Root cause: bot_flow.py injected configs.args.global_start_time = datetime.now()
which polluted the args namespace. SessionStateEncoder blindly serialized
args.__dict__ via json.dump, which crashed mid-write on the datetime object,
leaving sessions.json truncated/corrupt. Every subsequent restart failed.
Fixes:
- Remove global_start_time from configs.args (only lives on engine class vars)
- Harden SessionStateEncoder with _sanitize_value() to convert any
non-JSON-serializable type (datetime, timedelta, arbitrary objects) to strings
- Add test_system_session_persistence.py with 4 tests covering the exact
production crash scenario (datetime injection → json.dumps → round-trip)
- Fix test_engine_timeout.py broken GoalExecutor module reference
Marc Mintel
4af4ddb060