fix: fail safe on missing workspace revisions

frontend/src/shell/SteerInput.test.tsx

@@ -389,6 +389,35 @@ test("initial submit rejects a migration-required workspace after summaries load
   expect(body).toBeUndefined();
 });
 
+test("initial submit rejects a workspace summary that omits the canonical revision", async () => {
+  let body: unknown;
+  let failure: string | undefined;
+  localStorage.setItem("thothii.workspace-registry.v1.preferences", JSON.stringify({
+    workspaceId: "broken-workspace", provider: "zai", model: "glm-5.2", thinking: "medium",
+  }));
+  server.use(
+    http.get("/api/settings", () => HttpResponse.json({ workspace: "broken-workspace" })),
+    http.get("/api/workspaces", () => HttpResponse.json([{
+      id: "broken-workspace", name: "broken-workspace", file: "broken-workspace.yaml", displayName: "Broken workspace",
+    }])),
+    http.get("/api/models", () => HttpResponse.json({ models: [
+      { provider: "zai", id: "glm-5.2", name: "GLM-5.2", reasoning: true },
+    ] })),
+    http.post("/api/sessions", async ({ request }) => {
+      body = await request.json();
+      return HttpResponse.json({ id: "s1" });
+    }),
+  );
+  const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+  render(<QueryClientProvider client={client}><ComposerFooter /><SteerInput sessionId={null} onSessionCreateFailed={(message) => { failure = message; }} /></QueryClientProvider>);
+
+  await userEvent.type(screen.getByRole("textbox", { name: /new question/i }), "q");
+  await userEvent.click(screen.getByRole("button", { name: /send/i }));
+
+  await waitFor(() => expect(failure).toBe("Could not load selected workspace policy. Please retry."));
+  expect(body).toBeUndefined();
+});
+
 test("failed workspace summaries block creation and report a safe error", async () => {
   let body: unknown;
   let failure: string | undefined;