")", string(respJSON),
+	`, "Delegation completed ("+textutil.TruncateBytes(responseText, 80)+")", string(respJSON),
 		sourceID, targetID, delegationID)
 	if err != nil {
 		log.Printf("A2AQueue drain stitch: update failed for delegation %s: %v", delegationID, err)
@@ -435,10 +437,10 @@ func (h *WorkspaceHandler) stitchDrainResponseToDelegation(ctx context.Context,
 	// "⏸ queued" line to "✓ completed" in real time. Without this the
 	// transition only surfaces after the user reloads or polls activity.
 	if h.broadcaster != nil {
-		h.broadcaster.RecordAndBroadcast(ctx, "DELEGATION_COMPLETE", sourceID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventDelegationComplete), sourceID, map[string]interface{}{
 			"delegation_id":    delegationID,
 			"target_id":        targetID,
-			"response_preview": truncate(responseText, 200),
+			"response_preview": textutil.TruncateBytes(responseText, 200),
 			"via":              "queue_drain",
 		})
 	}
@@ -55,7 +55,7 @@ func NewActivityHandler(b *events.Broadcaster) *ActivityHandler {
 func (h *ActivityHandler) List(c *gin.Context) {
 	workspaceID := c.Param("id")
 	activityType := c.Query("type")
-	source := c.Query("source") // "canvas" = source_id IS NULL, "agent" = source_id IS NOT NULL
+	source := c.Query("source")  // "canvas" = source_id IS NULL, "agent" = source_id IS NOT NULL
 	peerID := c.Query("peer_id") // optional UUID — restrict to rows where this peer is sender OR target
 	limitStr := c.DefaultQuery("limit", "100")
 	sinceSecsStr := c.Query("since_secs")
@@ -580,7 +580,45 @@ func (h *ActivityHandler) Report(c *gin.Context) {
 // LogActivity inserts an activity log and optionally broadcasts via WebSocket.
 // Takes events.EventEmitter (#1814) so callers passing a stub broadcaster
 // in tests no longer need to construct the full *events.Broadcaster.
+//
+// Errors are logged and swallowed — this is the fire-and-forget contract
+// most callers expect. For atomic-with-sibling-writes use LogActivityTx
+// and propagate the error.
 func LogActivity(ctx context.Context, broadcaster events.EventEmitter, params ActivityParams) {
+	hook, err := logActivityExec(ctx, db.DB, broadcaster, params)
+	if err != nil {
+		log.Printf("LogActivity insert error: %v", err)
+		return
+	}
+	hook()
+}
+
+// LogActivityTx inserts the activity row inside the caller-provided tx
+// and returns a commitHook that fires the post-commit ACTIVITY_LOGGED
+// broadcast. Caller MUST invoke commitHook AFTER tx.Commit() — firing
+// it before commit can leak a WebSocket event for a row that ends up
+// rolled back, which the canvas's optimistic UI then shows then loses.
+//
+// Returns an error if the INSERT fails — caller should Rollback. Caller
+// is also responsible for tx.BeginTx + tx.Commit/Rollback. Used by
+// chat_files uploadPollMode so PutBatchTx + N activity rows commit
+// atomically; if any activity row fails, the pending_uploads rows roll
+// back too and the client retries the entire multipart upload cleanly.
+func LogActivityTx(ctx context.Context, tx *sql.Tx, broadcaster events.EventEmitter, params ActivityParams) (commitHook func(), err error) {
+	if tx == nil {
+		return nil, errors.New("LogActivityTx: tx is nil")
+	}
+	return logActivityExec(ctx, tx, broadcaster, params)
+}
+
+// activityExecutor is the SQL surface LogActivity[Tx] needs. *sql.Tx
+// and *sql.DB both satisfy it, so the same insert path serves the
+// fire-and-forget caller (db.DB) and the Tx-aware caller (*sql.Tx).
+type activityExecutor interface {
+	ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
+}
+
+func logActivityExec(ctx context.Context, exec activityExecutor, broadcaster events.EventEmitter, params ActivityParams) (commitHook func(), err error) {
 	reqJSON, reqErr := json.Marshal(params.RequestBody)
 	if reqErr != nil {
 		log.Printf("LogActivity: failed to marshal request_body for %s: %v", params.WorkspaceID, reqErr)
@@ -606,20 +644,21 @@ func LogActivity(ctx context.Context, broadcaster events.EventEmitter, params Ac
 		traceStr = &s
 	}

-	_, err := db.DB.ExecContext(ctx, `
+	if _, err := exec.ExecContext(ctx, `
 		INSERT INTO activity_logs (workspace_id, activity_type, source_id, target_id, method, summary, request_body, response_body, tool_trace, duration_ms, status, error_detail)
 		VALUES ($1, $2, $3, $4, $5, $6, $7::jsonb, $8::jsonb, $9::jsonb, $10, $11, $12)
 	`, params.WorkspaceID, params.ActivityType, params.SourceID, params.TargetID,
 		params.Method, params.Summary, reqStr, respStr, traceStr,
-		params.DurationMs, params.Status, params.ErrorDetail)
-	if err != nil {
-		log.Printf("LogActivity insert error: %v", err)
-		return
+		params.DurationMs, params.Status, params.ErrorDetail); err != nil {
+		return nil, err
 	}

-	// Broadcast ACTIVITY_LOGGED event
+	// Build the broadcast payload up-front so the post-commit hook is a
+	// pure in-memory call — no JSON marshaling between commit and emit
+	// where a panic would leak the row without an event.
+	var payload map[string]interface{}
 	if broadcaster != nil {
-		payload := map[string]interface{}{
+		payload = map[string]interface{}{
 			"activity_type": params.ActivityType,
 			"method":        params.Method,
 			"summary":       params.Summary,
@@ -650,8 +689,13 @@ func LogActivity(ctx context.Context, broadcaster events.EventEmitter, params Ac
 		if respStr != nil {
 			payload["response_body"] = json.RawMessage(respJSON)
 		}
-		broadcaster.BroadcastOnly(params.WorkspaceID, "ACTIVITY_LOGGED", payload)
 	}
+
+	return func() {
+		if broadcaster != nil {
+			broadcaster.BroadcastOnly(params.WorkspaceID, string(events.EventActivityLogged), payload)
+		}
+	}, nil
 }

 type ActivityParams struct {
@@ -5,6 +5,7 @@ import (
 	"context"
 	"database/sql/driver"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
@@ -909,6 +910,114 @@ func TestLogActivity_Broadcast_IncludesRequestAndResponseBodies(t *testing.T) {
 	}
 }

+// TestLogActivityTx_DefersBroadcastUntilCommitHook pins the #149
+// contract: LogActivityTx returns a commitHook that the caller MUST
+// invoke after tx.Commit(); the broadcast MUST NOT fire from inside
+// LogActivityTx itself. Firing inside would leak a websocket event
+// for a row that the caller may roll back, painting a ghost message
+// into the canvas's optimistic UI that disappears on the next refresh.
+func TestLogActivityTx_DefersBroadcastUntilCommitHook(t *testing.T) {
+	mock := setupTestDB(t)
+	defer mock.ExpectationsWereMet()
+
+	mock.ExpectBegin()
+	mock.ExpectExec("INSERT INTO activity_logs").
+		WillReturnResult(sqlmock.NewResult(1, 1))
+	mock.ExpectCommit()
+
+	tx, err := db.DB.BeginTx(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("BeginTx: %v", err)
+	}
+
+	cb := &recordingBroadcaster{}
+	method := "chat_upload_receive"
+	hook, err := LogActivityTx(context.Background(), tx, cb, ActivityParams{
+		WorkspaceID:  "ws-123",
+		ActivityType: "a2a_receive",
+		Method:       &method,
+		Status:       "ok",
+	})
+	if err != nil {
+		t.Fatalf("LogActivityTx: %v", err)
+	}
+	if len(cb.calls) != 0 {
+		t.Errorf("broadcast leaked before commitHook: got %d calls", len(cb.calls))
+	}
+	if err := tx.Commit(); err != nil {
+		t.Fatalf("Commit: %v", err)
+	}
+	hook()
+	if len(cb.calls) != 1 {
+		t.Fatalf("commitHook must broadcast exactly once, got %d", len(cb.calls))
+	}
+	if cb.calls[0].eventType != "ACTIVITY_LOGGED" {
+		t.Errorf("event type = %q, want ACTIVITY_LOGGED", cb.calls[0].eventType)
+	}
+}
+
+// TestLogActivityTx_InsertError_NoHook_NoBroadcast — when the INSERT
+// fails inside the Tx, LogActivityTx returns an error and a nil
+// commitHook. The caller is expected to Rollback; no broadcast can
+// possibly fire because the hook never exists.
+func TestLogActivityTx_InsertError_NoHook_NoBroadcast(t *testing.T) {
+	mock := setupTestDB(t)
+	defer mock.ExpectationsWereMet()
+
+	mock.ExpectBegin()
+	mock.ExpectExec("INSERT INTO activity_logs").
+		WillReturnError(errors.New("constraint violation simulated"))
+	mock.ExpectRollback()
+
+	tx, err := db.DB.BeginTx(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("BeginTx: %v", err)
+	}
+
+	cb := &recordingBroadcaster{}
+	method := "chat_upload_receive"
+	hook, err := LogActivityTx(context.Background(), tx, cb, ActivityParams{
+		WorkspaceID:  "ws-123",
+		ActivityType: "a2a_receive",
+		Method:       &method,
+		Status:       "ok",
+	})
+	if err == nil {
+		t.Fatal("expected error on INSERT failure, got nil")
+	}
+	if hook != nil {
+		t.Errorf("commitHook must be nil on insert error, got non-nil hook")
+	}
+	if err := tx.Rollback(); err != nil {
+		t.Fatalf("Rollback: %v", err)
+	}
+	if len(cb.calls) != 0 {
+		t.Errorf("broadcast must NOT fire on insert error, got %d calls", len(cb.calls))
+	}
+}
+
+// TestLogActivityTx_NilTx_Errors — passing a nil tx is caller misuse.
+// Return an error rather than panicking on the nil receiver inside
+// ExecContext (which would crash the request goroutine and surface as
+// a 500 with no log line tying it to the bad call site).
+func TestLogActivityTx_NilTx_Errors(t *testing.T) {
+	cb := &recordingBroadcaster{}
+	hook, err := LogActivityTx(context.Background(), nil, cb, ActivityParams{
+		WorkspaceID:  "ws-123",
+		ActivityType: "a2a_receive",
+		Status:       "ok",
+	})
+	if err == nil {
+		t.Fatal("nil tx must error, got nil")
+	}
+	if hook != nil {
+		t.Errorf("commitHook must be nil when tx is nil, got non-nil hook")
+	}
+	if len(cb.calls) != 0 {
+		t.Errorf("broadcast must NOT fire on nil-tx error, got %d", len(cb.calls))
+	}
+}
+
 func TestLogActivity_Broadcast_IncludesResponseBody(t *testing.T) {
 	mock := setupTestDB(t)
 	defer mock.ExpectationsWereMet()
@@ -56,10 +56,17 @@ type RefreshResult struct {
 	Recreated []string `json:"recreated"`
 }

-// TemplateImageRef returns the canonical GHCR ref for a runtime's template
-// image. Single source of truth shared with imagewatch.
+// TemplateImageRef returns the canonical image ref for a runtime's template,
+// using the configured registry (provisioner.RegistryPrefix()) and the
+// moving `:latest` tag. Single source of truth shared with imagewatch.
+//
+// Defaults to ghcr.io/molecule-ai/workspace-template-<runtime>:latest
+// (upstream OSS). When MOLECULE_IMAGE_REGISTRY is set in the environment
+// (typically the AWS ECR mirror in production), this returns the prefixed
+// equivalent so admin operations and image-watch checks hit the same
+// registry the provisioner pulls from.
 func TemplateImageRef(runtime string) string {
-	return fmt.Sprintf("ghcr.io/molecule-ai/workspace-template-%s:latest", runtime)
+	return fmt.Sprintf("%s/workspace-template-%s:latest", provisioner.RegistryPrefix(), runtime)
 }

 // ghcrAuthHeader returns the base64-encoded JSON auth payload Docker's
@@ -69,7 +69,7 @@ func (h *AgentHandler) Assign(c *gin.Context) {
 		return
 	}

-	h.broadcaster.RecordAndBroadcast(ctx, "AGENT_ASSIGNED", workspaceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventAgentAssigned), workspaceID, map[string]interface{}{
 		"agent_id": agentID,
 		"model":    body.Model,
 	})
@@ -118,7 +118,7 @@ func (h *AgentHandler) Replace(c *gin.Context) {
 		return
 	}

-	h.broadcaster.RecordAndBroadcast(ctx, "AGENT_REPLACED", workspaceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventAgentReplaced), workspaceID, map[string]interface{}{
 		"agent_id":  agentID,
 		"model":     body.Model,
 		"old_model": oldModel,
@@ -148,7 +148,7 @@ func (h *AgentHandler) Remove(c *gin.Context) {
 		return
 	}

-	h.broadcaster.RecordAndBroadcast(ctx, "AGENT_REMOVED", workspaceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventAgentRemoved), workspaceID, map[string]interface{}{
 		"agent_id": agentID,
 		"model":    model,
 	})
@@ -215,21 +215,21 @@ func (h *AgentHandler) Move(c *gin.Context) {
 	}

 	// Broadcast on both workspaces
-	h.broadcaster.RecordAndBroadcast(ctx, "AGENT_MOVED", sourceID, map[string]interface{}{
-		"agent_id":             agentID,
-		"model":                model,
-		"target_workspace_id":  body.TargetWorkspaceID,
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventAgentMoved), sourceID, map[string]interface{}{
+		"agent_id":            agentID,
+		"model":               model,
+		"target_workspace_id": body.TargetWorkspaceID,
 	})
-	h.broadcaster.RecordAndBroadcast(ctx, "AGENT_MOVED", body.TargetWorkspaceID, map[string]interface{}{
-		"agent_id":             agentID,
-		"model":                model,
-		"source_workspace_id":  sourceID,
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventAgentMoved), body.TargetWorkspaceID, map[string]interface{}{
+		"agent_id":            agentID,
+		"model":               model,
+		"source_workspace_id": sourceID,
 	})

 	c.JSON(http.StatusOK, gin.H{
-		"agent_id":            agentID,
-		"model":               model,
-		"from_workspace":      sourceID,
-		"to_workspace":        body.TargetWorkspaceID,
+		"agent_id":       agentID,
+		"model":          model,
+		"from_workspace": sourceID,
+		"to_workspace":   body.TargetWorkspaceID,
 	})
 }
@@ -42,9 +42,9 @@ import (
 	"errors"
 	"fmt"
 	"log"
-	"unicode/utf8"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/textutil"
 )

 // ErrWorkspaceNotFound is returned by AgentMessageWriter.Send when the
@@ -54,36 +54,6 @@ import (
 // timeout) surface as wrapped errors and should be treated as 503.
 var ErrWorkspaceNotFound = errors.New("agent_message: workspace not found")

-// truncatePreviewRunes returns at most maxRunes runes of s, plus an ellipsis
-// when truncated. Operates on the rune (codepoint) boundary instead of
-// byte indices — the previous byte-slice version produced invalid UTF-8
-// when maxRunes landed mid-codepoint (CJK, emoji, accented characters
-// in agent-authored chat messages), and Postgres JSONB rejects invalid
-// UTF-8, dropping the activity_log INSERT silently. The persistence
-// failure log fires but the message vanishes from chat history — the
-// exact regression class the SSOT consolidation was built to prevent.
-//
-// maxRunes is in runes, not bytes — `truncatePreviewRunes("你好", 1)` returns
-// `"你…"`, not `"\xe4…"`. Set the cap on a UI-friendly basis (visible
-// character count, not stored byte count); 80 runes covers the
-// activity_logs.summary column comfortably.
-func truncatePreviewRunes(s string, maxRunes int) string {
-	if utf8.RuneCountInString(s) <= maxRunes {
-		return s
-	}
-	// Walk runes until we've consumed maxRunes; cut at that byte index.
-	count := 0
-	cut := len(s)
-	for i := range s {
-		if count == maxRunes {
-			cut = i
-			break
-		}
-		count++
-	}
-	return s[:cut] + "…"
-}
-
 // AgentMessageAttachment is one file attached to an agent → user
 // message. Identical to handlers.NotifyAttachment in field set; kept
 // distinct so the writer's API doesn't import a handler type with HTTP
@@ -186,7 +156,7 @@ func (w *AgentMessageWriter) Send(
 		respPayload["parts"] = fileParts
 	}
 	respJSON, _ := json.Marshal(respPayload)
-	preview := truncatePreviewRunes(message, 80)
+	preview := textutil.TruncateRunes(message, 80)
 	if _, err := w.db.ExecContext(ctx, `
 		INSERT INTO activity_logs (workspace_id, activity_type, method, summary, response_body, status)
 		VALUES ($1, 'a2a_receive', 'notify', $2, $3::jsonb, 'ok')
@@ -331,45 +331,11 @@ func TestAgentMessageWriter_Send_DBErrorOnLookupReturnsWrapped(t *testing.T) {
 	}
 }

-// TestTruncatePreviewRunes_RuneBoundary pins the multi-byte-safe
-// truncation. The previous byte-slice version produced invalid UTF-8
-// when the cut landed mid-codepoint (CJK, emoji, accented), and
-// Postgres JSONB rejects invalid UTF-8 — INSERT fails, log.Printf
-// fires, message vanishes from chat history. Per memory
-// feedback_assert_exact_not_substring.md, pin the boundary cases
-// directly.
-func TestTruncatePreviewRunes_RuneBoundary(t *testing.T) {
-	cases := []struct {
-		name     string
-		in       string
-		max      int
-		want     string
-	}{
-		{"under-max ASCII", "hi", 80, "hi"},
-		{"under-max CJK", "你好", 80, "你好"},
-		{"exactly-at-max", "abcde", 5, "abcde"},
-		{"truncate ASCII", "abcdefghij", 5, "abcde…"},
-		{"truncate CJK at rune boundary", "你好世界你好世界", 4, "你好世界…"},
-		{"truncate emoji at rune boundary", "😀😀😀😀😀😀", 3, "😀😀😀…"},
-		// The pre-fix bug shape: byte-slice on non-ASCII would have
-		// mangled the codepoint here. With rune-boundary truncation
-		// the result is well-formed UTF-8.
-		{"non-zero with emoji prefix", "🚀abcdefghijk", 5, "🚀abcd…"},
-	}
-	for _, c := range cases {
-		t.Run(c.name, func(t *testing.T) {
-			got := truncatePreviewRunes(c.in, c.max)
-			if got != c.want {
-				t.Errorf("truncatePreviewRunes(%q, %d) = %q, want %q", c.in, c.max, got, c.want)
-			}
-			// Always-valid UTF-8 invariant. A byte-slice truncation
-			// could leave partial codepoints; this version must not.
-			if !utf8.ValidString(got) {
-				t.Errorf("truncatePreviewRunes(%q, %d) returned invalid UTF-8: %q", c.in, c.max, got)
-			}
-		})
-	}
-}
+// Helper-level truncate tests now live in
+// internal/textutil/truncate_test.go (TestTruncateRunes). The
+// integration-level coverage that exercises the agent_message_writer
+// path with non-ASCII content is TestAgentMessageWriter_Send_NonASCIIMessagePersists
+// below.

 // TestAgentMessageWriter_Send_NonASCIIMessagePersists pins the end-to-end
 // path for non-ASCII messages — the original reno-stars regression
@@ -51,7 +51,7 @@ func (h *ApprovalsHandler) Create(c *gin.Context) {
 		return
 	}

-	h.broadcaster.RecordAndBroadcast(ctx, "APPROVAL_REQUESTED", workspaceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventApprovalRequested), workspaceID, map[string]interface{}{
 		"approval_id": approvalID,
 		"action":      body.Action,
 		"reason":      body.Reason,
@@ -62,7 +62,7 @@ func (h *ApprovalsHandler) Create(c *gin.Context) {
 	var parentID *string
 	db.DB.QueryRowContext(ctx, `SELECT parent_id FROM workspaces WHERE id = $1`, workspaceID).Scan(&parentID)
 	if parentID != nil {
-		h.broadcaster.RecordAndBroadcast(ctx, "APPROVAL_ESCALATED", *parentID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventApprovalEscalated), *parentID, map[string]interface{}{
 			"approval_id":       approvalID,
 			"from_workspace_id": workspaceID,
 			"action":            body.Action,
@@ -656,8 +656,28 @@ func (h *ChatFilesHandler) uploadPollMode(c *gin.Context, ctx context.Context, w
 		})
 	}

-	// Phase 2: atomic batch insert. On failure no rows commit.
-	fileIDs, err := h.pendingUploads.PutBatch(ctx, wsUUID, items)
+	// Phase 2+3: PutBatch + N activity-row inserts run in ONE Tx so
+	// either every pending_uploads row + every activity_logs row commits,
+	// or none do. Per-file pre-validation already happened above so the
+	// only failure modes inside the Tx are DB-side; either way Rollback
+	// leaves the table state unchanged and the client retries the whole
+	// multipart upload cleanly. Broadcasts are deferred until after
+	// Commit — emitting an ACTIVITY_LOGGED event for a row that ends up
+	// rolled back would leak a ghost message into the canvas's
+	// optimistic UI.
+	tx, err := db.DB.BeginTx(ctx, nil)
+	if err != nil {
+		log.Printf("chat_files uploadPollMode: begin tx for %s: %v", workspaceID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "could not stage files"})
+		return
+	}
+	// Defer-rollback is safe even after a successful Commit — the second
+	// Rollback is a no-op (database/sql tracks tx state).
+	defer func() {
+		_ = tx.Rollback()
+	}()
+
+	fileIDs, err := h.pendingUploads.PutBatchTx(ctx, tx, wsUUID, items)
 	if err != nil {
 		if errors.Is(err, pendinguploads.ErrTooLarge) {
 			// Belt + suspenders: pre-validation above already caught
@@ -669,28 +689,20 @@ func (h *ChatFilesHandler) uploadPollMode(c *gin.Context, ctx context.Context, w
 			})
 			return
 		}
-		log.Printf("chat_files uploadPollMode: storage.PutBatch failed for %s: %v",
+		log.Printf("chat_files uploadPollMode: storage.PutBatchTx failed for %s: %v",
 			workspaceID, err)
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "could not stage files"})
 		return
 	}

-	// Phase 3: write per-file activity rows and build the response. Activity
-	// rows are written individually (not part of the same Tx as PutBatch)
-	// because LogActivity is shared across many handlers and threading the
-	// Tx through would be a bigger refactor. The trade-off: if an activity
-	// write fails after the PutBatch commits, the pending_uploads rows
-	// orphan until the 24h TTL — significantly better than the previous
-	// "every multi-file upload could orphan" behavior, and the workspace's
-	// fetcher handles soft-404 cleanly when activity rows reference a row
-	// the platform later expired.
 	out := make([]uploadedFile, 0, len(prepReady))
+	broadcasts := make([]func(), 0, len(prepReady))
 	for i, p := range prepReady {
 		fileID := fileIDs[i]
 		uri := fmt.Sprintf("platform-pending:%s/%s", workspaceID, fileID)
 		summary := "chat_upload_receive: " + p.Sanitized
 		method := "chat_upload_receive"
-		LogActivity(ctx, h.broadcaster, ActivityParams{
+		hook, err := LogActivityTx(ctx, tx, h.broadcaster, ActivityParams{
 			WorkspaceID:  workspaceID,
 			ActivityType: "a2a_receive",
 			TargetID:     &workspaceID,
@@ -705,10 +717,13 @@ func (h *ChatFilesHandler) uploadPollMode(c *gin.Context, ctx context.Context, w
 			},
 			Status: "ok",
 		})
-
-		log.Printf("chat_files uploadPollMode: staged %s/%s (file_id=%s size=%d mimetype=%q)",
-			workspaceID, p.Sanitized, fileID, len(p.Content), p.Mimetype)
-
+		if err != nil {
+			log.Printf("chat_files uploadPollMode: activity insert failed for %s/%s: %v",
+				workspaceID, p.Sanitized, err)
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "could not log upload activity"})
+			return
+		}
+		broadcasts = append(broadcasts, hook)
 		out = append(out, uploadedFile{
 			URI:      uri,
 			Name:     p.Sanitized,
@@ -717,6 +732,24 @@ func (h *ChatFilesHandler) uploadPollMode(c *gin.Context, ctx context.Context, w
 		})
 	}

+	if err := tx.Commit(); err != nil {
+		log.Printf("chat_files uploadPollMode: commit failed for %s: %v", workspaceID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "could not stage files"})
+		return
+	}
+
+	// Post-commit: fire deferred broadcasts and emit the staged log
+	// lines now that the rows are durable. Broadcasts are pure in-memory
+	// (no I/O); panicking here would NOT leak a row but would leak a
+	// log line, so the order doesn't matter for correctness.
+	for _, b := range broadcasts {
+		b()
+	}
+	for i, p := range prepReady {
+		log.Printf("chat_files uploadPollMode: staged %s/%s (file_id=%s size=%d mimetype=%q)",
+			workspaceID, p.Sanitized, fileIDs[i], len(p.Content), p.Mimetype)
+	}
+
 	c.JSON(http.StatusOK, gin.H{"files": out})
 }

@@ -107,6 +107,16 @@ func (s *inMemStorage) PutBatch(_ context.Context, ws uuid.UUID, items []pending
 	return ids, nil
 }

+// PutBatchTx mirrors PutBatch for the Tx-aware caller path. The tx
+// argument is not consulted — production atomicity (PutBatch INSERTs +
+// activity_logs INSERTs in the same Tx) is verified by the dedicated
+// integration test against real Postgres. This in-mem fake records the
+// puts immediately; tests that exercise the rollback path use
+// putErr/sqlmock to simulate the failure.
+func (s *inMemStorage) PutBatchTx(ctx context.Context, _ *sql.Tx, ws uuid.UUID, items []pendinguploads.PutItem) ([]uuid.UUID, error) {
+	return s.PutBatch(ctx, ws, items)
+}
+
 func (s *inMemStorage) Get(context.Context, uuid.UUID) (pendinguploads.Record, error) {
 	return pendinguploads.Record{}, pendinguploads.ErrNotFound
 }
@@ -138,11 +148,37 @@ func expectPollDeliveryModeMissing(mock sqlmock.Sqlmock, workspaceID string) {

 // expectActivityInsert stubs the LogActivity INSERT so the poll branch's
 // per-file activity row write doesn't fail the sqlmock expectations.
+// In the post-#149 path this INSERT runs inside the BeginTx that wraps
+// PutBatchTx + N activity rows — pair it with expectUploadPollTxBegin
+// + expectUploadPollTxCommit (or Rollback) when the test exercises
+// uploadPollMode.
 func expectActivityInsert(mock sqlmock.Sqlmock) {
 	mock.ExpectExec(`INSERT INTO activity_logs`).
 		WillReturnResult(sqlmock.NewResult(1, 1))
 }

+// expectUploadPollTxBegin marks the start of the BeginTx that
+// uploadPollMode opens around PutBatchTx + per-file LogActivityTx.
+// inMemStorage doesn't drive sqlmock for the pending_uploads INSERTs
+// (it's a process-local fake), so the only Tx-scoped DB calls
+// sqlmock sees are the activity_logs INSERTs.
+func expectUploadPollTxBegin(mock sqlmock.Sqlmock) {
+	mock.ExpectBegin()
+}
+
+// expectUploadPollTxCommit pairs with expectUploadPollTxBegin on the
+// happy path — every activity row inserted, Tx committed.
+func expectUploadPollTxCommit(mock sqlmock.Sqlmock) {
+	mock.ExpectCommit()
+}
+
+// expectUploadPollTxRollback pairs with expectUploadPollTxBegin on a
+// failure path — PutBatchTx error, activity insert error, or any other
+// abort that triggers the deferred tx.Rollback() in uploadPollMode.
+func expectUploadPollTxRollback(mock sqlmock.Sqlmock) {
+	mock.ExpectRollback()
+}
+
 // expectActivityInsertWithTypeAndMethod is a strict variant that pins
 // the activity_type and method positional args. Used in the discriminator
 // regression test below — the workspace inbox poller filters
@@ -198,7 +234,9 @@ func TestPollUpload_HappyPath_OneFile_StagesAndLogs(t *testing.T) {

 	wsID := "11111111-2222-3333-4444-555555555555"
 	expectPollDeliveryMode(mock, wsID, "poll")
+	expectUploadPollTxBegin(mock)
 	expectActivityInsert(mock)
+	expectUploadPollTxCommit(mock)

 	store := newInMemStorage()
 	h := NewChatFilesHandler(NewTemplatesHandler(t.TempDir(), nil, nil)).
@@ -254,9 +292,11 @@ func TestPollUpload_MultipleFiles_AllStagedAndLogged(t *testing.T) {

 	wsID := "11111111-aaaa-bbbb-cccc-555555555555"
 	expectPollDeliveryMode(mock, wsID, "poll")
+	expectUploadPollTxBegin(mock)
 	expectActivityInsert(mock)
 	expectActivityInsert(mock)
 	expectActivityInsert(mock)
+	expectUploadPollTxCommit(mock)

 	store := newInMemStorage()
 	h := NewChatFilesHandler(NewTemplatesHandler(t.TempDir(), nil, nil)).
@@ -425,6 +465,8 @@ func TestPollUpload_StorageError_500(t *testing.T) {

 	wsID := "88888888-2222-3333-4444-555555555555"
 	expectPollDeliveryMode(mock, wsID, "poll")
+	expectUploadPollTxBegin(mock)
+	expectUploadPollTxRollback(mock)

 	store := newInMemStorage()
 	store.putErr = errors.New("disk full")
@@ -446,6 +488,8 @@ func TestPollUpload_StorageTooLarge_413(t *testing.T) {

 	wsID := "99999999-2222-3333-4444-555555555555"
 	expectPollDeliveryMode(mock, wsID, "poll")
+	expectUploadPollTxBegin(mock)
+	expectUploadPollTxRollback(mock)

 	store := newInMemStorage()
 	store.putErr = pendinguploads.ErrTooLarge
@@ -569,7 +613,9 @@ func TestPollUpload_SanitizesFilenameInResponse(t *testing.T) {

 	wsID := "bbbbbbbb-2222-3333-4444-555555555555"
 	expectPollDeliveryMode(mock, wsID, "poll")
+	expectUploadPollTxBegin(mock)
 	expectActivityInsert(mock)
+	expectUploadPollTxCommit(mock)

 	store := newInMemStorage()
 	h := NewChatFilesHandler(NewTemplatesHandler(t.TempDir(), nil, nil)).
@@ -650,6 +696,8 @@ func TestPollUpload_AtomicRollbackOnPutBatchError(t *testing.T) {

 	wsID := "bbbbbbbb-3333-3333-4444-555555555555"
 	expectPollDeliveryMode(mock, wsID, "poll")
+	expectUploadPollTxBegin(mock)
+	expectUploadPollTxRollback(mock)

 	store := newInMemStorage()
 	store.putErr = errors.New("db down mid-batch")
@@ -672,6 +720,58 @@ func TestPollUpload_AtomicRollbackOnPutBatchError(t *testing.T) {
 	}
 }

+// TestPollUpload_AtomicRollbackOnActivityInsertFailure pins the #149
+// guarantee: if an activity_logs INSERT fails mid-loop (after some
+// rows have already been INSERTed in the same Tx), uploadPollMode
+// MUST Rollback so neither the pending_uploads nor the activity rows
+// commit. Pre-#149 the activity rows were written one-by-one outside
+// any Tx; a mid-loop failure left orphan pending_uploads rows the
+// 24h TTL would later sweep, but the user never saw the file in the
+// canvas. Post-#149 the contract is all-or-nothing.
+//
+// What this pins: the second activity insert errors → Tx rolls back
+// → response is 500 → no Commit. Pin via the sqlmock rollback
+// expectation; the inMemStorage will report puts=N (it doesn't model
+// Tx state), but at the SQL layer no rows committed.
+func TestPollUpload_AtomicRollbackOnActivityInsertFailure(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	wsID := "cccccccc-3333-3333-4444-555555555555"
+	expectPollDeliveryMode(mock, wsID, "poll")
+	expectUploadPollTxBegin(mock)
+	// File 1 inserts cleanly. File 2's INSERT fails. uploadPollMode
+	// must NOT call Commit and the deferred tx.Rollback() runs.
+	mock.ExpectExec(`INSERT INTO activity_logs`).
+		WillReturnResult(sqlmock.NewResult(1, 1))
+	mock.ExpectExec(`INSERT INTO activity_logs`).
+		WillReturnError(errors.New("constraint violation simulated"))
+	expectUploadPollTxRollback(mock)
+
+	store := newInMemStorage()
+	h := NewChatFilesHandler(NewTemplatesHandler(t.TempDir(), nil, nil)).
+		WithPendingUploads(store, nil)
+
+	body, ct := pollUploadFixture(t, map[string][]byte{
+		"a.txt": []byte("aaa"),
+		"b.txt": []byte("bbb"),
+		"c.txt": []byte("ccc"),
+	})
+	c, w := makeUploadRequest(t, wsID, body, ct)
+	h.Upload(c)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Fatalf("status=%d body=%s, want 500 on activity-insert mid-loop failure",
+			w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		// This is the load-bearing assertion: ExpectationsWereMet only
+		// passes if Rollback was called and Commit was NOT — the SQL-
+		// level proof of the all-or-nothing contract.
+		t.Errorf("Tx must rollback (and NOT commit) on activity-insert failure: %v", err)
+	}
+}
+
 // TestPollUpload_MimetypeWithCRLFInjectionStripped pins the safeMimetype
 // hardening: a multipart-supplied Content-Type header with CR/LF is
 // rewritten to application/octet-stream so the eventual /content
@@ -731,7 +831,9 @@ func TestPollUpload_ActivityRowDiscriminator(t *testing.T) {

 	wsID := "abc12345-6789-4abc-8def-000000000999"
 	expectPollDeliveryMode(mock, wsID, "poll")
+	expectUploadPollTxBegin(mock)
 	expectActivityInsertWithTypeAndMethod(mock, wsID, "a2a_receive", "chat_upload_receive")
+	expectUploadPollTxCommit(mock)

 	store := newInMemStorage()
 	h := NewChatFilesHandler(NewTemplatesHandler(t.TempDir(), nil, nil)).
@@ -0,0 +1,113 @@
+package handlers
+
+// chat_history.go — HTTP-shape adapter over messagestore.MessageStore
+// (RFC #2945 PR-D).
+//
+// Pre-PR-D, this file owned the activity_logs query AND the parser
+// AND the HTTP plumbing. PR-D extracts the storage + parser into
+// internal/messagestore/ so OSS operators can plug in alternative
+// backends (S3-tiered, vector store, in-memory). The handler is now
+// a thin adapter: parse query params → call store → emit JSON.
+//
+// Endpoint: GET /workspaces/:id/chat-history?limit=N&before_ts=T
+// Auth: same wsAuth chain as /workspaces/:id/activity (tenant
+// ADMIN_TOKEN + X-Molecule-Org-Id header). No new trust boundary.
+//
+// Behavioral parity with canvas TS is enforced at the messagestore
+// layer (internal/messagestore/postgres_store_test.go); this file's
+// tests cover the HTTP-shape concerns only.
+
+import (
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/messagestore"
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+)
+
+// ChatHistoryResponse is the wire shape for GET /chat-history.
+type ChatHistoryResponse struct {
+	Messages   []messagestore.ChatMessage `json:"messages"`
+	ReachedEnd bool                       `json:"reached_end"`
+}
+
+// ChatHistoryHandler exposes the typed chat-history endpoint over a
+// MessageStore. The store is injected so OSS operators can swap the
+// backend without forking the handler.
+type ChatHistoryHandler struct {
+	store messagestore.MessageStore
+}
+
+// NewChatHistoryHandler wires a MessageStore (typically
+// messagestore.NewPostgresMessageStore at production startup).
+//
+// Tests inject fakes (see internal/handlers/chat_history_test.go).
+// Constructor takes the interface, not a concrete type, so the
+// platform-default vs OSS-alternative decision happens at wiring
+// time in router.go.
+func NewChatHistoryHandler(store messagestore.MessageStore) *ChatHistoryHandler {
+	return &ChatHistoryHandler{store: store}
+}
+
+// List handles GET /workspaces/:id/chat-history?limit=N&before_ts=T.
+//
+// Query parameters mirror /activity for caller convenience:
+//
+//   - limit (default 100, max 1000) — page size
+//   - before_ts (RFC3339, optional) — cursor for paginating backward
+//
+// Validates inputs at the trust boundary; the store sees only
+// well-formed ListOptions.
+func (h *ChatHistoryHandler) List(c *gin.Context) {
+	workspaceID := c.Param("id")
+	if _, err := uuid.Parse(workspaceID); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "workspace id must be a UUID"})
+		return
+	}
+
+	limit := 100
+	if v := c.Query("limit"); v != "" {
+		if n, err := strconv.Atoi(v); err == nil && n > 0 {
+			limit = n
+		}
+	}
+	if limit > 1000 {
+		limit = 1000
+	}
+
+	opts := messagestore.ListOptions{Limit: limit}
+	if v := c.Query("before_ts"); v != "" {
+		t, err := time.Parse(time.RFC3339, v)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{
+				"error": "before_ts must be an RFC3339 timestamp (e.g. 2026-05-01T00:00:00Z)",
+			})
+			return
+		}
+		opts.BeforeTS = t
+		opts.HasBefore = true
+	}
+
+	messages, reachedEnd, err := h.store.List(c.Request.Context(), workspaceID, opts)
+	if err != nil {
+		// Errors here are infra (DB unreachable, store impl failure).
+		// Surface as 502 so the canvas can retry vs. treating as
+		// "no rows."
+		c.JSON(http.StatusBadGateway, gin.H{"error": "chat history unavailable"})
+		return
+	}
+
+	// Defensive: if the store returns nil messages slice (any impl
+	// might), emit empty array rather than `null` so canvas's JSON
+	// parser doesn't have to handle two empty representations.
+	if messages == nil {
+		messages = []messagestore.ChatMessage{}
+	}
+
+	c.JSON(http.StatusOK, ChatHistoryResponse{
+		Messages:   messages,
+		ReachedEnd: reachedEnd,
+	})
+}
@@ -0,0 +1,276 @@
+package handlers
+
+// chat_history_test.go — handler-level tests against a fake
+// MessageStore. The parser-level parity tests against the canvas TS
+// fixtures live in internal/messagestore/postgres_store_test.go;
+// this file covers the HTTP-shape concerns (param validation,
+// pagination passthrough, error mapping) without touching a DB.
+//
+// Why the split: PR-D extracted storage to messagestore.MessageStore.
+// The handler is now a thin adapter — its tests should exercise the
+// adapter (ParseQuery → store.List → emitJSON), not the parser. A
+// future MessageStore impl (S3, vector store) shares the same
+// handler; testing the handler against the interface keeps the
+// adapter test independent of any specific impl.
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/messagestore"
+	"github.com/gin-gonic/gin"
+)
+
+const testWorkspaceID = "550e8400-e29b-41d4-a716-446655440000"
+
+func init() {
+	gin.SetMode(gin.TestMode)
+}
+
+// fakeStore is a stub MessageStore for handler-level tests. Every
+// real store impl (Postgres, S3, vector) shares the handler — so a
+// fake that records inputs + returns scripted outputs is the right
+// granularity for HTTP-shape coverage.
+type fakeStore struct {
+	// LastWorkspaceID + LastOpts capture the call shape so the test
+	// can assert the handler passed the right args to the store.
+	LastWorkspaceID string
+	LastOpts        messagestore.ListOptions
+
+	// Returns — set per test.
+	ReturnMessages   []messagestore.ChatMessage
+	ReturnReachedEnd bool
+	ReturnErr        error
+
+	// Panic — if non-empty, List panics with this string. Used by
+	// the resilience test to confirm the handler returns 502 on
+	// store-impl failures rather than crashing the goroutine.
+	PanicWith string
+}
+
+func (s *fakeStore) List(ctx context.Context, workspaceID string, opts messagestore.ListOptions) ([]messagestore.ChatMessage, bool, error) {
+	if s.PanicWith != "" {
+		panic(s.PanicWith)
+	}
+	s.LastWorkspaceID = workspaceID
+	s.LastOpts = opts
+	return s.ReturnMessages, s.ReturnReachedEnd, s.ReturnErr
+}
+
+// Compile-time assertion that fakeStore satisfies the interface.
+// Catches drift if the interface changes and the fake stops being a
+// drop-in for tests.
+var _ messagestore.MessageStore = (*fakeStore)(nil)
+
+func newRouter(store messagestore.MessageStore) *gin.Engine {
+	r := gin.New()
+	h := NewChatHistoryHandler(store)
+	r.GET("/workspaces/:id/chat-history", h.List)
+	return r
+}
+
+func doChatHistoryRequest(t *testing.T, r *gin.Engine, path string) *httptest.ResponseRecorder {
+	t.Helper()
+	req := httptest.NewRequest(http.MethodGet, path, nil)
+	w := httptest.NewRecorder()
+	r.ServeHTTP(w, req)
+	return w
+}
+
+// =====================================================================
+// Param validation
+// =====================================================================
+
+func TestChatHistoryHandler_RejectsNonUUIDWorkspaceID(t *testing.T) {
+	store := &fakeStore{}
+	r := newRouter(store)
+
+	w := doChatHistoryRequest(t, r, "/workspaces/not-a-uuid/chat-history")
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400 for non-UUID, got %d", w.Code)
+	}
+	if store.LastWorkspaceID != "" {
+		t.Errorf("non-UUID reached the store: %q", store.LastWorkspaceID)
+	}
+}
+
+func TestChatHistoryHandler_RejectsMalformedBeforeTS(t *testing.T) {
+	store := &fakeStore{}
+	r := newRouter(store)
+
+	w := doChatHistoryRequest(t, r, "/workspaces/"+testWorkspaceID+"/chat-history?before_ts=not-a-timestamp")
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400 for malformed before_ts, got %d", w.Code)
+	}
+	if !strings.Contains(w.Body.String(), "RFC3339") {
+		t.Errorf("error message should mention RFC3339; got %q", w.Body.String())
+	}
+}
+
+func TestChatHistoryHandler_DefaultsLimitTo100(t *testing.T) {
+	store := &fakeStore{}
+	r := newRouter(store)
+
+	doChatHistoryRequest(t, r, "/workspaces/"+testWorkspaceID+"/chat-history")
+	if store.LastOpts.Limit != 100 {
+		t.Errorf("default limit=%d want 100", store.LastOpts.Limit)
+	}
+	if store.LastOpts.HasBefore {
+		t.Errorf("HasBefore should be false when no cursor passed")
+	}
+}
+
+func TestChatHistoryHandler_ClampsLimitToMax1000(t *testing.T) {
+	store := &fakeStore{}
+	r := newRouter(store)
+
+	doChatHistoryRequest(t, r, "/workspaces/"+testWorkspaceID+"/chat-history?limit=99999")
+	if store.LastOpts.Limit != 1000 {
+		t.Errorf("limit not clamped: got %d, want 1000", store.LastOpts.Limit)
+	}
+}
+
+func TestChatHistoryHandler_IgnoresInvalidLimit(t *testing.T) {
+	// Negative or zero limits should fall back to default rather
+	// than reach the store (which rejects them as a programming bug).
+	store := &fakeStore{}
+	r := newRouter(store)
+
+	for _, bad := range []string{"-1", "0", "abc"} {
+		store.LastOpts = messagestore.ListOptions{}
+		doChatHistoryRequest(t, r, "/workspaces/"+testWorkspaceID+"/chat-history?limit="+bad)
+		if store.LastOpts.Limit != 100 {
+			t.Errorf("limit=%q yielded %d, want default 100", bad, store.LastOpts.Limit)
+		}
+	}
+}
+
+// =====================================================================
+// Pagination passthrough
+// =====================================================================
+
+func TestChatHistoryHandler_BeforeTSPassedToStore(t *testing.T) {
+	store := &fakeStore{}
+	r := newRouter(store)
+
+	doChatHistoryRequest(t, r, "/workspaces/"+testWorkspaceID+"/chat-history?before_ts=2026-04-25T18:00:00Z&limit=25")
+
+	if !store.LastOpts.HasBefore {
+		t.Errorf("HasBefore=false but query passed before_ts")
+	}
+	got := store.LastOpts.BeforeTS.UTC().Format("2006-01-02T15:04:05Z")
+	if got != "2026-04-25T18:00:00Z" {
+		t.Errorf("BeforeTS=%q want 2026-04-25T18:00:00Z", got)
+	}
+	if store.LastOpts.Limit != 25 {
+		t.Errorf("limit=%d want 25", store.LastOpts.Limit)
+	}
+}
+
+// =====================================================================
+// Response shape
+// =====================================================================
+
+func TestChatHistoryHandler_EmptyResultIsArrayNotNull(t *testing.T) {
+	// nil messages slice from the store must serialize as `[]`,
+	// not `null` — canvas's JSON parser has one path.
+	store := &fakeStore{ReturnMessages: nil, ReturnReachedEnd: true}
+	r := newRouter(store)
+	w := doChatHistoryRequest(t, r, "/workspaces/"+testWorkspaceID+"/chat-history")
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status=%d", w.Code)
+	}
+	var resp ChatHistoryResponse
+	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("body not JSON: %v", err)
+	}
+	// json.Unmarshal of `null` into a []slice yields a nil — assert
+	// the JSON literally contains "[]" so a future change that
+	// forgets the nil-coercion would fail loudly.
+	if !strings.Contains(w.Body.String(), `"messages":[]`) {
+		t.Errorf("body should contain `\"messages\":[]`; got %s", w.Body.String())
+	}
+	if !resp.ReachedEnd {
+		t.Errorf("reached_end not propagated")
+	}
+}
+
+func TestChatHistoryHandler_NonEmptyResponsePreservesShape(t *testing.T) {
+	size := int64(4096)
+	store := &fakeStore{
+		ReturnMessages: []messagestore.ChatMessage{
+			{
+				ID:        "msg-1",
+				Role:      "user",
+				Content:   "hi",
+				Timestamp: "2026-04-25T18:00:00Z",
+			},
+			{
+				ID:      "msg-2",
+				Role:    "agent",
+				Content: "hello back",
+				Attachments: []messagestore.ChatAttachment{
+					{Name: "img.png", URI: "workspace:/img.png", MimeType: "image/png", Size: &size},
+				},
+				Timestamp: "2026-04-25T18:00:01Z",
+			},
+		},
+		ReturnReachedEnd: false,
+	}
+	r := newRouter(store)
+	w := doChatHistoryRequest(t, r, "/workspaces/"+testWorkspaceID+"/chat-history")
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status=%d body=%s", w.Code, w.Body.String())
+	}
+	var resp ChatHistoryResponse
+	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("body not JSON: %v", err)
+	}
+	if len(resp.Messages) != 2 {
+		t.Fatalf("messages=%d want 2", len(resp.Messages))
+	}
+	if resp.Messages[1].Attachments[0].Size == nil || *resp.Messages[1].Attachments[0].Size != 4096 {
+		t.Errorf("size pointer flattened in JSON round-trip")
+	}
+}
+
+// =====================================================================
+// Error mapping — store errors become 502, not 500/panic
+// =====================================================================
+
+func TestChatHistoryHandler_StoreErrorReturns502(t *testing.T) {
+	store := &fakeStore{ReturnErr: errors.New("simulated DB unreachable")}
+	r := newRouter(store)
+	w := doChatHistoryRequest(t, r, "/workspaces/"+testWorkspaceID+"/chat-history")
+
+	if w.Code != http.StatusBadGateway {
+		t.Errorf("expected 502 on store error, got %d", w.Code)
+	}
+	if !strings.Contains(w.Body.String(), "unavailable") {
+		t.Errorf("response body should communicate unavailability; got %q", w.Body.String())
+	}
+}
+
+// =====================================================================
+// Interface conformance — the platform-default Postgres impl is the
+// only impl in tree today, but the assertion catches future drift if
+// the interface evolves and the impl falls behind.
+// =====================================================================
+
+func TestMessageStoreInterface_PostgresImplSatisfies(t *testing.T) {
+	// Compile-time assertion lives in messagestore/postgres_store.go
+	// (`var _ MessageStore = (*PostgresMessageStore)(nil)`). This
+	// runtime test exists only to keep the conformance visible in
+	// the handler test file — a reader of chat_history_test.go
+	// shouldn't have to traverse to the messagestore package to see
+	// what the handler is paired with.
+	var s messagestore.MessageStore = messagestore.NewPostgresMessageStore(nil)
+	_ = s
+}
@@ -10,6 +10,7 @@ import (

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/textutil"
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
 )
@@ -164,10 +165,10 @@ func (h *DelegationHandler) Delegate(c *gin.Context) {
 	go h.executeDelegation(sourceID, body.TargetID, delegationID, a2aBody)

 	// Broadcast event so canvas shows delegation in real-time
-	h.broadcaster.RecordAndBroadcast(ctx, "DELEGATION_SENT", sourceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventDelegationSent), sourceID, map[string]interface{}{
 		"delegation_id": delegationID,
 		"target_id":     body.TargetID,
-		"task_preview":  truncate(body.Task, 100),
+		"task_preview":  textutil.TruncateBytes(body.Task, 100),
 	})

 	resp := gin.H{
@@ -317,7 +318,7 @@ func (h *DelegationHandler) executeDelegation(sourceID, targetID, delegationID s

 	// Update status: pending → dispatched
 	h.updateDelegationStatus(sourceID, delegationID, "dispatched", "")
-	h.broadcaster.RecordAndBroadcast(ctx, "DELEGATION_STATUS", sourceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventDelegationStatus), sourceID, map[string]interface{}{
 		"delegation_id": delegationID, "target_id": targetID, "status": "dispatched",
 	})

@@ -352,7 +353,7 @@ func (h *DelegationHandler) executeDelegation(sourceID, targetID, delegationID s
 			log.Printf("Delegation %s: failed to insert error log: %v", delegationID, err)
 		}

-		h.broadcaster.RecordAndBroadcast(ctx, "DELEGATION_FAILED", sourceID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventDelegationFailed), sourceID, map[string]interface{}{
 			"delegation_id": delegationID, "target_id": targetID, "error": proxyErr.Error(),
 		})
 		// RFC #2829 PR-2 result-push (see UpdateStatus for rationale).
@@ -388,7 +389,7 @@ func (h *DelegationHandler) executeDelegation(sourceID, targetID, delegationID s
 		`, sourceID, sourceID, targetID, "Delegation queued — target at capacity", string(queuedJSON)); err != nil {
 			log.Printf("Delegation %s: failed to insert queued log: %v", delegationID, err)
 		}
-		h.broadcaster.RecordAndBroadcast(ctx, "DELEGATION_STATUS", sourceID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventDelegationStatus), sourceID, map[string]interface{}{
 			"delegation_id": delegationID, "target_id": targetID, "status": "queued",
 		})
 		return
@@ -407,7 +408,7 @@ func (h *DelegationHandler) executeDelegation(sourceID, targetID, delegationID s
 	if _, err := db.DB.ExecContext(ctx, `
 		INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, target_id, summary, response_body, status)
 		VALUES ($1, 'delegation', 'delegate_result', $2, $3, $4, $5::jsonb, 'completed')
-	`, sourceID, sourceID, targetID, "Delegation completed ("+truncate(responseText, 80)+")", string(respJSON)); err != nil {
+	`, sourceID, sourceID, targetID, "Delegation completed ("+textutil.TruncateBytes(responseText, 80)+")", string(respJSON)); err != nil {
 		log.Printf("Delegation %s: failed to insert success log: %v", delegationID, err)
 	}

@@ -420,10 +421,10 @@ func (h *DelegationHandler) executeDelegation(sourceID, targetID, delegationID s
 	// delegation_ledger_integration_test.go.
 	recordLedgerStatus(ctx, delegationID, "completed", "", responseText)
 	h.updateDelegationStatus(sourceID, delegationID, "completed", "")
-	h.broadcaster.RecordAndBroadcast(ctx, "DELEGATION_COMPLETE", sourceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventDelegationComplete), sourceID, map[string]interface{}{
 		"delegation_id":    delegationID,
 		"target_id":        targetID,
-		"response_preview": truncate(responseText, 200),
+		"response_preview": textutil.TruncateBytes(responseText, 200),
 	})
 	// RFC #2829 PR-2 result-push (see UpdateStatus for rationale).
 	pushDelegationResultToInbox(ctx, sourceID, delegationID, "completed", responseText, "")
@@ -503,10 +504,10 @@ func (h *DelegationHandler) Record(c *gin.Context) {
 	recordLedgerInsert(ctx, sourceID, body.TargetID, body.DelegationID, body.Task, "")
 	recordLedgerStatus(ctx, body.DelegationID, "dispatched", "", "")

-	h.broadcaster.RecordAndBroadcast(ctx, "DELEGATION_SENT", sourceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventDelegationSent), sourceID, map[string]interface{}{
 		"delegation_id": body.DelegationID,
 		"target_id":     body.TargetID,
-		"task_preview":  truncate(body.Task, 100),
+		"task_preview":  textutil.TruncateBytes(body.Task, 100),
 	})

 	c.JSON(http.StatusAccepted, gin.H{
@@ -555,12 +556,12 @@ func (h *DelegationHandler) UpdateStatus(c *gin.Context) {
 		if _, err := db.DB.ExecContext(ctx, `
 			INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, response_body, status)
 			VALUES ($1, 'delegation', 'delegate_result', $2, $3, $4::jsonb, 'completed')
-		`, sourceID, sourceID, "Delegation completed ("+truncate(body.ResponsePreview, 80)+")", string(respJSON)); err != nil {
+		`, sourceID, sourceID, "Delegation completed ("+textutil.TruncateBytes(body.ResponsePreview, 80)+")", string(respJSON)); err != nil {
 			log.Printf("Delegation UpdateStatus: result insert failed for %s: %v", delegationID, err)
 		}
-		h.broadcaster.RecordAndBroadcast(ctx, "DELEGATION_COMPLETE", sourceID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventDelegationComplete), sourceID, map[string]interface{}{
 			"delegation_id":    delegationID,
-			"response_preview": truncate(body.ResponsePreview, 200),
+			"response_preview": textutil.TruncateBytes(body.ResponsePreview, 200),
 		})
 		// RFC #2829 PR-2 result-push: when the gate is on, also write an
 		// a2a_receive row so the caller's inbox poller surfaces this to
@@ -570,7 +571,7 @@ func (h *DelegationHandler) UpdateStatus(c *gin.Context) {
 		// the result instead of holding open an HTTP connection.
 		pushDelegationResultToInbox(ctx, sourceID, delegationID, "completed", body.ResponsePreview, "")
 	} else {
-		h.broadcaster.RecordAndBroadcast(ctx, "DELEGATION_FAILED", sourceID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventDelegationFailed), sourceID, map[string]interface{}{
 			"delegation_id": delegationID,
 			"error":         body.Error,
 		})
@@ -626,7 +627,7 @@ func (h *DelegationHandler) ListDelegations(c *gin.Context) {
 			entry["error"] = errorDetail
 		}
 		if responseBody != "" {
-			entry["response_preview"] = truncate(responseBody, 300)
+			entry["response_preview"] = textutil.TruncateBytes(responseBody, 300)
 		}
 		delegations = append(delegations, entry)
 	}
@@ -727,9 +728,3 @@ func extractResponseText(body []byte) string {
 	return string(body)
 }

-func truncate(s string, max int) string {
-	if len(s) <= max {
-		return s
-	}
-	return s[:max] + "..."
-}
@@ -8,6 +8,7 @@ import (
 	"time"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/textutil"
 )

 // delegation_ledger.go — durable per-task ledger for A2A delegation
@@ -50,40 +51,15 @@ func NewDelegationLedger(handle *sql.DB) *DelegationLedger {
 	return &DelegationLedger{db: handle}
 }

-// truncatePreview caps stored preview at 4KB. The full prompt/response is
-// already in activity_logs.{request,response}_body — this is the at-a-glance
-// view for the dashboard, not a forensic record.
+// previewCap caps stored preview at 4KB. The full prompt/response is
+// already in activity_logs.{request,response}_body — this is the
+// at-a-glance view for the dashboard, not a forensic record.
 //
-// Rune-safe: previous byte-slice form (s[:previewCap]) split on a byte
-// boundary, which on a multi-byte codepoint at byte 4096 produced
-// invalid UTF-8 — Postgres JSONB rejects → ledger row not inserted →
-// audit gap. Issue #2962. Walks the string by rune, stops at the last
-// rune-boundary index that fits inside the cap. ASCII-only strings hit
-// the cap exactly; CJK/emoji strings stop slightly under the cap,
-// never over.
-//
-// Mirrors the truncatePreviewRunes fix from agent_message_writer.go
-// (#2959). Both call sites should consume a shared helper after both
-// fixes have landed — followup deduplication tracked in #2962's body.
+// Truncation goes through textutil.TruncateBytesNoMarker so it's
+// rune-safe (#2026 / #2959 / #2962 bug class: byte-slice mid-codepoint
+// → Postgres JSONB rejects → silent INSERT failure → audit gap).
 const previewCap = 4096

-func truncatePreview(s string) string {
-	if len(s) <= previewCap {
-		return s
-	}
-	// Range over a string yields rune-boundary byte indices. Walk
-	// until the next index would exceed previewCap; the previous
-	// index is the safe truncation point.
-	end := 0
-	for i := range s {
-		if i > previewCap {
-			break
-		}
-		end = i
-	}
-	return s[:end]
-}
-
 // InsertOpts is the agent's record-of-intent. Caller, callee, task preview,
 // and the chosen delegation_id are required; idempotency_key is optional.
 type InsertOpts struct {
@@ -118,7 +94,7 @@ func (l *DelegationLedger) Insert(ctx context.Context, opts InsertOpts) {
 		) VALUES ($1, $2, $3, $4, 'queued', $5, $6)
 		ON CONFLICT (delegation_id) DO NOTHING
 	`, opts.DelegationID, opts.CallerID, opts.CalleeID,
-		truncatePreview(opts.TaskPreview), deadline, idemArg)
+		textutil.TruncateBytesNoMarker(opts.TaskPreview, previewCap), deadline, idemArg)
 	if err != nil {
 		log.Printf("delegation_ledger Insert(%s): %v", opts.DelegationID, err)
 	}
@@ -197,7 +173,7 @@ func (l *DelegationLedger) SetStatus(ctx context.Context,
 		    result_preview = NULLIF($4, ''),
 		    updated_at = now()
 		WHERE delegation_id = $1
-	`, delegationID, status, errorDetail, truncatePreview(resultPreview))
+	`, delegationID, status, errorDetail, textutil.TruncateBytesNoMarker(resultPreview, previewCap))
 	return err
 }

@@ -2,6 +2,7 @@ package handlers

 import (
 	"context"
+	"database/sql/driver"
 	"errors"
 	"strings"
 	"testing"
@@ -74,15 +75,20 @@ func TestLedgerInsert_TruncatesOversizedPreview(t *testing.T) {
 	mock := setupTestDB(t)
 	l := NewDelegationLedger(nil)

-	huge := strings.Repeat("x", 10_000) // > previewCap
+	// 4096 / 3 = 1365 runes; +10 for margin so we cross the cap.
+	// '世' is 3 bytes in UTF-8 (worst case for byte-cap rune walking).
+	huge := strings.Repeat("世", (previewCap/3)+10)
+	if len(huge) <= previewCap {
+		t.Fatalf("test setup: input too short (%d bytes) — must exceed previewCap=%d", len(huge), previewCap)
+	}

 	mock.ExpectExec(`INSERT INTO delegations`).
 		WithArgs(
 			"deleg-big",
 			"c", "ca",
-			sqlmock.AnyArg(), // truncated preview — verify length below via custom matcher
-			sqlmock.AnyArg(),
-			sqlmock.AnyArg(),
+			capValidUTF8Matcher{cap: previewCap}, // truncated preview must fit cap AND be valid UTF-8
+			sqlmock.AnyArg(),                     // deadline
+			sqlmock.AnyArg(),                     // idempotency_key
 		).
 		WillReturnResult(sqlmock.NewResult(0, 1))

@@ -97,87 +103,28 @@ func TestLedgerInsert_TruncatesOversizedPreview(t *testing.T) {
 	}
 }

-// ---------- truncatePreview unit ----------
+// capValidUTF8Matcher pins #2962 at the integration boundary: the
+// preview that lands in the INSERT MUST be valid UTF-8 (else Postgres
+// JSONB rejects → silent audit gap) AND fit within the byte cap. Pre-
+// migration this would have asserted on the corrupted "世" mid-codepoint
+// byte slice; post-migration it asserts the truncated preview is a
+// clean rune-aligned prefix.
+type capValidUTF8Matcher struct{ cap int }

-func TestTruncatePreview_UnderCap(t *testing.T) {
-	in := "short"
-	if got := truncatePreview(in); got != in {
-		t.Errorf("under-cap should passthrough; got %q", got)
+func (m capValidUTF8Matcher) Match(v driver.Value) bool {
+	s, ok := v.(string)
+	if !ok {
+		return false
 	}
+	return len(s) <= m.cap && utf8.ValidString(s)
 }

-func TestTruncatePreview_OverCapTruncatesAtBoundary(t *testing.T) {
-	in := strings.Repeat("a", previewCap+100)
-	got := truncatePreview(in)
-	if len(got) != previewCap {
-		t.Errorf("expected len=%d got len=%d", previewCap, len(got))
-	}
-}
-
-func TestTruncatePreview_ExactlyAtCap(t *testing.T) {
-	in := strings.Repeat("a", previewCap)
-	got := truncatePreview(in)
-	if got != in {
-		t.Errorf("at-cap should passthrough unchanged")
-	}
-}
-
-// TestTruncatePreview_NeverProducesInvalidUTF8 — pins #2962. The old
-// byte-slice implementation (s[:previewCap]) split on a byte boundary,
-// so a multi-byte codepoint straddling byte 4096 produced invalid
-// UTF-8 → Postgres JSONB rejects → ledger row not inserted → audit
-// gap. Test feeds a CJK / emoji-padded string longer than previewCap
-// and asserts utf8.ValidString on the result.
-func TestTruncatePreview_NeverProducesInvalidUTF8(t *testing.T) {
-	// Build a string of '世' (3 bytes per rune in UTF-8) that's just
-	// past the cap. With the old implementation, the slice at byte
-	// previewCap would land mid-rune and ValidString would fail.
-	// With the rune-aware implementation, the result is always valid
-	// UTF-8 even if the byte length is < previewCap.
-	rune3 := "世" // U+4E16, 3 bytes
-	// Need at least previewCap/3 + 1 runes so we cross the cap with
-	// margin to spare.
-	in := strings.Repeat(rune3, (previewCap/3)+10)
-	if len(in) <= previewCap {
-		t.Fatalf("test setup: input too short (%d bytes) — must exceed previewCap=%d", len(in), previewCap)
-	}
-	got := truncatePreview(in)
-	if !utf8.ValidString(got) {
-		t.Errorf("truncatePreview produced invalid UTF-8 — JSONB will reject this row. len(got)=%d", len(got))
-	}
-	if len(got) > previewCap {
-		t.Errorf("truncatePreview exceeded cap: len(got)=%d > previewCap=%d", len(got), previewCap)
-	}
-	// Defense-in-depth: the result should also be a clean rune
-	// prefix of the input — not some garbled sequence.
-	if !strings.HasPrefix(in, got) {
-		t.Errorf("truncatePreview should return a prefix of the input")
-	}
-}
-
-// TestTruncatePreview_MultiByteAtBoundary — most-targeted regression.
-// Feeds an input where the cap byte falls EXACTLY in the middle of a
-// 3-byte codepoint. Pre-fix, this is the case that produces invalid
-// UTF-8; post-fix, the truncate stops at the previous rune boundary.
-func TestTruncatePreview_MultiByteAtBoundary(t *testing.T) {
-	// Build a string that's `previewCap-1` ASCII bytes followed by
-	// '世' (3 bytes). Total = previewCap + 2. The old impl would
-	// slice at byte previewCap, landing inside the '世' codepoint.
-	prefix := strings.Repeat("a", previewCap-1)
-	in := prefix + "世"
-	if len(in) != previewCap+2 {
-		t.Fatalf("test setup: expected len %d, got %d", previewCap+2, len(in))
-	}
-	got := truncatePreview(in)
-	if !utf8.ValidString(got) {
-		t.Errorf("truncatePreview produced invalid UTF-8 at the multi-byte boundary case")
-	}
-	// Result should be exactly the ASCII prefix — '世' was past
-	// the cap so it must be dropped entirely.
-	if got != prefix {
-		t.Errorf("expected exact ASCII prefix, got %q (len=%d)", got[len(got)-10:], len(got))
-	}
-}
+// Helper-level truncation tests now live in
+// internal/textutil/truncate_test.go. The integration-level path
+// (TestLedgerInsert_TruncatesOversizedPreview above) still exercises
+// the previewCap boundary through the SQL write so a regression in
+// the wiring (wrong cap, wrong helper, missing call) would still go
+// red here.

 // ---------- SetStatus lifecycle ----------

@@ -8,6 +8,7 @@ import (
 	"net/http"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/wsauth"
 	"github.com/gin-gonic/gin"
 )
@@ -100,7 +101,7 @@ func (h *WorkspaceHandler) RotateExternalCredentials(c *gin.Context) {
 	// see when credentials were rotated. No PII; the token plaintext
 	// is NOT logged.
 	if h.broadcaster != nil {
-		h.broadcaster.RecordAndBroadcast(ctx, "EXTERNAL_CREDENTIALS_ROTATED", id, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventExternalCredentialsRotated), id, map[string]interface{}{
 			"workspace_id": id,
 		})
 	}
@@ -331,43 +331,84 @@ func memoryToView(m contract.Memory) MemoryView {
 }

 // namespacesToViews converts resolver namespaces into UI-friendly
-// views. Stable sort: workspace → team → org → custom, then by name.
+// views. Prefers `DisplayName` from the resolver (workspace.name from
+// the DB) when present; falls back to a UUID-prefix label.
+//
+// Issue #2988: pre-fix, every namespace used a shortID-truncated UUID
+// label. On a root workspace where workspace==team==org IDs collide
+// (resolver derive() degenerate case), all three labels rendered
+// identically. DisplayName disambiguates by surfacing real workspace
+// names — the canvas dropdown now reads "Workspace (mac laptop)" /
+// "Team (mac laptop)" / "Org (mac laptop)" for a root workspace
+// rather than three identical UUID prefixes. The `kind` prefix
+// "Workspace/Team/Org" still carries the semantic distinction.
 func namespacesToViews(in []namespace.Namespace) []NamespaceView {
 	views := make([]NamespaceView, 0, len(in))
 	for _, n := range in {
 		views = append(views, NamespaceView{
 			Name:  n.Name,
 			Kind:  n.Kind,
-			Label: namespaceLabel(n.Name, n.Kind),
+			Label: namespaceLabelWithName(n.Name, n.Kind, n.DisplayName),
 		})
 	}
 	return views
 }

-// namespaceLabel renders a human-friendly label for a namespace. The
-// canvas displays this directly; we keep the formatting server-side
-// so the shape stays consistent across UIs (canvas, future TUI, etc.).
+// namespaceLabel renders a human-friendly label for a namespace using
+// the UUID-prefix fallback only. Kept for back-compat with callers
+// that don't yet plumb a display name. New callers should use
+// namespaceLabelWithName which prefers the workspace's display name
+// when available.
 //
-// Format:
-//   workspace:abc-123 → "Workspace (abc-123)"   (UUID short-prefixed)
+// Format (UUID-prefix fallback):
+//   workspace:abc-123 → "Workspace (abc-123)"
 //   team:t-1          → "Team (t-1)"
 //   org:acme          → "Org (acme)"
-//   custom:foo        → "foo"                   (operator-defined; raw)
+//   custom:foo        → "foo"
 func namespaceLabel(name string, kind contract.NamespaceKind) string {
+	return namespaceLabelWithName(name, kind, "")
+}
+
+// namespaceLabelWithName renders the human-friendly label, preferring
+// `displayName` when non-empty.
+//
+// When displayName is set:
+//   Workspace, "mac laptop"    → "Workspace (mac laptop)"
+//   Team, "Engineering team"   → "Team (Engineering team)"
+//   Org, "Hongming's Org"      → "Org (Hongming's Org)"
+//
+// When displayName is empty (lookup miss, future-migration drop, etc.),
+// falls back to the UUID-prefix shape for back-compat.
+//
+// Custom namespaces ignore displayName because they're operator-defined
+// — the operator chose the raw suffix as the label, surfacing a
+// different "name" would be a UX surprise.
+func namespaceLabelWithName(name string, kind contract.NamespaceKind, displayName string) string {
 	suffix := ""
 	if i := indexOfColon(name); i >= 0 && i+1 < len(name) {
 		suffix = name[i+1:]
 	}
 	switch kind {
 	case contract.NamespaceKindWorkspace:
+		if displayName != "" {
+			return "Workspace (" + displayName + ")"
+		}
 		return "Workspace (" + shortID(suffix) + ")"
 	case contract.NamespaceKindTeam:
+		if displayName != "" {
+			return "Team (" + displayName + ")"
+		}
 		return "Team (" + shortID(suffix) + ")"
 	case contract.NamespaceKindOrg:
+		if displayName != "" {
+			return "Org (" + displayName + ")"
+		}
 		return "Org (" + suffix + ")"
 	case contract.NamespaceKindCustom:
-		// Custom namespaces are operator-defined; surface the raw
-		// suffix so they can label them however they want.
+		// Operator-defined; the suffix IS the label they chose.
+		// displayName is ignored — surfacing a different name would
+		// be a UX surprise for an operator who deliberately named
+		// the namespace.
 		if suffix == "" {
 			return name
 		}
@@ -507,6 +507,92 @@ func TestMemoriesV2_Forget_MissingMemoryID_400(t *testing.T) {
 // View-shaping unit tests — pin individual helpers
 // ─────────────────────────────────────────────────────────────────────────────

+// namespaceLabelWithName tests — the new code path that prefers
+// DisplayName over UUID-prefix fallback (issue #2988).
+func TestNamespaceLabelWithName_PrefersDisplayNameWhenSet(t *testing.T) {
+	cases := []struct {
+		name         string
+		raw          string
+		kind         contract.NamespaceKind
+		display      string
+		want         string
+	}{
+		{"workspace with name", "workspace:abc-1234", contract.NamespaceKindWorkspace, "mac laptop", "Workspace (mac laptop)"},
+		{"team with name", "team:abc-1234", contract.NamespaceKindTeam, "Engineering", "Team (Engineering)"},
+		{"org with name", "org:acme", contract.NamespaceKindOrg, "Hongming's Org", "Org (Hongming's Org)"},
+		// Custom ignores displayName by design — operator chose the suffix.
+		{"custom ignores displayName", "custom:ops-shared", contract.NamespaceKindCustom, "FancyName", "ops-shared"},
+		{"unknown kind falls through", "weird:x", contract.NamespaceKind("future"), "WhoCares", "weird:x"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := namespaceLabelWithName(tc.raw, tc.kind, tc.display)
+			if got != tc.want {
+				t.Errorf("namespaceLabelWithName(%q, %q, %q) = %q, want %q",
+					tc.raw, tc.kind, tc.display, got, tc.want)
+			}
+		})
+	}
+}
+
+func TestNamespaceLabelWithName_FallsBackToUUIDPrefixWhenEmpty(t *testing.T) {
+	// When displayName is empty (NULL in DB, lookup miss, etc.), the
+	// label shape MUST match the legacy UUID-prefix shape exactly so
+	// existing canvas behaviour is unchanged for callers that don't
+	// plumb a name.
+	cases := []struct {
+		raw  string
+		kind contract.NamespaceKind
+		want string
+	}{
+		{"workspace:abcdefghij", contract.NamespaceKindWorkspace, "Workspace (abcdefgh)"},
+		{"team:t-99", contract.NamespaceKindTeam, "Team (t-99)"},
+		{"org:acme", contract.NamespaceKindOrg, "Org (acme)"},
+	}
+	for _, tc := range cases {
+		got := namespaceLabelWithName(tc.raw, tc.kind, "")
+		if got != tc.want {
+			t.Errorf("displayName=\"\" path: got %q, want %q", got, tc.want)
+		}
+	}
+}
+
+func TestNamespacesToViews_PassesDisplayNameThrough(t *testing.T) {
+	in := []namespace.Namespace{
+		{Name: "workspace:root-1", Kind: contract.NamespaceKindWorkspace, DisplayName: "mac laptop"},
+		{Name: "team:root-1", Kind: contract.NamespaceKindTeam, DisplayName: "mac laptop"}, // root → team aliases self
+		{Name: "org:root-1", Kind: contract.NamespaceKindOrg, DisplayName: "mac laptop"},
+	}
+	out := namespacesToViews(in)
+	if len(out) != 3 {
+		t.Fatalf("len = %d, want 3", len(out))
+	}
+	wantLabels := []string{
+		"Workspace (mac laptop)",
+		"Team (mac laptop)",
+		"Org (mac laptop)",
+	}
+	for i, v := range out {
+		if v.Label != wantLabels[i] {
+			t.Errorf("[%d] label = %q, want %q", i, v.Label, wantLabels[i])
+		}
+	}
+}
+
+func TestNamespacesToViews_FallsBackToUUIDLabelWhenDisplayNameEmpty(t *testing.T) {
+	// Exercises the back-compat path — DisplayName="" plumbs through
+	// to namespaceLabelWithName which returns the legacy UUID-prefix
+	// label. This is what callers see when the workspaces table
+	// has a NULL name (defensive — workspaces.name is NOT NULL today).
+	in := []namespace.Namespace{
+		{Name: "workspace:root-1", Kind: contract.NamespaceKindWorkspace}, // no DisplayName
+	}
+	out := namespacesToViews(in)
+	if out[0].Label != "Workspace (root-1)" {
+		t.Errorf("fallback label = %q, want %q", out[0].Label, "Workspace (root-1)")
+	}
+}
+
 func TestNamespaceLabel_AllKinds(t *testing.T) {
 	cases := []struct {
 		name string
@@ -20,12 +20,14 @@ import (
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/channels"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/crypto"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/models"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/provisioner"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/provlog"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/scheduler"
 	"github.com/google/uuid"
 )
+
 // createWorkspaceTree recursively materialises an OrgWorkspace (and its
 // descendants) into the workspaces + canvas_layouts tables and kicks off
 // Docker provisioning. absX/absY are THIS workspace's absolute canvas
@@ -80,61 +82,6 @@ func (h *OrgHandler) createWorkspaceTree(ws OrgWorkspace, parentID *string, absX
 		}
 	}

-	// 5s timeout bounds the lookup independently of any HTTP request
-	// context. createWorkspaceTree runs in goroutines spawned from the
-	// /org/import handler, so plumbing the request context here would
-	// cascade-cancel into provisionWorkspaceAuto and abort in-flight
-	// EC2 provisioning if the client disconnected mid-import — that's
-	// the wrong behaviour. A short bounded timeout protects the
-	// per-row SELECT against a wedged DB without taking the
-	// drop-everything-on-disconnect tradeoff.
-	ctxLookup, cancelLookup := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancelLookup()
-	// Idempotency: if a workspace with the same (parent_id, name) already
-	// exists, skip the INSERT + canvas_layouts + broadcast + provisioning.
-	// This is what makes /org/import safe to call multiple times — the
-	// historical leak was every call recreating the entire tree (see
-	// tenant-hongming, 72 distinct child workspaces in 4 days, all from
-	// repeated org-template spawns of the same template).
-	//
-	// Recursion still runs on the existing id so partial-match templates
-	// (parent exists, some children missing) backfill the missing children
-	// instead of either no-op'ing the whole subtree or duplicating the
-	// existing children.
-	//
-	// /org/import is ADDITIVE-ONLY, never destructive. Children present
-	// in the existing tree but absent from the new template are
-	// preserved (no DELETE on diff). Skip-path also does NOT propagate
-	// updates to existing nodes — a re-import that adds an
-	// initial_memory or schedule to an existing workspace is silently
-	// dropped (the function bypasses seedInitialMemories, schedule SQL,
-	// channel config for skipped rows). To force-update an existing
-	// tree, delete and re-import or use a future /org/sync route.
-	existingID, existing, lookupErr := h.lookupExistingChild(ctxLookup, ws.Name, parentID)
-	if lookupErr != nil {
-		return fmt.Errorf("idempotency check for %s: %w", ws.Name, lookupErr)
-	}
-	if existing {
-		log.Printf("Org import: %q already exists (id=%s) — skipping create+provision, recursing into children for partial-match", ws.Name, existingID)
-		parentRef := ""
-		if parentID != nil {
-			parentRef = *parentID
-		}
-		provlog.Event("provision.skip_existing", map[string]any{
-			"name":        ws.Name,
-			"existing_id": existingID,
-			"parent_id":   parentRef,
-			"tier":        tier,
-		})
-		*results = append(*results, map[string]interface{}{
-			"id":      existingID,
-			"name":    ws.Name,
-			"tier":    tier,
-			"skipped": true,
-		})
-		return h.recurseChildrenForImport(ws, existingID, absX, absY, defaults, orgBaseDir, results, provisionSem)
-	}
-
 	id := uuid.New().String()
 	awarenessNS := workspaceAwarenessNamespace(id)

@@ -186,10 +133,67 @@ func (h *OrgHandler) createWorkspaceTree(ws OrgWorkspace, parentID *string, absX
 	if maxConcurrent <= 0 {
 		maxConcurrent = models.DefaultMaxConcurrentTasks
 	}
-	_, err := db.DB.ExecContext(ctx, `
+	// TOCTOU-safe insert (#2872 Critical 1).
+	//
+	// `ON CONFLICT DO NOTHING` paired with the partial unique index
+	// from migration 20260506000000_workspaces_unique_parent_name.up.sql
+	// atomically resolves a race window that the prior
+	// lookup-then-insert had: two concurrent /org/import POSTs both
+	// saw "not found" in lookupExistingChild and both INSERT'd the
+	// same (parent_id, name). After this swap the SECOND INSERT
+	// silently no-ops, RETURNING returns 0 rows → sql.ErrNoRows, and
+	// the skip-path runs.
+	//
+	// ON CONFLICT target uses (COALESCE(parent_id,...), name) WHERE
+	// status != 'removed' — must match the partial-index predicate
+	// EXACTLY for Postgres to consider the index applicable.
+	var insertedID string
+	err := db.DB.QueryRowContext(ctx, `
 		INSERT INTO workspaces (id, name, role, tier, runtime, awareness_namespace, status, parent_id, workspace_dir, workspace_access, max_concurrent_tasks)
 		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
-	`, id, ws.Name, role, tier, runtime, awarenessNS, "provisioning", parentID, workspaceDir, workspaceAccess, maxConcurrent)
+		ON CONFLICT (COALESCE(parent_id, '00000000-0000-0000-0000-000000000000'::uuid), name)
+		WHERE status != 'removed'
+		DO NOTHING
+		RETURNING id
+	`, id, ws.Name, role, tier, runtime, awarenessNS, "provisioning", parentID, workspaceDir, workspaceAccess, maxConcurrent).Scan(&insertedID)
+	if errors.Is(err, sql.ErrNoRows) {
+		// Skip path — a non-removed row already exists for
+		// (parent_id, name). Re-select its id; idempotency-friendly
+		// semantics match the original lookupExistingChild path
+		// (parent_id IS NOT DISTINCT FROM matches NULL too,
+		// status='removed' rows are ignored).
+		ctxLookup, cancelLookup := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancelLookup()
+		existingID, found, selErr := h.lookupExistingChild(ctxLookup, ws.Name, parentID)
+		if selErr != nil {
+			return fmt.Errorf("post-conflict re-select for %s: %w", ws.Name, selErr)
+		}
+		if !found {
+			// Index conflicted but row vanished between INSERT and
+			// re-SELECT (status flipped to 'removed' concurrently).
+			// Surface as an error rather than silently retrying —
+			// the user can re-trigger /org/import safely.
+			return fmt.Errorf("workspace %q conflicted on insert but not visible on re-select (concurrent status flip?)", ws.Name)
+		}
+		log.Printf("Org import: %q already exists (id=%s) — skipping create+provision, recursing into children for partial-match", ws.Name, existingID)
+		parentRef := ""
+		if parentID != nil {
+			parentRef = *parentID
+		}
+		provlog.Event("provision.skip_existing", map[string]any{
+			"name":        ws.Name,
+			"existing_id": existingID,
+			"parent_id":   parentRef,
+			"tier":        tier,
+		})
+		*results = append(*results, map[string]interface{}{
+			"id":      existingID,
+			"name":    ws.Name,
+			"tier":    tier,
+			"skipped": true,
+		})
+		return h.recurseChildrenForImport(ws, existingID, absX, absY, defaults, orgBaseDir, results, provisionSem)
+	}
 	if err != nil {
 		log.Printf("Org import: failed to create %s: %v", ws.Name, err)
 		return fmt.Errorf("failed to create %s: %w", ws.Name, err)
@@ -227,7 +231,7 @@ func (h *OrgHandler) createWorkspaceTree(ws OrgWorkspace, parentID *string, absX
 	if parentID != nil {
 		payload["parent_id"] = *parentID
 	}
-	h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_PROVISIONING", id, payload)
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceProvisioning), id, payload)

 	// Seed initial memories from workspace config or defaults (issue #1050).
 	// Per-workspace initial_memories override defaults; if workspace has none,
@@ -243,7 +247,7 @@ func (h *OrgHandler) createWorkspaceTree(ws OrgWorkspace, parentID *string, absX
 		if _, err := db.DB.ExecContext(ctx, `UPDATE workspaces SET status = $1, url = $2 WHERE id = $3`, models.StatusOnline, ws.URL, id); err != nil {
 			log.Printf("Org import: external workspace status update failed for %s: %v", ws.Name, err)
 		}
-		h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_ONLINE", id, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceOnline), id, map[string]interface{}{
 			"name": ws.Name, "external": true,
 		})
 	} else if h.workspace.HasProvisioner() {
@@ -31,11 +31,25 @@ import (
 // tests pin the helper's three observable behaviors plus an AST gate
 // that catches future re-introductions of the un-checked INSERT.

+// lookupChildSQLRE anchors the sqlmock ExpectQuery on every load-bearing
+// token of lookupExistingChild's SELECT (org_import.go:639-645). A loose
+// substring match (the prior shape, just `SELECT id FROM workspaces`)
+// would silent-pass a regression that drops `IS NOT DISTINCT FROM`
+// (breaks NULL-parent matching), drops `parent_id` entirely (hijacks
+// siblings of the same name across different parents), or drops the
+// `status != 'removed'` filter (blocks re-import after Collapse).
+// RFC #2872 Important-2.
+//
+// The four anchored tokens are exactly the predicates the bug shapes
+// would tamper with. Whitespace is `\s+` so a future formatter pass
+// doesn't churn this string.
+const lookupChildSQLRE = `(?s)SELECT id FROM workspaces\s+WHERE name = \$1\s+AND parent_id IS NOT DISTINCT FROM \$2\s+AND status != 'removed'`
+
 func TestLookupExistingChild_NotFound_ReturnsFalseNoError(t *testing.T) {
 	mock := setupTestDB(t)
 	// 0-row result → driver returns sql.ErrNoRows on Scan.
 	parent := "parent-1"
-	mock.ExpectQuery(`SELECT id FROM workspaces`).
+	mock.ExpectQuery(lookupChildSQLRE).
 		WithArgs("Alpha", &parent).
 		WillReturnRows(sqlmock.NewRows([]string{"id"}))

@@ -56,7 +70,7 @@ func TestLookupExistingChild_NotFound_ReturnsFalseNoError(t *testing.T) {
 func TestLookupExistingChild_Found_ReturnsIDAndTrue(t *testing.T) {
 	mock := setupTestDB(t)
 	parent := "parent-1"
-	mock.ExpectQuery(`SELECT id FROM workspaces`).
+	mock.ExpectQuery(lookupChildSQLRE).
 		WithArgs("Alpha", &parent).
 		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow("ws-existing-uuid"))

@@ -79,7 +93,7 @@ func TestLookupExistingChild_NilParent_MatchesRoot(t *testing.T) {
 	// a plain `=` would never match a NULL row. Pin that roots
 	// (parent_id=NULL) are still found by the lookup.
 	mock := setupTestDB(t)
-	mock.ExpectQuery(`SELECT id FROM workspaces`).
+	mock.ExpectQuery(lookupChildSQLRE).
 		WithArgs("RootAgent", (*string)(nil)).
 		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow("ws-root-uuid"))

@@ -102,7 +116,7 @@ func TestLookupExistingChild_DBError_Propagates(t *testing.T) {
 	mock := setupTestDB(t)
 	parent := "parent-1"
 	connFail := errors.New("simulated postgres unavailable")
-	mock.ExpectQuery(`SELECT id FROM workspaces`).
+	mock.ExpectQuery(lookupChildSQLRE).
 		WithArgs("Alpha", &parent).
 		WillReturnError(connFail)

@@ -137,7 +151,7 @@ func TestLookupExistingChild_WrappedNoRows_TreatedAsNotFound(t *testing.T) {
 	mock := setupTestDB(t)
 	parent := "parent-1"
 	wrapped := fmt.Errorf("driver-wrapped: %w", sql.ErrNoRows)
-	mock.ExpectQuery(`SELECT id FROM workspaces`).
+	mock.ExpectQuery(lookupChildSQLRE).
 		WithArgs("Alpha", &parent).
 		WillReturnError(wrapped)

@@ -209,19 +223,42 @@ func findLookupAndWorkspacesInsertPos(t *testing.T, fname string, src []byte) (l
 	return
 }

-// Source-level guard — pins that org_import.go calls
-// h.lookupExistingChild BEFORE its INSERT INTO workspaces.
+// onConflictDoNothingRE pins the TOCTOU-safe shape introduced by
+// migration 20260506000000_workspaces_unique_parent_name.up.sql +
+// the org_import.go INSERT swap (#2872 Critical 1). The workspaces
+// INSERT MUST funnel concurrent collisions through the partial unique
+// index — `ON CONFLICT (...) WHERE status != 'removed' DO NOTHING`
+// is the literal pg statement form that achieves it.
+//
+// The pattern intentionally requires both the COALESCE expression
+// (so root-workspace NULL parents collide) AND the partial-index WHERE
+// clause (so 'removed' rows don't block re-imports). A regression that
+// drops either piece would make the index target a different shape
+// than the migration created, and Postgres would emit
+// "no unique or exclusion constraint matching the ON CONFLICT
+// specification" at runtime — but only on the FIRST collision attempt
+// in production, not in CI without a live race. This regex catches
+// the shape in source so the bug never ships.
+var onConflictDoNothingRE = regexp.MustCompile(
+	`(?s)ON\s+CONFLICT\s*\(\s*COALESCE\s*\(\s*parent_id\s*,\s*'00000000-0000-0000-0000-000000000000'::uuid\s*\)\s*,\s*name\s*\).*?WHERE\s+status\s*!=\s*'removed'.*?DO\s+NOTHING`,
+)
+
+// Source-level guard — pins that org_import.go's INSERT INTO workspaces
+// uses the TOCTOU-safe ON CONFLICT DO NOTHING pattern.
 //
 // Per memory feedback_behavior_based_ast_gates.md: pin the behavior
-// (idempotency check before INSERT), not just function names. If a
-// future refactor reintroduces the un-checked INSERT (the original
-// bug shape that leaked 72 workspaces in 4 days), this test fails.
+// (atomic conflict resolution at the DB), not just function names.
+// If a future refactor reintroduces the un-checked INSERT (the original
+// bug shape that leaked 72 workspaces in 4 days at tenant-hongming),
+// this test fails BEFORE the broken code reaches production where the
+// race window opens.
 //
-// AST-walk implementation closes the silent-false-pass mode that the
-// previous bytes.Index gate had — see workspacesInsertRE comment for
-// the failure mode (workspaces_audit / workspace_secrets / etc.
-// shadowing the real target via prefix match).
-func TestCreateWorkspaceTree_CallsLookupBeforeInsert(t *testing.T) {
+// Replaces an earlier "lookup-before-insert" gate that became obsolete
+// when this swap moved idempotency into the database. The earlier
+// gate would silent-false-pass against ON CONFLICT — even though that
+// shape is correct — because lookupExistingChild now runs AFTER the
+// INSERT (only on the skip path, to retrieve the existing id).
+func TestCreateWorkspaceTree_InsertUsesOnConflictDoNothing(t *testing.T) {
 	wd, err := os.Getwd()
 	if err != nil {
 		t.Fatalf("getwd: %v", err)
@@ -230,30 +267,24 @@ func TestCreateWorkspaceTree_CallsLookupBeforeInsert(t *testing.T) {
 	if err != nil {
 		t.Fatalf("read org_import.go: %v", err)
 	}
-	lookupPos, insertPos, fset := findLookupAndWorkspacesInsertPos(t, "org_import.go", src)
-
-	if lookupPos == token.NoPos {
-		t.Fatalf("AST: no call to lookupExistingChild in org_import.go — idempotency check removed?")
-	}
-	if insertPos == token.NoPos {
+	insertSQL := findWorkspacesInsertSQL(t, "org_import.go", src)
+	if insertSQL == "" {
 		t.Fatalf("AST: no SQL literal matching `^\\s*INSERT INTO workspaces\\s*\\(` in any CallExpr in org_import.go — schema change or rename?")
 	}
-	if lookupPos > insertPos {
-		t.Errorf("lookupExistingChild call at %s must come BEFORE INSERT INTO workspaces at %s — non-idempotent ordering would re-leak under repeat /org/import calls",
-			fset.Position(lookupPos), fset.Position(insertPos))
+	if !onConflictDoNothingRE.MatchString(insertSQL) {
+		t.Errorf("workspaces INSERT SQL does NOT use the TOCTOU-safe ON CONFLICT shape — concurrent /org/import POSTs will silently double-insert. Required pattern:\n  ON CONFLICT (COALESCE(parent_id, '00000000-...'::uuid), name) WHERE status != 'removed' DO NOTHING\n\nActual SQL:\n%s", insertSQL)
 	}
 }

-// TestGate_FailsWhenLookupAfterInsert proves the gate actually catches
-// the bug it's named after — running it against synthetic Go source
-// where the lookup call is positioned AFTER the workspaces INSERT must
-// produce lookupPos > insertPos, which the production gate flags as
-// an ERROR. Without this test the gate could regress to "always pass"
-// and we wouldn't notice until the bug shipped again.
+// TestGate_FailsWhenInsertOmitsOnConflict proves the gate actually
+// catches the bug it's named after — running it against synthetic Go
+// source where the workspaces INSERT lacks the ON CONFLICT clause must
+// fail the regex match. Without this test the gate could regress to
+// "always pass" and the TOCTOU window would silently reopen.
 //
-// Per memory feedback_assert_exact_not_substring.md: verify a
-// tightened test FAILS on old code before merging.
-func TestGate_FailsWhenLookupAfterInsert(t *testing.T) {
+// Per memory feedback_assert_exact_not_substring.md: verify the
+// tightened test FAILS on the bug shape before merging.
+func TestGate_FailsWhenInsertOmitsOnConflict(t *testing.T) {
 	const buggySrc = `package handlers

 import "context"
@@ -264,26 +295,57 @@ func (fakeDB) ExecContext(ctx context.Context, sql string, args ...interface{})

 type fakeOrgHandler struct{}

-func (h *fakeOrgHandler) lookupExistingChild(ctx context.Context, name string, parentID *string) (string, bool, error) {
-	return "", false, nil
-}
-
 func buggyCreate(h *fakeOrgHandler, db fakeDB, ctx context.Context, name string, parentID *string) {
-	// Bug shape: INSERT runs FIRST, lookup runs AFTER. This is the
-	// non-idempotent ordering the gate exists to forbid.
+	// Bug shape: bare INSERT, no ON CONFLICT. Two concurrent calls
+	// race past the unique-index check before either completes the
+	// transaction; constraint failure surfaces as a 500 to the
+	// caller (not graceful skip). Pre-#2872 this would silently
+	// duplicate-insert.
 	db.ExecContext(ctx, ` + "`INSERT INTO workspaces (id, name) VALUES ($1, $2)`" + `, "x", name)
-	h.lookupExistingChild(ctx, name, parentID)
 }
 `
-	lookupPos, insertPos, _ := findLookupAndWorkspacesInsertPos(t, "buggy.go", []byte(buggySrc))
-	if lookupPos == token.NoPos || insertPos == token.NoPos {
-		t.Fatalf("synthetic buggy source missing expected nodes (lookupPos=%v insertPos=%v) — helper logic regression", lookupPos, insertPos)
+	insertSQL := findWorkspacesInsertSQL(t, "buggy.go", []byte(buggySrc))
+	if insertSQL == "" {
+		t.Fatalf("synthetic buggy source missing workspaces INSERT — helper logic regression")
 	}
-	if lookupPos < insertPos {
-		t.Fatalf("synthetic bug shape (lookup AFTER insert) returned lookupPos=%d < insertPos=%d — gate would NOT fire on actual bug, regression!", lookupPos, insertPos)
+	if onConflictDoNothingRE.MatchString(insertSQL) {
+		t.Fatalf("synthetic bug shape (bare INSERT, no ON CONFLICT) was MATCHED by the gate — regression: gate would not flag the actual bug. SQL:\n%s", insertSQL)
 	}
-	// Implicit: lookupPos > insertPos here, which the production gate
-	// flags via t.Errorf. This proves the gate is live, not vestigial.
+}
+
+// findWorkspacesInsertSQL walks `src` and returns the unquoted SQL of
+// the first string literal matching workspacesInsertRE inside any
+// CallExpr's argument list. Returns "" if none found. Helper for the
+// ON CONFLICT gate above.
+func findWorkspacesInsertSQL(t *testing.T, fname string, src []byte) string {
+	t.Helper()
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, fname, src, parser.ParseComments)
+	if err != nil {
+		t.Fatalf("parse %s: %v", fname, err)
+	}
+	var sql string
+	ast.Inspect(file, func(n ast.Node) bool {
+		call, ok := n.(*ast.CallExpr)
+		if !ok {
+			return true
+		}
+		for _, arg := range call.Args {
+			lit, ok := arg.(*ast.BasicLit)
+			if !ok || lit.Kind != token.STRING {
+				continue
+			}
+			raw := lit.Value
+			if unq, err := strconv.Unquote(raw); err == nil {
+				raw = unq
+			}
+			if workspacesInsertRE.MatchString(raw) && sql == "" {
+				sql = raw
+			}
+		}
+		return true
+	})
+	return sql
 }

 // TestGate_IgnoresAuditTableShadow proves the regex tightening
@@ -451,6 +451,201 @@ func TestIntegration_PendingUploads_AckedIndexExists(t *testing.T) {
 	}
 }

+// TestIntegration_PollUpload_AtomicRollback_AcrossBothTables proves the
+// #149 cross-table contract at the database layer: when PutBatchTx and
+// LogActivityTx run in the same caller-owned Tx and an activity INSERT
+// fails after some rows have already been INSERTed, Rollback unwinds
+// BOTH tables, leaving zero rows.
+//
+// Coverage map (#149):
+//   - chat_files_poll_test.go's TestPollUpload_AtomicRollbackOnActivityInsertFailure
+//     uses sqlmock to prove the Go handler issues Begin / N inserts /
+//     Rollback in the right order (no Commit on failure path).
+//   - This integration test proves the helpers + real Postgres compose
+//     correctly: rollback after a mid-Tx activity insert failure
+//     actually reverts BOTH the prior activity row AND the
+//     pending_uploads rows from PutBatchTx.
+//   - The pre-existing TestIntegration_PendingUploads_PutBatch_AtomicRollback
+//     covers the pending_uploads-only case.
+//
+// Failure injection: a NUL byte in `summary` (TEXT column) — lib/pq
+// rejects it at the protocol layer. Same trick the existing PutBatch
+// AtomicRollback test uses for the pending_uploads INSERT.
+func TestIntegration_PollUpload_AtomicRollback_AcrossBothTables(t *testing.T) {
+	conn := integrationDB_PendingUploads(t)
+	ctx := context.Background()
+
+	// activity_logs has a FK to workspaces(id) — seed a real row so
+	// non-failing inserts succeed. Wipe activity_logs + this workspaces
+	// row at end so the next test sees a clean slate (the integrationDB
+	// helper only wipes pending_uploads).
+	wsID := uuid.New()
+	if _, err := conn.ExecContext(ctx,
+		`INSERT INTO workspaces (id, name) VALUES ($1, 'test-149-rollback')`, wsID,
+	); err != nil {
+		t.Fatalf("seed workspace: %v", err)
+	}
+	t.Cleanup(func() {
+		// CASCADE on workspaces FK deletes the activity_logs rows; explicit
+		// DELETE on activity_logs catches any rows that somehow leaked.
+		_, _ = conn.ExecContext(context.Background(), `DELETE FROM activity_logs WHERE workspace_id = $1`, wsID)
+		_, _ = conn.ExecContext(context.Background(), `DELETE FROM workspaces WHERE id = $1`, wsID)
+	})
+
+	store := pendinguploads.NewPostgres(conn)
+
+	// Mirror uploadPollMode's Tx shape: BeginTx → PutBatchTx → N ×
+	// LogActivityTx → Commit (or Rollback on failure).
+	tx, err := conn.BeginTx(ctx, nil)
+	if err != nil {
+		t.Fatalf("BeginTx: %v", err)
+	}
+
+	items := []pendinguploads.PutItem{
+		{Content: []byte("first"), Filename: "a.txt", Mimetype: "text/plain"},
+		{Content: []byte("second"), Filename: "b.txt", Mimetype: "text/plain"},
+	}
+	fileIDs, err := store.PutBatchTx(ctx, tx, wsID, items)
+	if err != nil {
+		t.Fatalf("PutBatchTx: %v", err)
+	}
+	if len(fileIDs) != 2 {
+		t.Fatalf("len(fileIDs) = %d, want 2", len(fileIDs))
+	}
+
+	// First activity insert succeeds — would commit if not for the
+	// rollback that the second insert's failure forces.
+	wsIDStr := wsID.String()
+	method := "chat_upload_receive"
+	okSummary := "chat_upload_receive: a.txt"
+	if _, err := LogActivityTx(ctx, tx, nil, ActivityParams{
+		WorkspaceID:  wsIDStr,
+		ActivityType: "a2a_receive",
+		TargetID:     &wsIDStr,
+		Method:       &method,
+		Summary:      &okSummary,
+		Status:       "ok",
+	}); err != nil {
+		t.Fatalf("first LogActivityTx (should succeed): %v", err)
+	}
+
+	// Second activity insert: NUL byte in summary triggers lib/pq
+	// "invalid byte sequence for encoding UTF8: 0x00" — the canonical
+	// "DB-side error after some Tx work has already happened" we want.
+	badSummary := "chat_upload_receive: b\x00.txt"
+	_, err = LogActivityTx(ctx, tx, nil, ActivityParams{
+		WorkspaceID:  wsIDStr,
+		ActivityType: "a2a_receive",
+		TargetID:     &wsIDStr,
+		Method:       &method,
+		Summary:      &badSummary,
+		Status:       "ok",
+	})
+	if err == nil {
+		t.Fatal("expected error from NUL-byte summary, got nil")
+	}
+
+	// Caller (uploadPollMode in production) rolls back on the error.
+	if rbErr := tx.Rollback(); rbErr != nil {
+		t.Fatalf("Rollback: %v", rbErr)
+	}
+
+	// THE assertion this test exists for: BOTH tables must have zero
+	// rows for this workspace. Pre-#149 the activity_logs row from the
+	// first insert would persist (separate fire-and-forget INSERT) and
+	// pending_uploads would also persist (committed by PutBatch's own
+	// Tx). Post-#149 the shared Tx + Rollback unwinds both.
+	var puCount, alCount int
+	if err := conn.QueryRowContext(ctx,
+		`SELECT COUNT(*) FROM pending_uploads WHERE workspace_id = $1`, wsID,
+	).Scan(&puCount); err != nil {
+		t.Fatalf("count pending_uploads: %v", err)
+	}
+	if err := conn.QueryRowContext(ctx,
+		`SELECT COUNT(*) FROM activity_logs WHERE workspace_id = $1`, wsID,
+	).Scan(&alCount); err != nil {
+		t.Fatalf("count activity_logs: %v", err)
+	}
+	if puCount != 0 {
+		t.Errorf("pending_uploads leaked %d row(s) after Rollback — #149 regression", puCount)
+	}
+	if alCount != 0 {
+		t.Errorf("activity_logs leaked %d row(s) after Rollback — #149 regression "+
+			"(THIS is the scenario the ticket called out: pre-fix, the first activity row "+
+			"committed in its own implicit Tx, leaving an orphan)", alCount)
+	}
+}
+
+// TestIntegration_PollUpload_HappyPath_AcrossBothTables is the positive
+// counterpart to the rollback test: when nothing fails, both tables
+// commit together and the row counts match.
+func TestIntegration_PollUpload_HappyPath_AcrossBothTables(t *testing.T) {
+	conn := integrationDB_PendingUploads(t)
+	ctx := context.Background()
+
+	wsID := uuid.New()
+	if _, err := conn.ExecContext(ctx,
+		`INSERT INTO workspaces (id, name) VALUES ($1, 'test-149-happy')`, wsID,
+	); err != nil {
+		t.Fatalf("seed workspace: %v", err)
+	}
+	t.Cleanup(func() {
+		_, _ = conn.ExecContext(context.Background(), `DELETE FROM activity_logs WHERE workspace_id = $1`, wsID)
+		_, _ = conn.ExecContext(context.Background(), `DELETE FROM workspaces WHERE id = $1`, wsID)
+	})
+
+	store := pendinguploads.NewPostgres(conn)
+	tx, err := conn.BeginTx(ctx, nil)
+	if err != nil {
+		t.Fatalf("BeginTx: %v", err)
+	}
+
+	items := []pendinguploads.PutItem{
+		{Content: []byte("a"), Filename: "a.txt", Mimetype: "text/plain"},
+		{Content: []byte("b"), Filename: "b.txt", Mimetype: "text/plain"},
+		{Content: []byte("c"), Filename: "c.txt", Mimetype: "text/plain"},
+	}
+	if _, err := store.PutBatchTx(ctx, tx, wsID, items); err != nil {
+		t.Fatalf("PutBatchTx: %v", err)
+	}
+	wsIDStr := wsID.String()
+	method := "chat_upload_receive"
+	for _, it := range items {
+		summary := "chat_upload_receive: " + it.Filename
+		if _, err := LogActivityTx(ctx, tx, nil, ActivityParams{
+			WorkspaceID:  wsIDStr,
+			ActivityType: "a2a_receive",
+			TargetID:     &wsIDStr,
+			Method:       &method,
+			Summary:      &summary,
+			Status:       "ok",
+		}); err != nil {
+			t.Fatalf("LogActivityTx %q: %v", it.Filename, err)
+		}
+	}
+	if err := tx.Commit(); err != nil {
+		t.Fatalf("Commit: %v", err)
+	}
+
+	var puCount, alCount int
+	if err := conn.QueryRowContext(ctx,
+		`SELECT COUNT(*) FROM pending_uploads WHERE workspace_id = $1`, wsID,
+	).Scan(&puCount); err != nil {
+		t.Fatalf("count pending_uploads: %v", err)
+	}
+	if err := conn.QueryRowContext(ctx,
+		`SELECT COUNT(*) FROM activity_logs WHERE workspace_id = $1`, wsID,
+	).Scan(&alCount); err != nil {
+		t.Fatalf("count activity_logs: %v", err)
+	}
+	if puCount != 3 {
+		t.Errorf("pending_uploads count = %d, want 3", puCount)
+	}
+	if alCount != 3 {
+		t.Errorf("activity_logs count = %d, want 3", alCount)
+	}
+}
+
 func TestIntegration_PendingUploads_GetIgnoresExpiredAndAcked(t *testing.T) {
 	conn := integrationDB_PendingUploads(t)
 	store := pendinguploads.NewPostgres(conn)
@@ -2,6 +2,7 @@ package handlers_test

 import (
 	"context"
+	"database/sql"
 	"encoding/json"
 	"errors"
 	"net/http"
@@ -84,6 +85,9 @@ func (f *fakeStorage) Sweep(_ context.Context, _ time.Duration) (pendinguploads.
 func (f *fakeStorage) PutBatch(_ context.Context, _ uuid.UUID, _ []pendinguploads.PutItem) ([]uuid.UUID, error) {
 	return nil, nil
 }
+func (f *fakeStorage) PutBatchTx(_ context.Context, _ *sql.Tx, _ uuid.UUID, _ []pendinguploads.PutItem) ([]uuid.UUID, error) {
+	return nil, nil
+}

 func newRouter(handler *handlers.PendingUploadsHandler) *gin.Engine {
 	gin.SetMode(gin.TestMode)
@@ -414,7 +414,7 @@ func (h *RegistryHandler) Register(c *gin.Context) {
 	}

 	// Broadcast WORKSPACE_ONLINE
-	if err := h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_ONLINE", payload.ID, map[string]interface{}{
+	if err := h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceOnline), payload.ID, map[string]interface{}{
 		"url":           cachedURL,
 		"agent_card":    payload.AgentCard,
 		"delivery_mode": effectiveMode,
@@ -572,7 +572,7 @@ func (h *RegistryHandler) Heartbeat(c *gin.Context) {

 	// Broadcast current task update only when it changed (avoid spamming on every heartbeat)
 	if payload.CurrentTask != prevTask {
-		h.broadcaster.BroadcastOnly(payload.WorkspaceID, "TASK_UPDATED", map[string]interface{}{
+		h.broadcaster.BroadcastOnly(payload.WorkspaceID, string(events.EventTaskUpdated), map[string]interface{}{
 			"current_task": payload.CurrentTask,
 			"active_tasks": payload.ActiveTasks,
 		})
@@ -593,7 +593,7 @@ func (h *RegistryHandler) Heartbeat(c *gin.Context) {
 	// so per-heartbeat cost is one in-memory channel send per active
 	// SSE subscriber and one WS hub fan-out. At 30s heartbeat cadence
 	// this is far below any noise floor on either path.
-	h.broadcaster.BroadcastOnly(payload.WorkspaceID, "WORKSPACE_HEARTBEAT", map[string]interface{}{
+	h.broadcaster.BroadcastOnly(payload.WorkspaceID, string(events.EventWorkspaceHeartbeat), map[string]interface{}{
 		"active_tasks":   payload.ActiveTasks,
 		"uptime_seconds": payload.UptimeSeconds,
 	})
@@ -678,7 +678,7 @@ func (h *RegistryHandler) evaluateStatus(c *gin.Context, payload models.Heartbea
 		if err != nil {
 			log.Printf("Heartbeat: failed to mark %s degraded (wedged): %v", payload.WorkspaceID, err)
 		}
-		h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_DEGRADED", payload.WorkspaceID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceDegraded), payload.WorkspaceID, map[string]interface{}{
 			"runtime_state": "wedged",
 			"sample_error":  payload.SampleError,
 		})
@@ -699,7 +699,7 @@ func (h *RegistryHandler) evaluateStatus(c *gin.Context, payload models.Heartbea
 		if _, err := db.DB.ExecContext(ctx, `UPDATE workspaces SET status = $1, updated_at = now() WHERE id = $2`, models.StatusDegraded, payload.WorkspaceID); err != nil {
 			log.Printf("Heartbeat: failed to mark %s degraded: %v", payload.WorkspaceID, err)
 		}
-		h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_DEGRADED", payload.WorkspaceID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceDegraded), payload.WorkspaceID, map[string]interface{}{
 			"error_rate":   payload.ErrorRate,
 			"sample_error": payload.SampleError,
 		})
@@ -718,7 +718,7 @@ func (h *RegistryHandler) evaluateStatus(c *gin.Context, payload models.Heartbea
 		if _, err := db.DB.ExecContext(ctx, `UPDATE workspaces SET status = $1, updated_at = now() WHERE id = $2`, models.StatusOnline, payload.WorkspaceID); err != nil {
 			log.Printf("Heartbeat: failed to recover %s to online: %v", payload.WorkspaceID, err)
 		}
-		h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_ONLINE", payload.WorkspaceID, map[string]interface{}{})
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceOnline), payload.WorkspaceID, map[string]interface{}{})
 	}

 	// Recovery: if workspace was offline but is now sending heartbeats, bring it back online.
@@ -728,7 +728,7 @@ func (h *RegistryHandler) evaluateStatus(c *gin.Context, payload models.Heartbea
 		if _, err := db.DB.ExecContext(ctx, `UPDATE workspaces SET status = $1, updated_at = now() WHERE id = $2 AND status = 'offline'`, models.StatusOnline, payload.WorkspaceID); err != nil {
 			log.Printf("Heartbeat: failed to recover %s from offline: %v", payload.WorkspaceID, err)
 		}
-		h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_ONLINE", payload.WorkspaceID, map[string]interface{}{})
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceOnline), payload.WorkspaceID, map[string]interface{}{})
 	}

 	// Auto-recovery: if a workspace is marked "provisioning" but is actively sending
@@ -743,7 +743,7 @@ func (h *RegistryHandler) evaluateStatus(c *gin.Context, payload models.Heartbea
 		} else {
 			log.Printf("Heartbeat: transitioned %s from provisioning to online (heartbeat received)", payload.WorkspaceID)
 		}
-		h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_ONLINE", payload.WorkspaceID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceOnline), payload.WorkspaceID, map[string]interface{}{
 			"recovered_from": currentStatus,
 		})
 	}
@@ -771,7 +771,7 @@ func (h *RegistryHandler) evaluateStatus(c *gin.Context, payload models.Heartbea
 		} else {
 			log.Printf("Heartbeat: transitioned %s from awaiting_agent to online (heartbeat received)", payload.WorkspaceID)
 		}
-		h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_ONLINE", payload.WorkspaceID, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceOnline), payload.WorkspaceID, map[string]interface{}{
 			"recovered_from": currentStatus,
 		})
 	}
@@ -820,7 +820,7 @@ func (h *RegistryHandler) UpdateCard(c *gin.Context) {
 		return
 	}

-	h.broadcaster.RecordAndBroadcast(c.Request.Context(), "AGENT_CARD_UPDATED", payload.WorkspaceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(c.Request.Context(), string(events.EventAgentCardUpdated), payload.WorkspaceID, map[string]interface{}{
 		"agent_card": payload.AgentCard,
 	})

@@ -1,23 +1,20 @@
 package handlers

-// template_files_eic.go — SSH-backed file write for SaaS workspaces
-// (EC2-per-workspace). Pairs with the existing Docker-path in templates.go
-// (WriteFile) and template_import.go (ReplaceFiles).
+// template_files_eic.go — SSH-backed file operations for SaaS workspaces
+// (EC2-per-workspace). Pairs with the local-Docker path in templates.go
+// (List/Read/Write/Delete) and template_import.go (ReplaceFiles).
 //
-// Flow for a single file write:
-//  1. Generate ephemeral ed25519 keypair (on-disk for ≤ write duration).
-//  2. Push the public key via `aws ec2-instance-connect send-ssh-public-key`
-//     so the target sshd accepts it for the next 60s.
-//  3. Open a TLS-tunnelled TCP port via `aws ec2-instance-connect open-tunnel`
-//     from a local free port → workspace's sshd on 22.
-//  4. Pipe content to `ssh ... "install -D -m 0644 /dev/stdin <abs path>"`.
-//     `install -D` creates any missing parent dirs atomically. File is owned
-//     by whichever $OSUser we authenticated as (ubuntu by default).
-//  5. Close tunnel + wipe keydir.
+// Architecture note: every operation goes through `withEICTunnel`, which
+// owns the ephemeral-keypair → key-push → tunnel → port-wait dance. Per-
+// op helpers (list/read/write/delete) only carry the remote command +
+// stdin/stdout shape. This keeps the EIC connection logic in one place
+// so a fix to the dance — e.g. PR #2822's `LogLevel=ERROR` shim — only
+// touches one helper.
 //
-// All the AWS calls + ssh tunnel exec go through the same package-level
-// func vars defined in terminal.go (openTunnelCmd, sendSSHPublicKey) so
-// tests can stub them the same way the terminal tests do.
+// Path translation rules: see resolveWorkspaceFilePath. `/configs`
+// is the per-runtime managed-config indirection (claude-code → /configs,
+// hermes → /home/ubuntu/.hermes); other allow-listed roots (`/home`,
+// `/workspace`, `/plugins`) pass through literally.

 import (
 	"bytes"
@@ -32,8 +29,7 @@ import (
 )

 // workspaceFilePathPrefix maps a runtime name to the absolute base path on
-// the workspace EC2 where the Files API's relative paths land. New runtimes
-// can be added here without touching handler code.
+// the workspace EC2 where the runtime's managed-config dir lives.
 //
 // Keep these stable — changing the base path for an existing runtime
 // without a migration shim will make previously-saved files disappear from
@@ -60,41 +56,104 @@ var workspaceFilePathPrefix = map[string]string{
 	// those runtimes actually have on disk.
 }

-func resolveWorkspaceFilePath(runtime, relPath string) (string, error) {
+// resolveWorkspaceFilePath translates (runtime, root, relPath) into an
+// absolute path on the workspace EC2.
+//
+// `root="/configs"` (or empty / unrecognized) is treated as the
+// runtime's MANAGED-config dir via workspaceFilePathPrefix —
+// /home/ubuntu/.hermes for hermes, /configs for claude-code, etc.
+// This preserves the v1 ReadFile/WriteFile behavior where the canvas's
+// Config tab GETs/PUTs "config.yaml" without specifying a root and
+// lands in the runtime's own config dir, even though that dir's
+// absolute path differs per runtime.
+//
+// Any other allow-listed root (`/home`, `/workspace`, `/plugins`) is
+// treated as a LITERAL absolute path on the EC2 host. Those roots are
+// universal Linux paths that don't need per-runtime indirection.
+//
+// Restricting the literal pass-through to allowedRoots is the
+// security boundary — the handler also gates this same set, so the
+// resolver is defence-in-depth: even if a future caller forgets the
+// handler-side check, the resolver won't translate `?root=/etc` into
+// a real absolute path.
+//
+// relPath is sanitised by validateRelPath (no absolute, no `..`).
+func resolveWorkspaceFilePath(runtime, root, relPath string) (string, error) {
 	if err := validateRelPath(relPath); err != nil {
 		return "", err
 	}
-	base, ok := workspaceFilePathPrefix[strings.ToLower(strings.TrimSpace(runtime))]
-	if !ok {
-		base = "/configs"
-	}
+	base := resolveWorkspaceRootPath(runtime, root)
 	return filepath.Join(base, filepath.Clean(relPath)), nil
 }

-// eicFileWriteTimeout bounds the whole dance. Key push is <500ms, tunnel
-// is 1-2s, ssh + write is <2s. 30s gives headroom for slow pulls without
-// hanging the Files API forever under EIC misconfiguration.
-const eicFileWriteTimeout = 30 * time.Second
-
-// writeFileViaEIC writes a single file to the workspace EC2 at the
-// absolute path that resolveWorkspaceFilePath computed. On success,
-// optionally invokes the runtime's reload hook (not implemented yet —
-// tracked as follow-up; for today the canvas issues a separate Restart
-// after Save).
+// resolveWorkspaceRootPath returns the absolute base directory on the
+// workspace EC2 for a given (runtime, root) pair, without touching a
+// relative file path. Used by listFilesViaEIC to compute the directory
+// to walk; resolveWorkspaceFilePath joins this with relPath.
 //
-// instanceID: AWS EC2 instance id from workspaces.instance_id.
-// runtime: used only for path-prefix resolution.
-// relPath: the relative path the caller validated (no /, no ..).
-// content: file body bytes.
-func writeFileViaEIC(ctx context.Context, instanceID, runtime, relPath string, content []byte) error {
+// Centralising the runtime-vs-literal indirection here means
+// list/read/write/delete agree on what `?root=/configs` means for
+// hermes vs claude-code vs an unknown runtime — otherwise list could
+// show one directory while read/write target another.
+func resolveWorkspaceRootPath(runtime, root string) string {
+	root = strings.TrimSpace(root)
+	// "/configs" + empty + unrecognized → runtime's managed-config dir.
+	// The runtime prefix map is the SSOT for that translation.
+	if root == "" || root == "/configs" || !allowedRoots[root] {
+		base, ok := workspaceFilePathPrefix[strings.ToLower(strings.TrimSpace(runtime))]
+		if !ok {
+			base = "/configs"
+		}
+		return base
+	}
+	// Literal universal path (`/home`, `/workspace`, `/plugins`).
+	return root
+}
+
+// eicFileOpTimeout bounds the whole tunnel + ssh dance. Key push is
+// <500ms, tunnel is 1-2s, ssh + remote command is <2s for read/write.
+// 30s gives headroom for slow EIC pulls + the larger `find` walk that
+// listFilesViaEIC issues, without hanging the Files API forever under
+// EIC misconfiguration.
+const eicFileOpTimeout = 30 * time.Second
+
+// eicFileOpTimeout was historically named eicFileWriteTimeout when the
+// only EIC op was writeFile. Keep an alias so any external test that
+// pinned the old name still compiles; rename can land as a follow-up
+// once we've gone a release without the alias being touched.
+//
+//nolint:revive // intentional alias for back-compat with prior tests.
+const eicFileWriteTimeout = eicFileOpTimeout
+
+// eicSSHSession describes an open EIC tunnel ready for an ssh subprocess.
+// Only valid inside the closure passed to withEICTunnel — the underlying
+// keypair + tunnel are torn down when the closure returns.
+type eicSSHSession struct {
+	keyPath    string
+	localPort  int
+	osUser     string
+	instanceID string
+}
+
+// withEICTunnel sets up an EIC SSH session (ephemeral keypair → push
+// → AWS open-tunnel → wait-for-port), invokes fn with a session handle,
+// and tears everything down on return. The caller is responsible for
+// applying the per-op context.WithTimeout before calling — this helper
+// only owns the EIC dance, not the operation budget, so a caller that
+// needs a different timeout (e.g. a large bulk import) doesn't have to
+// fight a hard-coded one.
+//
+// All AWS calls go through the package-level func vars in terminal.go
+// (sendSSHPublicKey, openTunnelCmd) so tests can stub them the same way
+// terminal_test.go does. The whole helper is also assigned to a
+// `var` (`withEICTunnel`) so handler-dispatch tests can stub the entire
+// dance instead of having to wire up a fake tunnel + fake ssh server.
+var withEICTunnel = realWithEICTunnel
+
+func realWithEICTunnel(ctx context.Context, instanceID string, fn func(s eicSSHSession) error) error {
 	if instanceID == "" {
 		return fmt.Errorf("workspace has no instance_id — not a SaaS EC2 workspace")
 	}
-	absPath, err := resolveWorkspaceFilePath(runtime, relPath)
-	if err != nil {
-		return fmt.Errorf("invalid path: %w", err)
-	}
-
 	osUser := os.Getenv("WORKSPACE_EC2_OS_USER")
 	if osUser == "" {
 		osUser = "ubuntu"
@@ -104,11 +163,7 @@ func writeFileViaEIC(ctx context.Context, instanceID, runtime, relPath string, c
 		region = "us-east-2"
 	}

-	ctx, cancel := context.WithTimeout(ctx, eicFileWriteTimeout)
-	defer cancel()
-
-	// Ephemeral keypair.
-	keyDir, err := os.MkdirTemp("", "molecule-filewrite-*")
+	keyDir, err := os.MkdirTemp("", "molecule-eic-*")
 	if err != nil {
 		return fmt.Errorf("keydir mkdir: %w", err)
 	}
@@ -116,7 +171,7 @@ func writeFileViaEIC(ctx context.Context, instanceID, runtime, relPath string, c
 	keyPath := keyDir + "/id"
 	if out, kerr := exec.CommandContext(ctx, "ssh-keygen",
 		"-t", "ed25519", "-f", keyPath, "-N", "", "-q",
-		"-C", "molecule-filewrite",
+		"-C", "molecule-eic",
 	).CombinedOutput(); kerr != nil {
 		return fmt.Errorf("ssh-keygen: %w (%s)", kerr, strings.TrimSpace(string(out)))
 	}
@@ -125,24 +180,21 @@ func writeFileViaEIC(ctx context.Context, instanceID, runtime, relPath string, c
 		return fmt.Errorf("read pubkey: %w", err)
 	}

-	// 1. Push key.
 	if err := sendSSHPublicKey(ctx, region, instanceID, osUser, strings.TrimSpace(string(pubKey))); err != nil {
 		return fmt.Errorf("send-ssh-public-key: %w", err)
 	}

-	// 2. Open tunnel on an OS-picked free port.
 	localPort, err := pickFreePort()
 	if err != nil {
 		return fmt.Errorf("pick free port: %w", err)
 	}
-	opts := eicSSHOptions{
+	tunnel := openTunnelCmd(eicSSHOptions{
 		InstanceID:     instanceID,
 		OSUser:         osUser,
 		Region:         region,
 		LocalPort:      localPort,
 		PrivateKeyPath: keyPath,
-	}
-	tunnel := openTunnelCmd(opts)
+	})
 	tunnel.Env = os.Environ()
 	if err := tunnel.Start(); err != nil {
 		return fmt.Errorf("open-tunnel start: %w", err)
@@ -157,183 +209,330 @@ func writeFileViaEIC(ctx context.Context, instanceID, runtime, relPath string, c
 		return fmt.Errorf("tunnel never listened: %w", err)
 	}

-	// 3. SSH + install -D. `install` creates any missing parent dirs and
-	// writes the file atomically via temp-file-rename. Permissions 0644
-	// match the existing tar-unpack defaults on the Docker path.
-	//
-	// `sudo -n` (non-interactive) prefix: the canonical containerized
-	// workspace layout puts /configs at the root, owned by root because
-	// cloud-init runs as root (see
-	// molecule-controlplane/internal/provisioner/userdata_containerized.go).
-	// SSH-as-ubuntu can't write into /configs without escalation.
-	// Ubuntu has passwordless sudo on EC2 by default; sudo -n fails fast
-	// (no prompt) if that ever changes, surfacing a clean error instead
-	// of a hang. The hermes path /home/ubuntu/.hermes is ubuntu-owned
-	// and doesn't strictly need sudo, but using it uniformly avoids
-	// per-runtime branching here.
-	//
-	// The remote command is fully deterministic — no user-controlled
-	// input reaches a shell eval (absPath is built from a map + Clean()).
-	sshArgs := []string{
-		"-i", keyPath,
+	return fn(eicSSHSession{
+		keyPath:    keyPath,
+		localPort:  localPort,
+		osUser:     osUser,
+		instanceID: instanceID,
+	})
+}
+
+// sshArgs returns the standard ssh CLI args for an EIC session pointed
+// at the local tunnel port + a single remote command string.
+//
+// `LogLevel=ERROR` silences the benign "Warning: Permanently added
+// '[127.0.0.1]:NNNNN' to known hosts" notice that ssh emits on every
+// fresh tunnel connection. Without this, the notice lands on stderr
+// and fools the read/list "empty stdout + empty stderr → not found"
+// classifiers into thinking the warning is a real ssh-layer error → 500
+// instead of 404 (Hermes config.yaml load, hongming tenant, 2026-05-05
+// 02:38; PR #2822). Real auth/tunnel errors stay visible because they're
+// emitted at ERROR level.
+//
+// Originally each helper assembled its own ssh args inline, so PR #2822's
+// LogLevel=ERROR fix had to be applied to every copy. Centralising here
+// means future ssh-option tweaks only land in one place.
+func (s eicSSHSession) sshArgs(remoteCommand string) []string {
+	return []string{
+		"-i", s.keyPath,
 		"-o", "StrictHostKeyChecking=no",
 		"-o", "UserKnownHostsFile=/dev/null",
-		// LogLevel=ERROR silences the benign "Warning: Permanently
-		// added '[127.0.0.1]:NNNNN' to known hosts" notice that ssh
-		// emits on every fresh tunnel connection. Without this, the
-		// notice lands on stderr and fools readFileViaEIC's "empty
-		// stdout + empty stderr → file not found" classifier into
-		// thinking the warning is a real ssh-layer error → 500
-		// instead of 404 (Hermes config.yaml load, hongming tenant,
-		// 2026-05-05 02:38). Real auth/tunnel errors stay visible
-		// because they're emitted at ERROR level.
 		"-o", "LogLevel=ERROR",
 		"-o", "ServerAliveInterval=15",
-		"-p", fmt.Sprintf("%d", localPort),
-		fmt.Sprintf("%s@127.0.0.1", osUser),
-		fmt.Sprintf("sudo -n install -D -m 0644 /dev/stdin %s", shellQuote(absPath)),
+		"-p", fmt.Sprintf("%d", s.localPort),
+		fmt.Sprintf("%s@127.0.0.1", s.osUser),
+		remoteCommand,
 	}
-	sshCmd := exec.CommandContext(ctx, "ssh", sshArgs...)
-	sshCmd.Env = os.Environ()
-	sshCmd.Stdin = bytes.NewReader(content)
-	var stderr bytes.Buffer
-	sshCmd.Stderr = &stderr
-	if err := sshCmd.Run(); err != nil {
-		return fmt.Errorf("ssh install: %w (%s)", err, strings.TrimSpace(stderr.String()))
+}
+
+// buildInstallShell returns the remote command for atomically writing
+// `/dev/stdin` to absPath with mode 0644 via `sudo -n install -D`.
+// `install -D` creates any missing parent dirs and writes via
+// temp-file-rename (atomic). Pure function for direct testability —
+// the only variable input (absPath) is shellQuote-wrapped to defeat
+// any shell metachar in a future caller's path.
+func buildInstallShell(absPath string) string {
+	return fmt.Sprintf("sudo -n install -D -m 0644 /dev/stdin %s", shellQuote(absPath))
+}
+
+// buildCatShell returns the remote command for reading absPath and
+// swallowing missing-file stderr (so the empty-stdout + non-zero-exit
+// case is unambiguous → os.ErrNotExist at the caller).
+func buildCatShell(absPath string) string {
+	return fmt.Sprintf("sudo -n cat %s 2>/dev/null", shellQuote(absPath))
+}
+
+// buildRmShell returns the remote command for `sudo -n rm -f` against
+// absPath. `-f` (not `-rf`) is intentional — directory removal needs
+// its own explicit endpoint if/when the canvas grows that affordance,
+// and `-rf` would let a misclassified directory entry trigger a
+// recursive delete.
+func buildRmShell(absPath string) string {
+	return fmt.Sprintf("sudo -n rm -f %s", shellQuote(absPath))
+}
+
+// buildFindShell returns the remote command for enumerating files
+// under listPath up to maxDepth, emitting `TYPE|SIZE|REL_PATH` lines
+// (matches the local-Docker container path's parser exactly).
+//
+// `2>/dev/null` swallows find's "No such file" error so a missing
+// listing root surfaces as empty stdout (handler returns []) rather
+// than 500.
+//
+// `stat -c %s` is GNU coreutils; `stat -f %z` is BSD. Try GNU first,
+// fall back to BSD, then 0 — same shape the local-Docker `sh -c`
+// version uses so a future cross-runtime fleet (Alpine vs Ubuntu)
+// doesn't regress.
+//
+// Hidden / cache dir pruning matches the container path: .git,
+// __pycache__, node_modules, .DS_Store. Without these the tree drowns
+// in transient artefacts on a /workspace listing.
+func buildFindShell(listPath string, maxDepth int) string {
+	return fmt.Sprintf(
+		`sudo -n find %s -maxdepth %d -not -path '*/.git/*' -not -path '*/__pycache__/*' -not -path '*/node_modules/*' -not -name .DS_Store 2>/dev/null | while IFS= read -r f; do `+
+			`rel="${f#%s/}"; [ "$rel" = %s ] && continue; [ -z "$rel" ] && continue; `+
+			`if [ -d "$f" ]; then echo "d|0|$rel"; else `+
+			`s=$(stat -c %%s "$f" 2>/dev/null || stat -f %%z "$f" 2>/dev/null || echo 0); echo "f|$s|$rel"; `+
+			`fi; done`,
+		shellQuote(listPath), maxDepth, shellQuote(listPath), shellQuote(listPath),
+	)
+}
+
+// parseFindOutput parses TYPE|SIZE|REL_PATH lines emitted by
+// buildFindShell into eicFileEntry rows. Whitespace-only lines and
+// malformed rows are silently skipped — the same behaviour as the
+// local-Docker container parser for symmetric output.
+func parseFindOutput(raw []byte) []eicFileEntry {
+	files := make([]eicFileEntry, 0)
+	for _, line := range strings.Split(string(raw), "\n") {
+		parts := strings.SplitN(line, "|", 3)
+		if len(parts) != 3 || parts[2] == "" {
+			continue
+		}
+		var size int64
+		fmt.Sscanf(parts[1], "%d", &size)
+		files = append(files, eicFileEntry{
+			Path: parts[2],
+			Size: size,
+			Dir:  parts[0] == "d",
+		})
 	}
-	log.Printf("writeFileViaEIC: ws instance=%s runtime=%s wrote %d bytes → %s",
-		instanceID, runtime, len(content), absPath)
-	return nil
+	return files
 }

 // shellQuote wraps a value in single quotes + escapes embedded single
-// quotes for POSIX sh. Used for the sole piece of variable data in the
-// remote ssh command. (absPath is already built from a map + Clean() so
-// traversal is blocked regardless; this is defence-in-depth against
-// future refactor that might accept user paths here.)
+// quotes for POSIX sh. Used for the variable parts of remote ssh
+// commands (absolute paths). The paths are already built from a
+// validated allowlist + Clean(), so traversal is blocked regardless;
+// this is defence-in-depth against a future refactor that might accept
+// user paths directly here.
 func shellQuote(s string) string {
 	return "'" + strings.ReplaceAll(s, "'", `'\''`) + "'"
 }

+// writeFileViaEIC writes a single file to the workspace EC2 at the
+// absolute path that resolveWorkspaceFilePath computed. On success,
+// optionally invokes the runtime's reload hook (not implemented yet —
+// tracked as follow-up; for today the canvas issues a separate Restart
+// after Save).
+//
+// `install -D` creates any missing parent dirs and writes atomically
+// via temp-file-rename. Permissions 0644 match the existing tar-unpack
+// defaults on the Docker path.
+//
+// `sudo -n` (non-interactive) prefix: the canonical containerized
+// workspace layout puts /configs at the root, owned by root because
+// cloud-init runs as root (see
+// molecule-controlplane/internal/provisioner/userdata_containerized.go).
+// SSH-as-ubuntu can't write into /configs without escalation. Ubuntu
+// has passwordless sudo on EC2 by default; sudo -n fails fast (no
+// prompt) if that ever changes, surfacing a clean error instead of a
+// hang. The hermes path /home/ubuntu/.hermes is ubuntu-owned and
+// doesn't strictly need sudo, but using it uniformly avoids per-runtime
+// branching here.
+func writeFileViaEIC(ctx context.Context, instanceID, runtime, root, relPath string, content []byte) error {
+	absPath, err := resolveWorkspaceFilePath(runtime, root, relPath)
+	if err != nil {
+		return fmt.Errorf("invalid path: %w", err)
+	}
+	ctx, cancel := context.WithTimeout(ctx, eicFileOpTimeout)
+	defer cancel()
+
+	return withEICTunnel(ctx, instanceID, func(s eicSSHSession) error {
+		sshCmd := exec.CommandContext(ctx, "ssh", s.sshArgs(buildInstallShell(absPath))...)
+		sshCmd.Env = os.Environ()
+		sshCmd.Stdin = bytes.NewReader(content)
+		var stderr bytes.Buffer
+		sshCmd.Stderr = &stderr
+		if err := sshCmd.Run(); err != nil {
+			return fmt.Errorf("ssh install: %w (%s)", err, strings.TrimSpace(stderr.String()))
+		}
+		log.Printf("writeFileViaEIC: ws instance=%s runtime=%s root=%s wrote %d bytes → %s",
+			instanceID, runtime, root, len(content), absPath)
+		return nil
+	})
+}
+
 // readFileViaEIC reads a single file from the workspace EC2 at the
 // absolute path that resolveWorkspaceFilePath computes. Mirrors
-// writeFileViaEIC end-to-end (ephemeral keypair, EIC tunnel, ssh) so
-// canvas's Config tab can GET back what it just PUT. Pre-fix the GET
-// path (templates.go ReadFile) only handled local Docker containers
-// + a host-side template fallback; SaaS workspaces (EC2-per-workspace)
-// always 404'd because neither handles their on-EC2 layout.
+// writeFileViaEIC (ephemeral keypair, EIC tunnel, ssh) so the canvas's
+// Config tab can GET back what it just PUT.
 //
 // Returns ("", os.ErrNotExist) when the remote path doesn't exist so
 // the handler can map it to HTTP 404 cleanly. Other errors propagate.
-func readFileViaEIC(ctx context.Context, instanceID, runtime, relPath string) ([]byte, error) {
-	if instanceID == "" {
-		return nil, fmt.Errorf("workspace has no instance_id — not a SaaS EC2 workspace")
-	}
-	absPath, err := resolveWorkspaceFilePath(runtime, relPath)
+//
+// `sudo -n cat`: /configs is root-owned (same reason writeFileViaEIC
+// needs sudo). The path is built from a validated map + Clean(), so no
+// user-controlled string reaches the shell here. `2>/dev/null` swallows
+// `cat: ...: No such file` so the missing-file case returns empty
+// stdout + non-zero exit, which we translate to os.ErrNotExist.
+func readFileViaEIC(ctx context.Context, instanceID, runtime, root, relPath string) ([]byte, error) {
+	absPath, err := resolveWorkspaceFilePath(runtime, root, relPath)
 	if err != nil {
 		return nil, fmt.Errorf("invalid path: %w", err)
 	}
-
-	osUser := os.Getenv("WORKSPACE_EC2_OS_USER")
-	if osUser == "" {
-		osUser = "ubuntu"
-	}
-	region := os.Getenv("AWS_REGION")
-	if region == "" {
-		region = "us-east-2"
-	}
-
-	ctx, cancel := context.WithTimeout(ctx, eicFileWriteTimeout)
+	ctx, cancel := context.WithTimeout(ctx, eicFileOpTimeout)
 	defer cancel()

-	keyDir, err := os.MkdirTemp("", "molecule-fileread-*")
-	if err != nil {
-		return nil, fmt.Errorf("keydir mkdir: %w", err)
-	}
-	defer func() { _ = os.RemoveAll(keyDir) }()
-	keyPath := keyDir + "/id"
-	if out, kerr := exec.CommandContext(ctx, "ssh-keygen",
-		"-t", "ed25519", "-f", keyPath, "-N", "", "-q",
-		"-C", "molecule-fileread",
-	).CombinedOutput(); kerr != nil {
-		return nil, fmt.Errorf("ssh-keygen: %w (%s)", kerr, strings.TrimSpace(string(out)))
-	}
-	pubKey, err := os.ReadFile(keyPath + ".pub")
-	if err != nil {
-		return nil, fmt.Errorf("read pubkey: %w", err)
-	}
-
-	if err := sendSSHPublicKey(ctx, region, instanceID, osUser, strings.TrimSpace(string(pubKey))); err != nil {
-		return nil, fmt.Errorf("send-ssh-public-key: %w", err)
-	}
-
-	localPort, err := pickFreePort()
-	if err != nil {
-		return nil, fmt.Errorf("pick free port: %w", err)
-	}
-	tunnel := openTunnelCmd(eicSSHOptions{
-		InstanceID:     instanceID,
-		OSUser:         osUser,
-		Region:         region,
-		LocalPort:      localPort,
-		PrivateKeyPath: keyPath,
+	var out []byte
+	runErr := withEICTunnel(ctx, instanceID, func(s eicSSHSession) error {
+		sshCmd := exec.CommandContext(ctx, "ssh", s.sshArgs(buildCatShell(absPath))...)
+		sshCmd.Env = os.Environ()
+		var stdout, stderr bytes.Buffer
+		sshCmd.Stdout = &stdout
+		sshCmd.Stderr = &stderr
+		err := sshCmd.Run()
+		out = stdout.Bytes()
+		if err != nil {
+			// `cat` returns 1 on missing file; with 2>/dev/null we have no
+			// stderr distinguisher. Treat empty-stdout + empty-stderr +
+			// non-zero exit as not-found rather than a tunnel/auth error
+			// (those usually produce stderr from ssh itself, not from the
+			// remote command).
+			if len(out) == 0 && stderr.Len() == 0 {
+				return os.ErrNotExist
+			}
+			return fmt.Errorf("ssh cat: %w (%s)", err, strings.TrimSpace(stderr.String()))
+		}
+		log.Printf("readFileViaEIC: ws instance=%s runtime=%s root=%s read %d bytes ← %s",
+			instanceID, runtime, root, len(out), absPath)
+		return nil
 	})
-	tunnel.Env = os.Environ()
-	if err := tunnel.Start(); err != nil {
-		return nil, fmt.Errorf("open-tunnel start: %w", err)
-	}
-	defer func() {
-		if tunnel.Process != nil {
-			_ = tunnel.Process.Kill()
-		}
-		_ = tunnel.Wait()
-	}()
-	if err := waitForPort(ctx, "127.0.0.1", localPort, 10*time.Second); err != nil {
-		return nil, fmt.Errorf("tunnel never listened: %w", err)
-	}
-
-	// `sudo -n cat`: /configs is root-owned by cloud-init (same reason
-	// writeFileViaEIC needs sudo to install). The path is built from a
-	// validated map + Clean(), so no user-controlled string reaches the
-	// shell here. `2>/dev/null` swallows `cat: ...: No such file` so
-	// the missing-file case returns empty stdout + non-zero exit, which
-	// we translate to os.ErrNotExist below.
-	sshCmd := exec.CommandContext(ctx, "ssh",
-		"-i", keyPath,
-		"-o", "StrictHostKeyChecking=no",
-		"-o", "UserKnownHostsFile=/dev/null",
-		// LogLevel=ERROR silences the benign "Warning: Permanently
-		// added '[127.0.0.1]:NNNNN' to known hosts" notice that ssh
-		// emits on every fresh tunnel connection. Without this, the
-		// notice lands on stderr and fools readFileViaEIC's "empty
-		// stdout + empty stderr → file not found" classifier into
-		// thinking the warning is a real ssh-layer error → 500
-		// instead of 404 (Hermes config.yaml load, hongming tenant,
-		// 2026-05-05 02:38). Real auth/tunnel errors stay visible
-		// because they're emitted at ERROR level.
-		"-o", "LogLevel=ERROR",
-		"-o", "ServerAliveInterval=15",
-		"-p", fmt.Sprintf("%d", localPort),
-		fmt.Sprintf("%s@127.0.0.1", osUser),
-		fmt.Sprintf("sudo -n cat %s 2>/dev/null", shellQuote(absPath)),
-	)
-	sshCmd.Env = os.Environ()
-	var stdout, stderr bytes.Buffer
-	sshCmd.Stdout = &stdout
-	sshCmd.Stderr = &stderr
-	runErr := sshCmd.Run()
-	out := stdout.Bytes()
 	if runErr != nil {
-		// `cat` returns 1 on missing file; with 2>/dev/null we have no
-		// stderr distinguisher. Treat empty-stdout + non-zero exit as
-		// not-found rather than a tunnel/auth error (those usually
-		// produce stderr from ssh itself, not from the remote command).
-		if len(out) == 0 && stderr.Len() == 0 {
-			return nil, os.ErrNotExist
-		}
-		return nil, fmt.Errorf("ssh cat: %w (%s)", runErr, strings.TrimSpace(stderr.String()))
+		return nil, runErr
 	}
-	log.Printf("readFileViaEIC: ws instance=%s runtime=%s read %d bytes ← %s",
-		instanceID, runtime, len(out), absPath)
 	return out, nil
 }
+
+// eicFileEntry is the wire shape returned by listFilesViaEIC. It
+// matches the inline `fileEntry` in templates.go::ListFiles so the
+// handler can emit either path's output without a translation layer.
+type eicFileEntry struct {
+	Path string `json:"path"`
+	Size int64  `json:"size"`
+	Dir  bool   `json:"dir"`
+}
+
+// listFilesViaEIC enumerates files under <root>/<sub> on the workspace
+// EC2 host, up to the given depth, returning entries with paths
+// relative to the listing root (matching the local-Docker path's
+// output). Closes the symmetry gap that left ListFiles silently
+// returning [] for SaaS workspaces — see issue #2999.
+//
+// Output line format: TYPE|SIZE|REL_PATH (matches the container's find
+// shell so the parser is identical). `find -maxdepth N` traverses up
+// to N levels; the canvas requests depth=1 by default and re-fetches
+// when the user expands a directory.
+//
+// Pruning: same hidden / cache dirs as the container path (.git,
+// __pycache__, node_modules, .DS_Store) so the canvas's tree doesn't
+// drown in transient artefacts.
+//
+// `sudo -n` matches the read/write paths — even though the universal
+// roots (/home, /workspace, /plugins) are typically ubuntu-owned and
+// don't need it, /configs and runtime-prefix dirs do (root-owned by
+// cloud-init), and using sudo uniformly avoids per-root branching.
+func listFilesViaEIC(ctx context.Context, instanceID, runtime, root, sub string, depth int) ([]eicFileEntry, error) {
+	if sub != "" {
+		if err := validateRelPath(sub); err != nil {
+			return nil, fmt.Errorf("invalid sub: %w", err)
+		}
+	}
+	if depth < 1 {
+		depth = 1
+	}
+	if depth > 5 {
+		depth = 5
+	}
+	listPath := resolveWorkspaceRootPath(runtime, root)
+	if sub != "" {
+		listPath = filepath.Join(listPath, filepath.Clean(sub))
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, eicFileOpTimeout)
+	defer cancel()
+
+	var rawOutput []byte
+	runErr := withEICTunnel(ctx, instanceID, func(s eicSSHSession) error {
+		sshCmd := exec.CommandContext(ctx, "ssh", s.sshArgs(buildFindShell(listPath, depth))...)
+		sshCmd.Env = os.Environ()
+		var stdout, stderr bytes.Buffer
+		sshCmd.Stdout = &stdout
+		sshCmd.Stderr = &stderr
+		if err := sshCmd.Run(); err != nil {
+			// Empty stdout + empty stderr after we swallowed find's
+			// own error stream means the listing root genuinely
+			// doesn't exist on this workspace — return an empty
+			// slice rather than a 500. Real ssh/tunnel errors emit
+			// to stderr at LogLevel=ERROR.
+			if stdout.Len() == 0 && stderr.Len() == 0 {
+				rawOutput = nil
+				return nil
+			}
+			return fmt.Errorf("ssh find: %w (%s)", err, strings.TrimSpace(stderr.String()))
+		}
+		rawOutput = stdout.Bytes()
+		return nil
+	})
+	if runErr != nil {
+		return nil, runErr
+	}
+
+	files := parseFindOutput(rawOutput)
+	log.Printf("listFilesViaEIC: ws instance=%s runtime=%s root=%s sub=%s depth=%d → %d entries from %s",
+		instanceID, runtime, root, sub, depth, len(files), listPath)
+	return files, nil
+}
+
+// deleteFileViaEIC removes a single file from the workspace EC2.
+// Returns nil for both "deleted" and "didn't exist" — `rm -f` doesn't
+// distinguish, and the canvas's delete-then-refresh flow doesn't need
+// it to.
+//
+// Symmetry note: pre-fix DeleteFile (templates.go:514) had no EIC
+// branch, so right-click delete on a SaaS workspace would fall through
+// to the local-Docker path, find no container (dockerCli is nil on
+// SaaS), and try the ephemeral-volume path which itself only handles
+// local Docker volumes. Net effect: silent no-op. Closing this gap is
+// part of issue #2999.
+func deleteFileViaEIC(ctx context.Context, instanceID, runtime, root, relPath string) error {
+	absPath, err := resolveWorkspaceFilePath(runtime, root, relPath)
+	if err != nil {
+		return fmt.Errorf("invalid path: %w", err)
+	}
+	ctx, cancel := context.WithTimeout(ctx, eicFileOpTimeout)
+	defer cancel()
+
+	return withEICTunnel(ctx, instanceID, func(s eicSSHSession) error {
+		sshCmd := exec.CommandContext(ctx, "ssh", s.sshArgs(buildRmShell(absPath))...)
+		sshCmd.Env = os.Environ()
+		var stderr bytes.Buffer
+		sshCmd.Stderr = &stderr
+		if err := sshCmd.Run(); err != nil {
+			return fmt.Errorf("ssh rm: %w (%s)", err, strings.TrimSpace(stderr.String()))
+		}
+		log.Printf("deleteFileViaEIC: ws instance=%s runtime=%s root=%s removed %s",
+			instanceID, runtime, root, absPath)
+		return nil
+	})
+}
@@ -0,0 +1,303 @@
+package handlers
+
+// template_files_eic_dispatch_test.go — handler-level tests for the
+// EIC dispatch added in PR-A of issue #2999. Pre-PR-A, ListFiles and
+// DeleteFile silently fell through to the local-Docker path on SaaS
+// workspaces (where dockerCli is nil) and returned [] / silent no-op.
+// These tests pin the new behavior:
+//
+//   1. instance_id != "" → handler invokes the EIC helper
+//   2. EIC success → 200 with the helper's payload
+//   3. EIC error → 500 (does NOT fall through to local-Docker /
+//      template-dir, which would mask the real failure)
+//   4. instance_id == "" → existing local-Docker / template-dir
+//      fallback (back-compat with self-hosted operators)
+//
+// Stubs `withEICTunnel` so the entire EIC dance (keypair, AWS calls,
+// tunnel, ssh) is replaced with a fake closure that yields a captured
+// session — lets the test capture what the inner closure would have
+// done without spinning up a real sshd. The test for the actual
+// remote shell shapes lives in template_files_eic_shells_test.go
+// (pure-function tests on buildFindShell / buildInstallShell etc).
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/gin-gonic/gin"
+)
+
+// stubWithEICTunnel replaces the package-level withEICTunnel with a
+// closure that records its inputs and runs fn against a fake session,
+// returning fnErr from the inner fn if non-nil. Restores the original
+// on test cleanup.
+func stubWithEICTunnel(t *testing.T, fnErr error) (calls *[]string) {
+	t.Helper()
+	captured := []string{}
+	calls = &captured
+	prev := withEICTunnel
+	withEICTunnel = func(ctx context.Context, instanceID string, fn func(s eicSSHSession) error) error {
+		captured = append(captured, instanceID)
+		// Hand the closure a sentinel session so any code that pulls
+		// session fields gets deterministic non-empty values. The
+		// closure's exec.Command call will fail at runtime because no
+		// real ssh exists for instanceID="i-test"; but most
+		// dispatch-tests inject fnErr directly to skip that.
+		return fnErr
+	}
+	t.Cleanup(func() { withEICTunnel = prev })
+	return calls
+}
+
+// stubWithEICTunnelReturning is like stubWithEICTunnel but lets the
+// test substitute the inner fn entirely so it can populate `out` /
+// return shaped errors without invoking the real ssh closure.
+func stubWithEICTunnelReturning(t *testing.T, replacement func(s eicSSHSession) error) (calls *[]string) {
+	t.Helper()
+	captured := []string{}
+	calls = &captured
+	prev := withEICTunnel
+	withEICTunnel = func(ctx context.Context, instanceID string, _ func(s eicSSHSession) error) error {
+		captured = append(captured, instanceID)
+		return replacement(eicSSHSession{instanceID: instanceID, osUser: "ubuntu", localPort: 12345, keyPath: "/tmp/k"})
+	}
+	t.Cleanup(func() { withEICTunnel = prev })
+	return calls
+}
+
+// ---- ListFiles EIC dispatch ----
+
+// TestListFiles_EICDispatch_Success: a workspace with instance_id set
+// must route to listFilesViaEIC, NOT to local-Docker / template-dir.
+// Verifies the handler hands the EIC helper's output back as JSON.
+//
+// Until PR-A this test would fail no matter what mocks were in place —
+// the dispatch branch did not exist.
+func TestListFiles_EICDispatch_Success(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
+		WithArgs("ws-eic").
+		WillReturnRows(sqlmock.NewRows([]string{"name", "instance_id", "runtime"}).
+			AddRow("My Agent", "i-test", "claude-code"))
+
+	// The package-level withEICTunnel stub doesn't get to set the
+	// listFilesViaEIC outparam, so we have to override the helper at
+	// a higher level. Instead, we stub withEICTunnel to *return* the
+	// inner closure's err — but we can't reach the byte-output path.
+	// Use the dedicated stubWithEICTunnelReturning + intercept ssh:
+	// since the tunnel stub doesn't run the closure's ssh exec at all
+	// when we replace the inner fn, the helper's `rawOutput` stays
+	// nil and parseFindOutput returns []. Sufficient for "200 + empty"
+	// dispatch verification.
+	stubWithEICTunnelReturning(t, func(s eicSSHSession) error {
+		return nil // skip the real ssh; outer rawOutput stays nil → []
+	})
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: "ws-eic"}}
+	c.Request = httptest.NewRequest("GET", "/workspaces/ws-eic/files?root=/configs", nil)
+
+	(&TemplatesHandler{}).ListFiles(c)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	var got []map[string]interface{}
+	if err := json.Unmarshal(w.Body.Bytes(), &got); err != nil {
+		t.Fatalf("response not JSON array: %v (body=%s)", err, w.Body.String())
+	}
+	// EIC stub returned no output → empty list. The point of this
+	// assertion is "200 with [] from EIC", not "fell through to host
+	// template fallback which would 200 with []" — to discriminate,
+	// we ALSO assert mock expectations were met (proving the new SQL
+	// shape was queried) AND the local-Docker fallback path can't
+	// have run (handler.docker is nil here, so findContainer returns
+	// "" and the only paths that reach 200 are EIC or template-dir;
+	// template-dir requires a non-empty configsDir which we left at
+	// "" via the zero-value handler).
+	if got == nil {
+		t.Errorf("expected JSON array (even if empty); got null")
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
+}
+
+// TestListFiles_EICDispatch_Error: a real EIC failure (network blip,
+// AWS API throttle, sshd down) must surface as 500, NOT silently fall
+// through to the local-Docker path which would mask the failure as
+// "0 files" — which is the exact UX symptom the PR-A bug report cites.
+func TestListFiles_EICDispatch_Error(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
+		WithArgs("ws-eic-err").
+		WillReturnRows(sqlmock.NewRows([]string{"name", "instance_id", "runtime"}).
+			AddRow("My Agent", "i-test", "claude-code"))
+
+	stubWithEICTunnel(t, errors.New("eic open-tunnel: timeout"))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: "ws-eic-err"}}
+	c.Request = httptest.NewRequest("GET", "/workspaces/ws-eic-err/files?root=/home", nil)
+
+	(&TemplatesHandler{}).ListFiles(c)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Fatalf("expected 500, got %d: %s", w.Code, w.Body.String())
+	}
+	if !strings.Contains(w.Body.String(), "failed to list files") {
+		t.Errorf("error body should describe ListFiles failure; got %s", w.Body.String())
+	}
+}
+
+// TestListFiles_EICBranch_NotTakenForSelfHosted: workspaces with no
+// instance_id (self-hosted, local-Docker path) MUST NOT enter the EIC
+// branch. Stubs withEICTunnel to fail loudly if it's called — the
+// stub being invoked is itself the assertion failure.
+func TestListFiles_EICBranch_NotTakenForSelfHosted(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
+		WithArgs("ws-local").
+		WillReturnRows(sqlmock.NewRows([]string{"name", "instance_id", "runtime"}).
+			AddRow("Local Agent", "", ""))
+
+	prev := withEICTunnel
+	withEICTunnel = func(ctx context.Context, instanceID string, fn func(s eicSSHSession) error) error {
+		t.Errorf("withEICTunnel called for self-hosted workspace (instance_id=''); EIC branch must be gated on non-empty instance_id")
+		return errors.New("should not be called")
+	}
+	defer func() { withEICTunnel = prev }()
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: "ws-local"}}
+	c.Request = httptest.NewRequest("GET", "/workspaces/ws-local/files", nil)
+
+	(&TemplatesHandler{configsDir: t.TempDir()}).ListFiles(c)
+
+	// Don't pin the response code here — the local path's behavior is
+	// covered by TestListFiles_FallbackToHost_NoTemplate. Just confirm
+	// EIC wasn't called.
+}
+
+// ---- DeleteFile EIC dispatch ----
+
+// TestDeleteFile_EICDispatch_Success: same shape as ListFiles —
+// instance_id != "" routes to deleteFileViaEIC and returns 200 on
+// success. Pre-PR-A right-click delete on a SaaS workspace silently
+// no-op'd because findContainer returned "" and the ephemeral-volume
+// fallback only handles local Docker volumes.
+func TestDeleteFile_EICDispatch_Success(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
+		WithArgs("ws-eic-del").
+		WillReturnRows(sqlmock.NewRows([]string{"name", "instance_id", "runtime"}).
+			AddRow("My Agent", "i-test", "claude-code"))
+
+	stubWithEICTunnel(t, nil)
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{
+		{Key: "id", Value: "ws-eic-del"},
+		{Key: "path", Value: "old.txt"},
+	}
+	c.Request = httptest.NewRequest("DELETE", "/workspaces/ws-eic-del/files/old.txt", nil)
+
+	(&TemplatesHandler{}).DeleteFile(c)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	if !strings.Contains(w.Body.String(), `"deleted"`) {
+		t.Errorf("expected status:deleted; got %s", w.Body.String())
+	}
+}
+
+func TestDeleteFile_EICDispatch_Error(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
+		WithArgs("ws-eic-del-err").
+		WillReturnRows(sqlmock.NewRows([]string{"name", "instance_id", "runtime"}).
+			AddRow("My Agent", "i-test", "hermes"))
+
+	stubWithEICTunnel(t, errors.New("ssh rm: connection refused"))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{
+		{Key: "id", Value: "ws-eic-del-err"},
+		{Key: "path", Value: "old.txt"},
+	}
+	c.Request = httptest.NewRequest("DELETE", "/workspaces/ws-eic-del-err/files/old.txt", nil)
+
+	(&TemplatesHandler{}).DeleteFile(c)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Fatalf("expected 500, got %d: %s", w.Code, w.Body.String())
+	}
+}
+
+// TestListFiles_RootValidation: the handler must reject roots outside
+// the allowlist BEFORE any DB query (otherwise a bad root would burn
+// a tunnel + EIC call to discover what a 400 already knows). Critical
+// security guard — without it `?root=/etc` would translate via the
+// resolver's literal-pass-through. Let me prove the gate exists by
+// driving an out-of-allowlist root and asserting 400 + no DB query.
+func TestListFiles_RootValidation(t *testing.T) {
+	setupTestDB(t)
+	setupTestRedis(t)
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: "ws-x"}}
+	c.Request = httptest.NewRequest("GET", "/workspaces/ws-x/files?root=/etc", nil)
+
+	(&TemplatesHandler{}).ListFiles(c)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400 for /etc root, got %d: %s", w.Code, w.Body.String())
+	}
+}
+
+// TestDeleteFile_RootValidation mirrors the ListFiles guard. PR-A
+// added ?root= handling to DeleteFile so the canvas's right-click
+// delete works on any root (not just /configs) — that means the
+// allowlist guard has to be present here too, otherwise an unsafe
+// root flows straight into the resolver.
+func TestDeleteFile_RootValidation(t *testing.T) {
+	setupTestDB(t)
+	setupTestRedis(t)
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{
+		{Key: "id", Value: "ws-x"},
+		{Key: "path", Value: "f.txt"},
+	}
+	c.Request = httptest.NewRequest("DELETE", "/workspaces/ws-x/files/f.txt?root=/etc", nil)
+
+	(&TemplatesHandler{}).DeleteFile(c)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400 for /etc root, got %d: %s", w.Code, w.Body.String())
+	}
+}
@@ -0,0 +1,200 @@
+package handlers
+
+// template_files_eic_shells_test.go — pure-function tests for the
+// remote shell builders + parser. Factored out of the EIC helpers so
+// the wire shape can be pinned without standing up a real EIC tunnel
+// or sshd. If a future edit changes the find/install/cat/rm shell in
+// a way that drifts from the local-Docker container path, these tests
+// catch it before staging.
+
+import (
+	"strings"
+	"testing"
+)
+
+// TestBuildInstallShell pins the write-side remote command. `install`
+// (not `cp`/`tee`) is load-bearing — it creates parent dirs (-D) and
+// writes atomically via temp-file-rename. Permissions 0644 match the
+// local-Docker tar-unpack defaults so a save → restart → save → restart
+// cycle doesn't flip-flop file modes per backend.
+func TestBuildInstallShell(t *testing.T) {
+	got := buildInstallShell("/configs/config.yaml")
+	wants := []string{
+		"sudo -n",                                   // privilege escalation for root-owned /configs
+		"install -D",                                // creates parent dirs
+		"-m 0644",                                   // permission contract
+		"/dev/stdin",                                // pipe-from-ssh source
+		"'/configs/config.yaml'",                    // shell-quoted destination
+	}
+	for _, w := range wants {
+		if !strings.Contains(got, w) {
+			t.Errorf("buildInstallShell missing %q in: %s", w, got)
+		}
+	}
+}
+
+// TestBuildCatShell pins the read-side remote command. `2>/dev/null`
+// is load-bearing: without it the missing-file case emits "cat: ...:
+// No such file" to stderr, and the helper's "empty stdout + empty
+// stderr → os.ErrNotExist" classifier fires the wrong branch (500
+// instead of 404). The tunnel-warning silencer (LogLevel=ERROR in
+// sshArgs) handles the ssh side; this one handles the remote-cmd side.
+func TestBuildCatShell(t *testing.T) {
+	got := buildCatShell("/home/ubuntu/.hermes/config.yaml")
+	wants := []string{
+		"sudo -n",
+		"cat",
+		"'/home/ubuntu/.hermes/config.yaml'",
+		"2>/dev/null", // missing-file → empty stdout + non-zero exit
+	}
+	for _, w := range wants {
+		if !strings.Contains(got, w) {
+			t.Errorf("buildCatShell missing %q in: %s", w, got)
+		}
+	}
+}
+
+// TestBuildRmShell pins `rm -f`, NOT `rm -rf`. A misclassified
+// directory entry passing through the validator must NOT trigger a
+// recursive delete. Directory removal needs its own explicit endpoint
+// when/if the canvas grows that affordance.
+func TestBuildRmShell(t *testing.T) {
+	got := buildRmShell("/configs/dead.yaml")
+	wants := []string{"sudo -n", "rm -f", "'/configs/dead.yaml'"}
+	for _, w := range wants {
+		if !strings.Contains(got, w) {
+			t.Errorf("buildRmShell missing %q in: %s", w, got)
+		}
+	}
+	// Negative assertion: NEVER emit -rf.
+	if strings.Contains(got, "rm -rf") {
+		t.Errorf("buildRmShell uses -rf, must use -f only: %s", got)
+	}
+}
+
+// TestBuildFindShell pins the listing-side remote command — it must
+// match the local-Docker path's parser shape (TYPE|SIZE|REL_PATH per
+// line) AND prune the same hidden / cache directories. If either
+// side drifts, a /workspace listing on EC2 either drowns in node_modules
+// noise (pruning regression) or drops files entirely (parser shape
+// regression).
+func TestBuildFindShell(t *testing.T) {
+	got := buildFindShell("/workspace", 2)
+	wants := []string{
+		"sudo -n find",
+		"'/workspace'",
+		"-maxdepth 2",
+		// Matches local-Docker container path; without these the EC2
+		// listing fills with VCS/build artefacts.
+		"-not -path '*/.git/*'",
+		"-not -path '*/__pycache__/*'",
+		"-not -path '*/node_modules/*'",
+		"-not -name .DS_Store",
+		"2>/dev/null", // missing-root → empty stdout + non-zero exit
+		// Wire shape — emit "TYPE|SIZE|REL_PATH" so parseFindOutput
+		// (and the canvas tree builder) can decode each line.
+		"d|0|",
+		"f|",
+		// Portable stat: GNU first, BSD fallback, then 0.
+		"stat -c %s",
+		"stat -f %z",
+	}
+	for _, w := range wants {
+		if !strings.Contains(got, w) {
+			t.Errorf("buildFindShell missing %q in: %s", w, got)
+		}
+	}
+}
+
+// TestBuildFindShell_DepthForwarding catches a regression where the
+// helper hard-codes a depth instead of using the caller's value.
+// `?depth=` on the canvas side controls how many levels expand on
+// load — losing it means the file tree is either empty (depth=0) or
+// the network blows up on a top-level /home with everyone's $HOME
+// (uncapped).
+func TestBuildFindShell_DepthForwarding(t *testing.T) {
+	for _, d := range []int{1, 3, 5} {
+		got := buildFindShell("/configs", d)
+		want := "-maxdepth " + intToStr(d)
+		if !strings.Contains(got, want) {
+			t.Errorf("buildFindShell depth=%d output missing %q: %s", d, want, got)
+		}
+	}
+}
+
+// intToStr avoids pulling strconv into a one-liner; matches the shell
+// builder's fmt.Sprintf %d output exactly.
+func intToStr(n int) string {
+	if n == 0 {
+		return "0"
+	}
+	neg := n < 0
+	if neg {
+		n = -n
+	}
+	var buf [20]byte
+	i := len(buf)
+	for n > 0 {
+		i--
+		buf[i] = byte('0' + n%10)
+		n /= 10
+	}
+	s := string(buf[i:])
+	if neg {
+		return "-" + s
+	}
+	return s
+}
+
+// TestParseFindOutput pins the parser. Each line is TYPE|SIZE|REL,
+// blank/short lines silently skipped. Pre-PR-A this logic was inlined
+// in the handler with the same shape; extracting + testing separately
+// removes the "regex passes against the inline parser but a future
+// refactor of the handler subtly changes the parse" failure mode.
+func TestParseFindOutput(t *testing.T) {
+	in := []byte(`d|0|nested
+f|123|nested/a.yaml
+f|45|README.md
+
+invalid-line
+f||no-size
+d|0|
+`)
+	got := parseFindOutput(in)
+	// Want 4 entries: nested(d), nested/a.yaml(f,123), README.md(f,45),
+	// no-size(f,0). Blank lines, "invalid-line" (no pipes), and
+	// `d|0|` (empty rel) are skipped.
+	wantPaths := []string{"nested", "nested/a.yaml", "README.md", "no-size"}
+	if len(got) != len(wantPaths) {
+		t.Fatalf("got %d entries, want %d: %+v", len(got), len(wantPaths), got)
+	}
+	for i, w := range wantPaths {
+		if got[i].Path != w {
+			t.Errorf("entry[%d].Path = %q, want %q", i, got[i].Path, w)
+		}
+	}
+	if !got[0].Dir {
+		t.Errorf("entry[0] should be Dir")
+	}
+	if got[1].Size != 123 {
+		t.Errorf("entry[1].Size = %d, want 123", got[1].Size)
+	}
+	if got[3].Size != 0 {
+		t.Errorf("entry[3].Size on missing-size line = %d, want 0", got[3].Size)
+	}
+}
+
+// TestParseFindOutput_EmptyInput — a missing listing root yields
+// empty stdout (find swallows the "No such file" via 2>/dev/null),
+// which must round-trip to a JSON `[]`, not null. The handler does
+// `make([]eicFileEntry, 0)` to enforce this; the test pins the
+// helper-level guarantee independently.
+func TestParseFindOutput_EmptyInput(t *testing.T) {
+	got := parseFindOutput([]byte(""))
+	if got == nil {
+		t.Errorf("parseFindOutput(\"\") returned nil; want empty slice for JSON []")
+	}
+	if len(got) != 0 {
+		t.Errorf("parseFindOutput(\"\") = %+v; want []", got)
+	}
+}
@@ -7,39 +7,112 @@ import (
 	"testing"
 )

-// TestResolveWorkspaceFilePath_KnownRuntimes — the runtime → base-path
-// map is the source of truth for where saved files land on the workspace
-// EC2. Changing a base path without a migration shim silently orphans
-// previously-saved files; this test pins the current contract.
-func TestResolveWorkspaceFilePath_KnownRuntimes(t *testing.T) {
+// TestResolveWorkspaceFilePath_RuntimeIndirection pins the
+// `?root="/configs"` (or empty / unrecognized) → runtime managed-config
+// dir behavior. Hermes uses /home/ubuntu/.hermes; claude-code uses
+// /configs; unknowns fall back to /configs. This indirection is the
+// reason hermes Config-tab edits land in the right place even though
+// the canvas only ever sends `?root=/configs`. Changing it without a
+// migration shim silently orphans previously-saved files.
+func TestResolveWorkspaceFilePath_RuntimeIndirection(t *testing.T) {
 	cases := []struct {
 		runtime string
+		root    string
 		relPath string
 		want    string
 	}{
-		{"hermes", "config.yaml", "/home/ubuntu/.hermes/config.yaml"},
-		{"HERMES", "config.yaml", "/home/ubuntu/.hermes/config.yaml"}, // case-insensitive
-		{"hermes", "nested/a.yaml", "/home/ubuntu/.hermes/nested/a.yaml"},
+		{"hermes", "/configs", "config.yaml", "/home/ubuntu/.hermes/config.yaml"},
+		{"HERMES", "/configs", "config.yaml", "/home/ubuntu/.hermes/config.yaml"}, // case-insensitive
+		{"hermes", "/configs", "nested/a.yaml", "/home/ubuntu/.hermes/nested/a.yaml"},
+		{"hermes", "", "config.yaml", "/home/ubuntu/.hermes/config.yaml"},     // empty root → runtime indirection
+		{"hermes", "/etc", "config.yaml", "/home/ubuntu/.hermes/config.yaml"}, // out-of-allowlist → runtime indirection
 		// claude-code (and any future containerized runtime) lands at /configs —
 		// the path user-data creates and bind-mounts into the container. Pre-fix
 		// this fell through to /opt/configs which doesn't exist on workspace EC2s
 		// and would 500 with EACCES on save (the bug that motivated this gate).
-		{"claude-code", "config.yaml", "/configs/config.yaml"},
-		{"CLAUDE-CODE", "config.yaml", "/configs/config.yaml"}, // case-insensitive
-		{"langgraph", "config.yaml", "/opt/configs/config.yaml"},
-		{"external", "skills.json", "/opt/configs/skills.json"},
-		{"", "config.yaml", "/configs/config.yaml"},        // empty → default
-		{"unknown", "config.yaml", "/configs/config.yaml"}, // unknown → default
+		{"claude-code", "/configs", "config.yaml", "/configs/config.yaml"},
+		{"CLAUDE-CODE", "/configs", "config.yaml", "/configs/config.yaml"}, // case-insensitive
+		{"langgraph", "/configs", "config.yaml", "/opt/configs/config.yaml"},
+		{"external", "/configs", "skills.json", "/opt/configs/skills.json"},
+		{"", "/configs", "config.yaml", "/configs/config.yaml"},        // empty runtime → default
+		{"unknown", "/configs", "config.yaml", "/configs/config.yaml"}, // unknown → default
 	}
 	for _, tc := range cases {
-		t.Run(tc.runtime+"/"+tc.relPath, func(t *testing.T) {
-			got, err := resolveWorkspaceFilePath(tc.runtime, tc.relPath)
+		t.Run(tc.runtime+"+"+tc.root+"/"+tc.relPath, func(t *testing.T) {
+			got, err := resolveWorkspaceFilePath(tc.runtime, tc.root, tc.relPath)
 			if err != nil {
 				t.Fatalf("unexpected err: %v", err)
 			}
 			if got != tc.want {
-				t.Errorf("resolveWorkspaceFilePath(%q,%q) = %q, want %q",
-					tc.runtime, tc.relPath, got, tc.want)
+				t.Errorf("resolveWorkspaceFilePath(%q,%q,%q) = %q, want %q",
+					tc.runtime, tc.root, tc.relPath, got, tc.want)
+			}
+		})
+	}
+}
+
+// TestResolveWorkspaceFilePath_LiteralRoots pins that the universal
+// allow-listed roots (`/home`, `/workspace`, `/plugins`) pass through
+// LITERALLY rather than getting rewritten to the runtime prefix. This
+// is the half of the resolver that the FilesTab "/home" selector
+// depends on — without it, picking /home on a hermes workspace would
+// route to /home/ubuntu/.hermes (the runtime indirection) and the
+// canvas's tree row would never line up with what the user sees on
+// the EC2 host.
+func TestResolveWorkspaceFilePath_LiteralRoots(t *testing.T) {
+	cases := []struct {
+		runtime string
+		root    string
+		relPath string
+		want    string
+	}{
+		// /home is always literal regardless of runtime — it's a
+		// universal Linux path, not a managed-config indirection.
+		{"hermes", "/home", "ubuntu/.bashrc", "/home/ubuntu/.bashrc"},
+		{"claude-code", "/home", "ubuntu/notes.md", "/home/ubuntu/notes.md"},
+		{"langgraph", "/home", "ubuntu/x", "/home/ubuntu/x"},
+		// /workspace and /plugins are also literal — runtime is ignored.
+		{"hermes", "/workspace", "src/main.go", "/workspace/src/main.go"},
+		{"claude-code", "/plugins", "p/manifest.yaml", "/plugins/p/manifest.yaml"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.runtime+"+"+tc.root+"/"+tc.relPath, func(t *testing.T) {
+			got, err := resolveWorkspaceFilePath(tc.runtime, tc.root, tc.relPath)
+			if err != nil {
+				t.Fatalf("unexpected err: %v", err)
+			}
+			if got != tc.want {
+				t.Errorf("resolveWorkspaceFilePath(%q,%q,%q) = %q, want %q",
+					tc.runtime, tc.root, tc.relPath, got, tc.want)
+			}
+		})
+	}
+}
+
+// TestResolveWorkspaceRootPath pins the directory-only translation
+// used by listFilesViaEIC. Same indirection rules as
+// resolveWorkspaceFilePath but without joining a relative path.
+func TestResolveWorkspaceRootPath(t *testing.T) {
+	cases := []struct {
+		runtime string
+		root    string
+		want    string
+	}{
+		{"hermes", "/configs", "/home/ubuntu/.hermes"},
+		{"claude-code", "/configs", "/configs"},
+		{"hermes", "", "/home/ubuntu/.hermes"},
+		{"hermes", "/home", "/home"},
+		{"claude-code", "/workspace", "/workspace"},
+		{"hermes", "/plugins", "/plugins"},
+		{"unknown", "/configs", "/configs"},
+		{"hermes", "/etc", "/home/ubuntu/.hermes"}, // not allowlisted → runtime indirection
+	}
+	for _, tc := range cases {
+		t.Run(tc.runtime+"+"+tc.root, func(t *testing.T) {
+			got := resolveWorkspaceRootPath(tc.runtime, tc.root)
+			if got != tc.want {
+				t.Errorf("resolveWorkspaceRootPath(%q,%q) = %q, want %q",
+					tc.runtime, tc.root, got, tc.want)
 			}
 		})
 	}
@@ -53,48 +126,80 @@ func TestResolveWorkspaceFilePath_KnownRuntimes(t *testing.T) {
 // We only assert the cases that Clean() can't rescue.
 func TestResolveWorkspaceFilePath_RejectsTraversal(t *testing.T) {
 	bad := []string{
-		"../etc/shadow",   // escapes base via ..
-		"/etc/shadow",     // absolute path
-		"./../../etc",     // multiple ..
-		"a/../../etc",     // escapes via deeper ..
+		"../etc/shadow", // escapes base via ..
+		"/etc/shadow",   // absolute path
+		"./../../etc",   // multiple ..
+		"a/../../etc",   // escapes via deeper ..
 	}
 	for _, rel := range bad {
 		t.Run(rel, func(t *testing.T) {
-			_, err := resolveWorkspaceFilePath("hermes", rel)
+			_, err := resolveWorkspaceFilePath("hermes", "/configs", rel)
 			if err == nil {
-				t.Errorf("resolveWorkspaceFilePath(hermes, %q) should have errored, got nil", rel)
+				t.Errorf("resolveWorkspaceFilePath(hermes,/configs,%q) should have errored, got nil", rel)
 			}
 		})
 	}
 }

-// TestSSHArgs_LogLevelErrorBothSites pins that BOTH ssh invocations
-// (writeFileViaEIC + readFileViaEIC) include `-o LogLevel=ERROR`.
+// TestSSHArgs_HardenedFlags pins the ssh option set returned by
+// eicSSHSession.sshArgs(). Centralising the args was deliberate so a
+// fix like PR #2822's `LogLevel=ERROR` (silences the benign
+// known-hosts warning that fooled the read/list "empty stderr → not
+// found" classifier) only needs to land in one place.
 //
-// Without that flag, ssh emits a "Warning: Permanently added
-// '[127.0.0.1]:NNNNN' (ED25519) to the list of known hosts." line on
-// every fresh tunnel connection (even with UserKnownHostsFile=/dev/null
-// — that prevents persistence, not the warning). The warning lands on
-// stderr, which fools readFileViaEIC's "empty stdout + empty stderr →
-// file not found" classifier into thinking the warning is a real
-// ssh-layer error and returning 500 instead of 404.
-//
-// Caught 2026-05-05 02:38 on hongming.moleculesai.app: opening Hermes
-// workspace's Config tab returned 500 with body
+// Caught 2026-05-05 02:38 on hongming.moleculesai.app: opening
+// Hermes workspace's Config tab returned 500 with body
 // `ssh cat: exit status 1 (Warning: Permanently added '[127.0.0.1]:37951'…)`.
 //
-// LogLevel=ERROR silences info+warning while keeping real auth/tunnel
-// errors visible. This test reads the source and asserts the flag
-// appears at least twice (one per ssh block) — fires if a future edit
-// removes it from either site.
-func TestSSHArgs_LogLevelErrorBothSites(t *testing.T) {
+// Asserts each load-bearing flag appears in the args slice — fires if
+// a future edit removes any of them.
+func TestSSHArgs_HardenedFlags(t *testing.T) {
+	s := eicSSHSession{keyPath: "/tmp/k", localPort: 12345, osUser: "ubuntu", instanceID: "i-x"}
+	got := s.sshArgs("echo hi")
+	wantFragments := [][]string{
+		{"-i", "/tmp/k"},
+		{"-o", "StrictHostKeyChecking=no"},
+		{"-o", "UserKnownHostsFile=/dev/null"},
+		{"-o", "LogLevel=ERROR"},
+		{"-o", "ServerAliveInterval=15"},
+		{"-p", "12345"},
+	}
+	joined := strings.Join(got, " ")
+	for _, frag := range wantFragments {
+		if !strings.Contains(joined, strings.Join(frag, " ")) {
+			t.Errorf("sshArgs() missing fragment %v; got: %v", frag, got)
+		}
+	}
+	// Last two args must be `<user>@127.0.0.1` then the remote command.
+	if got[len(got)-2] != "ubuntu@127.0.0.1" {
+		t.Errorf("sshArgs() second-last must be user@127.0.0.1; got: %q", got[len(got)-2])
+	}
+	if got[len(got)-1] != "echo hi" {
+		t.Errorf("sshArgs() last must be the remote command; got: %q", got[len(got)-1])
+	}
+}
+
+// TestEicSSHSessionSingleSourceForSSHFlags is a structural guard: the
+// production EIC source must invoke s.sshArgs() exclusively for ssh
+// invocations — direct ssh args inlined in any helper would re-open
+// the regression that PR #2822 closed (LogLevel=ERROR drift between
+// helpers). Counts `s.sshArgs(` occurrences (one per file op) and
+// fails if anyone copy-pastes a raw ssh args slice.
+func TestEicSSHSessionSingleSourceForSSHFlags(t *testing.T) {
 	src, err := os.ReadFile("template_files_eic.go")
 	if err != nil {
 		t.Fatalf("read source: %v", err)
 	}
-	matches := regexp.MustCompile(`"-o", "LogLevel=ERROR"`).FindAllIndex(src, -1)
-	if len(matches) < 2 {
-		t.Errorf("expected LogLevel=ERROR in BOTH ssh blocks (write + read); found %d occurrences", len(matches))
+	// Each of write/read/list/delete should call s.sshArgs once.
+	matches := regexp.MustCompile(`s\.sshArgs\(`).FindAllIndex(src, -1)
+	if len(matches) < 4 {
+		t.Errorf("expected ≥4 s.sshArgs() callers (write/read/list/delete); found %d", len(matches))
+	}
+	// Belt and braces: no helper should be assembling its own
+	// `LogLevel=ERROR` literal outside of sshArgs.
+	literal := regexp.MustCompile(`"-o", "LogLevel=ERROR"`).FindAllIndex(src, -1)
+	if len(literal) != 1 {
+		t.Errorf("LogLevel=ERROR must appear exactly once (in sshArgs); found %d occurrences — drift risk", len(literal))
 	}
 }

@@ -216,7 +216,12 @@ func (h *TemplatesHandler) ReplaceFiles(c *gin.Context) {
 	// as a follow-up.
 	if instanceID != "" {
 		for relPath, content := range body.Files {
-			if err := writeFileViaEIC(ctx, instanceID, runtime, relPath, []byte(content)); err != nil {
+			// ReplaceFiles is a bulk template-import endpoint — files
+			// always land in the runtime's managed-config dir. Pass
+			// "/configs" so resolveWorkspaceFilePath routes through the
+			// runtime prefix map (matches the local-Docker arm below
+			// which always copies to /configs).
+			if err := writeFileViaEIC(ctx, instanceID, runtime, "/configs", relPath, []byte(content)); err != nil {
 				log.Printf("ReplaceFiles EIC for %s path=%s: %v", workspaceID, relPath, err)
 				c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("failed to write file %s: %v", relPath, err)})
 				return
@@ -243,8 +243,11 @@ func (h *TemplatesHandler) ListFiles(c *gin.Context) {
 		listPath = rootPath + "/" + subPath
 	}

-	var wsName string
-	if err := db.DB.QueryRowContext(ctx, `SELECT name FROM workspaces WHERE id = $1`, workspaceID).Scan(&wsName); err != nil {
+	var wsName, instanceID, runtime string
+	if err := db.DB.QueryRowContext(ctx,
+		`SELECT name, COALESCE(instance_id, ''), COALESCE(runtime, '') FROM workspaces WHERE id = $1`,
+		workspaceID,
+	).Scan(&wsName, &instanceID, &runtime); err != nil {
 		c.JSON(http.StatusNotFound, gin.H{"error": "workspace not found"})
 		return
 	}
@@ -255,6 +258,32 @@ func (h *TemplatesHandler) ListFiles(c *gin.Context) {
 		Dir  bool   `json:"dir"`
 	}

+	// SaaS workspace (EC2-per-workspace) — no Docker on this tenant. List
+	// via SSH through the EIC endpoint, mirroring ReadFile/WriteFile's
+	// dispatch. Pre-fix this branch was missing and SaaS workspaces
+	// always fell through to local-Docker check (finds nothing on a SaaS
+	// tenant) + template-dir fallback (returns the seed template, not
+	// the persisted state, and almost never matches on user-named
+	// workspaces). Net effect: the canvas Files tab always rendered "0
+	// files / No config files yet" for SaaS workspaces, regardless of
+	// what was actually on disk. See issue #2999.
+	if instanceID != "" {
+		entries, err := listFilesViaEIC(ctx, instanceID, runtime, rootPath, subPath, depth)
+		if err != nil {
+			log.Printf("ListFiles EIC for %s root=%s sub=%s: %v", workspaceID, rootPath, subPath, err)
+			c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("failed to list files: %v", err)})
+			return
+		}
+		// Translate to the handler's wire shape (the field names match
+		// 1:1, but Go can't implicit-convert named struct types).
+		out := make([]fileEntry, 0, len(entries))
+		for _, e := range entries {
+			out = append(out, fileEntry{Path: e.Path, Size: e.Size, Dir: e.Dir})
+		}
+		c.JSON(http.StatusOK, out)
+		return
+	}
+
 	// Try container filesystem first
 	if containerName := h.findContainer(ctx, workspaceID); containerName != "" {
 		// Portable file listing: works on both GNU and BusyBox/Alpine.
@@ -378,12 +407,13 @@ func (h *TemplatesHandler) ReadFile(c *gin.Context) {
 	// canvas Config tab always 404'd for SaaS workspaces — visible to
 	// users after #2781 added the "no config.yaml" error UX.
 	//
-	// The ?root= query param is intentionally ignored on the SaaS path —
-	// it's a local-Docker concept (arbitrary container roots). The
-	// runtime → base-path map (workspaceFilePathPrefix in
-	// template_files_eic.go) is the SaaS source of truth.
+	// `?root=` flows through resolveWorkspaceFilePath: "/configs" stays
+	// the per-runtime managed-config indirection (claude-code → /configs,
+	// hermes → /home/ubuntu/.hermes); other allow-listed roots
+	// (`/home`, `/workspace`, `/plugins`) pass through literally so
+	// list/read/write/delete agree on what file a tree row points to.
 	if instanceID != "" {
-		content, err := readFileViaEIC(ctx, instanceID, runtime, filePath)
+		content, err := readFileViaEIC(ctx, instanceID, runtime, rootPath, filePath)
 		if err == nil {
 			c.JSON(http.StatusOK, gin.H{
 				"path":    filePath,
@@ -468,6 +498,11 @@ func (h *TemplatesHandler) WriteFile(c *gin.Context) {
 	}

 	ctx := c.Request.Context()
+	rootPath := c.DefaultQuery("root", "/configs")
+	if !allowedRoots[rootPath] {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "root must be one of: /configs, /workspace, /home, /plugins"})
+		return
+	}
 	var wsName, instanceID, runtime string
 	if err := db.DB.QueryRowContext(ctx,
 		`SELECT name, COALESCE(instance_id, ''), COALESCE(runtime, '') FROM workspaces WHERE id = $1`,
@@ -479,8 +514,11 @@ func (h *TemplatesHandler) WriteFile(c *gin.Context) {

 	// SaaS workspace (EC2-per-workspace) — no Docker on this tenant. Write
 	// via SSH through the EIC endpoint to the runtime-specific path.
+	// `?root=` flows through the same per-runtime / literal indirection
+	// as ReadFile so list/read/write/delete agree on what file a tree
+	// row points to.
 	if instanceID != "" {
-		if err := writeFileViaEIC(ctx, instanceID, runtime, filePath, []byte(body.Content)); err != nil {
+		if err := writeFileViaEIC(ctx, instanceID, runtime, rootPath, filePath, []byte(body.Content)); err != nil {
 			log.Printf("WriteFile EIC for %s path=%s: %v", workspaceID, filePath, err)
 			c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("failed to write file: %v", err)})
 			return
@@ -528,12 +566,35 @@ func (h *TemplatesHandler) DeleteFile(c *gin.Context) {
 	}

 	ctx := c.Request.Context()
-	var wsName string
-	if err := db.DB.QueryRowContext(ctx, `SELECT name FROM workspaces WHERE id = $1`, workspaceID).Scan(&wsName); err != nil {
+	rootPath := c.DefaultQuery("root", "/configs")
+	if !allowedRoots[rootPath] {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "root must be one of: /configs, /workspace, /home, /plugins"})
+		return
+	}
+	var wsName, instanceID, runtime string
+	if err := db.DB.QueryRowContext(ctx,
+		`SELECT name, COALESCE(instance_id, ''), COALESCE(runtime, '') FROM workspaces WHERE id = $1`,
+		workspaceID,
+	).Scan(&wsName, &instanceID, &runtime); err != nil {
 		c.JSON(http.StatusNotFound, gin.H{"error": "workspace not found"})
 		return
 	}

+	// SaaS workspace (EC2-per-workspace) — no Docker on this tenant. Delete
+	// via SSH through the EIC endpoint, mirroring ReadFile/WriteFile's
+	// dispatch. Pre-fix this branch was missing — DeleteFile fell through
+	// to local-Docker (no container) + ephemeral-volume (no Docker) and
+	// silently 500'd. See issue #2999.
+	if instanceID != "" {
+		if err := deleteFileViaEIC(ctx, instanceID, runtime, rootPath, filePath); err != nil {
+			log.Printf("DeleteFile EIC for %s root=%s path=%s: %v", workspaceID, rootPath, filePath, err)
+			c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("failed to delete file: %v", err)})
+			return
+		}
+		c.JSON(http.StatusOK, gin.H{"status": "deleted", "path": filePath})
+		return
+	}
+
 	// Delete via docker exec when container is running
 	if containerName := h.findContainer(ctx, workspaceID); containerName != "" {
 		// CWE-78: use filepath.Join instead of string concat to prevent path
@@ -750,7 +750,11 @@ func TestListFiles_WorkspaceNotFound(t *testing.T) {

 	handler := NewTemplatesHandler(t.TempDir(), nil, nil)

-	mock.ExpectQuery("SELECT name FROM workspaces WHERE id =").
+	// SQL shape: SELECT name, COALESCE(instance_id, ''), COALESCE(runtime, '') FROM workspaces WHERE id = $1
+	// (matches the L/R/W/D unified shape so dispatchers can branch on
+	// instance_id; sqlmock matches via QueryMatcherRegexp so the parens
+	// need escaping.)
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
 		WithArgs("ws-nonexist").
 		WillReturnError(sql.ErrNoRows)

@@ -777,9 +781,9 @@ func TestListFiles_FallbackToHost_NoTemplate(t *testing.T) {
 	tmpDir := t.TempDir()
 	handler := NewTemplatesHandler(tmpDir, nil, nil) // nil docker = no container

-	mock.ExpectQuery("SELECT name FROM workspaces WHERE id =").
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
 		WithArgs("ws-fallback").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("Unknown Agent"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "instance_id", "runtime"}).AddRow("Unknown Agent", "", ""))

 	w := httptest.NewRecorder()
 	c, _ := gin.CreateTestContext(w)
@@ -817,9 +821,9 @@ func TestListFiles_FallbackToHost_WithTemplate(t *testing.T) {

 	handler := NewTemplatesHandler(tmpDir, nil, nil)

-	mock.ExpectQuery("SELECT name FROM workspaces WHERE id =").
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
 		WithArgs("ws-tmpl").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("Test Agent"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "instance_id", "runtime"}).AddRow("Test Agent", "", ""))

 	w := httptest.NewRecorder()
 	c, _ := gin.CreateTestContext(w)
@@ -1103,7 +1107,7 @@ func TestDeleteFile_WorkspaceNotFound(t *testing.T) {

 	handler := NewTemplatesHandler(t.TempDir(), nil, nil)

-	mock.ExpectQuery("SELECT name FROM workspaces WHERE id =").
+	mock.ExpectQuery(`SELECT name, COALESCE\(instance_id, ''\), COALESCE\(runtime, ''\) FROM workspaces WHERE id =`).
 		WithArgs("ws-del-nf").
 		WillReturnError(sql.ErrNoRows)

@@ -112,7 +112,6 @@ func (h *WorkspaceHandler) SetCPProvisioner(cp provisioner.CPProvisionerAPI) {
 	h.cpProv = cp
 }

-
 // SetEnvMutators wires a provisionhook.Registry into the handler. Plugins
 // living in separate repos register on the same Registry instance during
 // boot (see cmd/server/main.go) and main.go calls this setter once before
@@ -361,7 +360,7 @@ func (h *WorkspaceHandler) Create(c *gin.Context) {
 	// populate the Runtime pill on the side panel immediately — without it
 	// the node lives as "runtime: unknown" until something refetches the
 	// workspace row (which nothing does during provisioning).
-	h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_PROVISIONING", id, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceProvisioning), id, map[string]interface{}{
 		"name":    payload.Name,
 		"tier":    payload.Tier,
 		"runtime": payload.Runtime,
@@ -388,7 +387,7 @@ func (h *WorkspaceHandler) Create(c *gin.Context) {
 			if err := db.CacheURL(ctx, id, payload.URL); err != nil {
 				log.Printf("External workspace: failed to cache URL for %s: %v", id, err)
 			}
-			h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_ONLINE", id, map[string]interface{}{
+			h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceOnline), id, map[string]interface{}{
 				"name": payload.Name, "external": true,
 			})
 		} else {
@@ -407,7 +406,7 @@ func (h *WorkspaceHandler) Create(c *gin.Context) {
 			} else {
 				connectionToken = tok
 			}
-			h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_AWAITING_AGENT", id, map[string]interface{}{
+			h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceAwaitingAgent), id, map[string]interface{}{
 				"name": payload.Name, "external": true,
 			})
 		}
@@ -539,24 +538,24 @@ func scanWorkspaceRow(rows interface {
 	}

 	ws := map[string]interface{}{
-		"id":                id,
-		"name":              name,
-		"tier":              tier,
-		"status":            status,
-		"url":               url,
-		"parent_id":         parentID,
-		"active_tasks":          activeTasks,
-		"max_concurrent_tasks":  maxConcurrentTasks,
-		"last_error_rate":       errorRate,
-		"last_sample_error": sampleError,
-		"uptime_seconds":    uptimeSeconds,
-		"current_task":      currentTask,
-		"runtime":           runtime,
-		"workspace_dir":     nilIfEmpty(workspaceDir),
-		"monthly_spend":     monthlySpend,
-		"x":                 x,
-		"y":                 y,
-		"collapsed":         collapsed,
+		"id":                   id,
+		"name":                 name,
+		"tier":                 tier,
+		"status":               status,
+		"url":                  url,
+		"parent_id":            parentID,
+		"active_tasks":         activeTasks,
+		"max_concurrent_tasks": maxConcurrentTasks,
+		"last_error_rate":      errorRate,
+		"last_sample_error":    sampleError,
+		"uptime_seconds":       uptimeSeconds,
+		"current_task":         currentTask,
+		"runtime":              runtime,
+		"workspace_dir":        nilIfEmpty(workspaceDir),
+		"monthly_spend":        monthlySpend,
+		"x":                    x,
+		"y":                    y,
+		"collapsed":            collapsed,
 	}

 	// budget_limit: nil when no limit set, int64 otherwise
@@ -6,6 +6,7 @@ import (
 	"strings"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/models"
 	"github.com/gin-gonic/gin"
 )
@@ -85,7 +86,7 @@ func (h *WorkspaceHandler) BootstrapFailed(c *gin.Context) {
 		return
 	}

-	h.broadcaster.RecordAndBroadcast(c.Request.Context(), "WORKSPACE_PROVISION_FAILED", id, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(c.Request.Context(), string(events.EventWorkspaceProvisionFailed), id, map[string]interface{}{
 		"error":    errMsg,
 		"log_tail": tail,
 		"source":   "bootstrap_watcher",
@@ -16,12 +16,14 @@ import (
 	"time"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/models"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/wsauth"
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
 	"github.com/lib/pq"
 )
+
 // State handles GET /workspaces/:id/state — minimal status payload for
 // remote-agent polling (Phase 30.4). Returns `{status, paused, deleted,
 // workspace_id}` so a remote agent can detect pause/resume/delete
@@ -380,7 +382,7 @@ func (h *WorkspaceHandler) Delete(c *gin.Context) {
 		pq.Array(allIDs)); err != nil {
 		log.Printf("Delete token revocation error for %s: %v", id, err)
 	}
-// #1027: cascade-disable all schedules for the deleted workspaces so
+	// #1027: cascade-disable all schedules for the deleted workspaces so
 	// the scheduler never fires a cron into a removed container.
 	if _, err := db.DB.ExecContext(ctx,
 		`UPDATE workspace_schedules SET enabled = false, updated_at = now()
@@ -466,14 +468,14 @@ func (h *WorkspaceHandler) Delete(c *gin.Context) {
 		// leaving other WS clients ignorant of the cascade. The DB
 		// row is already 'removed' so it's recoverable, but the
 		// inconsistency is avoidable.
-		h.broadcaster.RecordAndBroadcast(cleanupCtx, "WORKSPACE_REMOVED", descID, map[string]interface{}{})
+		h.broadcaster.RecordAndBroadcast(cleanupCtx, string(events.EventWorkspaceRemoved), descID, map[string]interface{}{})
 	}

 	stopAndRemove(id)
 	db.ClearWorkspaceKeys(cleanupCtx, id)
 	restartStates.Delete(id) // #2269: same as descendants above

-	h.broadcaster.RecordAndBroadcast(cleanupCtx, "WORKSPACE_REMOVED", id, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(cleanupCtx, string(events.EventWorkspaceRemoved), id, map[string]interface{}{
 		"cascade_deleted": len(descendantIDs),
 	})

@@ -41,6 +41,7 @@ import (
 	"path/filepath"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/models"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/provisioner"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/wsauth"
@@ -212,7 +213,7 @@ func (h *WorkspaceHandler) markProvisionFailed(ctx context.Context, workspaceID,
 	} else if _, hasErr := extra["error"]; !hasErr {
 		extra["error"] = msg
 	}
-	h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_PROVISION_FAILED", workspaceID, extra)
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceProvisionFailed), workspaceID, extra)
 	if _, dbErr := db.DB.ExecContext(ctx,
 		`UPDATE workspaces SET status = $3, last_sample_error = $2, updated_at = now() WHERE id = $1`,
 		workspaceID, msg, models.StatusFailed); dbErr != nil {
@@ -11,6 +11,7 @@ import (
 	"time"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/models"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/provlog"
 	"github.com/gin-gonic/gin"
@@ -147,7 +148,7 @@ func (h *WorkspaceHandler) Restart(c *gin.Context) {
 	// Reset to provisioning
 	db.DB.ExecContext(ctx,
 		`UPDATE workspaces SET status = $1, url = '', updated_at = now() WHERE id = $2`, models.StatusProvisioning, id)
-	h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_PROVISIONING", id, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceProvisioning), id, map[string]interface{}{
 		"name":    wsName,
 		"tier":    tier,
 		"runtime": containerRuntime,
@@ -341,7 +342,7 @@ func (h *WorkspaceHandler) HibernateWorkspace(ctx context.Context, workspaceID s
 	}

 	db.ClearWorkspaceKeys(ctx, workspaceID)
-	h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_HIBERNATED", workspaceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceHibernated), workspaceID, map[string]interface{}{
 		"name": wsName,
 		"tier": tier,
 	})
@@ -552,7 +553,7 @@ func (h *WorkspaceHandler) runRestartCycle(workspaceID string) {

 	db.DB.ExecContext(ctx,
 		`UPDATE workspaces SET status = $1, url = '', updated_at = now() WHERE id = $2`, models.StatusProvisioning, workspaceID)
-	h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_PROVISIONING", workspaceID, map[string]interface{}{
+	h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceProvisioning), workspaceID, map[string]interface{}{
 		"name": wsName, "tier": tier, "runtime": dbRuntime,
 	})

@@ -640,7 +641,7 @@ func (h *WorkspaceHandler) Pause(c *gin.Context) {
 		db.DB.ExecContext(ctx,
 			`UPDATE workspaces SET status = $1, url = '', updated_at = now() WHERE id = $2`, models.StatusPaused, ws.id)
 		db.ClearWorkspaceKeys(ctx, ws.id)
-		h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_PAUSED", ws.id, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspacePaused), ws.id, map[string]interface{}{
 			"name": ws.name,
 		})
 	}
@@ -709,7 +710,7 @@ func (h *WorkspaceHandler) Resume(c *gin.Context) {
 	for _, ws := range toResume {
 		db.DB.ExecContext(ctx,
 			`UPDATE workspaces SET status = $1, updated_at = now() WHERE id = $2`, models.StatusProvisioning, ws.id)
-		h.broadcaster.RecordAndBroadcast(ctx, "WORKSPACE_PROVISIONING", ws.id, map[string]interface{}{
+		h.broadcaster.RecordAndBroadcast(ctx, string(events.EventWorkspaceProvisioning), ws.id, map[string]interface{}{
 			"name": ws.name, "tier": ws.tier, "runtime": ws.runtime,
 		})
 		payload := models.CreateWorkspacePayload{Name: ws.name, Tier: ws.tier, Runtime: ws.runtime}
@@ -35,6 +35,7 @@ import (
 	"time"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/memory/contract"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/textutil"
 )

 const (
@@ -340,7 +341,7 @@ func decodeError(resp *http.Response) error {
 		// have rather than dropping it.
 		return &contract.Error{
 			Code:    httpStatusToCode(resp.StatusCode),
-			Message: fmt.Sprintf("status %d: %s", resp.StatusCode, truncate(string(body), 256)),
+			Message: fmt.Sprintf("status %d: %s", resp.StatusCode, textutil.TruncateBytes(string(body), 256)),
 		}
 	}
 	return &e
@@ -359,12 +360,7 @@ func httpStatusToCode(status int) contract.ErrorCode {
 	}
 }

-func truncate(s string, n int) string {
-	if len(s) <= n {
-		return s
-	}
-	return s[:n] + "…"
-}
+// truncation moved to internal/textutil.TruncateBytes (#2962 SSOT).

 // --- Circuit breaker ---

@@ -499,14 +499,10 @@ func TestHttpStatusToCode(t *testing.T) {
 	}
 }

-func TestTruncate(t *testing.T) {
-	if got := truncate("short", 10); got != "short" {
-		t.Errorf("got %q", got)
-	}
-	if got := truncate(strings.Repeat("a", 300), 10); !strings.HasSuffix(got, "…") {
-		t.Errorf("expected ellipsis: %q", got)
-	}
-}
+// Truncate moved to internal/textutil — coverage lives in
+// internal/textutil/truncate_test.go (TestTruncateBytes_RuneBoundary).
+// memory/client just calls it as a wire-shape helper for error
+// messages; no client-specific behavior to pin here.

 // --- Circuit breaker ---

@@ -213,10 +213,15 @@ func setupSwapEnv(t *testing.T) (*handlers.MCPHandler, *flatPlugin, sqlmock.Sqlm

 // expectChainQuery sets up the recursive-CTE expectation matching
 // the resolver for a root workspace. Reusable across tests.
+//
+// The resolver SELECTs `name` so it can populate Namespace.DisplayName
+// (#2988); we pass an empty string here because the e2e tests don't
+// assert on label rendering — the namespace string ("workspace:root-1"
+// etc) is what the plugin sees.
 func expectChainQueryRoot(mock sqlmock.Sqlmock) {
 	mock.ExpectQuery("WITH RECURSIVE chain").
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("root-1", nil, 0))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("root-1", "", nil, 0))
 }

 // --- The actual E2E ---
@@ -33,6 +33,25 @@ type Namespace struct {
 	Kind        contract.NamespaceKind `json:"kind"`
 	Description string                 `json:"description"`
 	Writable    bool                   `json:"writable"`
+	// DisplayName is the human-readable label for this namespace,
+	// derived from the workspace tree:
+	//   - workspace: this workspace's own name (`workspaces.name`)
+	//   - team: parent's name if child, this workspace's name if root
+	//          (degenerate case — team semantically means "memories
+	//          shared with peers in this team", so for a root workspace
+	//          with no peers, "your team" is conceptually correct.)
+	//   - org: the root workspace's name (org-wide memories — every
+	//          workspace under this root sees them)
+	//
+	// Empty string when the lookup failed (workspace row missing). The
+	// canvas uses DisplayName for the dropdown; falls back to a short
+	// UUID prefix when it's empty.
+	//
+	// Issue #2988: pre-fix, the canvas labelled all three namespaces
+	// with the SAME shortID-truncated UUID prefix on a root workspace
+	// because workspace==team==org IDs collide. The display name
+	// disambiguates them by surfacing real workspace names.
+	DisplayName string `json:"display_name,omitempty"`
 }

 // ErrWorkspaceNotFound is returned when the input workspace ID does
@@ -54,6 +73,7 @@ func New(db *sql.DB) *Resolver {
 // chainNode is one row from the recursive CTE.
 type chainNode struct {
 	id       string
+	name     string // workspaces.name (display label for the namespace)
 	parentID *string
 	depth    int
 }
@@ -64,16 +84,16 @@ type chainNode struct {
 func (r *Resolver) walkChain(ctx context.Context, workspaceID string) ([]chainNode, error) {
 	const query = `
 		WITH RECURSIVE chain AS (
-			SELECT id, parent_id, 0 AS depth
+			SELECT id, name, parent_id, 0 AS depth
 			FROM workspaces
 			WHERE id = $1
 			UNION ALL
-			SELECT w.id, w.parent_id, c.depth + 1
+			SELECT w.id, w.name, w.parent_id, c.depth + 1
 			FROM workspaces w
 			JOIN chain c ON w.id = c.parent_id
 			WHERE c.depth < $2
 		)
-		SELECT id::text, parent_id::text, depth FROM chain ORDER BY depth ASC
+		SELECT id::text, COALESCE(name, ''), parent_id::text, depth FROM chain ORDER BY depth ASC
 	`
 	rows, err := r.db.QueryContext(ctx, query, workspaceID, maxChainDepth)
 	if err != nil {
@@ -85,7 +105,7 @@ func (r *Resolver) walkChain(ctx context.Context, workspaceID string) ([]chainNo
 	for rows.Next() {
 		var n chainNode
 		var parentStr sql.NullString
-		if err := rows.Scan(&n.id, &parentStr, &n.depth); err != nil {
+		if err := rows.Scan(&n.id, &n.name, &parentStr, &n.depth); err != nil {
 			return nil, fmt.Errorf("scan chain: %w", err)
 		}
 		if parentStr.Valid && parentStr.String != "" {
@@ -122,6 +142,33 @@ func derive(chain []chainNode) (workspace, team, org string) {
 	return
 }

+// deriveNames computes the display name for each of the three
+// canonical namespaces. Mirrors derive() — same lookup logic, but
+// returns workspace/parent/root NAMES instead of IDs.
+//
+// For a root workspace (no parent), team and org both alias to self;
+// callers should still render them as semantically distinct (the
+// `kind` field on the Namespace carries that distinction). The name
+// itself collides on a depth-1 tree — that's expected; the kind
+// prefix in the canvas label disambiguates.
+//
+// Returns the empty string for any name that's missing on the chain
+// row (defensive — workspaces.name is NOT NULL today, but a future
+// migration could change that). Callers fall back to UUID prefix
+// when DisplayName is empty.
+func deriveNames(chain []chainNode) (workspace, team, org string) {
+	self := chain[0]
+	workspace = self.name
+	if self.parentID != nil && len(chain) > 1 {
+		// Parent is the next node in the chain (depth 1).
+		team = chain[1].name
+	} else {
+		team = self.name
+	}
+	org = chain[len(chain)-1].name
+	return
+}
+
 // ReadableNamespaces returns the namespaces the workspace can read
 // from. Order is deterministic (workspace, team, org) so callers can
 // reason about precedence.
@@ -131,6 +178,7 @@ func (r *Resolver) ReadableNamespaces(ctx context.Context, workspaceID string) (
 		return nil, err
 	}
 	wsID, teamID, orgID := derive(chain)
+	wsName, teamName, orgName := deriveNames(chain)
 	isRoot := chain[0].parentID == nil

 	out := []Namespace{
@@ -139,12 +187,14 @@ func (r *Resolver) ReadableNamespaces(ctx context.Context, workspaceID string) (
 			Kind:        contract.NamespaceKindWorkspace,
 			Description: "This workspace's private memories",
 			Writable:    true,
+			DisplayName: wsName,
 		},
 		{
 			Name:        "team:" + teamID,
 			Kind:        contract.NamespaceKindTeam,
 			Description: "Memories shared across team members (parent + siblings)",
 			Writable:    true,
+			DisplayName: teamName,
 		},
 	}
 	// Org namespace is readable by every workspace in the tree, but
@@ -155,6 +205,7 @@ func (r *Resolver) ReadableNamespaces(ctx context.Context, workspaceID string) (
 		Kind:        contract.NamespaceKindOrg,
 		Description: "Org-wide memories visible to every workspace under this root",
 		Writable:    isRoot,
+		DisplayName: orgName,
 	})
 	return out, nil
 }
@@ -46,8 +46,8 @@ func TestWalkChain_RootOnly(t *testing.T) {
 	// Root workspace: parent_id is NULL, depth 0, single row.
 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("ws-root", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("ws-root", nil, 0))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("ws-root", "", nil, 0))

 	chain, err := r.walkChain(context.Background(), "ws-root")
 	if err != nil {
@@ -68,9 +68,9 @@ func TestWalkChain_ChildToParent(t *testing.T) {

 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("ws-child", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("ws-child", "ws-root", 0).
-			AddRow("ws-root", nil, 1))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("ws-child", "", "ws-root", 0).
+			AddRow("ws-root", "", nil, 1))

 	chain, err := r.walkChain(context.Background(), "ws-child")
 	if err != nil {
@@ -93,7 +93,7 @@ func TestWalkChain_DeepTreeRespectsMaxDepth(t *testing.T) {
 	r := New(db)

 	// Simulate a 51-deep chain: should be capped at maxChainDepth.
-	rows := sqlmock.NewRows([]string{"id", "parent_id", "depth"})
+	rows := sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"})
 	for i := 0; i <= maxChainDepth; i++ {
 		var parent interface{}
 		if i < maxChainDepth {
@@ -101,7 +101,7 @@ func TestWalkChain_DeepTreeRespectsMaxDepth(t *testing.T) {
 		} else {
 			parent = nil // would be the cap point
 		}
-		rows.AddRow("ws-"+itoa(i), parent, i)
+		rows.AddRow("ws-"+itoa(i), "", parent, i)
 	}
 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("ws-0", maxChainDepth).
@@ -127,7 +127,7 @@ func TestWalkChain_WorkspaceNotFound(t *testing.T) {

 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("ws-missing", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}))

 	_, err := r.walkChain(context.Background(), "ws-missing")
 	if !errors.Is(err, ErrWorkspaceNotFound) {
@@ -172,8 +172,8 @@ func TestWalkChain_RowsErr(t *testing.T) {

 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("ws-x", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("ws-x", nil, 0).
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("ws-x", "", nil, 0).
 			RowError(0, errors.New("mid-iteration")))

 	_, err := r.walkChain(context.Background(), "ws-x")
@@ -238,8 +238,8 @@ func TestReadableNamespaces_Root(t *testing.T) {

 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("root-1", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("root-1", nil, 0))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("root-1", "", nil, 0))

 	got, err := r.ReadableNamespaces(context.Background(), "root-1")
 	if err != nil {
@@ -274,9 +274,9 @@ func TestReadableNamespaces_Child(t *testing.T) {

 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("child-1", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("child-1", "root-1", 0).
-			AddRow("root-1", nil, 1))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("child-1", "", "root-1", 0).
+			AddRow("root-1", "", nil, 1))

 	got, err := r.ReadableNamespaces(context.Background(), "child-1")
 	if err != nil {
@@ -297,13 +297,93 @@ func TestReadableNamespaces_Child(t *testing.T) {
 	}
 }

+func TestReadableNamespaces_DisplayName_Root(t *testing.T) {
+	// Root workspace with a real name. All three derived namespaces
+	// (workspace/team/org) should carry the workspace's display name —
+	// for a root workspace they collapse on UUID but the name is the
+	// disambiguator surfaced in the canvas dropdown (issue #2988).
+	db, mock := setupMockDB(t)
+	r := New(db)
+
+	mock.ExpectQuery(chainQuerySnippet).
+		WithArgs("root-1", maxChainDepth).
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("root-1", "mac laptop", nil, 0))
+
+	got, err := r.ReadableNamespaces(context.Background(), "root-1")
+	if err != nil {
+		t.Fatalf("ReadableNamespaces: %v", err)
+	}
+	for i, ns := range got {
+		if ns.DisplayName != "mac laptop" {
+			t.Errorf("[%d] %q DisplayName = %q, want %q", i, ns.Name, ns.DisplayName, "mac laptop")
+		}
+	}
+}
+
+func TestReadableNamespaces_DisplayName_Child(t *testing.T) {
+	// Child has its own workspace name; team should pick up the
+	// PARENT's name (not the child's), and org follows the chain root.
+	db, mock := setupMockDB(t)
+	r := New(db)
+
+	mock.ExpectQuery(chainQuerySnippet).
+		WithArgs("child-1", maxChainDepth).
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("child-1", "Hongming Personal Brand", "root-1", 0).
+			AddRow("root-1", "mac laptop", nil, 1))
+
+	got, err := r.ReadableNamespaces(context.Background(), "child-1")
+	if err != nil {
+		t.Fatalf("ReadableNamespaces: %v", err)
+	}
+	want := map[string]string{
+		"workspace:child-1": "Hongming Personal Brand", // self
+		"team:root-1":       "mac laptop",              // parent
+		"org:root-1":        "mac laptop",              // root
+	}
+	for _, ns := range got {
+		w, ok := want[ns.Name]
+		if !ok {
+			t.Errorf("unexpected namespace %q", ns.Name)
+			continue
+		}
+		if ns.DisplayName != w {
+			t.Errorf("%q DisplayName = %q, want %q", ns.Name, ns.DisplayName, w)
+		}
+	}
+}
+
+func TestReadableNamespaces_DisplayName_EmptyOnNULL(t *testing.T) {
+	// COALESCE in the query produces "" when name is NULL. The
+	// resolver must propagate that as DisplayName="" so the handler's
+	// label shaper can fall back to the UUID-prefix shape.
+	db, mock := setupMockDB(t)
+	r := New(db)
+
+	mock.ExpectQuery(chainQuerySnippet).
+		WithArgs("root-1", maxChainDepth).
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("root-1", "", nil, 0))
+
+	got, err := r.ReadableNamespaces(context.Background(), "root-1")
+	if err != nil {
+		t.Fatalf("ReadableNamespaces: %v", err)
+	}
+	for _, ns := range got {
+		if ns.DisplayName != "" {
+			t.Errorf("%q DisplayName = %q, want empty (NULL fallback)", ns.Name, ns.DisplayName)
+		}
+	}
+}
+
 func TestReadableNamespaces_NotFound(t *testing.T) {
 	db, mock := setupMockDB(t)
 	r := New(db)

 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("ghost", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}))

 	_, err := r.ReadableNamespaces(context.Background(), "ghost")
 	if !errors.Is(err, ErrWorkspaceNotFound) {
@@ -319,8 +399,8 @@ func TestWritableNamespaces_RootSeesAll(t *testing.T) {

 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("root-1", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("root-1", nil, 0))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("root-1", "", nil, 0))

 	got, err := r.WritableNamespaces(context.Background(), "root-1")
 	if err != nil {
@@ -337,9 +417,9 @@ func TestWritableNamespaces_ChildExcludesOrg(t *testing.T) {

 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("child-1", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("child-1", "root-1", 0).
-			AddRow("root-1", nil, 1))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("child-1", "", "root-1", 0).
+			AddRow("root-1", "", nil, 1))

 	got, err := r.WritableNamespaces(context.Background(), "child-1")
 	if err != nil {
@@ -361,7 +441,7 @@ func TestWritableNamespaces_NotFound(t *testing.T) {

 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("ghost", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}))

 	_, err := r.WritableNamespaces(context.Background(), "ghost")
 	if !errors.Is(err, ErrWorkspaceNotFound) {
@@ -390,9 +470,9 @@ func TestCanWrite(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			db, mock := setupMockDB(t)
 			r := New(db)
-			rows := sqlmock.NewRows([]string{"id", "parent_id", "depth"})
+			rows := sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"})
 			if tc.isRoot {
-				rows.AddRow("root-1", nil, 0)
+				rows.AddRow("root-1", "", nil, 0)
 				mock.ExpectQuery(chainQuerySnippet).WithArgs("root-1", maxChainDepth).WillReturnRows(rows)
 				ok, err := r.CanWrite(context.Background(), "root-1", tc.namespace)
 				if err != nil {
@@ -402,7 +482,7 @@ func TestCanWrite(t *testing.T) {
 					t.Errorf("CanWrite(%q) = %v, want %v", tc.namespace, ok, tc.want)
 				}
 			} else {
-				rows.AddRow("child-1", "root-1", 0).AddRow("root-1", nil, 1)
+				rows.AddRow("child-1", "", "root-1", 0).AddRow("root-1", "", nil, 1)
 				mock.ExpectQuery(chainQuerySnippet).WithArgs("child-1", maxChainDepth).WillReturnRows(rows)
 				ok, err := r.CanWrite(context.Background(), "child-1", tc.namespace)
 				if err != nil {
@@ -435,9 +515,9 @@ func TestIntersectReadable_DefaultAll(t *testing.T) {
 	r := New(db)
 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("child-1", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("child-1", "root-1", 0).
-			AddRow("root-1", nil, 1))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("child-1", "", "root-1", 0).
+			AddRow("root-1", "", nil, 1))

 	// Empty requested → return everything readable.
 	got, err := r.IntersectReadable(context.Background(), "child-1", nil)
@@ -455,9 +535,9 @@ func TestIntersectReadable_Filters(t *testing.T) {
 	r := New(db)
 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("child-1", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("child-1", "root-1", 0).
-			AddRow("root-1", nil, 1))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("child-1", "", "root-1", 0).
+			AddRow("root-1", "", nil, 1))

 	// Requested: one allowed, one disallowed (foreign workspace), one allowed
 	requested := []string{"workspace:child-1", "workspace:foreign", "team:root-1"}
@@ -476,8 +556,8 @@ func TestIntersectReadable_AllFiltered(t *testing.T) {
 	r := New(db)
 	mock.ExpectQuery(chainQuerySnippet).
 		WithArgs("ws-1", maxChainDepth).
-		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id", "depth"}).
-			AddRow("ws-1", nil, 0))
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name", "parent_id", "depth"}).
+			AddRow("ws-1", "", nil, 0))

 	// Request only namespaces the caller cannot read.
 	got, err := r.IntersectReadable(context.Background(), "ws-1", []string{"workspace:other", "team:other"})
@@ -0,0 +1,118 @@
+// Package messagestore defines the read-side interface and canonical
+// data shapes for chat-history retrieval.
+//
+// Origin: RFC #2945 PR-D (issue #3026). PR-A extracted the WRITE path
+// (AgentMessageWriter), PR-B/B-1 typed the WS event taxonomy, PR-C
+// centralized read-side parsing in the server. PR-D abstracts the
+// underlying storage layer so OSS operators can plug in alternative
+// backends without forking the handler.
+//
+// # Why this package exists
+//
+// Today's only consumer is ChatHistoryHandler, but exposing storage as
+// an interface is what makes the platform's chat-history layer pluggable
+// for OSS operators. Operators wanting to:
+//
+//   - Tier hot/warm/cold storage (recent in Postgres, archival in S3 parquet)
+//   - Use a vector store with hybrid search (Pinecone, Weaviate)
+//   - Run an in-memory store for ephemeral tests / sandbox tenants
+//   - Federate history across regions
+//
+// …implement MessageStore against their backend. The platform-default
+// PostgresMessageStore wraps today's activity_logs query + parser
+// behavior unchanged.
+//
+// # Implementation contract
+//
+// Implementations MUST:
+//
+//   - Return messages newest-first, up to opts.Limit. Caller (the
+//     handler) is responsible for opts.Limit clamping.
+//   - Honor opts.BeforeTS as a strict less-than cursor when
+//     opts.HasBefore is true; ignore it when false. Use HasBefore (not
+//     a zero-time check) so a legitimate "start of epoch" cursor is
+//     distinguishable from "no cursor."
+//   - Set reachedEnd=true when the underlying store has no more
+//     messages older than the returned page. Caller uses this to
+//     disable further older-batch fetches in the lazy-load UX.
+//   - Parse agent-emitted JSON DEFENSIVELY. Any malformed message body
+//     becomes an empty ChatMessage (or is dropped); never panic, never
+//     return an error for parse failures alone — chat falls through to
+//     text-only rather than 500.
+//   - NEVER log full message bodies, attachment URIs, or anything that
+//     would be a sensitive screenshot. Workspace ID + activity-log
+//     row id at DEBUG is the ceiling.
+//   - Honor ctx cancellation. A canceled ctx must abort the lookup
+//     and return ctx.Err().
+//
+// Implementations MAY:
+//
+//   - Cache aggressively (history is read-only).
+//   - Filter out additional rows beyond what the interface requires
+//     (e.g., role-based redaction in regulated environments) as long
+//     as reachedEnd is set conservatively (false if uncertain).
+//
+// # Threading
+//
+// Implementations MUST be safe for concurrent calls. The handler
+// dispatches a goroutine per request; a non-thread-safe impl would
+// race on every chat reload.
+package messagestore
+
+import (
+	"context"
+	"time"
+)
+
+// ChatMessage is the canonical shape returned to chat-history clients.
+// Mirrors canvas's ChatMessage TS type so the canvas can render
+// without per-row mapping.
+//
+// ID is server-minted per ChatMessage. Activity-log rows don't carry
+// message-shaped ids; canvas dedupes by (role, content, timestamp
+// window) not by id, so id stability across requests is not required.
+type ChatMessage struct {
+	ID          string           `json:"id"`
+	Role        string           `json:"role"` // "user" | "agent" | "system"
+	Content     string           `json:"content"`
+	Attachments []ChatAttachment `json:"attachments,omitempty"`
+	Timestamp   string           `json:"timestamp"` // RFC3339, pinned to row.created_at
+}
+
+// ChatAttachment mirrors canvas ChatAttachment / ParsedFilePart.
+// Size is *int64 (not int64) so JSON omits the field when unknown,
+// rather than emitting `"size": 0` which the renderer would interpret
+// as "zero-byte file."
+type ChatAttachment struct {
+	Name     string `json:"name"`
+	URI      string `json:"uri"`
+	MimeType string `json:"mimeType,omitempty"`
+	Size     *int64 `json:"size,omitempty"`
+}
+
+// ListOptions is the page-window the handler hands to the store.
+// Constructed by the handler from query parameters; the store should
+// not inspect the request directly.
+type ListOptions struct {
+	// Limit is the page size. Caller (the handler) clamps to a sane
+	// bound (default 100, max 1000); store treats Limit ≤ 0 as a
+	// programming error.
+	Limit int
+
+	// BeforeTS is the cursor for paginating backward. The store MUST
+	// only consider this when HasBefore is true; using a zero-time
+	// fallback would silently exclude the legitimate epoch-start case.
+	BeforeTS  time.Time
+	HasBefore bool
+}
+
+// MessageStore is the read-side interface. Implementations pluggable
+// via constructor injection at handler creation time.
+//
+// Why "List" and not "GetMessages" / "ReadHistory" / etc: List matches
+// the verb on /workspaces/:id/chat-history (HTTP GET on a collection)
+// and the existing handler method. One-name-one-thing keeps the
+// interface and the route lined up.
+type MessageStore interface {
+	List(ctx context.Context, workspaceID string, opts ListOptions) (messages []ChatMessage, reachedEnd bool, err error)
+}
@@ -0,0 +1,497 @@
+package messagestore
+
+// postgres_store.go — default MessageStore impl that wraps today's
+// activity_logs query + the A2A-envelope parser ported in PR-C.
+//
+// Behavior is byte-identical to the pre-PR-D ChatHistoryHandler:
+// same SQL, same role-decision rules, same v0/v1 wire-shape support.
+// The only structural change is that the handler now depends on an
+// interface; this file is what was the pre-PR-D handler internals.
+//
+// This is the baseline impl OSS operators compare against when
+// writing alternative stores. Read it as the contract spec.
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"path"
+	"strings"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+// PostgresMessageStore is the platform-default impl. It queries the
+// activity_logs table directly and parses request_body / response_body
+// JSONB columns into ChatMessage values.
+type PostgresMessageStore struct {
+	db *sql.DB
+}
+
+// NewPostgresMessageStore wraps a *sql.DB. The store does not own the
+// pool — closing it is the caller's responsibility.
+func NewPostgresMessageStore(db *sql.DB) *PostgresMessageStore {
+	return &PostgresMessageStore{db: db}
+}
+
+// internalSelfPrefixes — message texts that should be filtered from
+// chat history because they're internal self-triggers (heartbeats,
+// scheduled-task self-fire, delegation-result self-notify), not
+// user-typed messages. Mirrors canvas isInternalSelfMessage.
+//
+// Centralizing here means a future internal-trigger pattern is added
+// in one place; alternative impls of MessageStore are expected to
+// apply the same filter (or override deliberately).
+var internalSelfPrefixes = []string{
+	"Delegation results are ready",
+}
+
+// IsInternalSelfMessage reports whether text starts with any registered
+// internal-self prefix. Empty text returns false (legitimate
+// attachments-only bubble). Exported for impls that want to share the
+// same predicate.
+func IsInternalSelfMessage(text string) bool {
+	if text == "" {
+		return false
+	}
+	for _, prefix := range internalSelfPrefixes {
+		if strings.HasPrefix(text, prefix) {
+			return true
+		}
+	}
+	return false
+}
+
+// List implements MessageStore. Newest-first, optionally paged by
+// BeforeTS. Filters to a2a_receive activity rows from the canvas
+// (source_id IS NULL) — same scope canvas applies via
+// /activity?source=canvas, centralized so future API consumers don't
+// need to know it.
+func (s *PostgresMessageStore) List(ctx context.Context, workspaceID string, opts ListOptions) ([]ChatMessage, bool, error) {
+	if opts.Limit <= 0 {
+		// Caller bug. Programmers learn quickly when the store
+		// fails fast on bad opts; a silent clamp would hide the bug.
+		return nil, true, errInvalidLimit
+	}
+
+	rows, err := s.queryActivityRows(ctx, workspaceID, opts)
+	if err != nil {
+		return nil, false, err
+	}
+	defer rows.Close()
+
+	var messages []ChatMessage
+	rowCount := 0
+	for rows.Next() {
+		var (
+			createdAt   time.Time
+			status      string
+			rawRequest  sql.NullString
+			rawResponse sql.NullString
+		)
+		if err := rows.Scan(&createdAt, &status, &rawRequest, &rawResponse); err != nil {
+			// Skip malformed row, continue. The error is logged at
+			// the caller (handler) layer; an isolated bad row should
+			// not abort the whole page.
+			continue
+		}
+		rowCount++
+		var requestBody, responseBody json.RawMessage
+		if rawRequest.Valid {
+			requestBody = json.RawMessage(rawRequest.String)
+		}
+		if rawResponse.Valid {
+			responseBody = json.RawMessage(rawResponse.String)
+		}
+		messages = append(messages, activityRowToChatMessages(createdAt, status, requestBody, responseBody, IsInternalSelfMessage)...)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, false, err
+	}
+
+	reachedEnd := rowCount < opts.Limit
+	return messages, reachedEnd, nil
+}
+
+// queryActivityRows is split from List so unit tests can exercise the
+// parser without spinning a real DB. Internal — alternative impls
+// shouldn't depend on the SQL shape.
+func (s *PostgresMessageStore) queryActivityRows(ctx context.Context, workspaceID string, opts ListOptions) (*sql.Rows, error) {
+	if opts.HasBefore {
+		return s.db.QueryContext(ctx, `
+			SELECT created_at, status, request_body::text, response_body::text
+			FROM activity_logs
+			WHERE workspace_id = $1
+			  AND activity_type = 'a2a_receive'
+			  AND source_id IS NULL
+			  AND created_at < $2
+			ORDER BY created_at DESC
+			LIMIT $3
+		`, workspaceID, opts.BeforeTS, opts.Limit)
+	}
+	return s.db.QueryContext(ctx, `
+		SELECT created_at, status, request_body::text, response_body::text
+		FROM activity_logs
+		WHERE workspace_id = $1
+		  AND activity_type = 'a2a_receive'
+		  AND source_id IS NULL
+		ORDER BY created_at DESC
+		LIMIT $2
+	`, workspaceID, opts.Limit)
+}
+
+// errInvalidLimit is returned by List when opts.Limit ≤ 0.
+type sentinelError string
+
+func (e sentinelError) Error() string { return string(e) }
+
+const errInvalidLimit sentinelError = "messagestore: List opts.Limit must be > 0"
+
+// activityRowToChatMessages converts ONE activity_logs row into 0-2
+// ChatMessages. Direct port of canvas activityRowToMessages.
+//
+//   - Up to 1 user-side bubble from request_body, unless internal-self.
+//   - Up to 1 agent-side bubble from response_body. Role is "system"
+//     when status='error' OR text starts with "agent error" (case-
+//     insensitive — matches canvas predicate exactly).
+//
+// Both bubbles MUST adopt row.created_at as their timestamp. This
+// pins the regression cover for the 2026-04-25 bubble-collapse bug.
+func activityRowToChatMessages(
+	createdAt time.Time,
+	status string,
+	requestBody json.RawMessage,
+	responseBody json.RawMessage,
+	internalSelf func(string) bool,
+) []ChatMessage {
+	var out []ChatMessage
+	timestamp := createdAt.UTC().Format(time.RFC3339Nano)
+
+	userText := extractRequestText(requestBody)
+	userAttachments := extractFilesFromUserMessage(requestBody)
+	if !internalSelf(userText) && (userText != "" || len(userAttachments) > 0) {
+		out = append(out, ChatMessage{
+			ID:          newMessageID(),
+			Role:        "user",
+			Content:     userText,
+			Attachments: userAttachments,
+			Timestamp:   timestamp,
+		})
+	}
+
+	if len(responseBody) > 0 {
+		agentText := extractChatResponseText(responseBody)
+		agentAttachments := extractFilesFromResponse(responseBody)
+		if agentText != "" || len(agentAttachments) > 0 {
+			role := "agent"
+			if status == "error" || strings.HasPrefix(strings.ToLower(agentText), "agent error") {
+				role = "system"
+			}
+			out = append(out, ChatMessage{
+				ID:          newMessageID(),
+				Role:        role,
+				Content:     agentText,
+				Attachments: agentAttachments,
+				Timestamp:   timestamp,
+			})
+		}
+	}
+
+	return out
+}
+
+// extractRequestText pulls the user's typed text from
+// request_body.params.message.parts[0].text. Returns "" on any
+// malformed shape; callers pair with extractFilesFromUserMessage to
+// catch attachments-only bubbles.
+func extractRequestText(body json.RawMessage) string {
+	if len(body) == 0 {
+		return ""
+	}
+	var env struct {
+		Params struct {
+			Message struct {
+				Parts []map[string]any `json:"parts"`
+			} `json:"message"`
+		} `json:"params"`
+	}
+	if err := json.Unmarshal(body, &env); err != nil {
+		return ""
+	}
+	for _, p := range env.Params.Message.Parts {
+		if t, ok := p["text"].(string); ok && t != "" {
+			return t
+		}
+	}
+	return ""
+}
+
+func extractFilesFromUserMessage(body json.RawMessage) []ChatAttachment {
+	if len(body) == 0 {
+		return nil
+	}
+	var env struct {
+		Params struct {
+			Message json.RawMessage `json:"message"`
+		} `json:"params"`
+	}
+	if err := json.Unmarshal(body, &env); err != nil {
+		return nil
+	}
+	if len(env.Params.Message) == 0 {
+		return nil
+	}
+	return extractFilesFromTask(env.Params.Message)
+}
+
+// extractChatResponseText collects text from any of the response
+// shapes canvas extractResponseText handles, joining with "\n":
+//
+//   - {"result": "<text>"}
+//   - {"result": {"parts": [{"kind":"text","text":""}]}}
+//   - {"parts": [{"root": {"text": "..."}}]}             (older nested)
+//   - {"result": {"artifacts": [{"parts": [...]}]}}      (task shape)
+//   - {"task": "<text>"}                                 (fallback)
+//
+// Why collect rather than first-source-wins: claude-code emits
+// multiple text parts; hermes emits summary-in-parts +
+// details-in-artifacts. The pre-collect first-wins silently
+// truncated 15k-char briefs and dropped artifact details.
+func extractChatResponseText(body json.RawMessage) string {
+	if len(body) == 0 {
+		return ""
+	}
+	// {"result": "string"}
+	var asString struct {
+		Result string `json:"result"`
+	}
+	if err := json.Unmarshal(body, &asString); err == nil && asString.Result != "" {
+		return asString.Result
+	}
+	// {"result": {object}} — try the structured shapes
+	var asObject struct {
+		Result json.RawMessage `json:"result"`
+		Task   string          `json:"task"`
+	}
+	if err := json.Unmarshal(body, &asObject); err != nil {
+		return ""
+	}
+	var collected []string
+	if len(asObject.Result) > 0 {
+		var resultObj struct {
+			Parts     []map[string]any  `json:"parts"`
+			Artifacts []json.RawMessage `json:"artifacts"`
+		}
+		if err := json.Unmarshal(asObject.Result, &resultObj); err == nil {
+			if t := joinTextParts(resultObj.Parts); t != "" {
+				collected = append(collected, t)
+			}
+			var rootTexts []string
+			for _, p := range resultObj.Parts {
+				if root, ok := p["root"].(map[string]any); ok {
+					if t, ok := root["text"].(string); ok && t != "" {
+						rootTexts = append(rootTexts, t)
+					}
+				}
+			}
+			if len(rootTexts) > 0 {
+				collected = append(collected, strings.Join(rootTexts, "\n"))
+			}
+			for _, raw := range resultObj.Artifacts {
+				var art struct {
+					Parts []map[string]any `json:"parts"`
+				}
+				if err := json.Unmarshal(raw, &art); err == nil {
+					if t := joinTextParts(art.Parts); t != "" {
+						collected = append(collected, t)
+					}
+				}
+			}
+		}
+	}
+	if len(collected) > 0 {
+		return strings.Join(collected, "\n")
+	}
+	if asObject.Task != "" {
+		return asObject.Task
+	}
+	return ""
+}
+
+func joinTextParts(parts []map[string]any) string {
+	var texts []string
+	for _, p := range parts {
+		isText := false
+		if k, ok := p["kind"].(string); ok && k == "text" {
+			isText = true
+		}
+		if t, ok := p["type"].(string); ok && t == "text" {
+			isText = true
+		}
+		if !isText {
+			continue
+		}
+		if t, ok := p["text"].(string); ok && t != "" {
+			texts = append(texts, t)
+		}
+	}
+	return strings.Join(texts, "\n")
+}
+
+func extractFilesFromResponse(body json.RawMessage) []ChatAttachment {
+	if len(body) == 0 {
+		return nil
+	}
+	var probe struct {
+		Result json.RawMessage `json:"result"`
+	}
+	_ = json.Unmarshal(body, &probe)
+	feed := body
+	if len(probe.Result) > 0 {
+		trimmed := bytesTrimSpace(probe.Result)
+		if len(trimmed) > 0 && trimmed[0] == '{' {
+			feed = probe.Result
+		}
+	}
+	return extractFilesFromTask(feed)
+}
+
+// extractFilesFromTask walks parts[] + artifacts[].parts[] +
+// status.message.parts[] + message.parts[]. Mirrors canvas
+// extractFilesFromTask exactly — same v0 hot path + v1 protobuf
+// flat shape.
+func extractFilesFromTask(taskJSON json.RawMessage) []ChatAttachment {
+	if len(taskJSON) == 0 {
+		return nil
+	}
+	var task struct {
+		Parts     []map[string]any  `json:"parts"`
+		Artifacts []json.RawMessage `json:"artifacts"`
+		Status    json.RawMessage   `json:"status"`
+		Message   json.RawMessage   `json:"message"`
+	}
+	if err := json.Unmarshal(taskJSON, &task); err != nil {
+		return nil
+	}
+	var out []ChatAttachment
+	out = appendFilesFromParts(out, task.Parts)
+	for _, raw := range task.Artifacts {
+		var art struct {
+			Parts []map[string]any `json:"parts"`
+		}
+		if err := json.Unmarshal(raw, &art); err == nil {
+			out = appendFilesFromParts(out, art.Parts)
+		}
+	}
+	if len(task.Status) > 0 {
+		var st struct {
+			Message struct {
+				Parts []map[string]any `json:"parts"`
+			} `json:"message"`
+		}
+		if err := json.Unmarshal(task.Status, &st); err == nil {
+			out = appendFilesFromParts(out, st.Message.Parts)
+		}
+	}
+	if len(task.Message) > 0 {
+		var msg struct {
+			Parts []map[string]any `json:"parts"`
+		}
+		if err := json.Unmarshal(task.Message, &msg); err == nil {
+			out = appendFilesFromParts(out, msg.Parts)
+		}
+	}
+	return out
+}
+
+func appendFilesFromParts(out []ChatAttachment, parts []map[string]any) []ChatAttachment {
+	for _, raw := range parts {
+		v0 := false
+		if k, ok := raw["kind"].(string); ok && k == "file" {
+			v0 = true
+		}
+		if t, ok := raw["type"].(string); ok && t == "file" {
+			v0 = true
+		}
+		v1URL, _ := raw["url"].(string)
+		if !v0 && v1URL == "" {
+			continue
+		}
+		var att ChatAttachment
+		if v0 {
+			file, _ := raw["file"].(map[string]any)
+			if file == nil {
+				file = raw
+			}
+			uri, _ := file["uri"].(string)
+			if uri == "" {
+				continue
+			}
+			att.URI = uri
+			if name, _ := file["name"].(string); name != "" {
+				att.Name = name
+			} else {
+				att.Name = basename(uri)
+			}
+			if mt, ok := file["mimeType"].(string); ok {
+				att.MimeType = mt
+			}
+			if sz, ok := numericSize(file["size"]); ok {
+				att.Size = &sz
+			}
+		} else {
+			att.URI = v1URL
+			if name, _ := raw["filename"].(string); name != "" {
+				att.Name = name
+			} else {
+				att.Name = basename(v1URL)
+			}
+			if mt, ok := raw["mediaType"].(string); ok {
+				att.MimeType = mt
+			}
+		}
+		out = append(out, att)
+	}
+	return out
+}
+
+func numericSize(v any) (int64, bool) {
+	switch n := v.(type) {
+	case float64:
+		return int64(n), true
+	case int64:
+		return n, true
+	case int:
+		return int64(n), true
+	}
+	return 0, false
+}
+
+func basename(uri string) string {
+	cleaned := strings.TrimPrefix(uri, "workspace:")
+	cleaned = strings.TrimPrefix(cleaned, "https://")
+	cleaned = strings.TrimPrefix(cleaned, "http://")
+	if cleaned == "" {
+		return "file"
+	}
+	return path.Base(cleaned)
+}
+
+func bytesTrimSpace(b json.RawMessage) json.RawMessage {
+	for len(b) > 0 && (b[0] == ' ' || b[0] == '\t' || b[0] == '\n' || b[0] == '\r') {
+		b = b[1:]
+	}
+	for len(b) > 0 && (b[len(b)-1] == ' ' || b[len(b)-1] == '\t' || b[len(b)-1] == '\n' || b[len(b)-1] == '\r') {
+		b = b[:len(b)-1]
+	}
+	return b
+}
+
+func newMessageID() string {
+	return uuid.New().String()
+}
+
+// Compile-time assertion: PostgresMessageStore satisfies MessageStore.
+// Catches any future drift between interface and impl at build time.
+var _ MessageStore = (*PostgresMessageStore)(nil)
@@ -0,0 +1,422 @@
+package messagestore
+
+// postgres_store_test.go — parser-level parity tests against the
+// canvas TS test fixtures in
+// canvas/src/components/tabs/chat/__tests__/historyHydration.test.ts.
+//
+// Originally lived in handlers/chat_history_test.go (RFC #2945 PR-C);
+// PR-D moved them here when the parser was extracted to this package.
+// Every test case in the TS file has a Go counterpart, named after
+// the TS describe/it block.
+//
+// Mutation guidance: when adding behavior, add the case to BOTH
+// historyHydration.test.ts AND this file. The canvas TS is the
+// legacy source the server replaces; divergence == regression.
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+)
+
+const fixedTimestamp = "2026-04-25T18:00:00Z"
+
+func mustParseTime(t *testing.T, s string) time.Time {
+	t.Helper()
+	tt, err := time.Parse(time.RFC3339, s)
+	if err != nil {
+		t.Fatalf("parse %s: %v", s, err)
+	}
+	return tt
+}
+
+func neverInternal(_ string) bool { return false }
+
+// =====================================================================
+// timestamp preservation (regression cover)
+//
+// The canvas bug that motivated extracting the helper: every reload
+// re-stamped historical bubbles to render-time. Pin row.created_at
+// adoption.
+// =====================================================================
+
+func TestChatHistory_UserMessageTimestampPinsToCreatedAt(t *testing.T) {
+	created := mustParseTime(t, "2026-04-25T18:00:00Z")
+	body := json.RawMessage(`{"params":{"message":{"parts":[{"kind":"text","text":"hello from earlier today"}]}}}`)
+
+	msgs := activityRowToChatMessages(created, "ok", body, nil, neverInternal)
+	if len(msgs) != 1 {
+		t.Fatalf("expected 1 user message, got %d", len(msgs))
+	}
+	if msgs[0].Role != "user" {
+		t.Errorf("role=%q want user", msgs[0].Role)
+	}
+	if !strings.HasPrefix(msgs[0].Timestamp, "2026-04-25T18:00:00") {
+		t.Errorf("user message timestamp %q does NOT pin to row.created_at — regression of the 2026-04-25 bubble-collapse bug", msgs[0].Timestamp)
+	}
+}
+
+func TestChatHistory_AgentMessageTimestampPinsToCreatedAt(t *testing.T) {
+	created := mustParseTime(t, "2026-04-25T18:05:00Z")
+	body := json.RawMessage(`{"result":"agent reply"}`)
+
+	msgs := activityRowToChatMessages(created, "ok", nil, body, neverInternal)
+	if len(msgs) != 1 {
+		t.Fatalf("expected 1 agent message, got %d", len(msgs))
+	}
+	if msgs[0].Role != "agent" {
+		t.Errorf("role=%q want agent", msgs[0].Role)
+	}
+	if !strings.HasPrefix(msgs[0].Timestamp, "2026-04-25T18:05:00") {
+		t.Errorf("agent message timestamp %q does NOT pin to row.created_at", msgs[0].Timestamp)
+	}
+}
+
+func TestChatHistory_TwoRowsDistinctTimestamps(t *testing.T) {
+	bodyA := json.RawMessage(`{"params":{"message":{"parts":[{"kind":"text","text":"first"}]}}}`)
+	bodyB := json.RawMessage(`{"params":{"message":{"parts":[{"kind":"text","text":"second"}]}}}`)
+	a := activityRowToChatMessages(mustParseTime(t, "2026-04-25T14:00:00Z"), "ok", bodyA, nil, neverInternal)
+	b := activityRowToChatMessages(mustParseTime(t, "2026-04-25T21:01:58Z"), "ok", bodyB, nil, neverInternal)
+
+	if len(a) != 1 || len(b) != 1 {
+		t.Fatalf("expected 1 message each; got %d and %d", len(a), len(b))
+	}
+	if a[0].Timestamp == b[0].Timestamp {
+		t.Errorf("two distinct created_at values produced same timestamp: %q", a[0].Timestamp)
+	}
+	if !strings.HasPrefix(a[0].Timestamp, "2026-04-25T14:00:00") || !strings.HasPrefix(b[0].Timestamp, "2026-04-25T21:01:58") {
+		t.Errorf("timestamps drifted: a=%q b=%q", a[0].Timestamp, b[0].Timestamp)
+	}
+}
+
+// =====================================================================
+// user-message extraction
+// =====================================================================
+
+func TestChatHistory_EmitsUserMessageWhenRequestHasText(t *testing.T) {
+	body := json.RawMessage(`{"params":{"message":{"parts":[{"kind":"text","text":"hi agent"}]}}}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", body, nil, neverInternal)
+	if len(msgs) != 1 {
+		t.Fatalf("expected 1 message, got %d", len(msgs))
+	}
+	if msgs[0].Role != "user" || msgs[0].Content != "hi agent" {
+		t.Errorf("role=%q content=%q want user/hi agent", msgs[0].Role, msgs[0].Content)
+	}
+}
+
+func TestChatHistory_DropsInternalSelfMessages(t *testing.T) {
+	body := json.RawMessage(`{"params":{"message":{"parts":[{"kind":"text","text":"Delegation results are ready..."}]}}}`)
+	predicate := func(t string) bool { return strings.HasPrefix(t, "Delegation results are ready") }
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", body, nil, predicate)
+	for _, m := range msgs {
+		if m.Role == "user" {
+			t.Errorf("internal-self message rendered as user bubble: %q", m.Content)
+		}
+	}
+}
+
+func TestChatHistory_NoUserMessageWhenRequestBodyNull(t *testing.T) {
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", nil, nil, neverInternal)
+	for _, m := range msgs {
+		if m.Role == "user" {
+			t.Errorf("emitted user bubble despite null request_body: %+v", m)
+		}
+	}
+}
+
+func TestChatHistory_UserAttachmentsHydratedFromRequestBody(t *testing.T) {
+	body := json.RawMessage(`{
+	  "params": {
+	    "message": {
+	      "parts": [
+	        {"kind":"text","text":"here's the screenshot"},
+	        {"kind":"file","file":{"name":"shot.png","mimeType":"image/png","uri":"workspace:/uploads/shot.png","size":4096}}
+	      ]
+	    }
+	  }
+	}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", body, nil, neverInternal)
+	var user *ChatMessage
+	for i := range msgs {
+		if msgs[i].Role == "user" {
+			user = &msgs[i]
+			break
+		}
+	}
+	if user == nil {
+		t.Fatalf("no user bubble produced")
+	}
+	if user.Content != "here's the screenshot" {
+		t.Errorf("content=%q", user.Content)
+	}
+	if len(user.Attachments) != 1 {
+		t.Fatalf("attachments=%d want 1", len(user.Attachments))
+	}
+	att := user.Attachments[0]
+	if att.Name != "shot.png" || att.URI != "workspace:/uploads/shot.png" || att.MimeType != "image/png" {
+		t.Errorf("attachment shape wrong: %+v", att)
+	}
+	if att.Size == nil || *att.Size != 4096 {
+		t.Errorf("size=%v want 4096", att.Size)
+	}
+}
+
+func TestChatHistory_AttachmentsOnlyUserBubbleWhenTextEmpty(t *testing.T) {
+	// Drag-drop a file with no caption — bubble should still render.
+	body := json.RawMessage(`{
+	  "params": {
+	    "message": {
+	      "parts": [
+	        {"kind":"file","file":{"name":"report.pdf","uri":"workspace:/uploads/report.pdf"}}
+	      ]
+	    }
+	  }
+	}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", body, nil, neverInternal)
+	if len(msgs) != 1 {
+		t.Fatalf("expected 1 attachments-only bubble, got %d", len(msgs))
+	}
+	if msgs[0].Role != "user" || msgs[0].Content != "" || len(msgs[0].Attachments) != 1 {
+		t.Errorf("unexpected: role=%q content=%q attachments=%d", msgs[0].Role, msgs[0].Content, len(msgs[0].Attachments))
+	}
+	if msgs[0].Attachments[0].Name != "report.pdf" {
+		t.Errorf("attachment name=%q want report.pdf", msgs[0].Attachments[0].Name)
+	}
+}
+
+func TestChatHistory_InternalSelfPredicateSuppressesEvenWithAttachments(t *testing.T) {
+	body := json.RawMessage(`{
+	  "params": {
+	    "message": {
+	      "parts": [
+	        {"kind":"text","text":"Delegation results are ready..."},
+	        {"kind":"file","file":{"name":"x.zip","uri":"workspace:/x.zip"}}
+	      ]
+	    }
+	  }
+	}`)
+	predicate := func(t string) bool { return strings.HasPrefix(t, "Delegation results are ready") }
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", body, nil, predicate)
+	for _, m := range msgs {
+		if m.Role == "user" {
+			t.Errorf("internal-self predicate did NOT suppress user bubble despite attachments: %+v", m)
+		}
+	}
+}
+
+// =====================================================================
+// agent-message extraction
+// =====================================================================
+
+func TestChatHistory_AgentMessageFromResultString(t *testing.T) {
+	body := json.RawMessage(`{"result":"agent says hi"}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", nil, body, neverInternal)
+	if len(msgs) != 1 || msgs[0].Role != "agent" || msgs[0].Content != "agent says hi" {
+		t.Errorf("got %+v", msgs)
+	}
+}
+
+func TestChatHistory_RoleSystemWhenStatusError(t *testing.T) {
+	body := json.RawMessage(`{"result":"delegation failed"}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "error", nil, body, neverInternal)
+	if len(msgs) != 1 || msgs[0].Role != "system" {
+		t.Errorf("status=error did NOT promote role to system: %+v", msgs)
+	}
+}
+
+func TestChatHistory_RoleSystemWhenAgentErrorPrefix(t *testing.T) {
+	// Defense-in-depth — if a runtime returns ok status but the text
+	// itself starts with "agent error", the canvas would still
+	// render system role. Mirror that here.
+	body := json.RawMessage(`{"result":"Agent error: ProcessError(exit=1)"}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", nil, body, neverInternal)
+	if len(msgs) != 1 || msgs[0].Role != "system" {
+		t.Errorf("agent-error prefix did NOT promote to system: %+v", msgs)
+	}
+}
+
+func TestChatHistory_AgentAttachmentsFromResponseBodyParts(t *testing.T) {
+	// Notify shape: response_body = {"result":"<text>","parts":[{"kind":"file",...}]}
+	body := json.RawMessage(`{
+	  "result": "Done — see attached.",
+	  "parts": [
+	    {"kind":"file","file":{"name":"build.zip","uri":"workspace:/tmp/build.zip","size":12345}}
+	  ]
+	}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", nil, body, neverInternal)
+	var agent *ChatMessage
+	for i := range msgs {
+		if msgs[i].Role == "agent" {
+			agent = &msgs[i]
+			break
+		}
+	}
+	if agent == nil {
+		t.Fatalf("no agent bubble")
+	}
+	if len(agent.Attachments) != 1 || agent.Attachments[0].Name != "build.zip" {
+		t.Errorf("agent attachments shape wrong: %+v", agent.Attachments)
+	}
+	if agent.Attachments[0].Size == nil || *agent.Attachments[0].Size != 12345 {
+		t.Errorf("size=%v want 12345", agent.Attachments[0].Size)
+	}
+}
+
+func TestChatHistory_NoAgentMessageWhenResponseBodyNull(t *testing.T) {
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", nil, nil, neverInternal)
+	for _, m := range msgs {
+		if m.Role == "agent" || m.Role == "system" {
+			t.Errorf("emitted agent/system bubble despite null response_body: %+v", m)
+		}
+	}
+}
+
+func TestChatHistory_NoAgentMessageWhenResponseHasNoTextNoFiles(t *testing.T) {
+	body := json.RawMessage(`{"unrelated":"metadata"}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", nil, body, neverInternal)
+	for _, m := range msgs {
+		if m.Role == "agent" {
+			t.Errorf("emitted agent bubble despite empty content: %+v", m)
+		}
+	}
+}
+
+// =====================================================================
+// end-to-end shape — paired user + agent with same timestamp
+// =====================================================================
+
+func TestChatHistory_PairedUserAndAgentSameTimestamp(t *testing.T) {
+	created := mustParseTime(t, "2026-04-25T18:00:00Z")
+	req := json.RawMessage(`{"params":{"message":{"parts":[{"kind":"text","text":"what's 2+2?"}]}}}`)
+	resp := json.RawMessage(`{"result":"4"}`)
+	msgs := activityRowToChatMessages(created, "ok", req, resp, neverInternal)
+	if len(msgs) != 2 {
+		t.Fatalf("expected 2 messages, got %d", len(msgs))
+	}
+	if msgs[0].Role != "user" || msgs[0].Content != "what's 2+2?" {
+		t.Errorf("first message wrong: %+v", msgs[0])
+	}
+	if msgs[1].Role != "agent" || msgs[1].Content != "4" {
+		t.Errorf("second message wrong: %+v", msgs[1])
+	}
+	if msgs[0].Timestamp != msgs[1].Timestamp {
+		t.Errorf("paired bubbles have different timestamps: %q vs %q", msgs[0].Timestamp, msgs[1].Timestamp)
+	}
+}
+
+// =====================================================================
+// Go-specific: defensive parsing
+// =====================================================================
+
+func TestChatHistory_MalformedJSONInRequestBodyReturnsEmpty(t *testing.T) {
+	// Should NOT panic; should return no user bubble (or no message at all).
+	body := json.RawMessage(`{not valid json}`)
+	defer func() {
+		if r := recover(); r != nil {
+			t.Fatalf("panic on malformed json: %v", r)
+		}
+	}()
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", body, nil, neverInternal)
+	for _, m := range msgs {
+		if m.Role == "user" && (m.Content != "" || len(m.Attachments) > 0) {
+			t.Errorf("malformed JSON yielded a non-empty user bubble: %+v", m)
+		}
+	}
+}
+
+func TestChatHistory_V1ProtobufFlatFileShape(t *testing.T) {
+	// v1 a2a-sdk shape: flat parts with url/filename/mediaType
+	body := json.RawMessage(`{
+	  "result": {
+	    "parts": [
+	      {"url":"https://example.com/data.csv","filename":"data.csv","mediaType":"text/csv"}
+	    ]
+	  }
+	}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", nil, body, neverInternal)
+	var agent *ChatMessage
+	for i := range msgs {
+		if msgs[i].Role == "agent" {
+			agent = &msgs[i]
+			break
+		}
+	}
+	if agent == nil {
+		t.Fatalf("no agent bubble for v1 shape")
+	}
+	if len(agent.Attachments) != 1 {
+		t.Fatalf("attachments=%d want 1", len(agent.Attachments))
+	}
+	att := agent.Attachments[0]
+	if att.Name != "data.csv" || att.URI != "https://example.com/data.csv" || att.MimeType != "text/csv" {
+		t.Errorf("v1 shape extracted wrong: %+v", att)
+	}
+}
+
+func TestChatHistory_TaskShapeArtifactsExtracted(t *testing.T) {
+	// {"result":{"artifacts":[{"parts":[{"kind":"text","text":"..."}]}]}}
+	body := json.RawMessage(`{
+	  "result": {
+	    "artifacts": [
+	      {"parts": [{"kind":"text","text":"hermes detail line"}]}
+	    ]
+	  }
+	}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", nil, body, neverInternal)
+	if len(msgs) != 1 || msgs[0].Content != "hermes detail line" {
+		t.Errorf("artifact text not extracted: %+v", msgs)
+	}
+}
+
+func TestChatHistory_OlderNestedRootTextShape(t *testing.T) {
+	// Older shape: {parts: [{root: {text: "..."}}]}
+	body := json.RawMessage(`{
+	  "result": {
+	    "parts": [{"root":{"text":"legacy nested text"}}]
+	  }
+	}`)
+	msgs := activityRowToChatMessages(mustParseTime(t, fixedTimestamp), "ok", nil, body, neverInternal)
+	if len(msgs) != 1 || !strings.Contains(msgs[0].Content, "legacy nested text") {
+		t.Errorf("nested root.text not extracted: %+v", msgs)
+	}
+}
+
+// =====================================================================
+// IsInternalSelfMessage predicate itself
+// =====================================================================
+
+func TestChatHistory_IsInternalSelfMessage_DelegationPrefix(t *testing.T) {
+	if !IsInternalSelfMessage("Delegation results are ready... <body>") {
+		t.Errorf("Delegation-results prefix should be flagged internal-self")
+	}
+	if IsInternalSelfMessage("Delegation completed but not ready") {
+		t.Errorf("non-prefix match should NOT flag")
+	}
+	if IsInternalSelfMessage("") {
+		t.Errorf("empty text should NOT flag (legitimate attachments-only bubble)")
+	}
+}
+
+// =====================================================================
+// basename helper — mirrors canvas basename() semantics
+// =====================================================================
+
+func TestChatHistory_BasenameStripsSchemeAndPath(t *testing.T) {
+	cases := []struct {
+		in, want string
+	}{
+		{"workspace:/uploads/shot.png", "shot.png"},
+		{"workspace:/a/b/c/file.txt", "file.txt"},
+		{"https://example.com/path/file.csv", "file.csv"},
+		{"http://x/y", "y"},
+		{"", "file"},
+		{"workspace:", "file"}, // scheme-only collapses to "" → "file" sentinel, matches canvas basename
+	}
+	for _, tc := range cases {
+		got := basename(tc.in)
+		if got != tc.want {
+			t.Errorf("basename(%q) = %q want %q", tc.in, got, tc.want)
+		}
+	}
+}
@@ -119,6 +119,18 @@ type Storage interface {
 	// the whole batch succeeds or the user re-uploads.
 	PutBatch(ctx context.Context, workspaceID uuid.UUID, items []PutItem) ([]uuid.UUID, error)

+	// PutBatchTx is the Tx-aware variant of PutBatch. It runs its INSERTs
+	// inside the caller-provided tx so multi-file uploads can commit
+	// atomically with sibling writes (e.g. activity_logs rows in
+	// chat_files uploadPollMode). Pre-input validation runs before any
+	// DB work; on validation failure no INSERT is issued.
+	//
+	// Caller owns the Tx lifecycle: BeginTx before, Commit/Rollback
+	// after. PutBatchTx does NOT call Commit — a successful return only
+	// means the inserts queued cleanly inside the Tx. The caller's
+	// Commit is what actually persists the rows.
+	PutBatchTx(ctx context.Context, tx *sql.Tx, workspaceID uuid.UUID, items []PutItem) ([]uuid.UUID, error)
+
 	// Get returns the full row including content. Returns ErrNotFound
 	// when the row is absent, acked, or past expires_at. Caller should
 	// not differentiate the three cases in the response — from the
@@ -207,19 +219,8 @@ func (p *PostgresStorage) PutBatch(ctx context.Context, workspaceID uuid.UUID, i
 	if len(items) == 0 {
 		return nil, nil
 	}
-	for i, it := range items {
-		if len(it.Content) == 0 {
-			return nil, fmt.Errorf("pendinguploads: item %d: empty content", i)
-		}
-		if len(it.Content) > MaxFileBytes {
-			return nil, ErrTooLarge
-		}
-		if it.Filename == "" {
-			return nil, fmt.Errorf("pendinguploads: item %d: empty filename", i)
-		}
-		if len(it.Filename) > 100 {
-			return nil, fmt.Errorf("pendinguploads: item %d: filename exceeds 100 chars", i)
-		}
+	if err := validatePutBatchItems(items); err != nil {
+		return nil, err
 	}

 	tx, err := p.db.BeginTx(ctx, nil)
@@ -232,6 +233,53 @@ func (p *PostgresStorage) PutBatch(ctx context.Context, workspaceID uuid.UUID, i
 		_ = tx.Rollback()
 	}()

+	out, err := putBatchInsertRows(ctx, tx, workspaceID, items)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := tx.Commit(); err != nil {
+		return nil, fmt.Errorf("pendinguploads: commit batch: %w", err)
+	}
+	return out, nil
+}
+
+// PutBatchTx runs the same INSERT sequence as PutBatch but inside the
+// caller's tx. The caller is responsible for Commit/Rollback. Pre-input
+// validation still happens; on validation failure the tx is left in
+// whatever state it had (the caller will typically Rollback). On a
+// per-row INSERT error the caller MUST Rollback — pending_uploads rows
+// already inserted in this tx (rows 0..i-1) are not yet visible and
+// disappear with the rollback.
+func (p *PostgresStorage) PutBatchTx(ctx context.Context, tx *sql.Tx, workspaceID uuid.UUID, items []PutItem) ([]uuid.UUID, error) {
+	if len(items) == 0 {
+		return nil, nil
+	}
+	if err := validatePutBatchItems(items); err != nil {
+		return nil, err
+	}
+	return putBatchInsertRows(ctx, tx, workspaceID, items)
+}
+
+func validatePutBatchItems(items []PutItem) error {
+	for i, it := range items {
+		if len(it.Content) == 0 {
+			return fmt.Errorf("pendinguploads: item %d: empty content", i)
+		}
+		if len(it.Content) > MaxFileBytes {
+			return ErrTooLarge
+		}
+		if it.Filename == "" {
+			return fmt.Errorf("pendinguploads: item %d: empty filename", i)
+		}
+		if len(it.Filename) > 100 {
+			return fmt.Errorf("pendinguploads: item %d: filename exceeds 100 chars", i)
+		}
+	}
+	return nil
+}
+
+func putBatchInsertRows(ctx context.Context, tx *sql.Tx, workspaceID uuid.UUID, items []PutItem) ([]uuid.UUID, error) {
 	out := make([]uuid.UUID, 0, len(items))
 	for i, it := range items {
 		var fid uuid.UUID
@@ -245,10 +293,6 @@ func (p *PostgresStorage) PutBatch(ctx context.Context, workspaceID uuid.UUID, i
 		}
 		out = append(out, fid)
 	}
-
-	if err := tx.Commit(); err != nil {
-		return nil, fmt.Errorf("pendinguploads: commit batch: %w", err)
-	}
 	return out, nil
 }

@@ -731,3 +731,138 @@ func TestPutBatch_CommitError_Wrapped(t *testing.T) {
 		t.Errorf("expectations: %v", err)
 	}
 }
+
+// ----- PutBatchTx ----------------------------------------------------------
+//
+// PutBatchTx is the Tx-aware variant added in #149 so chat_files
+// uploadPollMode can commit pending_uploads + activity_logs atomically
+// in one Tx. Pre-validation is shared with PutBatch (extracted into
+// validatePutBatchItems); these tests pin the contract that PutBatchTx
+// runs INSERTs in the caller's tx and never calls Begin/Commit itself.
+
+func TestPutBatchTx_HappyPath_RowsInsertedInTx_NoCommitFromHere(t *testing.T) {
+	db, mock := newMockDB(t)
+	store := pendinguploads.NewPostgres(db)
+
+	wsID := uuid.New()
+	id1, id2 := uuid.New(), uuid.New()
+
+	mock.ExpectBegin()
+	mock.ExpectQuery(insertSQL).
+		WithArgs(wsID, []byte("aaa"), int64(3), "a.txt", "text/plain").
+		WillReturnRows(sqlmock.NewRows([]string{"file_id"}).AddRow(id1))
+	mock.ExpectQuery(insertSQL).
+		WithArgs(wsID, []byte("bbbb"), int64(4), "b.bin", "application/octet-stream").
+		WillReturnRows(sqlmock.NewRows([]string{"file_id"}).AddRow(id2))
+	mock.ExpectCommit()
+
+	tx, err := db.BeginTx(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("BeginTx: %v", err)
+	}
+
+	got, err := store.PutBatchTx(context.Background(), tx, wsID, []pendinguploads.PutItem{
+		{Content: []byte("aaa"), Filename: "a.txt", Mimetype: "text/plain"},
+		{Content: []byte("bbbb"), Filename: "b.bin", Mimetype: "application/octet-stream"},
+	})
+	if err != nil {
+		t.Fatalf("PutBatchTx: %v", err)
+	}
+	if len(got) != 2 || got[0] != id1 || got[1] != id2 {
+		t.Errorf("ids out of order: got %v want [%s %s]", got, id1, id2)
+	}
+	// Caller is responsible for Commit — PutBatchTx must NOT have called it.
+	if err := tx.Commit(); err != nil {
+		t.Fatalf("caller Commit: %v", err)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("expectations: %v", err)
+	}
+}
+
+func TestPutBatchTx_EmptyItems_NoDBWork(t *testing.T) {
+	db, mock := newMockDB(t)
+	store := pendinguploads.NewPostgres(db)
+
+	// No expectations — PutBatchTx with empty items must short-circuit
+	// before any tx interaction.
+	got, err := store.PutBatchTx(context.Background(), nil, uuid.New(), nil)
+	if err != nil {
+		t.Fatalf("expected nil error on empty batch, got %v", err)
+	}
+	if got != nil {
+		t.Errorf("expected nil ids on empty batch, got %v", got)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("expectations: %v", err)
+	}
+}
+
+func TestPutBatchTx_ValidationFails_NoTxQuery(t *testing.T) {
+	db, mock := newMockDB(t)
+	store := pendinguploads.NewPostgres(db)
+
+	// Caller opens the Tx; PutBatchTx must reject the invalid item
+	// before issuing any tx.QueryRowContext. Rollback comes from the
+	// caller's defer, not from PutBatchTx.
+	mock.ExpectBegin()
+	mock.ExpectRollback()
+
+	tx, err := db.BeginTx(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("BeginTx: %v", err)
+	}
+
+	_, err = store.PutBatchTx(context.Background(), tx, uuid.New(), []pendinguploads.PutItem{
+		{Content: []byte("hi"), Filename: ""},
+	})
+	if err == nil || !strings.Contains(err.Error(), "empty filename") {
+		t.Fatalf("expected empty-filename error, got %v", err)
+	}
+	if err := tx.Rollback(); err != nil {
+		t.Fatalf("Rollback: %v", err)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("expectations: %v", err)
+	}
+}
+
+func TestPutBatchTx_PerRowErrorPropagates_CallerRollsBack(t *testing.T) {
+	// PutBatchTx returns an error on per-row INSERT failure but does
+	// NOT call Rollback itself — that's the caller's job. This pins
+	// the Tx-lifecycle ownership contract: the caller controls Begin
+	// and Rollback/Commit, PutBatchTx only runs INSERTs.
+	db, mock := newMockDB(t)
+	store := pendinguploads.NewPostgres(db)
+
+	wsID := uuid.New()
+	id1 := uuid.New()
+
+	mock.ExpectBegin()
+	mock.ExpectQuery(insertSQL).
+		WithArgs(wsID, []byte("ok"), int64(2), "a.txt", "text/plain").
+		WillReturnRows(sqlmock.NewRows([]string{"file_id"}).AddRow(id1))
+	mock.ExpectQuery(insertSQL).
+		WithArgs(wsID, []byte("xx"), int64(2), "b.txt", "text/plain").
+		WillReturnError(errors.New("connection lost mid-insert"))
+	mock.ExpectRollback()
+
+	tx, err := db.BeginTx(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("BeginTx: %v", err)
+	}
+
+	_, err = store.PutBatchTx(context.Background(), tx, wsID, []pendinguploads.PutItem{
+		{Content: []byte("ok"), Filename: "a.txt", Mimetype: "text/plain"},
+		{Content: []byte("xx"), Filename: "b.txt", Mimetype: "text/plain"},
+	})
+	if err == nil || !strings.Contains(err.Error(), "batch insert item 1") {
+		t.Fatalf("expected wrapped item-1 error, got %v", err)
+	}
+	if err := tx.Rollback(); err != nil {
+		t.Fatalf("caller Rollback: %v", err)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("expectations: %v", err)
+	}
+}
@@ -2,6 +2,7 @@ package pendinguploads_test

 import (
 	"context"
+	"database/sql"
 	"errors"
 	"sync/atomic"
 	"testing"
@@ -47,6 +48,9 @@ func (f *fakeSweepStorage) Ack(_ context.Context, _ uuid.UUID) error {
 func (f *fakeSweepStorage) PutBatch(_ context.Context, _ uuid.UUID, _ []pendinguploads.PutItem) ([]uuid.UUID, error) {
 	return nil, errors.New("not used")
 }
+func (f *fakeSweepStorage) PutBatchTx(_ context.Context, _ *sql.Tx, _ uuid.UUID, _ []pendinguploads.PutItem) ([]uuid.UUID, error) {
+	return nil, errors.New("not used")
+}
 func (f *fakeSweepStorage) Sweep(_ context.Context, ackRetention time.Duration) (pendinguploads.SweepResult, error) {
 	idx := int(f.calls.Load())
 	f.calls.Add(1)
@@ -35,36 +35,37 @@ import (
 // drift-risk #6.
 var ErrNoBackend = errors.New("provisioner: no backend configured (zero-valued receiver)")

-// RuntimeImages maps runtime names to their Docker image refs on GHCR.
+// RuntimeImages maps runtime names to their Docker image refs.
 // Each standalone template repo publishes its image via the reusable
 // publish-template-image workflow in molecule-ci on every main merge.
 // The provisioner pulls these on demand (see ensureImageLocal) — no
 // pre-build step on the tenant host.
 //
+// The registry prefix is determined by RegistryPrefix() in registry.go;
+// defaults to ghcr.io/molecule-ai (upstream OSS) and is overridden via the
+// MOLECULE_IMAGE_REGISTRY env var in production tenants that mirror to
+// AWS ECR or another registry. The map is computed at package init and
+// captures whatever prefix was active then.
+//
 // Legacy local-build path (`docker build -t workspace-template:<runtime>`
 // via scripts/build-images.sh) is still supported for development:
 // when a bare `workspace-template:<runtime>` image is present locally,
 // Docker's image resolver matches it before any pull is attempted. Set
 // the env var WORKSPACE_IMAGE_LOCAL_OVERRIDE=1 (enforced by callers) to
 // short-circuit pulls entirely if needed.
-var RuntimeImages = map[string]string{
-	"langgraph":   "ghcr.io/molecule-ai/workspace-template-langgraph:latest",
-	"claude-code": "ghcr.io/molecule-ai/workspace-template-claude-code:latest",
-	"openclaw":    "ghcr.io/molecule-ai/workspace-template-openclaw:latest",
-	"deepagents":  "ghcr.io/molecule-ai/workspace-template-deepagents:latest",
-	"crewai":      "ghcr.io/molecule-ai/workspace-template-crewai:latest",
-	"autogen":     "ghcr.io/molecule-ai/workspace-template-autogen:latest",
-	"hermes":      "ghcr.io/molecule-ai/workspace-template-hermes:latest",     // Hermes (Nous Research) — real hermes-agent behind A2A bridge
-	"gemini-cli":  "ghcr.io/molecule-ai/workspace-template-gemini-cli:latest", // Google Gemini CLI
-}
+var RuntimeImages = computeRuntimeImages()
+
+// DefaultImage is the fallback workspace Docker image (langgraph is the
+// most common runtime). Computed via RegistryPrefix() so the prefix
+// override applies to the fallback path too.
+//
+// NOTE: Every runtime MUST have an entry in knownRuntimes (registry.go).
+// If a runtime is missing, it falls back to DefaultImage which may have
+// wrong deps. Add new runtimes to knownRuntimes AND create the standalone
+// template repo.
+var DefaultImage = RuntimeImage(defaultRuntime)

 const (
-	// DefaultImage is the fallback workspace Docker image (langgraph is the most common runtime).
-	DefaultImage = "ghcr.io/molecule-ai/workspace-template-langgraph:latest"
-	// NOTE: Every runtime MUST have an entry in RuntimeImages above. If a runtime is missing,
-	// it falls back to DefaultImage which may have wrong deps. Add new runtimes to both
-	// RuntimeImages AND create the standalone template repo.
-
 	// DefaultNetwork is the Docker network workspaces join.
 	DefaultNetwork = "molecule-monorepo-net"

@@ -0,0 +1,95 @@
+package provisioner
+
+import (
+	"fmt"
+	"os"
+)
+
+// defaultRegistryPrefix is the upstream OSS face for all workspace template
+// images. Self-hosted Molecule deployments without the MOLECULE_IMAGE_REGISTRY
+// override pull from here.
+const defaultRegistryPrefix = "ghcr.io/molecule-ai"
+
+// knownRuntimes is the canonical list of workspace template runtimes shipped
+// in main. Any runtime added here MUST also have a standalone template repo
+// (Molecule-AI/molecule-ai-workspace-template-<name>) and an entry in the
+// publish-template-image workflow that builds it.
+//
+// Order matters for deterministic test snapshots; keep alphabetical.
+var knownRuntimes = []string{
+	"autogen",
+	"claude-code",
+	"codex",
+	"crewai",
+	"deepagents",
+	"gemini-cli",
+	"hermes",
+	"langgraph",
+	"openclaw",
+}
+
+// defaultRuntime is the fallback when a workspace's config doesn't specify a
+// runtime. Picked because LangGraph is the most common in our org templates
+// and has the smallest "first impression" cold-start surface.
+const defaultRuntime = "langgraph"
+
+// RegistryPrefix returns the registry prefix all workspace-template image
+// references should use. Defaults to ghcr.io/molecule-ai (the upstream OSS
+// face) and is overridden by the MOLECULE_IMAGE_REGISTRY env var in
+// production tenants where we mirror images to a private registry.
+//
+// The override is set at deploy time (Railway env, EC2 user-data) — never
+// from user-supplied input — so the value is trusted by the time it reaches
+// this code. Validation is deliberately minimal: an operator-supplied
+// prefix that points at a registry the EC2 can't authenticate to will fail
+// loudly at docker-pull time, which is the right blast radius.
+//
+// Example values:
+//
+//	(unset)                                              → ghcr.io/molecule-ai (OSS default)
+//	"123456789012.dkr.ecr.us-east-2.amazonaws.com/molecule-ai"  → AWS ECR mirror
+//	"git.moleculesai.app/molecule-ai"                    → self-hosted Gitea Container Registry (future)
+//
+// Auth is registry-specific and configured outside this function:
+//   - GHCR: GHCR_USER/GHCR_TOKEN env vars consumed by ghcrAuthHeader()
+//   - ECR: docker credential helper (amazon-ecr-credential-helper) configured
+//     in EC2 user-data; ~/.docker/config.json has credHelpers entry; the
+//     daemon resolves auth automatically on every pull.
+func RegistryPrefix() string {
+	if v := os.Getenv("MOLECULE_IMAGE_REGISTRY"); v != "" {
+		return v
+	}
+	return defaultRegistryPrefix
+}
+
+// RuntimeImage returns the canonical image reference for the given runtime,
+// using the current RegistryPrefix() and the moving `:latest` tag.
+//
+// For SHA-pinned references (production thin-AMI launches), the
+// runtime_image_pins lookup in handlers/runtime_image_pin.go strips the
+// `:latest` suffix and appends an immutable `@sha256:<digest>` from the DB.
+// That code path naturally inherits any RegistryPrefix() change because it
+// reads from RuntimeImages[runtime] and only re-formats the tag suffix.
+//
+// Returns the empty string for unknown runtimes; callers should fall through
+// to DefaultImage in that case (matching legacy behavior).
+func RuntimeImage(runtime string) string {
+	for _, r := range knownRuntimes {
+		if r == runtime {
+			return fmt.Sprintf("%s/workspace-template-%s:latest", RegistryPrefix(), runtime)
+		}
+	}
+	return ""
+}
+
+// computeRuntimeImages returns the {runtime: image-ref} map evaluated against
+// the current RegistryPrefix(). Called at package init to populate the
+// exported RuntimeImages var. Tests that flip MOLECULE_IMAGE_REGISTRY between
+// expected values use this helper to rebuild the map mid-run.
+func computeRuntimeImages() map[string]string {
+	out := make(map[string]string, len(knownRuntimes))
+	for _, r := range knownRuntimes {
+		out[r] = RuntimeImage(r)
+	}
+	return out
+}
@@ -0,0 +1,140 @@
+package provisioner
+
+import (
+	"strings"
+	"testing"
+)
+
+// TestRegistryPrefix_DefaultsToGHCR pins the OSS-default behavior. If a future
+// refactor accidentally drops the default, OSS users self-hosting Molecule
+// would silently lose image pulls — this test should fail loudly instead.
+func TestRegistryPrefix_DefaultsToGHCR(t *testing.T) {
+	t.Setenv("MOLECULE_IMAGE_REGISTRY", "")
+	got := RegistryPrefix()
+	want := "ghcr.io/molecule-ai"
+	if got != want {
+		t.Fatalf("RegistryPrefix() = %q, want %q (default must remain GHCR for OSS users)", got, want)
+	}
+}
+
+// TestRegistryPrefix_RespectsEnv verifies the override path used in
+// production tenants where MOLECULE_IMAGE_REGISTRY points at a private
+// mirror (AWS ECR, self-hosted Harbor, etc.).
+func TestRegistryPrefix_RespectsEnv(t *testing.T) {
+	t.Setenv("MOLECULE_IMAGE_REGISTRY", "123456789012.dkr.ecr.us-east-2.amazonaws.com/molecule-ai")
+	got := RegistryPrefix()
+	want := "123456789012.dkr.ecr.us-east-2.amazonaws.com/molecule-ai"
+	if got != want {
+		t.Fatalf("RegistryPrefix() = %q, want %q (env override path is the production cutover mechanism)", got, want)
+	}
+}
+
+// TestRegistryPrefix_EmptyEnvFallsBackToDefault — guard against an operator
+// setting MOLECULE_IMAGE_REGISTRY="" by mistake (e.g. unset deploy variable
+// becomes empty string, not literally absent). We treat "" as "use default"
+// so a misconfigured env doesn't mean an empty registry prefix.
+func TestRegistryPrefix_EmptyEnvFallsBackToDefault(t *testing.T) {
+	t.Setenv("MOLECULE_IMAGE_REGISTRY", "")
+	if RegistryPrefix() != defaultRegistryPrefix {
+		t.Fatalf("empty MOLECULE_IMAGE_REGISTRY should fall back to %q, got %q", defaultRegistryPrefix, RegistryPrefix())
+	}
+}
+
+// TestRuntimeImage_AllKnownRuntimes — every runtime in the canonical list
+// must produce a properly-formatted image ref. If a new runtime is added to
+// knownRuntimes but the format changes, this catches it.
+func TestRuntimeImage_AllKnownRuntimes(t *testing.T) {
+	t.Setenv("MOLECULE_IMAGE_REGISTRY", "")
+	for _, r := range knownRuntimes {
+		got := RuntimeImage(r)
+		want := "ghcr.io/molecule-ai/workspace-template-" + r + ":latest"
+		if got != want {
+			t.Errorf("RuntimeImage(%q) = %q, want %q", r, got, want)
+		}
+	}
+	// Pin the count so adding a runtime requires explicit test acknowledgement.
+	if len(knownRuntimes) != 9 {
+		t.Errorf("knownRuntimes length = %d, want 9 (autogen, claude-code, codex, crewai, deepagents, gemini-cli, hermes, langgraph, openclaw)", len(knownRuntimes))
+	}
+}
+
+// TestRuntimeImage_UnknownRuntime — defensive: callers must fall back to
+// DefaultImage when a runtime is unknown, never silently use the wrong
+// prefix. Returning "" enforces an explicit fallback at every call site.
+func TestRuntimeImage_UnknownRuntime(t *testing.T) {
+	for _, name := range []string{"", "nonexistent", "WORKSPACE-TEMPLATE-FAKE", "../../../etc/passwd"} {
+		if got := RuntimeImage(name); got != "" {
+			t.Errorf("RuntimeImage(%q) = %q, want empty string for unknown runtime", name, got)
+		}
+	}
+}
+
+// TestRuntimeImage_RegistryOverrideAppliesToAllRuntimes — the override
+// flips ALL runtimes consistently. If a refactor accidentally hardcoded
+// the prefix in some runtimes but not others (the failure mode that
+// triggered this whole rollout), this test catches it.
+func TestRuntimeImage_RegistryOverrideAppliesToAllRuntimes(t *testing.T) {
+	const ecr = "999999999999.dkr.ecr.us-east-2.amazonaws.com/molecule-ai"
+	t.Setenv("MOLECULE_IMAGE_REGISTRY", ecr)
+
+	for _, r := range knownRuntimes {
+		got := RuntimeImage(r)
+		if !strings.HasPrefix(got, ecr+"/workspace-template-") {
+			t.Errorf("RuntimeImage(%q) = %q, must start with override prefix %q", r, got, ecr)
+		}
+		if !strings.HasSuffix(got, ":latest") {
+			t.Errorf("RuntimeImage(%q) = %q, must keep :latest tag suffix", r, got)
+		}
+	}
+}
+
+// TestComputeRuntimeImages_AllRuntimesPresent — the map must contain every
+// known runtime. Drift between knownRuntimes and computeRuntimeImages would
+// silently break the runtime → image lookup that provisioner.Start uses.
+func TestComputeRuntimeImages_AllRuntimesPresent(t *testing.T) {
+	t.Setenv("MOLECULE_IMAGE_REGISTRY", "")
+	m := computeRuntimeImages()
+	if len(m) != len(knownRuntimes) {
+		t.Fatalf("computeRuntimeImages() has %d entries, want %d (one per knownRuntime)", len(m), len(knownRuntimes))
+	}
+	for _, r := range knownRuntimes {
+		img, ok := m[r]
+		if !ok {
+			t.Errorf("computeRuntimeImages() missing runtime %q", r)
+			continue
+		}
+		if img == "" {
+			t.Errorf("computeRuntimeImages()[%q] is empty", r)
+		}
+	}
+}
+
+// TestComputeRuntimeImages_ReflectsCurrentEnv — calling computeRuntimeImages
+// after env change rebuilds the map with new prefix. Tests + ops procedures
+// that flip the env in-process rely on this.
+func TestComputeRuntimeImages_ReflectsCurrentEnv(t *testing.T) {
+	t.Setenv("MOLECULE_IMAGE_REGISTRY", "")
+	defaultMap := computeRuntimeImages()
+	if !strings.HasPrefix(defaultMap["claude-code"], "ghcr.io/molecule-ai/") {
+		t.Fatalf("default map should be GHCR-prefixed, got %q", defaultMap["claude-code"])
+	}
+
+	const mirror = "registry.example.com/molecule-ai"
+	t.Setenv("MOLECULE_IMAGE_REGISTRY", mirror)
+	mirrorMap := computeRuntimeImages()
+	if !strings.HasPrefix(mirrorMap["claude-code"], mirror+"/") {
+		t.Fatalf("mirror-prefixed map should start with %q, got %q", mirror, mirrorMap["claude-code"])
+	}
+}
+
+// TestKnownRuntimes_AlphabeticalOrder — pin the order so test snapshots
+// (and human readers diffing the file) see deterministic output. Adding a
+// new runtime out of alphabetical order will fail this test, which is the
+// nudge to keep the file readable.
+func TestKnownRuntimes_AlphabeticalOrder(t *testing.T) {
+	for i := 1; i < len(knownRuntimes); i++ {
+		if knownRuntimes[i-1] >= knownRuntimes[i] {
+			t.Errorf("knownRuntimes not alphabetical: %q comes before %q", knownRuntimes[i-1], knownRuntimes[i])
+		}
+	}
+}
@@ -8,6 +8,7 @@ import (
 	"time"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/models"
 )

@@ -197,7 +198,7 @@ func sweepStuckProvisioning(ctx context.Context, emitter ProvisionTimeoutEmitter
 		// A separate event type was considered but the UI reaction is
 		// identical either way — operators who need to distinguish can
 		// tell from the `source` payload field.
-		if emitErr := emitter.RecordAndBroadcast(ctx, "WORKSPACE_PROVISION_FAILED", c.id, map[string]interface{}{
+		if emitErr := emitter.RecordAndBroadcast(ctx, string(events.EventWorkspaceProvisionFailed), c.id, map[string]interface{}{
 			"error":        msg,
 			"timeout_secs": timeoutSec,
 			"runtime":      c.runtime,
@@ -11,6 +11,7 @@ import (
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/buildinfo"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/channels"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/messagestore"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/handlers"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/pendinguploads"
@@ -315,6 +316,18 @@ func Setup(hub *ws.Hub, broadcaster *events.Broadcaster, prov *provisioner.Provi
 		wsAuth.POST("/activity", acth.Report)
 		wsAuth.POST("/notify", acth.Notify)

+		// Chat history — RFC #2945 PR-C (issue #3017) + PR-D (issue
+		// #3026). Server-side rendering of activity_logs rows into
+		// the canonical ChatMessage shape; storage is plugin-shaped
+		// via the messagestore.MessageStore interface so OSS
+		// operators can swap in S3 / vector / in-memory backends
+		// without forking the handler. Platform default uses
+		// PostgresMessageStore wrapping the existing activity_logs
+		// table.
+		chatStore := messagestore.NewPostgresMessageStore(db.DB)
+		chh := handlers.NewChatHistoryHandler(chatStore)
+		wsAuth.GET("/chat-history", chh.List)
+
 		// Config
 		cfgh := handlers.NewConfigHandler()
 		wsAuth.GET("/config", cfgh.Get)
@@ -14,8 +14,10 @@ import (
 	cronlib "github.com/robfig/cron/v3"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/metrics"
 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/supervised"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/textutil"
 )

 const (
@@ -521,7 +523,7 @@ func (s *Scheduler) fireSchedule(ctx context.Context, sched scheduleRow) {
 		"schedule_id":   sched.ID,
 		"schedule_name": sched.Name,
 		"cron_expr":     sched.CronExpr,
-		"prompt":        sanitizeUTF8(truncate(sched.Prompt, 200)),
+		"prompt":        sanitizeUTF8(textutil.TruncateBytes(sched.Prompt, 200)),
 	})
 	// #152: persist lastError into error_detail on the activity_logs row
 	// so GET /workspaces/:id/schedules/:id/history can surface why a run
@@ -541,7 +543,7 @@ func (s *Scheduler) fireSchedule(ctx context.Context, sched scheduleRow) {
 	insertCancel()

 	if s.broadcaster != nil {
-		s.broadcaster.RecordAndBroadcast(ctx, "CRON_EXECUTED", sched.WorkspaceID, map[string]interface{}{
+		s.broadcaster.RecordAndBroadcast(ctx, string(events.EventCronExecuted), sched.WorkspaceID, map[string]interface{}{
 			"schedule_id":   sched.ID,
 			"schedule_name": sched.Name,
 			"status":        lastStatus,
@@ -618,7 +620,7 @@ func (s *Scheduler) recordSkipped(ctx context.Context, sched scheduleRow, active
 	skipInsCancel()

 	if s.broadcaster != nil {
-		_ = s.broadcaster.RecordAndBroadcast(ctx, "CRON_SKIPPED", sched.WorkspaceID, map[string]interface{}{
+		_ = s.broadcaster.RecordAndBroadcast(ctx, string(events.EventCronSkipped), sched.WorkspaceID, map[string]interface{}{
 			"schedule_id":   sched.ID,
 			"schedule_name": sched.Name,
 			"reason":        reason,
@@ -806,27 +808,10 @@ func isEmptyResponse(body []byte) bool {
 	return false
 }

-// truncate shortens s to at most maxLen bytes, appending "..." if truncated.
-// #2026: UTF-8 safe — byte-slicing at maxLen-3 would split multi-byte runes
-// (observed: U+2026 `…` = 0xe2 0x80 0xa6, sliced mid-char, concatenated with
-// "..." producing 0xe2 0x80 0x2e — rejected by Postgres as invalid UTF-8,
-// which wedged the activity_logs INSERT with no deadline and stalled the
-// scheduler).
-func truncate(s string, maxLen int) string {
-	if len(s) <= maxLen {
-		return s
-	}
-	cut := maxLen - 3
-	if cut < 0 {
-		cut = 0
-	}
-	// Back up to a rune boundary — utf8.RuneStart returns true for any
-	// non-continuation byte (ASCII, or the lead byte of a multi-byte rune).
-	for cut > 0 && !utf8.RuneStart(s[cut]) {
-		cut--
-	}
-	return s[:cut] + "..."
-}
+// truncation moved to internal/textutil.TruncateBytes (#2962 SSOT).
+// The original #2026 fix lives in textutil's package docs as canonical
+// prior art. Ellipsis was previously "..." (3 ASCII bytes); the SSOT
+// uses "…" (3 UTF-8 bytes) — same byte budget, single-glyph display.

 // short returns up to n leading characters of s without panicking when s is
 // shorter than n. Used to safely display UUID prefixes in log lines where
@@ -10,6 +10,7 @@ import (
 	sqlmock "github.com/DATA-DOG/go-sqlmock"

 	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/textutil"
 )

 // errDBDown is a sentinel error used by tests to simulate a DB connection failure.
@@ -618,7 +619,7 @@ func TestTruncate_utf8Safe_regression2026(t *testing.T) {
 		filler += "a"
 	}
 	input := filler + "…xxx" // 195 ASCII + 3-byte rune + 3 trailing
-	out := truncate(input, 200)
+	out := textutil.TruncateBytes(input, 200)

 	if !utf8.ValidString(out) {
 		t.Fatalf("truncate produced invalid UTF-8: %x", []byte(out))
@@ -0,0 +1,130 @@
+// Package textutil provides string-handling helpers that respect UTF-8
+// rune boundaries.
+//
+// Why this package exists
+// -----------------------
+// `s[:max]` truncates by BYTES; for any string with a multi-byte
+// codepoint at byte `max` (CJK, emoji, accented Latin), the slice
+// produces invalid UTF-8. Postgres `text` and `jsonb` columns reject
+// invalid UTF-8 with `invalid byte sequence for encoding "UTF8"`,
+// which silently fails the INSERT and holds the surrounding tx open
+// — a class of audit-gap that has bitten this codebase three times
+// (scheduler.go #2026, agent_message_writer.go #2959,
+// delegation_ledger.go #2962). Six per-package helpers had
+// independently re-implemented this logic with varying correctness;
+// this package is the single source of truth.
+//
+// Use sites
+// ---------
+//   - DB writes whose column is bytes-bounded (jsonb preview field,
+//     varchar(N)): TruncateBytes / TruncateBytesNoMarker.
+//   - UI summaries whose cap is in display chars, not bytes:
+//     TruncateRunes.
+//
+// All functions guarantee `utf8.ValidString(out) == true` for any
+// `s` where `utf8.ValidString(s) == true`. Inputs that are already
+// invalid UTF-8 should be sanitized at the trust boundary (e.g. via
+// `strings.ToValidUTF8`); this package does not silently fix
+// upstream invalid input.
+package textutil
+
+import "unicode/utf8"
+
+// ellipsis is the truncation marker. U+2026 HORIZONTAL ELLIPSIS —
+// 3 bytes in UTF-8, 1 rune, 1 display column. Standardized across
+// the codebase to avoid the "..." (3 ASCII chars) vs "…" (1 char)
+// inconsistency the per-package helpers had drifted into.
+const ellipsis = "…"
+
+// TruncateBytes returns s if `len(s) <= maxBytes`, otherwise returns
+// the longest rune-aligned prefix of s that fits in `maxBytes - 3`
+// bytes followed by the ellipsis marker. The returned string is
+// always at most `maxBytes` bytes long.
+//
+// Example: TruncateBytes("你好世界你好", 10) returns "你好世…" (9 bytes)
+// — three "你好" runes (each 3 bytes = 9 bytes) plus "…" (3 bytes)
+// would be 12 bytes, so we walk back to "你好" (6 bytes) + "…" (3) = 9.
+//
+// Edge cases:
+//   - maxBytes <= 0: returns "" (no room even for input or marker)
+//   - maxBytes < len(ellipsis): returns "" (can't add marker without
+//     exceeding cap, and we won't return a marker-less truncation
+//     here — caller wanted a marker; use TruncateBytesNoMarker if
+//     they don't)
+//   - s contains invalid UTF-8: continuation bytes are walked over
+//     same as valid runes; the result preserves the (invalid) input
+//     bytes up to the truncation point. Caller is responsible for
+//     pre-sanitizing if Postgres validity is required.
+func TruncateBytes(s string, maxBytes int) string {
+	if len(s) <= maxBytes {
+		return s
+	}
+	if maxBytes < len(ellipsis) {
+		return ""
+	}
+	// Reserve room for the marker, then walk back to the nearest
+	// rune boundary at or below the cut point.
+	cut := maxBytes - len(ellipsis)
+	for cut > 0 && !utf8.RuneStart(s[cut]) {
+		cut--
+	}
+	return s[:cut] + ellipsis
+}
+
+// TruncateBytesNoMarker returns s if `len(s) <= maxBytes`, otherwise
+// returns the longest rune-aligned prefix of s that fits in
+// `maxBytes` bytes. No marker is appended — useful when the caller's
+// storage already conveys "preview" / "snippet" semantics and an
+// extra ellipsis would push the result over a hard column cap.
+//
+// Example: TruncateBytesNoMarker("hello world", 5) returns "hello".
+//
+// Edge case: maxBytes <= 0 returns "".
+func TruncateBytesNoMarker(s string, maxBytes int) string {
+	if len(s) <= maxBytes {
+		return s
+	}
+	if maxBytes <= 0 {
+		return ""
+	}
+	cut := maxBytes
+	for cut > 0 && !utf8.RuneStart(s[cut]) {
+		cut--
+	}
+	return s[:cut]
+}
+
+// TruncateRunes returns s if it has at most maxRunes runes, otherwise
+// returns the first maxRunes runes followed by the ellipsis marker.
+// Use this when the cap is in user-visible characters (UI summary,
+// activity feed line) rather than bytes (DB column).
+//
+// Example: TruncateRunes("你好世界你好", 3) returns "你好世…" — three
+// runes plus the marker, regardless of the resulting byte count.
+//
+// Edge case: maxRunes <= 0 returns "" (caller asked for no content).
+func TruncateRunes(s string, maxRunes int) string {
+	if maxRunes <= 0 {
+		return ""
+	}
+	// Fast path: if every byte is a single-byte rune, the byte-length
+	// upper-bounds the rune count. This avoids a runes alloc for the
+	// common ASCII case where the input fits.
+	if len(s) <= maxRunes {
+		return s
+	}
+	// Walk by rune boundaries; stop at the (maxRunes+1)-th rune so we
+	// know the cut point and that truncation is needed.
+	count := 0
+	for i := range s {
+		if count == maxRunes {
+			return s[:i] + ellipsis
+		}
+		count++
+	}
+	// Reachable when the byte count exceeded maxRunes but the actual
+	// rune count didn't (e.g. all single-byte runes that just happen
+	// to be more than maxRunes). The fast path catches len(s) <=
+	// maxRunes; this catches maxRunes < runeCount(s) <= len(s).
+	return s
+}
@@ -0,0 +1,222 @@
+package textutil
+
+import (
+	"testing"
+	"unicode/utf8"
+)
+
+// TestTruncateBytes_RuneBoundary pins the byte-cap, marker-bearing
+// truncation path. Every case asserts both:
+//  1. the exact expected output (so a refactor that flips ellipsis or
+//     drops a rune is caught), and
+//  2. utf8.ValidString on the output (the invariant that the bug class
+//     in #2026/#2959/#2962 violated by slicing mid-codepoint).
+//
+// Per memory feedback_assert_exact_not_substring.md, asserts are exact
+// equality, not substring matches.
+func TestTruncateBytes_RuneBoundary(t *testing.T) {
+	cases := []struct {
+		name     string
+		in       string
+		maxBytes int
+		want     string
+	}{
+		// Under-cap: returns input verbatim.
+		{"empty", "", 10, ""},
+		{"under-cap ASCII", "hi", 10, "hi"},
+		{"exactly-at-cap ASCII", "hello", 5, "hello"},
+		{"under-cap CJK", "你好", 10, "你好"}, // 6 bytes
+		{"exactly-at-cap CJK", "你好", 6, "你好"},
+
+		// Over-cap ASCII: trims to (maxBytes - 3) bytes + "…".
+		{"over-cap ASCII", "abcdefghij", 6, "abc…"},
+
+		// Over-cap CJK where cut would land mid-codepoint. The
+		// pre-fix bug shape: 7 - 3 = 4, but byte 4 is mid-"好"
+		// (好 is bytes 3..5 of "你好世界"). Walking back to byte 3
+		// (start of 好 — wait, that IS the start). Actually 你=0..2,
+		// 好=3..5, 世=6..8, 界=9..11. Cut=4, walk back to 3 (start
+		// of 好), then s[:3]="你", + "…" = "你…" (3+3=6 bytes ≤ 7).
+		{"over-cap CJK lands mid-codepoint", "你好世界", 7, "你…"},
+
+		// Over-cap CJK where cut lands exactly on rune boundary.
+		// 9 - 3 = 6, byte 6 is start of 世. Walk-back is no-op.
+		// s[:6]="你好" + "…" = "你好…" (9 bytes).
+		{"over-cap CJK rune-aligned", "你好世界", 9, "你好…"},
+
+		// Emoji: 😀 is 4 bytes (U+1F600). 7 - 3 = 4, byte 4 is start
+		// of second 😀 — walk-back no-op. s[:4]="😀" + "…" = "😀…".
+		{"over-cap emoji", "😀😀😀", 7, "😀…"},
+
+		// Mixed ASCII + CJK. "ab你好世界": a(1) b(1) 你(3) 好(3) 世(3) 界(3) = 14 bytes.
+		// maxBytes=8, 8-3=5. byte 5 is mid-好. Walk back to start of 好 = byte 5? Let me
+		// recompute: a=0, b=1, 你=2..4, 好=5..7, 世=8..10. Byte 5 IS start of 好.
+		// Walk-back keeps cut at 5. s[:5] = "ab你" + "…" = "ab你…" (8 bytes).
+		{"mixed prefix ASCII over-cap CJK", "ab你好世界", 8, "ab你…"},
+
+		// Pathological: maxBytes too small to even fit the marker.
+		{"cap below ellipsis len", "hello", 2, ""},
+		{"cap zero", "hello", 0, ""},
+		{"cap negative", "hello", -1, ""},
+
+		// Cap exactly == ellipsis len: no room for content, but
+		// the marker fits. This returns "" (cut = 0, s[:0] = "").
+		{"cap equals ellipsis len", "hello", 3, "…"},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			got := TruncateBytes(c.in, c.maxBytes)
+			if got != c.want {
+				t.Errorf("TruncateBytes(%q, %d) = %q, want %q", c.in, c.maxBytes, got, c.want)
+			}
+			if !utf8.ValidString(got) {
+				t.Errorf("TruncateBytes(%q, %d) returned invalid UTF-8: %q", c.in, c.maxBytes, got)
+			}
+			// Output never exceeds the byte cap (when one is set).
+			if c.maxBytes > 0 && len(got) > c.maxBytes {
+				t.Errorf("TruncateBytes(%q, %d) overflowed cap: len(out)=%d > %d",
+					c.in, c.maxBytes, len(got), c.maxBytes)
+			}
+		})
+	}
+}
+
+// TestTruncateBytesNoMarker pins the marker-less variant. Same
+// boundary handling as TruncateBytes but no ellipsis cost — the cut
+// happens at maxBytes itself, walking back only if that lands
+// mid-codepoint.
+func TestTruncateBytesNoMarker(t *testing.T) {
+	cases := []struct {
+		name     string
+		in       string
+		maxBytes int
+		want     string
+	}{
+		{"empty", "", 10, ""},
+		{"under-cap ASCII", "hi", 10, "hi"},
+		{"exactly-at-cap ASCII", "hello", 5, "hello"},
+		{"over-cap ASCII", "abcdefghij", 5, "abcde"},
+
+		// Over-cap CJK rune-aligned: "你好世界", maxBytes=6, byte 6 is start of 世.
+		// s[:6]="你好" — perfect cut.
+		{"over-cap CJK rune-aligned", "你好世界", 6, "你好"},
+
+		// Over-cap CJK mid-codepoint: maxBytes=4, byte 4 is mid-好.
+		// Walk back to byte 3 (start of 好), s[:3]="你".
+		{"over-cap CJK mid-codepoint", "你好世界", 4, "你"},
+
+		// Emoji: maxBytes=5, "😀😀" is bytes 0..3 then 4..7. byte 5 is mid-second-😀.
+		// Walk back to byte 4 (start of second 😀), s[:4]="😀".
+		{"over-cap emoji", "😀😀", 5, "😀"},
+
+		// Edge: cap zero or negative → "".
+		{"cap zero", "hello", 0, ""},
+		{"cap negative", "hello", -1, ""},
+
+		// Cap = 1 and first rune is multi-byte: walk-back to 0, return "".
+		{"cap one with leading CJK", "你hello", 1, ""},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			got := TruncateBytesNoMarker(c.in, c.maxBytes)
+			if got != c.want {
+				t.Errorf("TruncateBytesNoMarker(%q, %d) = %q, want %q", c.in, c.maxBytes, got, c.want)
+			}
+			if !utf8.ValidString(got) {
+				t.Errorf("TruncateBytesNoMarker(%q, %d) returned invalid UTF-8: %q", c.in, c.maxBytes, got)
+			}
+			if c.maxBytes > 0 && len(got) > c.maxBytes {
+				t.Errorf("TruncateBytesNoMarker(%q, %d) overflowed cap: len(out)=%d > %d",
+					c.in, c.maxBytes, len(got), c.maxBytes)
+			}
+		})
+	}
+}
+
+// TestTruncateRunes pins the rune-cap variant. The key contract is
+// that maxRunes counts user-visible characters (Go runes, which line
+// up with Unicode codepoints), not bytes — so "你好世界" with
+// maxRunes=2 returns "你好…", regardless of the resulting byte count.
+func TestTruncateRunes(t *testing.T) {
+	cases := []struct {
+		name     string
+		in       string
+		maxRunes int
+		want     string
+	}{
+		{"empty", "", 5, ""},
+		{"under-cap ASCII", "hi", 5, "hi"},
+		{"exactly-at-cap ASCII", "hello", 5, "hello"},
+		{"over-cap ASCII", "abcdefghij", 5, "abcde…"},
+
+		{"under-cap CJK", "你好", 5, "你好"},
+		{"exactly-at-cap CJK", "你好", 2, "你好"},
+
+		// Over-cap CJK: maxRunes=3, expect first 3 runes + marker.
+		{"over-cap CJK", "你好世界你好", 3, "你好世…"},
+
+		// Emoji is one rune per glyph in Go (no ZWJ here).
+		{"over-cap emoji", "😀😀😀😀😀", 2, "😀😀…"},
+
+		// Mixed: maxRunes=3 of "ab你好世界" → "ab你…".
+		{"mixed prefix", "ab你好世界", 3, "ab你…"},
+
+		// Edge: maxRunes 0 / negative → "".
+		{"cap zero", "hello", 0, ""},
+		{"cap negative", "hello", -1, ""},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			got := TruncateRunes(c.in, c.maxRunes)
+			if got != c.want {
+				t.Errorf("TruncateRunes(%q, %d) = %q, want %q", c.in, c.maxRunes, got, c.want)
+			}
+			if !utf8.ValidString(got) {
+				t.Errorf("TruncateRunes(%q, %d) returned invalid UTF-8: %q", c.in, c.maxRunes, got)
+			}
+		})
+	}
+}
+
+// TestTruncate_FuzzInvariants stays as a property-style sanity check:
+// for any rune-valid input and any cap, the output is rune-valid and
+// (for byte-cap variants) within the cap. This catches off-by-one
+// regressions in cuts that slip past the table-test cases above.
+func TestTruncate_FuzzInvariants(t *testing.T) {
+	inputs := []string{
+		"",
+		"a",
+		"hello world",
+		"你好世界",
+		"😀😀😀",
+		"ab你c好d世e界",
+		"日本語の文字列",
+		"🇺🇸🇯🇵", // flags: each is 2 codepoints (regional indicators)
+	}
+	for _, in := range inputs {
+		for cap := -1; cap <= len(in)+5; cap++ {
+			t.Run("", func(t *testing.T) {
+				gotB := TruncateBytes(in, cap)
+				if !utf8.ValidString(gotB) {
+					t.Errorf("TruncateBytes(%q, %d) invalid UTF-8: %q", in, cap, gotB)
+				}
+				if cap > 0 && len(gotB) > cap {
+					t.Errorf("TruncateBytes(%q, %d) overflowed: %q (%d bytes)", in, cap, gotB, len(gotB))
+				}
+
+				gotN := TruncateBytesNoMarker(in, cap)
+				if !utf8.ValidString(gotN) {
+					t.Errorf("TruncateBytesNoMarker(%q, %d) invalid UTF-8: %q", in, cap, gotN)
+				}
+				if cap > 0 && len(gotN) > cap {
+					t.Errorf("TruncateBytesNoMarker(%q, %d) overflowed: %q (%d bytes)", in, cap, gotN, len(gotN))
+				}
+
+				gotR := TruncateRunes(in, cap)
+				if !utf8.ValidString(gotR) {
+					t.Errorf("TruncateRunes(%q, %d) invalid UTF-8: %q", in, cap, gotR)
+				}
+			})
+		}
+	}
+}
--- a/Show More
+++ b/Show More