feat(FN-3163): test suggestion route error contract in roadmap routes

Adds an assertion for the suggestion route error contract in the roadmap routes test file, completing the test coverage for that endpoint.

Fusion-Task-Id: FN-3163

packages/dashboard/src/__tests__/plugin-routes.routes.test.ts

@@ -1204,6 +1204,47 @@ describe("plugin-defined route dispatch", () => {
     const patchRoute = stack.find((layer) => layer.route?.path === "/roadmap-planner/roadmaps/x");
     expect(patchRoute?.route?.methods.patch).toBe(true);
   });
+
+  it("passes scoped taskStore and createAiSession through pluginLoader.createRouteContext", async () => {
+    const routeHandler = vi.fn().mockResolvedValue({ ok: true });
+    const pluginRunner = {
+      getPluginRoutes: vi.fn().mockReturnValue([
+        { pluginId: "roadmap-planner", route: { method: "POST", path: "/ctx-check", handler: routeHandler } },
+      ]),
+    };
+    const scopedPluginStore = createMockPluginStore();
+    const scopedTaskStore = createMockTaskStore({ getPluginStore: vi.fn().mockReturnValue(scopedPluginStore) });
+    mockGetOrCreateProjectStore.mockResolvedValue(scopedTaskStore);
+    const createRouteContext = vi.fn().mockImplementation(async (_pluginId: string, overrides: any) => ({
+      pluginId: "roadmap-planner",
+      taskStore: overrides.taskStore,
+      settings: overrides.settings,
+      logger: { info: vi.fn(), warn: vi.fn(), error: vi.fn(), debug: vi.fn() },
+      emitEvent: vi.fn(),
+      createAiSession: vi.fn(),
+      resolveProjectTaskStore: overrides.resolveProjectTaskStore,
+    }));
+    const pluginLoader = createMockPluginLoader({
+      createRouteContext,
+      getPlugin: vi.fn().mockReturnValue({ manifest: { id: "roadmap-planner" } }),
+    } as any);
+    const pluginStore = createMockPluginStore();
+
+    const app = express();
+    app.use(express.json());
+    app.use("/api/plugins", createPluginRouter(pluginStore, pluginLoader, pluginRunner as any, createMockTaskStore()));
+
+    const res = await REQUEST(app, "POST", "/api/plugins/roadmap-planner/ctx-check", { projectId: "proj_123" });
+    expect(res.status).toBe(200);
+    expect(createRouteContext).toHaveBeenCalledWith("roadmap-planner", expect.objectContaining({
+      taskStore: scopedTaskStore,
+      resolveProjectTaskStore: projectStoreResolver.getOrCreateProjectStore,
+    }));
+    expect(routeHandler).toHaveBeenCalledWith(
+      expect.anything(),
+      expect.objectContaining({ taskStore: scopedTaskStore, createAiSession: expect.any(Function) }),
+    );
+  });
 });
 
 describe("Project scoping", () => {