diff --git a/frontend/src/features/layout/LayoutGrid.chat.test.tsx b/frontend/src/features/layout/LayoutGrid.chat.test.tsx
index 8424779..0948baa 100644
--- a/frontend/src/features/layout/LayoutGrid.chat.test.tsx
+++ b/frontend/src/features/layout/LayoutGrid.chat.test.tsx
@@ -253,4 +253,58 @@ describe("LayoutGrid custom agent CLI (#147)", () => {
     );
     expect(window.localStorage.getItem(`idea.agent-cell-mode.p1.${leafId}`)).toBe("custom");
   });
+
+  it("falls back to native TUI once the catalog confirms the pinned profile is incompatible", async () => {
+    const layout = new MockLayoutGateway();
+    const agent = new MockAgentGateway();
+    const profileGateway = new MockProfileGateway();
+    const terminal = new MockTerminalGateway();
+    const system = new MockSystemGateway();
+    await profileGateway.configureProfiles([ptyProfile]);
+    const created = await agent.createAgent("p1", {
+      name: "Worker",
+      profileId: ptyProfile.id,
+    });
+    const tree = await layout.loadLayout("p1");
+    const leafId = leaves(tree)[0].id;
+    await layout.mutateLayout("p1", {
+      type: "setCellAgent",
+      target: leafId,
+      agent: created.id,
+    });
+    window.localStorage.setItem(`idea.agent-cell-mode.p1.${leafId}`, "custom");
+
+    const agentsLoaded = deferred<void>();
+    const profilesLoaded = deferred<void>();
+    const originalListAgents = agent.listAgents.bind(agent);
+    const originalListProfiles = profileGateway.listProfiles.bind(profileGateway);
+    vi.spyOn(agent, "listAgents").mockImplementation(async (projectId) => {
+      await agentsLoaded.promise;
+      return originalListAgents(projectId);
+    });
+    vi.spyOn(profileGateway, "listProfiles").mockImplementation(async () => {
+      await profilesLoaded.promise;
+      return originalListProfiles();
+    });
+
+    renderGrid({
+      layout,
+      agent,
+      profile: profileGateway,
+      terminal,
+      system,
+    } as unknown as Gateways);
+
+    await waitFor(() => expect(screen.getByTestId("layout-leaf")).toBeTruthy());
+    expect(window.localStorage.getItem(`idea.agent-cell-mode.p1.${leafId}`)).toBe("custom");
+
+    agentsLoaded.resolve();
+    profilesLoaded.resolve();
+
+    await waitFor(() =>
+      expect(window.localStorage.getItem(`idea.agent-cell-mode.p1.${leafId}`)).toBe("tui"),
+    );
+    expect(screen.getByTestId("terminal-view")).toBeTruthy();
+    expect(screen.queryByTestId("custom-agent-chat-view")).toBeNull();
+  });
 });