diff --git a/.changeset/d12-fake-inventory-gate.md b/.changeset/d12-fake-inventory-gate.md
new file mode 100644
index 0000000000..ed385bf892
--- /dev/null
+++ b/.changeset/d12-fake-inventory-gate.md
@@ -0,0 +1,7 @@
+---
+---
+
+test-only: the D12 honesty gate iterates the known-fake inventory — every
+`CORE_FALLBACK_FACTORIES` product registered slot-by-slot must come out of
+both discovery builders as `degraded`, never `available` (#3898 suggestion 4;
+`cache`/`queue`/`job` had no per-slot pin before). Releases nothing.
diff --git a/packages/objectql/src/protocol-discovery.test.ts b/packages/objectql/src/protocol-discovery.test.ts
index d41f52d9da..1341c654ae 100644
--- a/packages/objectql/src/protocol-discovery.test.ts
+++ b/packages/objectql/src/protocol-discovery.test.ts
@@ -2,7 +2,7 @@
 
 import { describe, it, expect, beforeEach } from 'vitest';
 import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
-import { createMemoryMetadata } from '@objectstack/core';
+import { createMemoryMetadata, CORE_FALLBACK_FACTORIES } from '@objectstack/core';
 import { ObjectQL } from './engine.js';
 
 describe('ObjectStackProtocolImplementation - Dynamic Service Discovery', () => {
@@ -219,6 +219,31 @@ describe('ObjectStackProtocolImplementation - Dynamic Service Discovery', () =>
     expect(discovery.services.data.message).toBeUndefined();
   });
 
+  // ── The class-wide gate (#3898): the fake INVENTORY, not spot checks ──────
+  // Same gate as the dispatcher's: every in-memory fallback the kernel can
+  // auto-register (CORE_FALLBACK_FACTORIES — the complete fake inventory now
+  // that plugin-dev's stub table is retired, ADR-0115, and the `_fallback`
+  // marker was eliminated rather than recognized, #4058 step 1) goes through
+  // THIS builder too and must never come out `available`. Table-driven so a
+  // new fallback is gated the day it is added; cache/queue/job had no
+  // per-slot pin here either.
+  it('reports every CORE_FALLBACK_FACTORIES product as degraded, never available (#3898)', async () => {
+    expect(Object.keys(CORE_FALLBACK_FACTORIES).length).toBeGreaterThan(0);
+
+    for (const [slot, factory] of Object.entries(CORE_FALLBACK_FACTORIES)) {
+      const mockServices = new Map<string, any>();
+      mockServices.set(slot, factory());
+
+      protocol = new ObjectStackProtocolImplementation(engine, () => mockServices);
+      const reported = (await protocol.getDiscovery()).services[slot];
+
+      expect(reported, `services.${slot}`).toBeDefined();
+      expect(reported.enabled, `services.${slot}.enabled`).toBe(true);
+      expect(reported.status, `services.${slot}.status`).toBe('degraded');
+      expect(reported.message, `services.${slot}.message`).toBeTruthy();
+    }
+  });
+
   // #3891 — the degraded ObjectQL fallback is retired. Analytics is an
   // ordinary optional service now: absent ⇒ unavailable, and the route must
   // NOT be advertised (an advertised route with no handler 404s — the exact
diff --git a/packages/runtime/src/http-dispatcher.test.ts b/packages/runtime/src/http-dispatcher.test.ts
index ecd5f2fda5..e17970c372 100644
--- a/packages/runtime/src/http-dispatcher.test.ts
+++ b/packages/runtime/src/http-dispatcher.test.ts
@@ -2653,6 +2653,38 @@ describe('HttpDispatcher', () => {
             expect(fromDispatcher.message).toBe(fromProtocol.message);
             expect(fromDispatcher.route).toBe(fromProtocol.route);
         });
+
+        // ── The class-wide gate (#3898): the fake INVENTORY, not spot checks ──
+        //
+        // Everything above pins one slot each. This iterates the actual list of
+        // in-memory fallbacks the kernel auto-registers — CORE_FALLBACK_FACTORIES
+        // is the complete fake inventory now that plugin-dev's stub table is
+        // retired (ADR-0115) and the third marker kind, `_fallback`, was
+        // eliminated rather than recognized (#4058 step 1) — and registers each
+        // product into its own slot: discovery must never call any of them
+        // `available`. Table-driven so the next fallback added to the table is
+        // gated the day it lands; this class of hole recurs with every new
+        // fallback. cache/queue/job had no per-slot pin before this — dropping
+        // their `svcAvailable(…, svc)` third argument, the exact #4130
+        // regression shape, was test-invisible.
+
+        it('reports every CORE_FALLBACK_FACTORIES product as degraded, never available (#3898)', async () => {
+            const { CORE_FALLBACK_FACTORIES } = await import('@objectstack/core');
+            expect(Object.keys(CORE_FALLBACK_FACTORIES).length).toBeGreaterThan(0);
+
+            for (const [slot, factory] of Object.entries(CORE_FALLBACK_FACTORIES)) {
+                const fallback = factory();
+                (kernel as any).getService = vi.fn().mockImplementation((n: string) => (n === slot ? fallback : null));
+                (kernel as any).services = new Map([[slot, fallback]]);
+
+                const info = await dispatcher.getDiscoveryInfo('/api/v1');
+                const reported = (info.services as Record<string, any>)[slot];
+                expect(reported, `services.${slot}`).toBeDefined();
+                expect(reported.enabled, `services.${slot}.enabled`).toBe(true);
+                expect(reported.status, `services.${slot}.status`).toBe('degraded');
+                expect(reported.message, `services.${slot}.message`).toBeTruthy();
+            }
+        });
     });
 
     // ═══════════════════════════════════════════════════════════════