refactor(review): address PR #185 review (lease leak, tests, changelog, jsonb seam)

8-point multi-aspect review of the batch PR; security/regressions were clean.

1. Lease leak: the #180 reorder moved `toolsFor` (which leases external MCP
   clients, refCount+1) ahead of buildSystemPrompt + forUser, but the only
   release (closeExternalClients) was bound to the streamText callbacks. A throw
   in between leaked the lease (refCount stuck, undici sockets held until
   restart). Define closeExternalClients right after the lease and wrap
   buildSystemPrompt+forUser in try/catch that closes-then-rethrows.
2. Cover the patch_node/delete_node dup-id refusal (#159 #6): extract the guard
   into a pure `assertUnambiguousMatch` (node-ops) and unit-test 0/1/>1.
3. Regress the body-before-title order (#159 #10): mock-HTTP test (collab fails
   fast against a server with no WS upgrade) asserts /pages/update (title) is
   NEVER posted when the body write fails — for updatePage AND updatePageJson.
4. CHANGELOG [Unreleased]: #180, #168 (Added); #163 (Fixed).
5. Add the missing en-US i18n keys (Back to references / {{label}}).
6. Drop the duplicate content/empty/blank cases in ai-chat.prompt.spec.ts (they
   repeat the buildMcpToolingBlock unit tests); keep only sandwich placement +
   both-safety-copies.
7. CI Postgres pg16 -> pg18 (match docker-compose).
8. jsonb decode seam: shared `parseJsonbValue(value, guard)` in database/utils.ts
   holds the legacy double-encoding self-heal in one place; parseToolAllowlist /
   parseModelConfig keep only a type-guard.

Verified: server build + 124 unit + 15 integration; mcp 311; prettier clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/server/src/database/repos/ai-agent-roles/ai-agent-roles.repo.ts

@@ -1,7 +1,7 @@
 import { Injectable } from '@nestjs/common';
 import { InjectKysely } from 'nestjs-kysely';
 import { KyselyDB, KyselyTransaction } from '../../types/kysely.types';
-import { dbOrTx, jsonbBind } from '../../utils';
+import { dbOrTx, jsonbBind, parseJsonbValue } from '../../utils';
 import { AiAgentRole } from '@docmost/db/types/entity.types';
 
 /** The jsonb shape persisted in `model_config` (loosely typed for the column). */
@@ -183,17 +183,13 @@ export class AiAgentRoleRepo {
 export function parseModelConfig(
   value: unknown,
 ): Record<string, unknown> | null {
-  let v: unknown = value;
-  if (typeof v === 'string') {
-    try {
-      v = JSON.parse(v); // legacy double-encoded read
-    } catch {
-      return null;
-    }
-  }
-  return v !== null && typeof v === 'object' && !Array.isArray(v)
-    ? (v as Record<string, unknown>)
-    : null;
+  // Shape guard only; the legacy double-encoding self-heal lives in
+  // parseJsonbValue (database/utils.ts).
+  return parseJsonbValue(
+    value,
+    (v): v is Record<string, unknown> =>
+      v !== null && typeof v === 'object' && !Array.isArray(v),
+  );
 }
 
 /** Normalize a DB row so `modelConfig` is always an object or null. The cast

apps/server/src/database/repos/ai-chat/ai-mcp-server.repo.ts

@@ -1,7 +1,7 @@
 import { Injectable, Logger } from '@nestjs/common';
 import { InjectKysely } from 'nestjs-kysely';
 import { KyselyDB, KyselyTransaction } from '../../types/kysely.types';
-import { dbOrTx, jsonbBind } from '../../utils';
+import { dbOrTx, jsonbBind, parseJsonbValue } from '../../utils';
 import { AiMcpServer } from '@docmost/db/types/entity.types';
 
 const logger = new Logger('AiMcpServerRepo');
@@ -161,17 +161,13 @@ export function blankToNull(value: string | null | undefined): string | null {
  * array with a non-string element all become null (unrestricted).
  */
 export function parseToolAllowlist(value: unknown): string[] | null {
-  let v: unknown = value;
-  if (typeof v === 'string') {
-    try {
-      v = JSON.parse(v); // legacy double-encoded read
-    } catch {
-      return null;
-    }
-  }
-  return Array.isArray(v) && v.every((x) => typeof x === 'string')
-    ? (v as string[])
-    : null;
+  // Shape guard only; the legacy double-encoding self-heal lives in
+  // parseJsonbValue (database/utils.ts).
+  return parseJsonbValue(
+    value,
+    (v): v is string[] =>
+      Array.isArray(v) && v.every((x) => typeof x === 'string'),
+  );
 }
 
 /**

apps/server/src/database/utils.ts

@@ -64,3 +64,29 @@ export function jsonbBind<T>(
   }
   return sql<T>`${JSON.stringify(value)}::text::jsonb`;
 }
+
+/**
+ * READ-side counterpart to {@link jsonbBind}: tolerantly decode a jsonb value
+ * read back from the DB and validate its shape with `guard`. THE single place
+ * the legacy double-encoding self-heal lives, so repos keep only a type-guard.
+ *
+ * A row written by the old `::jsonb` bind round-trips as a JSON STRING (see the
+ * quirk in jsonbBind), so the driver hands back e.g. `'["a"]'` / `'{"k":1}'`
+ * rather than the structure. This parses such a string once, then applies the
+ * caller's `guard`. Returns `null` for null / an unparseable string / a value
+ * the guard rejects (so a corrupt or wrong-shaped value degrades to "unset").
+ */
+export function parseJsonbValue<T>(
+  value: unknown,
+  guard: (v: unknown) => v is T,
+): T | null {
+  let v: unknown = value;
+  if (typeof v === 'string') {
+    try {
+      v = JSON.parse(v); // legacy double-encoded read
+    } catch {
+      return null;
+    }
+  }
+  return guard(v) ? v : null;
+}