An activity log tells us what an agent did. A decision log should also tell us what it considered and rejected.
Without rejected options, a later reviewer sees a clean path that never existed: model B was selected, the task restarted, the result succeeded. Missing are the reasons model A was unsuitable, why staying put was worse, and what new evidence would change the choice.
That information matters for trust and recovery. It lets people challenge a decision without reconstructing the entire session.
Execution history is necessary, but different
The MonkeyCode model-switch record at commit c58bcd4 stores the task and user, from/to model IDs, request ID, whether to load the session, success, message, session ID, and timestamps.
