/model thinking effort level resets between sessions

Bug

The /model command allows setting a thinking effort level (e.g., auto, low, medium, high). This setting does not persist between sessions. After setting it to auto in one session, starting a new session reverts it to medium.

Expected behavior

The thinking effort level chosen via /model should persist across sessions, similar to how the model selection itself is remembered.

Steps to reproduce

1. Run /model and set thinking effort to auto
2. Confirm it's set (works correctly within the session)
3. End the session
4. Start a new session
5. Run /model to check the current setting
6. Observe: effort has reverted to medium instead of auto

Environment

• Claude Code CLI (latest)
• macOS
• Model: Opus 4.6 (1M context)