fix(plugins): preserve frozen hosted workers on stale library

tests/unit/coding-plugin-effective-resolver.test.ts

@@ -322,6 +322,44 @@ describe('effective plugin resolver', () => {
     });
   });
 
+  it('keeps a frozen hosted worker usable through a transient stale Library refresh', async () => {
+    const currentHostedLibrary = {
+      ...library(),
+      items: [{ ...library().items[0], pluginId: serverDefinition.id }],
+    };
+    const getLibrary = vi.fn()
+      .mockResolvedValueOnce(currentHostedLibrary)
+      .mockResolvedValue({ ...currentHostedLibrary, stale: true });
+    const hosted = createEffectivePluginResolver({
+      definitions: [serverDefinition],
+      getAccountBinding: () => binding,
+      getLibrary,
+      getInstalled: vi.fn(async () => installed(serverDefinition)),
+      getEnabledPluginIds: vi.fn(async () => [serverDefinition.id]),
+      policyClient: { getState: currentPolicy, refresh: vi.fn() },
+    });
+    const input = {
+      projectId: 'project-a', projectPath: 'C:/project-a',
+      assignedSkillIds: ['remote'], role: 'parent' as const,
+    };
+
+    const frozen = await hosted.resolve(input);
+    expect(frozen.toolDefinitions).toEqual([expect.objectContaining({ name: 'remote_read' })]);
+    await expect(hosted.resolveForInvocation(input)).resolves.toMatchObject({
+      accountSessionId: frozen.accountSessionId,
+      pluginReleaseIds: frozen.pluginReleaseIds,
+      toolDefinitions: [{ name: 'remote_read' }],
+      runtimePolicies: [{ pluginId: serverDefinition.id, operation: 'read' }],
+      unavailableReasons: [],
+    });
+
+    await expect(hosted.resolve(input)).resolves.toMatchObject({
+      toolDefinitions: [],
+      runtimePolicies: [],
+      unavailableReasons: [expect.objectContaining({ code: 'library_unavailable' })],
+    });
+  });
+
   it('never exposes plugin resources to a child worker', async () => {
     const result = await resolver().resolve({
       projectId: 'project-a', projectPath: 'C:/project-a', assignedSkillIds: ['notes'], role: 'child',