- Expand validate_config_structure() to catch:
- fallback_providers format errors (non-list, missing provider/model)
- session_reset.idle_minutes <= 0 (causes immediate resets)
- session_reset.at_hour out of 0-23 range
- API_SERVER enabled without API_SERVER_KEY
- Unknown root-level keys that look like misplaced custom_providers fields
- Add _validate_fallback_providers() in gateway/config.py to validate
fallback chain at gateway startup (logs warnings for malformed entries)
- Add API_SERVER_KEY check in gateway config loader (warns on unauthenticated endpoint)
- Expand _KNOWN_ROOT_KEYS to include all valid top-level config sections
(session_reset, browser, checkpoints, voice, stt, tts, etc.)
- Add 13 new tests for fallback_providers and session_reset validation
- All existing tests pass (47/47)
Closes#328
992498463e