feat(gui2): Integrate core event system

Integrates the ai_client.events emitter into the gui_2.py App class. Adds a new test file to verify that the App subscribes to API lifecycle events upon initialization. This is the first step in aligning gui_2.py with the project's event-driven architecture.

gui_2.py

@@ -14,6 +14,7 @@ import session_logger
 import project_manager
 import theme_2 as theme
 import tomllib
+import events
 
 from imgui_bundle import imgui, hello_imgui, immapp
 
@@ -187,6 +188,15 @@ class App:
         ai_client.comms_log_callback = self._on_comms_entry
         ai_client.tool_log_callback = self._on_tool_log
 
+        # Subscribe to API lifecycle events
+        ai_client.events.on("request_start", self._on_api_event)
+        ai_client.events.on("response_received", self._on_api_event)
+        ai_client.events.on("tool_execution", self._on_api_event)
+
+    def _on_api_event(self, *args, **kwargs):
+        """Callback for ai_client events. For now, a placeholder."""
+        pass
+
     # ---------------------------------------------------------------- project loading
 
     def _load_active_project(self):

tests/test_gui2_events.py

@@ -0,0 +1,48 @@
+import pytest
+from unittest.mock import MagicMock, patch
+from gui_2 import App
+import ai_client
+from events import EventEmitter
+
+@pytest.fixture
+def app_instance():
+    """
+    Fixture to create an instance of the gui_2.App class for testing.
+    It mocks functions that would render a window or block execution.
+    """
+    if not hasattr(ai_client, 'events') or ai_client.events is None:
+        ai_client.events = EventEmitter()
+
+    with (
+        patch('gui_2.load_config', return_value={'ai': {}, 'projects': {}}),
+        patch('gui_2.save_config'),
+        patch('gui_2.project_manager'),
+        patch('gui_2.session_logger'),
+        patch('gui_2.immapp.run'),
+        patch.object(App, '_load_active_project'),
+        patch.object(App, '_fetch_models'),
+        patch.object(App, '_load_fonts'),
+        patch.object(App, '_post_init')
+    ):
+        yield App
+
+def test_app_subscribes_to_events(app_instance):
+    """
+    This test checks that the App's __init__ method subscribes the necessary
+    event handlers to the ai_client.events emitter.
+    This test will fail until the event subscription logic is added to gui_2.App.
+    """
+    with patch.object(ai_client.events, 'on') as mock_on:
+        app = app_instance()
+        mock_on.assert_called()
+        
+        calls = mock_on.call_args_list
+        event_names = [call.args[0] for call in calls]
+        assert "request_start" in event_names
+        assert "response_received" in event_names
+        assert "tool_execution" in event_names
+
+        for call in calls:
+            handler = call.args[1]
+            assert hasattr(handler, '__self__')
+            assert handler.__self__ is app