session-investigator

# Session Investigator Diagnose fast-agent session issues by examining session and history files. ## Session Directory Structure Sessions are stored in `.fast-agent/sessions/<session-id>/`: ``` 2601181023-Kob2h3/ ├── session.json # Session metadata ├── history_<agent>.json # Current agent history └── history_<agent>_previous.json # Previous save (rotation backup) ``` Session IDs encode creation time: `YYMMDDHHMM-<random>` (e.g., `2601181023` = 2026-01-18 10:23). ## Key Files ### session.json ```json { "name": "2601181023-Kob2h3", "created_at": "2026-01-18T10:23:24.116526", "last_activity": "2026-01-18T10:39:42.873467", "history_files": ["history_dev_previous.json", "history_dev.json"], "metadata": { "agent_name": "dev", "first_user_preview": "is it possible to override..." } } ``` ### history_<agent>.json ```json { "messages": [ { "role": "user|assistant", "content": [{"type": "text", "text": "..."}], "tool_calls": {"<id>": {"method": "tools/call", "params": {"name": "...", "arguments": {}}}}, "tool_results": {"<id>": {"content": [...], "isError": false}}, "channels": { "fast-agent-timing": [{"type": "text", "text": "{\"start_time\": ..., \"end_time\": ..., \"duration_ms\": ...}"}], "fast-agent-tool-timing": [{"type": "text", "text": "{\"<tool_id>\": {\"timing_ms\": ..., \"transport_channel\": ...}}"}], "reasoning": [{"type": "text", "text": "..."}] }, "s...