Summary

After changing the primary model in openclaw.json, existing sessions remain stuck on the old model (in my case delivery-mirror), causing empty responses in the Chat UI.

Steps to Reproduce

1. Have an active session running with model A
2. Change model.primary in openclaw.json to model B
3. Restart gateway (pkill -USR1 openclaw-gateway or openclaw gateway restart)
4. Send a message in the existing session via Chat UI

Expected Behavior

Session should pick up the new model from config after gateway restart.

Actual Behavior

• Session remains stuck on old model (delivery-mirror in my case)
• Agent runs and completes (logs show run_completed with duration)
• But response text is empty in the UI
• openclaw sessions list shows the session still using the old model

Workaround

Delete the stuck session file manually:

rm ~/.openclaw/agents/main/sessions/<session-id>.jsonl
openclaw gateway restart

Then create a new session.

Environment

• OpenClaw version: 2026.2.1
• macOS
• Gateway mode: local

Additional Context

The CLI works fine (openclaw agent --message "hi" returns proper response), confirming the config is correct. Only the persisted session in the UI was affected.