fix(resume): recover cleanly after Pi exits

backend/test/session-bridge.test.ts

@@ -68,6 +68,19 @@ test("assistant provider errors are sanitized and leave the turn failed", () =>
   expect(JSON.stringify(seen)).not.toContain("DO_NOT_LEAK");
 });
 
+test("markFailed records backend-detected failure without emitting raw detail", () => {
+  const { rpc } = fakeRpc();
+  const bridge = new SessionBridge(rpc);
+  const seen: any[] = [];
+  bridge.onClientEvent((event) => seen.push(event));
+  bridge.beginTurn();
+
+  bridge.markFailed();
+
+  expect(bridge.turnState()).toBe("failed");
+  expect(seen).toEqual([]);
+});
+
 test("reviewer wait and response transition waiting back to running", () => {
   const { rpc, fire } = fakeRpc();
   const bridge = new SessionBridge(rpc);