fix: fail safe on missing workspace revisions

frontend/src/api/sessions.test.ts

@@ -15,7 +15,12 @@ test("createSession migrates legacy selections and POSTs browser preferences", a
     })),
     http.get("/api/workspaces", () => HttpResponse.json([{
       id: "psd-clinical", name: "psd-clinical", file: "psd-clinical.yaml", displayName: "PSD Clinical",
+      revision: { id: "psd-clinical", commit: "a".repeat(40), blob: "b".repeat(40), snapshotPath: "/snapshot", state: "operational" },
     }])),
+    http.get("/api/workspaces/psd-clinical", () => HttpResponse.json({
+      workspace: { llm_policy: { allowed: ["zai/glm-5.2"] } },
+      revision: { id: "psd-clinical", commit: "a".repeat(40), blob: "b".repeat(40), snapshotPath: "/snapshot", state: "operational" },
+    })),
     http.post("/api/sessions", async ({ request }) => {
       body = await request.json();
       return HttpResponse.json({ id: "s1" });
@@ -30,6 +35,28 @@ test("createSession migrates legacy selections and POSTs browser preferences", a
   });
 });
 
+test("createSession rejects a workspace summary that omits the canonical revision", async () => {
+  localStorage.clear();
+  let posted = false;
+  server.use(
+    http.get("/api/settings", () => HttpResponse.json({
+      workspace: "psd-clinical", provider: "zai", model: "glm-5.2", thinking: "low",
+    })),
+    http.get("/api/workspaces", () => HttpResponse.json([{
+      id: "psd-clinical", name: "psd-clinical", file: "psd-clinical.yaml", displayName: "PSD Clinical",
+    }])),
+    http.post("/api/sessions", async () => {
+      posted = true;
+      return HttpResponse.json({ id: "s1" });
+    }),
+  );
+
+  await expect(createSession({ question: "q" })).rejects.toMatchObject({
+    message: "Could not load selected workspace policy. Please retry.",
+  });
+  expect(posted).toBe(false);
+});
+
 test.each([202, 204])("prewarmRuntime accepts a body-less %s response", async (status) => {
   let called = false;
   server.use(

frontend/src/api/sessions.ts

@@ -59,7 +59,11 @@ async function ensureWorkspaceSelectionPolicy(): Promise<WorkspacePreference> {
       throw new WorkspaceSelectionError(WORKSPACE_SUMMARY_ERROR);
     }
     if (workspacePreferences.load().workspaceId !== workspaceId) continue;
-    if (workspace?.revision.state === "migration_required") {
+    if (workspace && !workspace.revision) {
+      workspacePolicyGate.reject(workspaceId);
+      throw new WorkspaceSelectionError(WORKSPACE_POLICY_ERROR);
+    }
+    if (workspace?.revision?.state === "migration_required") {
       workspacePolicyGate.rejectSummary(workspaceId);
       throw new WorkspaceSelectionError(WORKSPACE_POLICY_ERROR);
     }