- teach.py: use _proxy_model() + pass api_key/api_base from settings (fixes LiteLLM provider error for openrouter/bedrock models)
- teach.py: accept model_id in ChatRequest so frontend can select model
- main.py: remove titan-embed-v2 from general seed, auto-delete legacy entry on startup
- main.py: kill stale idle-in-transaction DB connections at startup to prevent DDL lock hangs
- main.py: set lock_timeout=10s on DDL connection as fast-fail safety net
- TeachChat.jsx: fetch /teach/models, show selector dropdown in header when >1 model available
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>