@@ -69,6 +69,9 @@ const NON_OVERRIDABLE = 'object';
 /** The value every read assertion looks for. */
 const MARKER = 'AUTHORED_AT_RUNTIME';
 
+/** The second revision's marker — two PUTs, two history events. */
+const MARKER_2 = 'AUTHORED_AT_RUNTIME_REV2';
+
 /**
  * A SPEC-VALID body per type, carrying `label` as the marker the reads assert
  * on. Real bodies, not `{ label }` stubs: the write door runs full spec
@@ -77,8 +80,8 @@ const MARKER = 'AUTHORED_AT_RUNTIME';
  * nothing to do with org scoping. Each shape was measured against the real
  * validator, not guessed.
  */
-function bodyFor(type: string, name: string): Record<string, unknown> {
-    const marker = { name, label: MARKER };
+function bodyFor(type: string, name: string, label = MARKER): Record<string, unknown> {
+    const marker = { name, label };
     switch (type) {
         case 'view':
             // [#7741] the inline arm requires the object-binding pair.
@@ -114,25 +117,41 @@ interface Row {
     state: string; metadata: string; checksum?: string; version?: number;
 }
 
+interface HistoryRow {
+    id: string; type: string; name: string;
+    organization_id: string | null;
+    version: number; event_seq: number;
+    operation_type: string; metadata: string | null;
+}
+
 const keyOf = (w: Record<string, unknown>) =>
     `${w.type}|${w.name}|${w.organization_id ?? '__env__'}|${w.state ?? 'active'}|${w.package_id ?? '__nopkg__'}`;
 
-function matchesWhere(r: Row, where: Record<string, unknown>): boolean {
+function matchesWhere(r: Record<string, unknown>, where: Record<string, unknown>): boolean {
     for (const [k, v] of Object.entries(where)) {
         if (k === '$or') {
             const clauses = v as Array<Record<string, unknown>>;
             if (!clauses.some((c) => matchesWhere(r, c))) return false;
             continue;
         }
+        // ⛔ REFUSE any other combinator rather than reading it as a field
+        // name. `$or` is the only one the read paths under test emit, and a
+        // double that answered `$and` by looking for a column literally called
+        // `$and` would return a well-formed WRONG answer — the same silent
+        // class as a double that drops the predicate entirely. Refusing loudly
+        // is the convention the sibling harness already follows.
+        if (k.startsWith('$')) {
+            throw new Error(`stub engine: unsupported WHERE combinator \`${k}\``);
+        }
         if (v === undefined) continue;
-        if ((r as unknown as Record<string, unknown>)[k] !== v) return false;
+        if (r[k] !== v) return false;
     }
     return true;
 }
 
 function makeStubEngine() {
     const rows = new Map<string, Row>();
-    const historyRows: any[] = [];
+    const historyRows: HistoryRow[] = [];
     let nextId = 0;
 
     const findRow = (w: Record<string, unknown>): { key: string; row: Row } | null => {
@@ -145,25 +164,63 @@ function makeStubEngine() {
             const r = rows.get(k);
             if (r) return { key: k, row: r };
         }
-        for (const [k, r] of rows) if (matchesWhere(r, w)) return { key: k, row: r };
+        for (const [k, r] of rows) if (matchesWhere(r as unknown as Record<string, unknown>, w)) return { key: k, row: r };
         return null;
     };
 
     const engine: any = {
         async findOne(table: string, opts: { where: Record<string, unknown> }) {
             assertEngineFindOnePredicate(table, opts);
-            if (table === 'sys_metadata_history') return null;
+            if (table === 'sys_metadata_history') {
+                // [#13764] Was `return null` UNCONDITIONALLY. Measured before
+                // changing it: the unconditional null is NOT load-bearing for
+                // the PUT path this fixture drives — production reaches this
+                // seam only from `getByHash`, `restoreVersion` and
+                // `resolveMetaItemOrgScope`, none of which a PUT calls; the
+                // write path reads history through `find`
+                // (`nextEventSeq` / `nextItemVersion`).
+                return historyRows.find(
+                    (h) => matchesWhere(h as unknown as Record<string, unknown>, opts.where),
+                ) ?? null;
+            }
             return findRow(opts.where)?.row ?? null;
         },
-        async find(table: string, opts?: { where?: Record<string, unknown> }) {
-            if (table === 'sys_metadata_history') return historyRows;
-            return Array.from(rows.values()).filter((r) => matchesWhere(r, opts?.where ?? {}));
+        async find(table: string, opts?: { where?: Record<string, unknown>; limit?: number }) {
+            // [#13764] Two silences repaired on one seam, for one reason.
+            //
+            // WHERE: this branch used to `return historyRows` UNFILTERED.
+            // `SysMetadataRepository.history()` and `diffMetaItem` filter
+            // `organization_id` by STRICT EQUALITY and post-filter nothing, so
+            // an unfiltered answer made the org predicate a no-op: an
+            // org-scoping assertion for `/history` was green whether or not the
+            // door forwarded the organization. Measured, not argued — the
+            // `#13764` block at the bottom of this file is green over the old
+            // stub in BOTH states and reddens over this one when the org is
+            // dropped.
+            //
+            // LIMIT: applied AFTER the filter and BY PRESENCE
+            // (`typeof === 'number'`), so `limit: 0` returns nothing rather
+            // than everything, and bounding never decides WHICH rows survive
+            // the predicate — only how many of the survivors come back. Every
+            // call this fixture makes passes no bound and is untouched.
+            // `check:objectql-double-limit`. Applied on BOTH tables so the two
+            // branches cannot disagree.
+            if (table === 'sys_metadata_history') {
+                const matched = historyRows.filter(
+                    (h) => matchesWhere(h as unknown as Record<string, unknown>, opts?.where ?? {}),
+                );
+                return typeof opts?.limit === 'number' ? matched.slice(0, opts.limit) : matched;
+            }
+            const matched = Array.from(rows.values()).filter(
+                (r) => matchesWhere(r as unknown as Record<string, unknown>, opts?.where ?? {}),
+            );
+            return typeof opts?.limit === 'number' ? matched.slice(0, opts.limit) : matched;
         },
         async insert(table: string, data: Record<string, unknown>) {
             if (table === 'sys_metadata_audit') return { id: 'audit_skip' };
             if (table === 'sys_metadata_history') {
                 nextId += 1;
-                historyRows.push({ ...data, id: `h_${nextId}` });
+                historyRows.push({ ...(data as unknown as HistoryRow), id: `h_${nextId}` });
                 return { id: `h_${nextId}` };
             }
             if (table !== 'sys_metadata') return { id: 'side_effect_skip' };
@@ -203,7 +260,7 @@ function makeStubEngine() {
             isPackageDisabled: () => false,
         },
     };
-    return { engine, rows };
+    return { engine, rows, historyRows };
 }
 
 // ── REST harness: real protocol, real routes, one boot ────────────────────
@@ -236,7 +293,7 @@ function mockRes() {
  * can read the same store on the same boot (the cross-tenant control).
  */
 function boot() {
-    const { engine, rows } = makeStubEngine();
+    const { engine, rows, historyRows } = makeStubEngine();
     const protocol = new ObjectStackProtocolImplementation(engine, () => new Map()) as any;
     protocol.getDiscovery = async () => ({
         version: 'v0', routes: { data: '', metadata: '', ui: '', auth: '/auth' },
@@ -269,17 +326,24 @@ function boot() {
 
     return {
         rows,
+        historyRows,
         as(tenantId: string | undefined) {
             session = tenantId === undefined
                 ? { userId: 'u1', systemPermissions: ['manage_metadata'] }
                 : { userId: 'u1', systemPermissions: ['manage_metadata'], tenantId };
         },
-        put: (type: string, name: string) =>
-            drive('PUT', `${META}/:type/:name`, { params: { type, name }, body: bodyFor(type, name) }),
+        put: (type: string, name: string, label = MARKER) =>
+            drive('PUT', `${META}/:type/:name`, { params: { type, name }, body: bodyFor(type, name, label) }),
         get: (type: string, name: string) =>
             drive('GET', `${META}/:type/:name`, { params: { type, name } }),
         list: (type: string) =>
             drive('GET', `${META}/:type`, { params: { type } }),
+        history: (type: string, name: string) =>
+            drive('GET', `${META}/:type/:name/history`, { params: { type, name }, query: {} }),
+        /** The fixture proof every history assertion below is gated on. */
+        historyRowsFor: (type: string, name: string, org: string | null) =>
+            historyRows.filter((h) => h.type === type && h.name === name
+                && (h.organization_id ?? null) === org),
     };
 }
 
@@ -407,3 +471,87 @@ describe('#9454 every REST /meta read door serves what the write door persisted'
         });
     });
 });
+
+// ── #13764 — the instrument's own discriminating power, pinned ────────────
+//
+// This file's stub used to DISCARD `opts.where` on both `sys_metadata_history`
+// seams: `findOne` answered `null` unconditionally and `find` handed back every
+// history row unfiltered. `SysMetadataRepository.history()` and `diffMetaItem`
+// filter `organization_id` by STRICT EQUALITY and post-filter nothing, so over
+// that stub the org predicate was a NO-OP — an org-scoping assertion for
+// `/history` was green whether or not the door forwarded the organization.
+//
+// ⭐ THE ASSERTION THAT HOLDS THE STUB RIGHT is `does not serve org A history to
+// org B`. The positive case below cannot do that job: un-partition the stub
+// again and it stays GREEN, because an unfiltered read still contains the rows
+// it looks for. Only the cross-tenant case reddens, because only it asks for an
+// answer the unfiltered stub cannot give. It is here for the stub, not for the
+// door.
+//
+// ⛔ These are NOT this file's pins for the two doors' behaviour — those live in
+// `rest-server-meta-history-diff-org-scope.test.ts` (#13406), whose partitioned
+// stub is the positive control this repair was calibrated against, and which
+// owns `?limit=`, `/diff`, and the non-overridable env-wide control. What is
+// asserted here is the narrow fact that THIS harness can now tell a forwarded
+// org from a dropped one.
+describe('#13764 the history seams of this harness honour the org partition', () => {
+    let b: ReturnType<typeof boot>;
+    beforeEach(() => { b = boot(); });
+
+    it('serves the org-scoped change log of an item the active org authored', async () => {
+        // The measurement that names the repair: with the door's org dropped
+        // this reads the ENV partition and answers zero events. Over the old
+        // unfiltered stub it answered two in BOTH states.
+        const first = await b.put(CACHED_ARM, 'authored_at_runtime');
+        expect(first.status, 'the fixture never wrote').toBe(200);
+        await b.put(CACHED_ARM, 'authored_at_runtime', MARKER_2);
+
+        // Fixture proof first — "the read is org-scoped" is worthless if the
+        // fixture never created an org-scoped row.
+        expect(
+            b.historyRowsFor(CACHED_ARM, 'authored_at_runtime', ORG_A).length,
+            'nothing landed in the org partition; the read below would then pass '
+            + 'or fail for a reason unrelated to org scoping',
+        ).toBe(2);
+        expect(
+            b.historyRowsFor(CACHED_ARM, 'authored_at_runtime', null).length,
+            'the write also landed env-wide — the partition is not real',
+        ).toBe(0);
+
+        const read = await b.history(CACHED_ARM, 'authored_at_runtime');
+        expect(read.thrown, `GET /history threw: ${read.thrown?.message}`).toBeUndefined();
+        expect(read.status).toBe(200);
+        expect(
+            read.body?.events?.length,
+            'the door answered an empty change log for an item whose org partition holds two events',
+        ).toBe(2);
+    });
+
+    it('does not serve org A history to org B on the same boot', async () => {
+        // ⭐ The one that reddens if the stub is ever un-partitioned again.
+        await b.put(UNCACHED_ARM, 'tenant_bound');
+        await b.put(UNCACHED_ARM, 'tenant_bound', MARKER_2);
+        expect(b.historyRowsFor(UNCACHED_ARM, 'tenant_bound', ORG_A).length).toBe(2);
+
+        b.as(ORG_B);
+        const read = await b.history(UNCACHED_ARM, 'tenant_bound');
+        expect(read.status).toBe(200);
+        expect(
+            read.body?.events ?? [],
+            'org B was served org A\'s change log',
+        ).toEqual([]);
+    });
+
+    it('does not serve an org-scoped change log to a caller that named no org', async () => {
+        await b.put(CACHED_ARM, 'org_a_only');
+        expect(b.historyRowsFor(CACHED_ARM, 'org_a_only', ORG_A).length).toBe(1);
+
+        b.as(undefined);
+        const read = await b.history(CACHED_ARM, 'org_a_only');
+        expect(read.status).toBe(200);
+        expect(
+            read.body?.events ?? [],
+            'an org-less caller was served an org-scoped change log',
+        ).toEqual([]);
+    });
+});
@@ -714,9 +714,6 @@
     "packages/rest/src/rest-exec-ctx-principal-kind.test.ts": {
       "unjudged": 1
     },
-    "packages/rest/src/rest-server-meta-read-org-scope.test.ts": {
-      "blind": 1
-    },
     "packages/rest/src/rest-server-timing.test.ts": {
       "unjudged": 1
     },