feat(workspace): user-configurable EC2 sizing override, decoupled from tier

canvas/src/components/tabs/ConfigTab.tsx

@@ -178,6 +178,26 @@ export function deriveProvidersFromModels(models: ModelSpec[]): string[] {
 // not this one.
 const RUNTIMES_WITH_OWN_CONFIG = new Set<string>(["external", "kimi", "kimi-cli", "openclaw"]);
 
+// Workspace EC2 sizing options. The control-plane is the authoritative
+// allowlist + bounds enforcement point (controlplane
+// internal/provisioner/ec2.go workspaceInstanceTypeAllowlist; disk
+// clamped to [30,500]); this list MUST stay in sync — an entry here the
+// CP rejects would let the user save an override the CP then silently
+// falls back to the default for. "" = the platform default
+// (t3.large / 50GB). Sizing is decoupled from the access tier.
+const WORKSPACE_INSTANCE_TYPES: { value: string; label: string }[] = [
+  { value: "", label: "Default (t3.large — 2 vCPU / 8GB)" },
+  { value: "t3.medium", label: "t3.medium — 2 vCPU / 4GB (smallest)" },
+  { value: "t3.large", label: "t3.large — 2 vCPU / 8GB" },
+  { value: "t3.xlarge", label: "t3.xlarge — 4 vCPU / 16GB" },
+  { value: "t3.2xlarge", label: "t3.2xlarge — 8 vCPU / 32GB (largest)" },
+  { value: "m6i.large", label: "m6i.large — 2 vCPU / 8GB (steady CPU)" },
+  { value: "m6i.xlarge", label: "m6i.xlarge — 4 vCPU / 16GB (steady CPU)" },
+  { value: "c6i.xlarge", label: "c6i.xlarge — 4 vCPU / 8GB (compute)" },
+];
+const WORKSPACE_DISK_MIN_GB = 30;
+const WORKSPACE_DISK_MAX_GB = 500;
+
 const FALLBACK_RUNTIME_OPTIONS: RuntimeOption[] = [
   { value: "", label: "LangGraph (default)", models: [], providers: [] },
   { value: "claude-code", label: "Claude Code", models: [], providers: [] },
@@ -210,6 +230,19 @@ export function ConfigTab({ workspaceId }: Props) {
   // data, written into /configs/config.yaml on next provision too).
   const [provider, setProvider] = useState("");
   const [originalProvider, setOriginalProvider] = useState("");
+  // Per-workspace EC2 sizing override (DB-backed, NOT in config.yaml).
+  // Separate state from `config` for the same reason as provider/model:
+  // these live on the workspace row, not the template YAML. Empty
+  // instanceType + 0 diskGB = "use the platform default" (t3.large /
+  // 50GB). Sizing is ORTHOGONAL to the access tier (the Tier select in
+  // General) — T4 = full root access only; it does not size the box.
+  // Resize semantics: provision-time only (AWS can't change instance
+  // type live / shrink EBS in place) — surfaced in the section copy.
+  const [instanceType, setInstanceType] = useState("");
+  const [originalInstanceType, setOriginalInstanceType] = useState("");
+  const [diskGB, setDiskGB] = useState(0);
+  const [originalDiskGB, setOriginalDiskGB] = useState(0);
+  const [sizingError, setSizingError] = useState<string | null>(null);
   // Track the model the form first rendered, so handleSave can detect
   // whether the user actually changed it (vs. only edited tier/skills/etc).
   // Two field sources contribute:
@@ -259,8 +292,8 @@ export function ConfigTab({ workspaceId }: Props) {
     // See GH #1894 for the workspace-row-as-source-of-truth rationale
     // that motivated splitting from a single config.yaml read.
     const [wsRes, modelRes, providerRes] = await Promise.all([
-      api.get<{ runtime?: string; tier?: number }>(`/workspaces/${workspaceId}`)
-        .catch(() => ({} as { runtime?: string; tier?: number })),
+      api.get<{ runtime?: string; tier?: number; instance_type?: string | null; disk_gb?: number | null }>(`/workspaces/${workspaceId}`)
+        .catch(() => ({} as { runtime?: string; tier?: number; instance_type?: string | null; disk_gb?: number | null })),
       api.get<{ model?: string }>(`/workspaces/${workspaceId}/model`)
         .catch(() => ({} as { model?: string })),
       api.get<{ provider?: string }>(`/workspaces/${workspaceId}/provider`)
@@ -278,6 +311,19 @@ export function ConfigTab({ workspaceId }: Props) {
       setProvider("");
       setOriginalProvider("");
     }
+    // Sizing override comes from the workspace row (GET /workspaces/:id
+    // returns instance_type/disk_gb, null when no override → render as
+    // the platform default). Snapshot originals so handleSave only
+    // PATCHes when the user actually changed them.
+    {
+      const loadedType = (wsRes.instance_type || "").trim();
+      const loadedDisk =
+        typeof wsRes.disk_gb === "number" ? wsRes.disk_gb : 0;
+      setInstanceType(loadedType);
+      setOriginalInstanceType(loadedType);
+      setDiskGB(loadedDisk);
+      setOriginalDiskGB(loadedDisk);
+    }
     // originalModel is set further down once the YAML has been parsed —
     // we want it to reflect what the form ACTUALLY rendered, which may
     // be the YAML's runtime_config.model fallback when MODEL_PROVIDER
@@ -581,6 +627,31 @@ export function ConfigTab({ workspaceId }: Props) {
         }
       }
 
+      // Sizing override → PATCH /workspaces/:id. Send only the fields
+      // the user changed. "" / 0 clears the override (handler maps to
+      // NULL → CP default). Sizing is provision-time only; the handler
+      // returns needs_restart so the user knows it takes effect on the
+      // next (re)provision — we do NOT pretend it applied live.
+      let sizingSaveError: string | null = null;
+      const instanceTypeChanged = instanceType !== originalInstanceType;
+      const diskChanged = diskGB !== originalDiskGB;
+      let sizingWillNeedRestart = false;
+      if (instanceTypeChanged || diskChanged) {
+        const sizingPatch: Record<string, unknown> = {};
+        if (instanceTypeChanged) sizingPatch.instance_type = instanceType || null;
+        if (diskChanged) sizingPatch.disk_gb = diskGB || null;
+        try {
+          await api.patch(`/workspaces/${workspaceId}`, sizingPatch);
+          setOriginalInstanceType(instanceType);
+          setOriginalDiskGB(diskGB);
+          setSizingError(null);
+          sizingWillNeedRestart = true;
+        } catch (e) {
+          sizingSaveError = e instanceof Error ? e.message : "Sizing update was rejected";
+          setSizingError(sizingSaveError);
+        }
+      }
+
       setOriginalYaml(content);
       if (rawMode) {
         const parsed = parseYaml(content);
@@ -598,18 +669,25 @@ export function ConfigTab({ workspaceId }: Props) {
       if (restart && !providerWillAutoRestart) {
         await useCanvasStore.getState().restartWorkspace(workspaceId);
       } else if (!restart) {
-        useCanvasStore.getState().updateNodeData(workspaceId, { needsRestart: !providerWillAutoRestart });
+        // A sizing change only takes effect on the next (re)provision
+        // (AWS can't resize a live instance), so flag needsRestart so
+        // the user gets the "restart to apply" affordance instead of
+        // silently believing the new size is active.
+        const needsRestart = !providerWillAutoRestart || sizingWillNeedRestart;
+        useCanvasStore.getState().updateNodeData(workspaceId, { needsRestart });
       }
-      // Aggregate partial-save errors. Both modelSaveError and
-      // providerSaveError describe rejected updates from independent
-      // endpoints — show whichever fired so the user knows which
-      // field reverts on next reload (otherwise they'd see "Saved" and
-      // be confused why Provider snapped back).
-      const partialError = providerSaveError
-        ? `Other fields saved, but provider update failed: ${providerSaveError}`
-        : modelSaveError
-          ? `Other fields saved, but model update failed: ${modelSaveError}`
-          : null;
+      // Aggregate partial-save errors. modelSaveError, providerSaveError
+      // and sizingSaveError describe rejected updates from independent
+      // endpoints — show whichever fired so the user knows which field
+      // reverts on next reload (otherwise they'd see "Saved" and be
+      // confused why a field snapped back).
+      const partialError = sizingSaveError
+        ? `Other fields saved, but sizing update failed: ${sizingSaveError}`
+        : providerSaveError
+          ? `Other fields saved, but provider update failed: ${providerSaveError}`
+          : modelSaveError
+            ? `Other fields saved, but model update failed: ${modelSaveError}`
+            : null;
       if (partialError) {
         setError(partialError);
       } else {
@@ -628,6 +706,8 @@ export function ConfigTab({ workspaceId }: Props) {
   const descriptionId = useId();
   const tierId = useId();
   const runtimeId = useId();
+  const instanceTypeId = useId();
+  const diskGBId = useId();
   const effortId = useId();
   const taskBudgetId = useId();
   const sandboxBackendId = useId();
@@ -706,6 +786,55 @@ export function ConfigTab({ workspaceId }: Props) {
             </div>
           </Section>
 
+          <Section title="Sizing" defaultOpen={false}>
+            <p className="text-[10px] text-ink-mid mb-2 leading-relaxed">
+              Per-workspace EC2 size. Independent of Tier — Tier controls
+              access (T4 = full root), this controls how big the box is.
+              Default is t3.large / 50&nbsp;GB. Changes apply on the next
+              restart / re-provision (AWS cannot resize a running instance
+              or shrink a disk in place).
+            </p>
+            <div className="grid grid-cols-2 gap-3">
+              <div>
+                <label htmlFor={instanceTypeId} className="text-[10px] text-ink-mid block mb-1">Instance type</label>
+                <select
+                  id={instanceTypeId}
+                  value={instanceType}
+                  onChange={(e) => setInstanceType(e.target.value)}
+                  aria-label="Instance type"
+                  className="w-full bg-surface-card border border-line rounded px-2 py-1 text-xs text-ink focus:outline-none focus:border-accent"
+                >
+                  {WORKSPACE_INSTANCE_TYPES.map((o) => (
+                    <option key={o.value} value={o.value}>{o.label}</option>
+                  ))}
+                </select>
+              </div>
+              <div>
+                <label htmlFor={diskGBId} className="text-[10px] text-ink-mid block mb-1">
+                  Disk (GB) — 0 = default 50
+                </label>
+                <input
+                  id={diskGBId}
+                  type="number"
+                  value={diskGB}
+                  min={0}
+                  max={WORKSPACE_DISK_MAX_GB}
+                  onChange={(e) => setDiskGB(parseInt(e.target.value, 10) || 0)}
+                  aria-label="Disk size in GB"
+                  className="w-full bg-surface-card border border-line rounded px-2 py-1 text-xs text-ink focus:outline-none focus:border-accent font-mono"
+                />
+                {diskGB !== 0 && (diskGB < WORKSPACE_DISK_MIN_GB || diskGB > WORKSPACE_DISK_MAX_GB) && (
+                  <div className="text-[10px] text-bad mt-1">
+                    Will be clamped to {WORKSPACE_DISK_MIN_GB}–{WORKSPACE_DISK_MAX_GB} GB by the platform.
+                  </div>
+                )}
+              </div>
+            </div>
+            {sizingError && (
+              <div className="text-[10px] text-bad mt-2">{sizingError}</div>
+            )}
+          </Section>
+
           <Section title="Runtime">
             <div>
               <label htmlFor={runtimeId} className="text-[10px] text-ink-mid block mb-1">Runtime</label>

canvas/src/components/tabs/__tests__/ConfigTab.sizing.test.tsx

@@ -0,0 +1,145 @@
+// @vitest-environment jsdom
+//
+// Tests for the workspace EC2 Sizing section (tier↔sizing decoupling,
+// Hongming 2026-05-15).
+//
+// What this pins:
+//   1. A "Sizing" section exists, separate from the Tier control.
+//   2. It loads the workspace's instance_type / disk_gb from
+//      GET /workspaces/:id and renders them.
+//   3. Changing the override + Save PATCHes /workspaces/:id with the
+//      changed sizing fields (proves the override is not a silent
+//      no-op in the UI — feedback_no_proxy_e2e_claims).
+//   4. Section copy states sizing is independent of Tier and applies
+//      on the next restart (provision-time only).
+
+import { describe, it, expect, vi, afterEach, beforeEach } from "vitest";
+import { render, screen, cleanup, waitFor, fireEvent } from "@testing-library/react";
+import React from "react";
+
+afterEach(cleanup);
+
+const apiGet = vi.fn();
+const apiPatch = vi.fn();
+const apiPut = vi.fn();
+vi.mock("@/lib/api", () => ({
+  api: {
+    get: (path: string) => apiGet(path),
+    patch: (path: string, body?: unknown) => apiPatch(path, body),
+    put: (path: string, body?: unknown) => apiPut(path, body),
+    post: vi.fn(),
+    del: vi.fn(),
+  },
+}));
+
+const storeUpdateNodeData = vi.fn();
+const storeRestartWorkspace = vi.fn();
+vi.mock("@/store/canvas", () => ({
+  useCanvasStore: Object.assign(
+    (selector: (s: unknown) => unknown) =>
+      selector({ restartWorkspace: storeRestartWorkspace, updateNodeData: storeUpdateNodeData }),
+    {
+      getState: () => ({
+        restartWorkspace: storeRestartWorkspace,
+        updateNodeData: storeUpdateNodeData,
+      }),
+    },
+  ),
+}));
+
+vi.mock("../AgentCardSection", () => ({
+  AgentCardSection: () => <div data-testid="agent-card-stub" />,
+}));
+
+import { ConfigTab } from "../ConfigTab";
+
+function mockApi(opts: { instanceType?: string | null; diskGB?: number | null } = {}) {
+  apiGet.mockReset();
+  apiPatch.mockReset();
+  apiPut.mockReset();
+  apiPatch.mockResolvedValue({});
+  apiPut.mockResolvedValue({});
+  apiGet.mockImplementation((path: string) => {
+    if (path === `/workspaces/ws-test`) {
+      return Promise.resolve({
+        runtime: "claude-code",
+        tier: 4,
+        instance_type: opts.instanceType ?? null,
+        disk_gb: opts.diskGB ?? null,
+      });
+    }
+    if (path === `/workspaces/ws-test/model`) return Promise.resolve({ model: "claude-opus-4-7" });
+    if (path === `/workspaces/ws-test/provider`) return Promise.resolve({ provider: "anthropic-oauth" });
+    if (path === `/workspaces/ws-test/files/config.yaml`) {
+      return Promise.resolve({ content: "name: test\nruntime: claude-code\n" });
+    }
+    if (path === "/templates") {
+      return Promise.resolve([{ id: "claude-code", name: "Claude Code", runtime: "claude-code", providers: [] }]);
+    }
+    return Promise.reject(new Error(`unmocked api.get: ${path}`));
+  });
+}
+
+describe("ConfigTab Sizing section", () => {
+  beforeEach(() => mockApi());
+
+  it("renders a Sizing section distinct from the Tier control", async () => {
+    render(<ConfigTab workspaceId="ws-test" />);
+    await waitFor(() => expect(apiGet).toHaveBeenCalled());
+    const sizingBtn = screen.getByRole("button", { name: /^Sizing/i });
+    expect(sizingBtn).toBeTruthy();
+    fireEvent.click(sizingBtn);
+    // Copy must state independence from Tier + restart-to-apply.
+    await waitFor(() => {
+      const blurb = screen.queryAllByText((_, el) =>
+        (el?.textContent || "").includes("Independent of Tier"),
+      );
+      expect(blurb.length).toBeGreaterThan(0);
+    });
+  });
+
+  it("loads the workspace's saved override into the controls", async () => {
+    mockApi({ instanceType: "t3.xlarge", diskGB: 120 });
+    render(<ConfigTab workspaceId="ws-test" />);
+    await waitFor(() => expect(apiGet).toHaveBeenCalled());
+    fireEvent.click(screen.getByRole("button", { name: /^Sizing/i }));
+    const typeSelect = (await screen.findByLabelText("Instance type")) as HTMLSelectElement;
+    const diskInput = screen.getByLabelText("Disk size in GB") as HTMLInputElement;
+    expect(typeSelect.value).toBe("t3.xlarge");
+    expect(diskInput.value).toBe("120");
+  });
+
+  it("PATCHes /workspaces/:id with the changed sizing on Save", async () => {
+    render(<ConfigTab workspaceId="ws-test" />);
+    await waitFor(() => expect(apiGet).toHaveBeenCalled());
+    fireEvent.click(screen.getByRole("button", { name: /^Sizing/i }));
+
+    const typeSelect = (await screen.findByLabelText("Instance type")) as HTMLSelectElement;
+    fireEvent.change(typeSelect, { target: { value: "t3.2xlarge" } });
+    const diskInput = screen.getByLabelText("Disk size in GB") as HTMLInputElement;
+    fireEvent.change(diskInput, { target: { value: "200" } });
+
+    fireEvent.click(screen.getByRole("button", { name: /^Save$/i }));
+
+    await waitFor(() => {
+      const sizingCall = apiPatch.mock.calls.find(
+        (c) => c[0] === "/workspaces/ws-test" && c[1] && ("instance_type" in c[1] || "disk_gb" in c[1]),
+      );
+      expect(sizingCall).toBeTruthy();
+      expect(sizingCall![1]).toMatchObject({ instance_type: "t3.2xlarge", disk_gb: 200 });
+    });
+  });
+
+  it("does not PATCH sizing when the user did not change it", async () => {
+    mockApi({ instanceType: "t3.large", diskGB: 50 });
+    render(<ConfigTab workspaceId="ws-test" />);
+    await waitFor(() => expect(apiGet).toHaveBeenCalled());
+    fireEvent.click(screen.getByRole("button", { name: /^Sizing/i }));
+    fireEvent.click(screen.getByRole("button", { name: /^Save$/i }));
+    await waitFor(() => expect(screen.queryByText(/Saving/i)).toBeNull());
+    const sizingCall = apiPatch.mock.calls.find(
+      (c) => c[1] && ("instance_type" in c[1] || "disk_gb" in c[1]),
+    );
+    expect(sizingCall).toBeFalsy();
+  });
+});

workspace-server/internal/handlers/workspace.go

@@ -805,5 +805,28 @@ func (h *WorkspaceHandler) Get(c *gin.Context) {
 		h.addProvisionTimeoutMs(ws, rt)
 	}
 
+	// Per-workspace EC2 sizing override (canvas Config tab). NULL → the
+	// CP applies its default (t3.large / 50GB); we surface null so the
+	// UI can render "Default" rather than a stale value. Non-sensitive
+	// (it's the size the user themselves configured). Separate query
+	// for the same reason as last_outbound_at above — keeps the shared
+	// scanWorkspaceRow column list (used by list endpoints too) stable.
+	var instanceType sql.NullString
+	var diskGB sql.NullInt64
+	if err := db.DB.QueryRowContext(c.Request.Context(),
+		`SELECT instance_type, disk_gb FROM workspaces WHERE id = $1`, id,
+	).Scan(&instanceType, &diskGB); err == nil {
+		if instanceType.Valid && instanceType.String != "" {
+			ws["instance_type"] = instanceType.String
+		} else {
+			ws["instance_type"] = nil
+		}
+		if diskGB.Valid && diskGB.Int64 != 0 {
+			ws["disk_gb"] = diskGB.Int64
+		} else {
+			ws["disk_gb"] = nil
+		}
+	}
+
 	c.JSON(http.StatusOK, ws)
 }

workspace-server/internal/handlers/workspace_crud.go

@@ -218,6 +218,78 @@ func (h *WorkspaceHandler) Update(c *gin.Context) {
 		}
 	}
 	needsRestart := false
+
+	// Per-workspace EC2 sizing override (canvas Config tab). Sizing is
+	// ORTHOGONAL to tier — tier is the ACCESS model (T4 = full root
+	// access), it does NOT drive sizing. The CP is the enforcement
+	// point (allowlist + [30,500] disk clamp); here we persist intent
+	// and reject obviously-bad input early. instance_type="" / disk_gb=0
+	// (or JSON null) clears the override → CP falls back to its default
+	// (t3.large / 50GB).
+	//
+	// Resize semantics: provision-time only. AWS cannot change instance
+	// type live (needs stop/start) and cannot shrink EBS in place. So a
+	// sizing change sets needs_restart=true — the new spec takes effect
+	// when the workspace is next (re)provisioned. We do NOT pretend it
+	// applied live.
+	if it, ok := body["instance_type"]; ok {
+		if it == nil {
+			if _, err := db.DB.ExecContext(ctx, `UPDATE workspaces SET instance_type = NULL, updated_at = now() WHERE id = $1`, id); err != nil {
+				log.Printf("Update instance_type (clear) error for %s: %v", id, err)
+			}
+			needsRestart = true
+		} else if s, isStr := it.(string); isStr {
+			if s != "" && !isAllowedWorkspaceInstanceType(s) {
+				c.JSON(http.StatusBadRequest, gin.H{
+					"error":   "unsupported instance_type",
+					"allowed": allowedWorkspaceInstanceTypes,
+				})
+				return
+			}
+			// Empty string also clears the override (store NULL).
+			var val interface{}
+			if s != "" {
+				val = s
+			}
+			if _, err := db.DB.ExecContext(ctx, `UPDATE workspaces SET instance_type = $2, updated_at = now() WHERE id = $1`, id, val); err != nil {
+				log.Printf("Update instance_type error for %s: %v", id, err)
+			}
+			needsRestart = true
+		} else {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "instance_type must be a string or null"})
+			return
+		}
+	}
+	if dg, ok := body["disk_gb"]; ok {
+		if dg == nil {
+			if _, err := db.DB.ExecContext(ctx, `UPDATE workspaces SET disk_gb = NULL, updated_at = now() WHERE id = $1`, id); err != nil {
+				log.Printf("Update disk_gb (clear) error for %s: %v", id, err)
+			}
+			needsRestart = true
+		} else if f, isNum := dg.(float64); isNum {
+			gb := int(f)
+			if gb == 0 {
+				if _, err := db.DB.ExecContext(ctx, `UPDATE workspaces SET disk_gb = NULL, updated_at = now() WHERE id = $1`, id); err != nil {
+					log.Printf("Update disk_gb (clear) error for %s: %v", id, err)
+				}
+			} else {
+				// Reject implausible values early; the CP still clamps
+				// to [30,500] authoritatively.
+				if gb < 0 || gb > 100000 {
+					c.JSON(http.StatusBadRequest, gin.H{"error": "disk_gb out of range"})
+					return
+				}
+				if _, err := db.DB.ExecContext(ctx, `UPDATE workspaces SET disk_gb = $2, updated_at = now() WHERE id = $1`, id, gb); err != nil {
+					log.Printf("Update disk_gb error for %s: %v", id, err)
+				}
+			}
+			needsRestart = true
+		} else {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "disk_gb must be a number or null"})
+			return
+		}
+	}
+
 	if wsDir, ok := body["workspace_dir"]; ok {
 		// ValidateWorkspaceDir was already called above before the existence check;
 		// the UPDATE itself is unconditional.
@@ -251,6 +323,35 @@ func (h *WorkspaceHandler) Update(c *gin.Context) {
 	c.JSON(http.StatusOK, resp)
 }
 
+// allowedWorkspaceInstanceTypes is the user-selectable workspace EC2
+// instance-type allowlist surfaced to the canvas Config tab and used
+// for early rejection in the PATCH handler. It MIRRORS the CP's
+// authoritative allowlist (controlplane internal/provisioner/ec2.go
+// workspaceInstanceTypeAllowlist) — the CP is the enforcement point;
+// this copy gives the user a fast, clear 400 instead of letting the
+// CP silently fall back to the default. Keep the two in sync: a value
+// here that the CP rejects would let the user save an override that
+// then silently no-ops at provision (exactly the failure mode this
+// feature is meant to avoid). Covered by a drift test.
+var allowedWorkspaceInstanceTypes = []string{
+	"c6i.xlarge",
+	"m6i.large",
+	"m6i.xlarge",
+	"t3.2xlarge",
+	"t3.large",
+	"t3.medium",
+	"t3.xlarge",
+}
+
+func isAllowedWorkspaceInstanceType(t string) bool {
+	for _, a := range allowedWorkspaceInstanceTypes {
+		if a == t {
+			return true
+		}
+	}
+	return false
+}
+
 // validateWorkspaceDir checks that a workspace_dir path is safe to bind-mount.
 func validateWorkspaceDir(dir string) error {
 	if !filepath.IsAbs(dir) {

workspace-server/internal/handlers/workspace_provision.go

@@ -2,6 +2,7 @@ package handlers
 
 import (
 	"context"
+	"database/sql"
 	"fmt"
 	"log"
 	"os"
@@ -259,17 +260,34 @@ func (h *WorkspaceHandler) buildProvisionerConfig(
 	// present) wins, matching the existing WorkspaceDir precedence.
 	workspacePath := payload.WorkspaceDir
 	workspaceAccess := payload.WorkspaceAccess
-	if (workspacePath == "" || workspaceAccess == "") && db.DB != nil {
-		var dbDir, dbAccess string
-		if err := db.DB.QueryRow(
-			`SELECT COALESCE(workspace_dir, ''), COALESCE(workspace_access, 'none') FROM workspaces WHERE id = $1`,
-			workspaceID,
-		).Scan(&dbDir, &dbAccess); err == nil {
-			if workspacePath == "" && dbDir != "" {
-				workspacePath = dbDir
-			}
-			if workspaceAccess == "" {
-				workspaceAccess = dbAccess
+	// Per-workspace sizing override (instance_type / disk_gb). Like
+	// workspace_dir/workspace_access these are DB-backed so a restart /
+	// reprovision picks up an override the user set via the canvas
+	// Config tab AFTER create. NULL/0 → leave the CP request fields
+	// empty so the CP applies its default (t3.large/50GB). Sizing is
+	// orthogonal to tier — see migration 20260515140000.
+	var instanceType string
+	var diskGB int32
+	{
+		var dbDir, dbAccess, dbInstanceType string
+		var dbDiskGB sql.NullInt64
+		if (workspacePath == "" || workspaceAccess == "") && db.DB != nil {
+			if err := db.DB.QueryRow(
+				`SELECT COALESCE(workspace_dir, ''), COALESCE(workspace_access, 'none'),
+				        COALESCE(instance_type, ''), disk_gb
+				   FROM workspaces WHERE id = $1`,
+				workspaceID,
+			).Scan(&dbDir, &dbAccess, &dbInstanceType, &dbDiskGB); err == nil {
+				if workspacePath == "" && dbDir != "" {
+					workspacePath = dbDir
+				}
+				if workspaceAccess == "" {
+					workspaceAccess = dbAccess
+				}
+				instanceType = dbInstanceType
+				if dbDiskGB.Valid {
+					diskGB = int32(dbDiskGB.Int64)
+				}
 			}
 		}
 	}
@@ -288,6 +306,8 @@ func (h *WorkspaceHandler) buildProvisionerConfig(
 		WorkspacePath:      workspacePath,
 		WorkspaceAccess:    workspaceAccess,
 		Tier:               payload.Tier,
+		InstanceType:       instanceType,
+		DiskGB:             diskGB,
 		Runtime:            payload.Runtime,
 		EnvVars:            envVars,
 		PlatformURL:        h.platformURL,

workspace-server/internal/handlers/workspace_sizing_allowlist_test.go

@@ -0,0 +1,77 @@
+package handlers
+
+import (
+	"sort"
+	"testing"
+)
+
+// TestWorkspaceInstanceTypeAllowlist_MirrorsCP pins the workspace-server
+// copy of the instance-type allowlist to the CP's authoritative list
+// (controlplane internal/provisioner/ec2.go workspaceInstanceTypeAllowlist).
+//
+// The CP is the enforcement point — it returns 400 on an unsupported
+// type. workspace-server keeps a copy ONLY so the user gets a fast,
+// clear rejection in the canvas Config tab instead of a round-trip to
+// the CP. If the two drift, a user could save an override that the CP
+// then silently falls back to the default for — exactly the
+// "told a change took when it didn't" failure this feature exists to
+// prevent. The two repos can't share a Go package (separate modules),
+// so this test hard-codes the expected set; updating it is the
+// deliberate checkpoint when the CP allowlist changes.
+//
+// CP source of truth (controlplane internal/provisioner/ec2.go):
+//
+//	var workspaceInstanceTypeAllowlist = map[string]struct{}{
+//	  "t3.medium", "t3.large", "t3.xlarge", "t3.2xlarge",
+//	  "m6i.large", "m6i.xlarge", "c6i.xlarge",
+//	}
+func TestWorkspaceInstanceTypeAllowlist_MirrorsCP(t *testing.T) {
+	cpAuthoritative := []string{
+		"c6i.xlarge",
+		"m6i.large",
+		"m6i.xlarge",
+		"t3.2xlarge",
+		"t3.large",
+		"t3.medium",
+		"t3.xlarge",
+	}
+
+	got := append([]string(nil), allowedWorkspaceInstanceTypes...)
+	sort.Strings(got)
+	want := append([]string(nil), cpAuthoritative...)
+	sort.Strings(want)
+
+	if len(got) != len(want) {
+		t.Fatalf("allowlist size drift: workspace-server has %d (%v), CP has %d (%v) — keep in sync with controlplane workspaceInstanceTypeAllowlist",
+			len(got), got, len(want), want)
+	}
+	for i := range got {
+		if got[i] != want[i] {
+			t.Fatalf("allowlist drift at %d: workspace-server=%q CP=%q\nfull ws=%v\nfull CP=%v",
+				i, got[i], want[i], got, want)
+		}
+	}
+}
+
+// TestIsAllowedWorkspaceInstanceType pins the membership helper used by
+// the PATCH handler's early-reject path.
+func TestIsAllowedWorkspaceInstanceType(t *testing.T) {
+	if !isAllowedWorkspaceInstanceType("t3.large") {
+		t.Error("t3.large (the default) must be allowed")
+	}
+	if !isAllowedWorkspaceInstanceType("t3.medium") {
+		t.Error("t3.medium (floor) must be allowed")
+	}
+	if !isAllowedWorkspaceInstanceType("t3.2xlarge") {
+		t.Error("t3.2xlarge (ceiling) must be allowed")
+	}
+	if isAllowedWorkspaceInstanceType("p4d.24xlarge") {
+		t.Error("p4d.24xlarge (off allowlist, GPU/cost blowout) must NOT be allowed")
+	}
+	if isAllowedWorkspaceInstanceType("'; DROP TABLE workspaces;--") {
+		t.Error("SQL-injection-shaped garbage must NOT be allowed")
+	}
+	if isAllowedWorkspaceInstanceType("") {
+		t.Error("empty string is not a valid instance type for the membership check")
+	}
+}

workspace-server/internal/handlers/workspace_sizing_integration_test.go

@@ -0,0 +1,168 @@
+//go:build integration
+// +build integration
+
+// workspace_sizing_integration_test.go — REAL Postgres integration
+// test for the per-workspace EC2 sizing override round-trip.
+//
+// Run with:
+//
+//	INTEGRATION_DB_URL="postgres://dev:dev@localhost:5432/molecule?sslmode=disable" \
+//	  go test -tags=integration ./internal/handlers/ -run Integration_WorkspaceSizing -v
+//
+// CI: piggybacks on handlers-postgres-integration.yml (path filter
+// covers workspace-server/internal/handlers/** and migrations/**).
+//
+// Why this is NOT a sqlmock test
+// ------------------------------
+// sqlmock pins query SHAPE, not behaviour. Only a real Postgres with
+// migration 20260515140000 applied can confirm:
+//
+//   - The instance_type/disk_gb columns actually exist and accept the
+//     values the canvas Config tab writes.
+//   - A persisted override is read back by the SAME SELECT
+//     buildProvisionerConfig issues on the (re)provision path — i.e.
+//     the override actually reaches the CP request, not a silent drop
+//     (feedback_no_proxy_e2e_claims: prove the literal path).
+//   - The "no override" default leaves the columns NULL so the CP
+//     applies its own default (t3.large / 50GB).
+//
+// Per feedback_mandatory_local_e2e_before_ship: ship-mode requires the
+// round-trip exercised against a real Postgres before the PR merges.
+
+package handlers
+
+import (
+	"context"
+	"database/sql"
+	"testing"
+
+	"github.com/google/uuid"
+	_ "github.com/lib/pq"
+)
+
+func integrationDB_WorkspaceSizing(t *testing.T) *sql.DB {
+	t.Helper()
+	conn := integrationDB_WorkspaceCreateName(t) // reuses INTEGRATION_DB_URL + skip
+	// Ensure the sizing columns exist (idempotent — the migration is
+	// the dev/CI default; this covers a pre-2026-05-15 snapshot DB).
+	if _, err := conn.ExecContext(context.Background(), `
+		ALTER TABLE workspaces
+		  ADD COLUMN IF NOT EXISTS instance_type TEXT,
+		  ADD COLUMN IF NOT EXISTS disk_gb       INTEGER
+	`); err != nil {
+		t.Fatalf("ensure sizing columns: %v", err)
+	}
+	return conn
+}
+
+// TestIntegration_WorkspaceSizing_OverrideRoundTrips proves the full
+// persisted path: an override written to the workspaces row (what the
+// PATCH /workspaces/:id handler does) is read back exactly the way
+// buildProvisionerConfig reads it on the (re)provision path.
+func TestIntegration_WorkspaceSizing_OverrideRoundTrips(t *testing.T) {
+	conn := integrationDB_WorkspaceSizing(t)
+	ctx := context.Background()
+	const namePrefix = "sizing-itest-"
+	t.Cleanup(func() { cleanupTestRows(t, conn, namePrefix) })
+
+	id := uuid.NewString()
+	if _, err := conn.ExecContext(ctx,
+		`INSERT INTO workspaces (id, name, tier, status) VALUES ($1, $2, 4, 'online')`,
+		id, namePrefix+"override"); err != nil {
+		t.Fatalf("insert: %v", err)
+	}
+
+	// Simulate PATCH /workspaces/:id { instance_type, disk_gb }.
+	if _, err := conn.ExecContext(ctx,
+		`UPDATE workspaces SET instance_type = $2, disk_gb = $3 WHERE id = $1`,
+		id, "t3.xlarge", 120); err != nil {
+		t.Fatalf("patch sizing: %v", err)
+	}
+
+	// Read it back with the EXACT projection buildProvisionerConfig
+	// uses (workspace_provision.go) so this test fails if that query
+	// drifts away from the columns.
+	var dbDir, dbAccess, dbInstanceType string
+	var dbDiskGB sql.NullInt64
+	if err := conn.QueryRowContext(ctx,
+		`SELECT COALESCE(workspace_dir, ''), COALESCE(workspace_access, 'none'),
+		        COALESCE(instance_type, ''), disk_gb
+		   FROM workspaces WHERE id = $1`, id,
+	).Scan(&dbDir, &dbAccess, &dbInstanceType, &dbDiskGB); err != nil {
+		t.Fatalf("read back: %v", err)
+	}
+
+	if dbInstanceType != "t3.xlarge" {
+		t.Errorf("instance_type round-trip: got %q, want t3.xlarge", dbInstanceType)
+	}
+	if !dbDiskGB.Valid || dbDiskGB.Int64 != 120 {
+		t.Errorf("disk_gb round-trip: got %v, want 120", dbDiskGB)
+	}
+}
+
+// TestIntegration_WorkspaceSizing_DefaultIsNull proves the no-override
+// path leaves both columns NULL, so buildProvisionerConfig sends empty
+// fields and the CP applies its default (t3.large / 50GB) — never a
+// stale or zero value misread as an override.
+func TestIntegration_WorkspaceSizing_DefaultIsNull(t *testing.T) {
+	conn := integrationDB_WorkspaceSizing(t)
+	ctx := context.Background()
+	const namePrefix = "sizing-itest-"
+	t.Cleanup(func() { cleanupTestRows(t, conn, namePrefix) })
+
+	id := uuid.NewString()
+	if _, err := conn.ExecContext(ctx,
+		`INSERT INTO workspaces (id, name, tier, status) VALUES ($1, $2, 1, 'online')`,
+		id, namePrefix+"default"); err != nil {
+		t.Fatalf("insert: %v", err)
+	}
+
+	var instanceType sql.NullString
+	var diskGB sql.NullInt64
+	if err := conn.QueryRowContext(ctx,
+		`SELECT instance_type, disk_gb FROM workspaces WHERE id = $1`, id,
+	).Scan(&instanceType, &diskGB); err != nil {
+		t.Fatalf("read: %v", err)
+	}
+	if instanceType.Valid {
+		t.Errorf("fresh workspace instance_type should be NULL, got %q", instanceType.String)
+	}
+	if diskGB.Valid {
+		t.Errorf("fresh workspace disk_gb should be NULL, got %d", diskGB.Int64)
+	}
+}
+
+// TestIntegration_WorkspaceSizing_ClearReverts proves clearing the
+// override (PATCH with null) returns the workspace to the CP default
+// rather than pinning a previous value — the override is genuinely
+// user-reversible.
+func TestIntegration_WorkspaceSizing_ClearReverts(t *testing.T) {
+	conn := integrationDB_WorkspaceSizing(t)
+	ctx := context.Background()
+	const namePrefix = "sizing-itest-"
+	t.Cleanup(func() { cleanupTestRows(t, conn, namePrefix) })
+
+	id := uuid.NewString()
+	if _, err := conn.ExecContext(ctx,
+		`INSERT INTO workspaces (id, name, tier, status, instance_type, disk_gb)
+		 VALUES ($1, $2, 4, 'online', 't3.2xlarge', 200)`,
+		id, namePrefix+"clear"); err != nil {
+		t.Fatalf("insert: %v", err)
+	}
+	// Simulate PATCH clearing both (handler maps "" / 0 / null → NULL).
+	if _, err := conn.ExecContext(ctx,
+		`UPDATE workspaces SET instance_type = NULL, disk_gb = NULL WHERE id = $1`, id); err != nil {
+		t.Fatalf("clear: %v", err)
+	}
+
+	var instanceType sql.NullString
+	var diskGB sql.NullInt64
+	if err := conn.QueryRowContext(ctx,
+		`SELECT instance_type, disk_gb FROM workspaces WHERE id = $1`, id,
+	).Scan(&instanceType, &diskGB); err != nil {
+		t.Fatalf("read: %v", err)
+	}
+	if instanceType.Valid || diskGB.Valid {
+		t.Errorf("after clear, expected both NULL; got instance_type=%v disk_gb=%v", instanceType, diskGB)
+	}
+}

workspace-server/internal/provisioner/cp_provisioner.go

@@ -152,12 +152,20 @@ func (p *CPProvisioner) adminAuthHeaders(req *http.Request) {
 }
 
 type cpProvisionRequest struct {
-	OrgID       string            `json:"org_id"`
-	WorkspaceID string            `json:"workspace_id"`
-	Runtime     string            `json:"runtime"`
-	Tier        int               `json:"tier"`
-	PlatformURL string            `json:"platform_url"`
-	Env         map[string]string `json:"env"`
+	OrgID       string `json:"org_id"`
+	WorkspaceID string `json:"workspace_id"`
+	Runtime     string `json:"runtime"`
+	// Tier is the ACCESS model only (T4 = full root access). It does
+	// NOT drive sizing — see InstanceType / DiskGB.
+	Tier int `json:"tier"`
+	// InstanceType + DiskGB are the optional per-workspace sizing
+	// override. Omitted (empty / 0) → CP applies its default
+	// (t3.large / 50GB). The CP validates instance_type against its
+	// allowlist and returns 400 on an unsupported value.
+	InstanceType string            `json:"instance_type,omitempty"`
+	DiskGB       int32             `json:"disk_gb,omitempty"`
+	PlatformURL  string            `json:"platform_url"`
+	Env          map[string]string `json:"env"`
 	// ConfigFiles are template + generated config files to write into the
 	// EC2 instance's /configs directory. OFFSEC-010: collected by
 	// collectCPConfigFiles which rejects symlinks and non-regular files
@@ -197,13 +205,15 @@ func (p *CPProvisioner) Start(ctx context.Context, cfg WorkspaceConfig) (string,
 	}
 
 	req := cpProvisionRequest{
-		OrgID:       p.orgID,
-		WorkspaceID: cfg.WorkspaceID,
-		Runtime:     cfg.Runtime,
-		Tier:        cfg.Tier,
-		PlatformURL: cfg.PlatformURL,
-		Env:         env,
-		ConfigFiles: configFiles,
+		OrgID:        p.orgID,
+		WorkspaceID:  cfg.WorkspaceID,
+		Runtime:      cfg.Runtime,
+		Tier:         cfg.Tier,
+		InstanceType: cfg.InstanceType,
+		DiskGB:       cfg.DiskGB,
+		PlatformURL:  cfg.PlatformURL,
+		Env:          env,
+		ConfigFiles:  configFiles,
 	}
 
 	body, err := json.Marshal(req)

workspace-server/internal/provisioner/cp_provisioner_test.go

@@ -1062,3 +1062,77 @@ func TestCollectCPConfigFiles_RejectsRootSymlink(t *testing.T) {
 		t.Errorf("expected symlink-related error, got: %v", err)
 	}
 }
+
+// TestStart_ForwardsSizingOverride proves the per-workspace sizing
+// override (instance_type + disk_gb) actually reaches the CP provision
+// request — not a silent drop. This is the workspace-server half of
+// the tier↔sizing decoupling: sizing is independent of Tier and is
+// plumbed canvas → workspace-server → CP.
+func TestStart_ForwardsSizingOverride(t *testing.T) {
+	var got cpProvisionRequest
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_ = json.NewDecoder(r.Body).Decode(&got)
+		w.WriteHeader(http.StatusCreated)
+		_, _ = io.WriteString(w, `{"instance_id":"i-size","state":"pending"}`)
+	}))
+	defer srv.Close()
+
+	p := &CPProvisioner{
+		baseURL:      srv.URL,
+		orgID:        "org-1",
+		sharedSecret: "s3cret",
+		httpClient:   srv.Client(),
+	}
+
+	if _, err := p.Start(context.Background(), WorkspaceConfig{
+		WorkspaceID:  "ws-size",
+		Runtime:      "claude-code",
+		Tier:         4, // access tier — must NOT influence sizing
+		InstanceType: "t3.xlarge",
+		DiskGB:       120,
+		PlatformURL:  "http://tenant",
+	}); err != nil {
+		t.Fatalf("Start: %v", err)
+	}
+
+	if got.InstanceType != "t3.xlarge" {
+		t.Errorf("CP request instance_type = %q, want t3.xlarge (override dropped)", got.InstanceType)
+	}
+	if got.DiskGB != 120 {
+		t.Errorf("CP request disk_gb = %d, want 120 (override dropped)", got.DiskGB)
+	}
+	// Tier still forwarded (access model), independently of sizing.
+	if got.Tier != 4 {
+		t.Errorf("CP request tier = %d, want 4 (access model must still forward)", got.Tier)
+	}
+}
+
+// TestStart_NoSizingOverrideOmitsFields proves the default path sends
+// NO instance_type / disk_gb so the CP applies its own default
+// (t3.large / 50GB) rather than receiving a zero-value that could be
+// misread.
+func TestStart_NoSizingOverrideOmitsFields(t *testing.T) {
+	var rawBody []byte
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		rawBody, _ = io.ReadAll(r.Body)
+		w.WriteHeader(http.StatusCreated)
+		_, _ = io.WriteString(w, `{"instance_id":"i-def","state":"pending"}`)
+	}))
+	defer srv.Close()
+
+	p := &CPProvisioner{
+		baseURL: srv.URL, orgID: "org-1", sharedSecret: "s", httpClient: srv.Client(),
+	}
+	if _, err := p.Start(context.Background(), WorkspaceConfig{
+		WorkspaceID: "ws-def", Runtime: "python", Tier: 1, PlatformURL: "http://t",
+	}); err != nil {
+		t.Fatalf("Start: %v", err)
+	}
+	// omitempty on InstanceType/DiskGB → absent from the JSON entirely.
+	if strings.Contains(string(rawBody), "instance_type") {
+		t.Errorf("default request leaked instance_type into body: %s", rawBody)
+	}
+	if strings.Contains(string(rawBody), "disk_gb") {
+		t.Errorf("default request leaked disk_gb into body: %s", rawBody)
+	}
+}

workspace-server/internal/provisioner/provisioner.go

@@ -78,12 +78,21 @@ const (
 
 // WorkspaceConfig holds the parameters needed to provision a workspace container.
 type WorkspaceConfig struct {
-	WorkspaceID        string
-	TemplatePath       string            // Host path to template dir to copy from (e.g. claude-code-default/)
-	ConfigFiles        map[string][]byte // Generated config files to write into /configs volume
-	PluginsPath        string            // Host path to plugins directory (mounted at /plugins)
-	WorkspacePath      string            // Host path to bind-mount as /workspace (if empty, uses Docker named volume)
-	Tier               int
+	WorkspaceID   string
+	TemplatePath  string            // Host path to template dir to copy from (e.g. claude-code-default/)
+	ConfigFiles   map[string][]byte // Generated config files to write into /configs volume
+	PluginsPath   string            // Host path to plugins directory (mounted at /plugins)
+	WorkspacePath string            // Host path to bind-mount as /workspace (if empty, uses Docker named volume)
+	Tier          int
+	// InstanceType + DiskGB are the optional per-workspace,
+	// user-configurable EC2 sizing override (canvas Config tab,
+	// DB-backed). Empty / 0 = "use the CP default" (t3.large / 50GB).
+	// Decoupled from Tier by design — Tier is the ACCESS model only
+	// (T4 = full root access), it does NOT drive sizing. Only the
+	// SaaS CP provisioner path consumes these; the local Docker
+	// provisioner ignores them (sizing is an EC2 concept).
+	InstanceType       string
+	DiskGB             int32
 	Runtime            string            // "langgraph" (default) or "claude-code", "codex", "ollama", "custom"
 	EnvVars            map[string]string // Additional env vars (API keys, etc.)
 	PlatformURL        string

workspace-server/migrations/20260515140000_workspace_sizing_override.down.sql

@@ -0,0 +1,3 @@
+ALTER TABLE workspaces
+  DROP COLUMN IF EXISTS instance_type,
+  DROP COLUMN IF EXISTS disk_gb;

workspace-server/migrations/20260515140000_workspace_sizing_override.up.sql

@@ -0,0 +1,23 @@
+-- Per-workspace, user-configurable EC2 sizing override.
+--
+-- Sizing is ORTHOGONAL to the access tier. The access `tier` column
+-- (T1..T4; T4 = full root-level access to the dedicated EC2) controls
+-- how much of the box the agent can touch — it has NOTHING to do with
+-- how big the box is. Sizing used to be wrongly derived from tier in
+-- the control-plane provisioner (workspaceTierResources); that coupling
+-- is removed (controlplane PR #173). These columns carry the optional
+-- user override the canvas Config tab sets.
+--
+-- NULL / 0 = "no override — use the CP default" (t3.large + 50GB).
+-- The CP clamps instance_type to its allowlist (t3.medium..t3.2xlarge)
+-- and disk_gb to [30, 500]; these columns are the persisted intent,
+-- the CP is the enforcement point.
+--
+-- Resize semantics: provision-time only. AWS cannot change instance
+-- type live (needs stop/start) and cannot shrink EBS in place — the
+-- new spec takes effect on the next provision/restart, surfaced in the
+-- canvas Config copy.
+
+ALTER TABLE workspaces
+  ADD COLUMN IF NOT EXISTS instance_type TEXT,
+  ADD COLUMN IF NOT EXISTS disk_gb       INTEGER;