Resuming a session has strange ux with regards to model and reasoning #4340

Describe the bug

If you have a session that's was done on gpt-5.6-terra with medium, and you --resume it, with either --model=gpt-5.6-luna --reasoning-effort=xhigh or gpt-5.6-luna + xhigh in your ~/.copilot/settings.json, the reasoningEffort is honoured, but the model is not, and your resumed session will be on gpt-5.6-terra xhigh

Feels like this should be consistent? It should either:

• Explicitly honour the original session, keeping the settings the same
• Explicitly honour your copilot CLI args and/or settings.json

I would rather the latter personally, but raising this as a UX bug.

This also affects sessions resumed via copilot-sdk.

Affected version

1.0.77

Steps to reproduce the behavior

No response

Expected behavior

No response

Additional context

No response