docs: Add session debrief about test fixes and MCP tool lesson

add_debug2.py

@@ -0,0 +1,30 @@
+with open("src/app_controller.py", "r", encoding="utf-8", newline="") as f:
+    content = f.read()
+
+# Add debug to _cb_plan_epic
+old = """def _cb_plan_epic(self) -> None:
+  def _bg_task() -> None:
+   sys.stderr.write("[DEBUG] _cb_plan_epic _bg_task started\\n")
+   sys.stderr.flush()
+   try:
+    self._set_status("Planning Epic (Tier 1)...")
+    history = orchestrator_pm.get_track_history_summary()"""
+
+new = """def _cb_plan_epic(self) -> None:
+  def _bg_task() -> None:
+   sys.stderr.write("[DEBUG] _cb_plan_epic _bg_task started\\n")
+   sys.stderr.flush()
+   try:
+    self._set_status("Planning Epic (Tier 1)...")
+    # DEBUG: Check provider
+    import src.ai_client as ai_client
+    sys.stderr.write(f"[DEBUG] _cb_plan_epic: ai_client._provider={ai_client._provider}, _model={ai_client._model}\\n")
+    sys.stderr.flush()
+    history = orchestrator_pm.get_track_history_summary()"""
+
+content = content.replace(old, new)
+
+with open("src/app_controller.py", "w", encoding="utf-8", newline="") as f:
+    f.write(content)
+
+print("Added debug to _cb_plan_epic")