Model's injected self-identity isn't refreshed after a mid-session model switch (self-misidentifies; wrong git co-author trailer)

Preflight

• [x] Searched existing issues — did not find this one
• [x] Single bug report
• [x] Reproduced on a current version

Version

Claude Code 2.1.207 (running session; note the binary on PATH reported 2.1.208, so the installed and running versions can differ)

What's wrong

When the active model changes during a session, the identity injected into the model's context — the "You are powered by the model named X" environment block — is not updated. The model keeps believing it is the session's original model for the rest of the session.

Observed

• The session started on one model (Fable 5) and the active model later became another (Opus 4.8), confirmed by /model → "currently Opus 4.8".
• The model's injected context still stated the original model, so it continued to self-identify as that model — including stamping git commit Co-Authored-By: trailers as Claude Fable 5 on commits that were actually authored while running Opus 4.8.
• The model also dismissed the correct /model reading as an inconsistency, because its own context contradicted it.

Impact

• Incorrect commit attribution (Co-Authored-By: names the wrong model).
• The model answers "which model are you?" incorrectly.
• Any behavior keyed on model self-identity is wrong for the remainder of the session after a switch.

Note

/model reports the correct current model throughout — only the model's injected self-identity string is stale. So the fix is presumably to refresh that identity block when the active model changes mid-session (the same way /model already knows).