Model selection via /model affects all concurrent sessions instead of being per-session

When changing the model in one Claude Code session using /model, the status line updates across all other running sessions. Expected behavior would be for each session to maintain its own independent model selection.

Steps to reproduce

1. Open two or more concurrent Claude Code sessions
2. In one session, run /model and select a different model
3. Observe that the status line in all other sessions also reflects the change

Expected

Each session maintains its own model independently.

Actual

Model change propagates to all sessions.