Possible: resume from the agents UI may apply the global default model instead of the session's (evidence withdrawn, needs verification)

Correction (filed by me, shortly after opening): the transcript trace in the first version of this report was misread and has been removed. See "Why the original evidence was withdrawn" below. Keeping the report open as needs verification — the symptom was observed in the UI, but I do not yet have a transcript that demonstrates it.

What I observed

Resuming an existing session from the claude agents UI, the resumed session appeared to
run on a different model than the session had been using before it was resumed, matching
the global "model" value in ~/.claude/settings.json rather than the session's own.

What I expected

Resume restores the model that session was last running. The global model setting should
apply to new sessions, not to resumed ones.

Why the original evidence was withdrawn

The trace I first posted showed a session on claude-fable-5-1, a resume, and then
claude-opus-5. Re-reading the transcript with the intermediate turns included:

[09-03T13:55] claude-fable-5-1
<<RESUME    09-04T02:48>>
[09-04T02:48] claude-fable-5-1     <- resume PRESERVED the model
[09-04T03:18] claude-opus-5        <- switch 30 minutes later, mid-session

The resume preserved the model; the switch happened half an hour afterwards and is
therefore a separate, mid-session change. I then checked every session active that day
(~10 sessions, several resumed multiple times per day over three weeks): every resume
shows the same model on both sides of the marker. So the recorded turns do not
reproduce the symptom.

What this might still be

If the discrepancy is real, it may live in the model the agents UI selects or displays on
resume rather than in the model recorded per turn — which a transcript would not capture.
Happy to close this if that is expected behaviour; otherwise I will attach a verified
trace (session id + timestamp of the resume, with before/after turns) the next time I
catch it.

Environment

• Claude Code 2.1.278
• macOS 27.0, node v24.3.0
• Relevant settings: "model": "opus", "switchModelsOnFlag": true