feat(FN-965): add per-task planning model override

- Add planningModelProvider and planningModelId fields to core Task type
- Update backend API validation to accept planning model fields on create/update
- Update frontend API client and TaskForm to handle planning model
- Add planning model selector row to ModelSelectorTab component
- Wire up planning model in TaskDetailModal edit mode with save support
- Update AGENTS.md with planning model override documentation
- Add comprehensive tests for ModelSelectorTab and API routes
- Bump schema version from 10 to 11

packages/dashboard/src/routes.test.ts

@@ -1410,6 +1410,8 @@ describe("PATCH /tasks/:id", () => {
       modelId: null,
       validatorModelProvider: null,
       validatorModelId: null,
+      planningModelProvider: null,
+      planningModelId: null,
     });
     expect(res.body.dependencies).toEqual(["FN-002"]);
   });
@@ -1432,6 +1434,8 @@ describe("PATCH /tasks/:id", () => {
       modelId: null,
       validatorModelProvider: null,
       validatorModelId: null,
+      planningModelProvider: null,
+      planningModelId: null,
     });
   });
 
@@ -1464,6 +1468,8 @@ describe("PATCH /tasks/:id", () => {
       modelId: "claude-sonnet-4-5",
       validatorModelProvider: "openai",
       validatorModelId: "gpt-4o",
+      planningModelProvider: null,
+      planningModelId: null,
     });
   });
 
@@ -1514,6 +1520,90 @@ describe("PATCH /tasks/:id", () => {
       modelId: null,
       validatorModelProvider: null,
       validatorModelId: null,
+      planningModelProvider: null,
+      planningModelId: null,
+    });
+  });
+
+  it("forwards planning model override fields to store.updateTask", async () => {
+    (store.updateTask as ReturnType<typeof vi.fn>).mockResolvedValue({
+      ...FAKE_TASK_DETAIL,
+      planningModelProvider: "google",
+      planningModelId: "gemini-2.5-pro",
+    });
+
+    const res = await REQUEST(buildApp(), "PATCH", "/api/tasks/KB-001", JSON.stringify({
+      planningModelProvider: "google",
+      planningModelId: "gemini-2.5-pro",
+    }), {
+      "Content-Type": "application/json",
+    });
+
+    expect(res.status).toBe(200);
+    expect(store.updateTask).toHaveBeenCalledWith("KB-001", {
+      title: undefined,
+      description: undefined,
+      prompt: undefined,
+      dependencies: undefined,
+      enabledWorkflowSteps: undefined,
+      modelProvider: null,
+      modelId: null,
+      validatorModelProvider: null,
+      validatorModelId: null,
+      planningModelProvider: "google",
+      planningModelId: "gemini-2.5-pro",
+    });
+  });
+
+  it("returns 400 for invalid planningModelProvider type", async () => {
+    const res = await REQUEST(buildApp(), "PATCH", "/api/tasks/KB-001", JSON.stringify({
+      planningModelProvider: 123,
+    }), {
+      "Content-Type": "application/json",
+    });
+
+    expect(res.status).toBe(400);
+    expect(res.body.error).toContain("planningModelProvider must be a string");
+  });
+
+  it("returns 400 for invalid planningModelId type", async () => {
+    const res = await REQUEST(buildApp(), "PATCH", "/api/tasks/KB-001", JSON.stringify({
+      planningModelId: true,
+    }), {
+      "Content-Type": "application/json",
+    });
+
+    expect(res.status).toBe(400);
+    expect(res.body.error).toContain("planningModelId must be a string");
+  });
+
+  it("accepts null to clear planning model fields", async () => {
+    (store.updateTask as ReturnType<typeof vi.fn>).mockResolvedValue({
+      ...FAKE_TASK_DETAIL,
+      planningModelProvider: undefined,
+      planningModelId: undefined,
+    });
+
+    const res = await REQUEST(buildApp(), "PATCH", "/api/tasks/KB-001", JSON.stringify({
+      planningModelProvider: null,
+      planningModelId: null,
+    }), {
+      "Content-Type": "application/json",
+    });
+
+    expect(res.status).toBe(200);
+    expect(store.updateTask).toHaveBeenCalledWith("KB-001", {
+      title: undefined,
+      description: undefined,
+      prompt: undefined,
+      dependencies: undefined,
+      enabledWorkflowSteps: undefined,
+      modelProvider: null,
+      modelId: null,
+      validatorModelProvider: null,
+      validatorModelId: null,
+      planningModelProvider: null,
+      planningModelId: null,
     });
   });
 
@@ -1540,6 +1630,8 @@ describe("PATCH /tasks/:id", () => {
       modelId: null,
       validatorModelProvider: null,
       validatorModelId: null,
+      planningModelProvider: null,
+      planningModelId: null,
     });
   });
 

packages/dashboard/src/routes.ts

@@ -2546,7 +2546,7 @@ export function createApiRoutes(store: TaskStore, options?: ServerOptions): Rout
   router.patch("/tasks/:id", async (req, res) => {
     try {
       const scopedStore = await getScopedStore(req);
-      const { title, description, prompt, dependencies, enabledWorkflowSteps, modelProvider, modelId, validatorModelProvider, validatorModelId } = req.body;
+      const { title, description, prompt, dependencies, enabledWorkflowSteps, modelProvider, modelId, validatorModelProvider, validatorModelId, planningModelProvider, planningModelId } = req.body;
 
       // Validate model fields are strings or undefined/null
       const validateModelField = (value: unknown, name: string): string | null | undefined => {
@@ -2561,6 +2561,8 @@ export function createApiRoutes(store: TaskStore, options?: ServerOptions): Rout
       const validatedModelId = validateModelField(modelId, "modelId");
       const validatedValidatorModelProvider = validateModelField(validatorModelProvider, "validatorModelProvider");
       const validatedValidatorModelId = validateModelField(validatorModelId, "validatorModelId");
+      const validatedPlanningModelProvider = validateModelField(planningModelProvider, "planningModelProvider");
+      const validatedPlanningModelId = validateModelField(planningModelId, "planningModelId");
 
       if (enabledWorkflowSteps !== undefined) {
         if (!Array.isArray(enabledWorkflowSteps) || !enabledWorkflowSteps.every((id: unknown) => typeof id === "string")) {
@@ -2578,6 +2580,8 @@ export function createApiRoutes(store: TaskStore, options?: ServerOptions): Rout
         modelId: validatedModelId,
         validatorModelProvider: validatedValidatorModelProvider,
         validatorModelId: validatedValidatorModelId,
+        planningModelProvider: validatedPlanningModelProvider,
+        planningModelId: validatedPlanningModelId,
       });
       res.json(task);
     } catch (err: any) {