gpt-5-mini is not persistent set for future sessions

[luis-baquero-dnv]

Describe the bug

Model selection not persisted: after running /model gpt-5-mini, the selection is active for the
current session, but after closing and reopening the Copilot CL,I the model reverts to claude-sonnet-4.6 instead of
persisting "gpt-5-mini".has reverted; expected behavior is that the chosen model persists across sessions; it occurs every time.

Affected version

GitHub Copilot CLI 0.0.422.

Steps to reproduce the behavior

(1) run "/model gpt-5-mini"
(2) close the terminal
(3) reopen Copilot

and observe that the model is changed and not gpt-5-miniany longer

Expected behavior

If the user previously selected the gpt-5-mini model using the coman /model command, then for all future Copilot CLI sessions, gpt-5-mini should be set as the default model unless changed again. This ensures continuity in model selection based on the user's last explicit choice.

Additional context

No response

[luis-baquero-dnv]

I created a .bat file to launch Copilot with the gpt-5-mini model, so I don't have to switch to a free model manually

@echo off
powershell -NoProfile -ExecutionPolicy Bypass -NoExit -Command "copilot -i '/model gpt-5-mini'"

[tangrufus]

Encountering the same issue.

Steps:

1. add "model": "gpt-5-mini" in ~/.copilot/config.json.
2. run $ copilot (without --model gpt-5-mini)

Expected Behaviors:

1. Boot with gpt-5-mini
2. ~/.copilot/config.json remains unchanged

Actual Behaviors:

1. Boot with Claude Sonnet 4.6
2. ~/.copilot/config.json got reverted. model is removed.

Copilot itself said it's probably because of some sanitation and/or validation, but provided no solutions.

[cyberjob001]

Encountering the same issue.

added "model": "gpt-5-mini" in ~/.copilot/config.json.
start copilot (without --model gpt-5-mini)

Expected Behaviors:
Boot with gpt-5-mini
~/.copilot/config.json remains unchanged

Actual Behaviors:
Boot with Claude Sonnet 4.6
~/.copilot/config.json is auto updated and the model is being removed.