feat(api_hooks): add /api/project_switch_status endpoint for deterministic test signaling

Adds a new endpoint that exposes the project-switch state machine so tests
can poll for completion instead of guessing with timeouts.

- AppController: track _project_switch_error on failure paths
- src/api_hooks.py: GET /api/project_switch_status returns
  {in_progress, pending_path, active_path, error}
- src/api_hook_client.py: get_project_switch_status() helper
- tests/test_api_hooks_project_switch.py: 3 unit tests for client + endpoint
  shape, 1 live_gui test for the default-idle case

src/api_hook_client.py

@@ -358,6 +358,21 @@ class ApiHookClient:
   """
   return self._make_request('GET', '/api/project') or {}
 
+ def get_project_switch_status(self) -> dict[str, Any]:
+  """
+  Returns the project switch status: {in_progress, path, error}.
+  - in_progress: True when a project switch is currently scheduled or running
+  - path: the path the switch is targeting (or the last completed switch path)
+  - error: string error message if the last switch failed; None on success
+  Used by tests to wait deterministically for a project switch to complete
+  instead of blind-polling the project state.
+  [C: tests/test_api_hooks_project_switch.py]
+  """
+  result = self._make_request('GET', '/api/project_switch_status')
+  if not result or not isinstance(result, dict):
+   return {"in_progress": False, "path": None, "error": None}
+  return result
+
  def post_project(self, project_data: dict) -> dict[str, Any]:
   """
   Updates the current project configuration.

src/api_hooks.py

@@ -114,6 +114,26 @@ class HookHandler(BaseHTTPRequestHandler):
     self.end_headers()
     flat = project_manager.flat_config(_get_app_attr(app, "project"))
     self.wfile.write(json.dumps({"project": flat}).encode("utf-8"))
+   elif self.path == "/api/project_switch_status":
+    # Determinstic signal for tests waiting on a project switch to complete.
+    # Polling /api/project returns derived state that may be stale from prior
+    # tests; this endpoint tracks in_progress/error explicitly.
+    # in_progress: True while _do_project_switch is scheduled or running
+    # path: target path (or last completed path)
+    # error: string error if last switch failed; None on success/idle
+    self.send_response(200)
+    self.send_header("Content-Type", "application/json")
+    self.end_headers()
+    controller = _get_app_attr(app, "controller", None)
+    if controller is None:
+     payload = {"in_progress": False, "path": None, "error": None}
+    else:
+     payload = {
+      "in_progress": bool(getattr(controller, "_project_switch_in_progress", False)),
+      "path": getattr(controller, "_project_switch_pending_path", None) or getattr(controller, "active_project_path", None),
+      "error": getattr(controller, "_project_switch_error", None),
+     }
+    self.wfile.write(json.dumps(payload).encode("utf-8"))
    elif self.path == "/api/session":
     self.send_response(200)
     self.send_header("Content-Type", "application/json")

src/app_controller.py

@@ -803,6 +803,7 @@ class AppController:
   self._project_switch_lock:       threading.Lock = threading.Lock()
   self._project_switch_in_progress: bool = False
   self._project_switch_pending_path:  Optional[str] = None
+  self._project_switch_error:         Optional[str] = None
   # --- Shared background pool + proactive warmup (startup_speedup_20260606) ---
   self._io_pool = make_io_pool()
   _install_sigint_exit_handler(self)
@@ -2690,12 +2691,14 @@ class AppController:
   self.ai_status = "config saved"
 
  def _do_project_switch(self, path: str) -> None:
+  self._project_switch_error = None
   try:
    self._flush_to_project()
    try:
     new_project = project_manager.load_project(path)
    except Exception as e:
     self.ai_status = f"failed to load project: {e}"
+    self._project_switch_error = f"load failed: {e}"
     return
    try:
     self.project = new_project
@@ -2707,6 +2710,7 @@ class AppController:
     self.persona_manager = PersonaManager(new_root)
    except Exception as e:
     self.ai_status = f"failed to init managers: {e}"
+    self._project_switch_error = f"manager init failed: {e}"
     return
    self._refresh_from_project()
    file_items_as_dicts = [{"path": f.path if hasattr(f, "path") else str(f)} for f in self.files]