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

fix_show_track.py

@@ -0,0 +1,29 @@
+with open("src/app_controller.py", "r", encoding="utf-8", newline="") as f:
+    content = f.read()
+
+# Fix show_track_proposal handler to debug and handle properly
+old = """elif action == "show_track_proposal":
+     self.proposed_tracks = task.get("payload", [])
+     self._show_track_proposal_modal = True"""
+
+new = """elif action == "show_track_proposal":
+     # Handle both nested payload and direct list
+     raw_payload = task.get("payload")
+     sys.stderr.write(f"[DEBUG] show_track_proposal: raw_payload type={type(raw_payload)}, task={task}\\n")
+     sys.stderr.flush()
+     if isinstance(raw_payload, list):
+         self.proposed_tracks = raw_payload
+     elif isinstance(raw_payload, dict) and "tracks" in raw_payload:
+         self.proposed_tracks = raw_payload.get("tracks", [])
+     else:
+         self.proposed_tracks = []
+     sys.stderr.write(f"[DEBUG] show_track_proposal: final proposed_tracks={self.proposed_tracks}\\n")
+     sys.stderr.flush()
+     self._show_track_proposal_modal = True"""
+
+content = content.replace(old, new)
+
+with open("src/app_controller.py", "w", encoding="utf-8", newline="") as f:
+    f.write(content)
+
+print("Fixed show_track_proposal handler")