feat(events): Add EventEmitter and instrument ai_client.py

ai_client.py

@@ -19,6 +19,7 @@ from pathlib import Path
 import file_cache
 import mcp_client
 import google.genai
+from events import EventEmitter
 
 _provider: str = "gemini"
 _model: str = "gemini-2.5-flash"
@@ -27,6 +28,9 @@ _max_tokens: int = 8192
 
 _history_trunc_limit: int = 8000
 
+# Global event emitter for API lifecycle events
+events = EventEmitter()
+
 def set_model_params(temp: float, max_tok: int, trunc_limit: int = 8000):
     global _temperature, _max_tokens, _history_trunc_limit
     _temperature = temp

events.py

@@ -0,0 +1,14 @@
+
+class EventEmitter:
+    def __init__(self):
+        self._listeners = {}
+
+    def on(self, event_name, callback):
+        if event_name not in self._listeners:
+            self._listeners[event_name] = []
+        self._listeners[event_name].append(callback)
+
+    def emit(self, event_name, *args, **kwargs):
+        if event_name in self._listeners:
+            for callback in self._listeners[event_name]:
+                callback(*args, **kwargs)

tests/test_api_events.py

@@ -0,0 +1,20 @@
+
+import pytest
+from unittest.mock import MagicMock
+import ai_client
+
+def test_ai_client_event_emitter_exists():
+    # This should fail initially because 'events' won't exist on ai_client
+    assert hasattr(ai_client, 'events')
+    assert ai_client.events is not None
+
+def test_event_emission():
+    # We'll expect these event names based on the spec
+    mock_callback = MagicMock()
+    ai_client.events.on("request_start", mock_callback)
+    
+    # Trigger something that should emit the event (once implemented)
+    # For now, we just test the emitter itself if we were to call it manually
+    ai_client.events.emit("request_start", payload={"model": "test"})
+    
+    mock_callback.assert_called_once_with(payload={"model": "test"})