diff --git a/docs/memory-plugins/CHANGELOG.md b/docs/memory-plugins/CHANGELOG.md
new file mode 100644
index 00000000..a811620b
--- /dev/null
+++ b/docs/memory-plugins/CHANGELOG.md
@@ -0,0 +1,113 @@
+# Memory Plugin Contract — Changelog
+
+Every breaking or operationally-relevant change to the v1 plugin
+contract or the workspace-server-side wiring lands here. Plugin
+authors should subscribe to PRs touching this file.
+
+## [Unreleased] — fixup wave 1 (post-RFC-#2728 self-review)
+
+A self-review of the initial 11-PR rollout (PRs #2729-#2742) flagged
+two correctness bugs and three operational hazards. This wave fixes
+all of them. Order matches operator-impact severity.
+
+### Critical: backfill idempotency via `MemoryWrite.id` (#2744)
+
+**The bug.** The backfill CLI claimed idempotent on re-run, but
+`gen_random_uuid()` in the plugin's INSERT meant every retry created
+a fresh row. Operators retrying a failed `-apply` would silently
+double their memory count.
+
+**The fix.** Optional `id` field on `MemoryWrite`. When supplied,
+plugins MUST upsert. The backfill now forwards `agent_memories.id`
+to `MemoryWrite.id`, so retries update in place.
+
+**Plugin author action.** If your plugin uses
+`INSERT INTO ... DEFAULT gen_random_uuid()`, switch to
+`INSERT ... ON CONFLICT (id) DO UPDATE` when `id` is set. The wire
+contract is forward-compatible — plugins that ignore the field still
+work for production agent commits (which leave `id` empty), but they
+will silently corrupt backfill retries.
+
+### Critical: `memory-backfill -verify` mode (#2747)
+
+**The miss.** The original PR-7 task spec called for a parity-check
+mode but it never landed. Operators had no way to confirm a
+migration succeeded short of "no errors logged."
+
+**The fix.** New `-verify` flag samples N workspaces, queries
+`agent_memories` direct, runs an equivalent plugin search via the
+namespace resolver, multiset-compares contents. Reports mismatches
+to stdout and exits non-zero so CI can gate the cutover.
+
+```bash
+memory-backfill -verify                        # default sample 50
+memory-backfill -verify -verify-sample=200     # bigger
+memory-backfill -verify -workspace=<uuid>      # one workspace
+```
+
+### Important: `expires_at` validation (#2746)
+
+**The bug.** `commit_memory_v2` silently dropped malformed
+`expires_at` strings. Agent passes `expires_at: "tomorrow"`, gets a
+200, memory has no TTL — agent thinks it set a TTL, didn't.
+
+**The fix.** Returns
+`fmt.Errorf("invalid expires_at: must be RFC3339")` on parse
+failure. Plugin is not called in this case.
+
+**Plugin author action.** None — this is a workspace-server-side
+fix. But: if your plugin advertises the `ttl` capability, make sure
+you actually evict expired rows on read (not just on a janitor cron
+that runs once a day). The harness in `testing-your-plugin.md` has
+a TTL-eviction test you should run.
+
+### Important: audit log JSON via `json.Marshal` (#2746)
+
+**The bug.** `auditOrgWrite` built `activity_logs.metadata` via
+`fmt.Sprintf` with `%q`. For ASCII (today's UUID + hex digest) this
+coincidentally produces valid JSON; for unicode or control bytes it
+silently produces non-JSON.
+
+**The fix.** Replaced with `json.Marshal(map[string]string{...})`.
+Same wire shape today, won't regress when metadata grows.
+
+**Plugin author action.** None — workspace-server-internal.
+
+### Operator action: staging verification (#292)
+
+**Status.** Tracked as task #292. PR-merged ≠ verified. Operator
+must:
+1. Provision a staging tenant, set `MEMORY_PLUGIN_URL`
+2. Run real `commit_memory_v2` from a workspace
+3. `memory-backfill -dry-run` against staging data
+4. `memory-backfill -apply`, then `-verify`
+5. Set `MEMORY_V2_CUTOVER=true`, verify admin export still works
+6. Run a legacy `commit_memory` from a workspace, verify it lands
+   in plugin storage via the PR-6 shim
+
+### Other follow-ups still open
+
+- **#289**: admin export O(workspaces) → O(namespaces) — N+1 pattern
+  in `exportViaPlugin` (1000-workspace tenants run 1000× resolver
+  CTEs + 1000× plugin searches today).
+- **#291**: workspace deletion must call `DELETE
+  /v1/namespaces/{name}` — orphans accumulate today.
+- **#293**: real-subprocess boot E2E — current PR-11 is integration
+  (httptest + sqlmock), not E2E.
+
+These are tracked but deferred; they're operationally annoying, not
+incident-shaped.
+
+## [v1.0.0] — initial release (RFC #2728, PRs #2729-#2742)
+
+Initial plugin contract + 11-PR rollout. See
+[issue #2728](https://github.com/Molecule-AI/molecule-core/issues/2728)
+for the full RFC.
+
+Endpoints: `/v1/health`, `/v1/namespaces/{name}` (PUT/PATCH/DELETE),
+`/v1/namespaces/{name}/memories` (POST), `/v1/search` (POST),
+`/v1/memories/{id}` (DELETE).
+
+Capabilities: `embedding`, `fts`, `ttl`, `pin`, `propagation`.
+
+Operator runbook: see [README.md § Replacing the built-in plugin](README.md#replacing-the-built-in-plugin).
diff --git a/docs/memory-plugins/README.md b/docs/memory-plugins/README.md
index f790787e..c950acd1 100644
--- a/docs/memory-plugins/README.md
+++ b/docs/memory-plugins/README.md
@@ -54,6 +54,26 @@ security perimeter:
   defines
 - `/v1/health` reporting your supported capabilities (see below)
 - Idempotency on namespace upsert (PUT semantics, not POST)
+- Idempotency on memory commit when `MemoryWrite.id` is supplied
+  (see "Memory idempotency" below)
+
+## Memory idempotency
+
+`MemoryWrite.id` is optional. Two contracts to honor:
+
+| Caller passes | Plugin MUST |
+|---|---|
+| `id` omitted | Generate a fresh UUID, return it in the response |
+| `id` set | Upsert keyed on this id — if a row with that id already exists, UPDATE it in place rather than inserting a duplicate |
+
+The backfill CLI (`memory-backfill`) relies on the upsert behavior
+so retries don't duplicate rows. Production agent commits leave `id`
+empty and rely on the plugin's UUID generator — the hot path is
+unchanged.
+
+The built-in postgres plugin implements this with `INSERT ... ON
+CONFLICT (id) DO UPDATE`. A vector-DB plugin (e.g., Pinecone) would
+use the database's native upsert primitive on the same id.
 
 ## Capability negotiation
 
@@ -99,16 +119,51 @@ network. workspace-server is the only sanctioned client.
 
 ## Replacing the built-in plugin
 
-1. Apply [PR-7's backfill](../../workspace-server/cmd/memory-backfill/) to
-   copy `agent_memories` into your plugin's storage.
-2. Stop workspace-server, point `MEMORY_PLUGIN_URL` at your plugin,
-   restart.
-3. Existing data in the postgres plugin's tables is **not auto-
-   dropped** — that's a deliberate safety property. Operator drops
-   manually after they're confident they don't want to switch back.
+This is the canonical operator runbook for swapping the default
+plugin out. The same sequence applies whether you're swapping for
+another postgres plugin variant, Pinecone, Letta, or a custom
+implementation.
 
-If you switch back later, the old postgres tables come back into use
-(no data loss).
+1. **Stand up the new plugin.** Deploy the binary/container, confirm
+   it boots, confirm `/v1/health` returns `ok` with the capability
+   list you expect.
+
+2. **Run the backfill in dry-run mode** to scope the migration:
+   ```bash
+   DATABASE_URL=postgres://... \
+   MEMORY_PLUGIN_URL=http://your-plugin:9100 \
+   memory-backfill -dry-run
+   ```
+   Reports row count + namespace mapping per workspace, no writes.
+
+3. **Apply the backfill:**
+   ```bash
+   memory-backfill -apply
+   ```
+   Idempotent on retry — the backfill passes each `agent_memories.id`
+   to `MemoryWrite.id`, so partial-then-full re-runs upsert in place.
+
+4. **Verify parity** before flipping the cutover flag:
+   ```bash
+   memory-backfill -verify -verify-sample=200
+   ```
+   Random-samples N workspaces, diffs `agent_memories` direct query
+   against plugin search via the workspace's readable namespaces.
+   Reports mismatches and exits non-zero if any are found — wire
+   into your CI to gate the cutover.
+
+5. **Flip the cutover flag.** Set `MEMORY_V2_CUTOVER=true` on
+   workspace-server and restart. Admin export/import now route
+   through the plugin; legacy `agent_memories` becomes read-only.
+
+6. **Existing data in the old plugin's tables is NOT auto-dropped.**
+   Deliberate safety property — operator drops manually after the
+   ~60-day grace window. If you switch back later, old data comes
+   back into use (no loss).
+
+If `-verify` reports mismatches, do NOT set `MEMORY_V2_CUTOVER` —
+inspect the output, re-run `-apply` to backfill missing rows (it
+upserts, so this is safe), and re-verify.
 
 ## Worked examples
 
@@ -130,6 +185,7 @@ Write a fresh plugin if:
 
 ## See also
 
+- [`CHANGELOG.md`](CHANGELOG.md) — contract revisions and fixup waves
 - RFC #2728 — design rationale
 - [`cmd/memory-plugin-postgres/`](../../workspace-server/cmd/memory-plugin-postgres/) — reference implementation
 - [`docs/api-protocol/memory-plugin-v1.yaml`](../api-protocol/memory-plugin-v1.yaml) — full OpenAPI spec
diff --git a/docs/memory-plugins/pinecone-example/README.md b/docs/memory-plugins/pinecone-example/README.md
index ddc6ead5..9a76cd55 100644
--- a/docs/memory-plugins/pinecone-example/README.md
+++ b/docs/memory-plugins/pinecone-example/README.md
@@ -29,7 +29,8 @@ are different:
 | Contract field | Pinecone shape |
 |---|---|
 | `namespace` | `namespace` (Pinecone's first-class concept) |
-| `id` | `id` |
+| `id` (caller-supplied) | `id` (Pinecone vector id; plugin upserts on this) |
+| `id` (omitted) | Plugin generates `uuid.NewString()` before upsert |
 | `content` | metadata.text |
 | `embedding` | `values` |
 | `kind` / `source` / `pin` / `expires_at` | `metadata.{kind, source, pin, expires_at}` |
@@ -38,6 +39,12 @@ are different:
 The contract's `expires_at` becomes a metadata field; a separate
 janitor cron periodically queries `expires_at < now` and deletes.
 
+Pinecone's native upsert is the right fit for the idempotency-key
+contract: passing the same `id` twice updates in place. So a
+Pinecone plugin gets idempotent backfill retries "for free" if it
+just forwards `MemoryWrite.id` (or its generated UUID) to the
+upsert call.
+
 ## Skeleton
 
 ```go
@@ -103,6 +110,9 @@ A production-ready Pinecone plugin would add:
 - **Connection pooling**: keep one Pinecone client alive across requests
 - **Retry + circuit breaker**: Pinecone occasionally returns 5xx
 - **Metrics**: latency histograms per endpoint, write/read counters
+- **Idempotency-key handling**: when `MemoryWrite.id` is supplied,
+  forward it as the Pinecone vector id verbatim; otherwise generate
+  one. Pinecone's `Upsert` is naturally idempotent on id match.
 
 But the mapping above is the load-bearing part — the rest is
 operational hardening, not contract-specific.
diff --git a/docs/memory-plugins/testing-your-plugin.md b/docs/memory-plugins/testing-your-plugin.md
index a858c4a3..0b7df8e6 100644
--- a/docs/memory-plugins/testing-your-plugin.md
+++ b/docs/memory-plugins/testing-your-plugin.md
@@ -77,6 +77,68 @@ func TestMyPlugin_FullRoundTrip(t *testing.T) {
 }
 ```
 
+## Testing idempotency
+
+The contract requires that `MemoryWrite.id`, when supplied, behaves
+as an upsert key. The backfill CLI relies on this — without it,
+operator retries silently duplicate every memory.
+
+```go
+func TestMyPlugin_IDIsIdempotencyKey(t *testing.T) {
+    pluginURL := startMyPlugin(t)
+    cl := mclient.New(mclient.Config{BaseURL: pluginURL})
+    if _, err := cl.UpsertNamespace(context.Background(), "workspace:test-1",
+        contract.NamespaceUpsert{Kind: contract.NamespaceKindWorkspace}); err != nil {
+        t.Fatal(err)
+    }
+
+    fixedID := "11111111-2222-3333-4444-555555555555"
+
+    // First write with a specific id.
+    resp1, err := cl.CommitMemory(context.Background(), "workspace:test-1",
+        contract.MemoryWrite{
+            ID:      fixedID,
+            Content: "first version",
+            Kind:    contract.MemoryKindFact,
+            Source:  contract.MemorySourceAgent,
+        })
+    if err != nil {
+        t.Fatalf("first commit: %v", err)
+    }
+    if resp1.ID != fixedID {
+        t.Errorf("plugin must echo the supplied id, got %q", resp1.ID)
+    }
+
+    // Second write with the same id — must update, not insert.
+    if _, err := cl.CommitMemory(context.Background(), "workspace:test-1",
+        contract.MemoryWrite{
+            ID:      fixedID,
+            Content: "second version (updated)",
+            Kind:    contract.MemoryKindFact,
+            Source:  contract.MemorySourceAgent,
+        }); err != nil {
+        t.Fatalf("second commit: %v", err)
+    }
+
+    // Search must return exactly one row, with the updated content.
+    sresp, _ := cl.Search(context.Background(), contract.SearchRequest{
+        Namespaces: []string{"workspace:test-1"},
+    })
+    matches := 0
+    for _, m := range sresp.Memories {
+        if m.ID == fixedID {
+            matches++
+            if m.Content != "second version (updated)" {
+                t.Errorf("upsert didn't update content: got %q", m.Content)
+            }
+        }
+    }
+    if matches != 1 {
+        t.Errorf("upsert produced %d rows for id=%s, want 1", matches, fixedID)
+    }
+}
+```
+
 ## What the harness does NOT cover
 
 - **Capability accuracy**: if you list `embedding` you must actually
@@ -88,6 +150,13 @@ func TestMyPlugin_FullRoundTrip(t *testing.T) {
   no IDs collide.
 - **Recovery**: kill your plugin's storage backend, send a request,
   assert your plugin returns 503 (not 200 with stale data).
+- **Backfill compatibility**: run the operator backfill against your
+  plugin twice in a row (`memory-backfill -apply`); assert the row
+  count doesn't double. The idempotency test above verifies the unit
+  contract; this checks the operational integration.
+- **Verify-mode parity**: after a backfill, run `memory-backfill
+  -verify`; assert it reports zero mismatches against
+  `agent_memories`.
 
 ## Smoke test against workspace-server