- Implement automatic agent/model selection for new sessions (first agent, prioritize Anthropic default)
- Extract and restore agent/model from last assistant message when resuming sessions
- Add subagent support: child sessions can select subagents, parent sessions cannot
- Display subagent badge in agent dropdown for identification
- Truncate agent descriptions to 50 characters in dropdown
- Improve model search to include full provider/model ID path
- Auto-select input text on focus for easy model search
- Add getDefaultModel() with priority: agent model → Anthropic → first provider
