docs(spec,showcase): the prescription must not over-promise — ADR-0121 D1 renames paths on restore

ADR-0121 (accepted 2026-08-04, after this branch opened) namespaces
endpoint paths as `<runtime-prefix>/apps/<namespace>/<subpath>`. The
rejection message said definitions "stay valid"; that is true of every
key except `path`, so it is now stated precisely, with the FROM -> TO.
The showcase's commented endpoints carry the same note — they would be
rejected under D1 if uncommented verbatim.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EYGdmvWP1ieZSLqvAW6uyd

Author: claude

examples/app-showcase/src/system/apis/index.ts

@@ -35,8 +35,16 @@ import type { ApiEndpoint } from '@objectstack/spec/api';
  * retiring it, because endpoint shapes are an industry-stable form that would
  * only be re-introduced identically later. When the executor ships (#5040 —
  * mounting + endpoint matching + per-key wiring), the rejection is replaced by
- * real execution and the two definitions below can be uncommented as-is. They
- * are kept verbatim for exactly that reason.
+ * real execution and these two come back. They are kept verbatim for that.
+ *
+ * ⚠️ ONE edit is required when restoring them, and it is not cosmetic:
+ * ADR-0121 D1 (accepted 2026-08-04, after these were commented out) namespaces
+ * endpoint paths as `<runtime-prefix>/apps/<namespace>/<subpath>`, so that an
+ * app can only claim its own namespace and can never collide with a built-in
+ * domain or another installed package. The `path` values below predate that
+ * rule and would be rejected under it. Per that ADR they return as
+ * `/api/v1/apps/showcase/tasks` and `/api/v1/apps/showcase/inquiries/purge`
+ * (its §D1 names them explicitly, restored by #5040 E8).
  */
 
 // /** Read-only data projection: GET a filtered task list through a stable URL. */

packages/spec/src/stack.zod.ts

@@ -147,7 +147,11 @@ const APIS_NO_EXECUTOR_GUIDANCE =
   + 'The `ApiEndpoint` vocabulary is deliberately KEPT: the executor (mounting + endpoint '
   + 'matching + per-key wiring for authRequired/cacheTtl/inputMapping/outputMapping/rateLimit) '
   + 'is tracked by https://github.com/objectstack-ai/objectstack/issues/5040, and this '
-  + 'rejection is replaced by real execution there — your endpoint definitions stay valid.';
+  + 'rejection is replaced by real execution there — so keep your definitions, do not '
+  + 'redesign around the refusal. One thing WILL change when they come back: ADR-0121 D1 '
+  + 'namespaces endpoint paths as `<runtime-prefix>/apps/<namespace>/<subpath>`, so a path '
+  + 'like `/api/v1/my/thing` becomes `/api/v1/apps/<your manifest.namespace>/thing`. Everything '
+  + 'else about the endpoint is unchanged.';
 
 /**
  * ObjectStack Ecosystem Definition