[Bug] Model reverts to Sonnet after compact when multiple sessions exist with different models

Bug Description
if i have 2 sessions of claude code. the initial one was open with Opus, the second one was open with Opus but changed to Sonnet. Then i run compact in the first session, the model will change to Sonnet after compaction.

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.1.104
• Feedback ID: 15d7e6b4-b1f0-4b2e-9a17-dce3ebebae76

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/yaronharel/.local/share/claude/versions/2.1.104 (expected in multi-process scenarios)\n    at Tc_ (/$bunfs/root/src/entrypoints/cli.js:2836:2153)\n    at Se6 (/$bunfs/root/src/entrypoints/cli.js:2836:1233)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-13T08:01:35.310Z"}]