[BUG] Worker launches fail when gpt-5.4-mini is unavailable for account

What version of Codex is running?

codex-cli 0.114.0

What subscription do you have?

Pro

Which model were you using?

gpt-5.4-mini (as worker model)

What platform is your computer?

macOS Tahoe v26.3.1

What issue are you seeing?

Worker agent launches fail because gpt-5.4-mini is not available in the account context. The CLI attempts to spawn workers using this model but the API rejects the request, causing the worker to fail entirely rather than falling back to a supported model.

Thread ID: 019cfcc8-2459-7b50-8444-8ca94167bb4f

What steps can reproduce the bug?

1. Run codex CLI v0.114.0 with a Pro subscription
2. Trigger a task that spawns worker agents
3. Workers attempt to use gpt-5.4-mini
4. Worker launches fail because the model is not available for the account

What is the expected behavior?

The CLI should either:

• Validate model availability before attempting to spawn workers
• Fall back gracefully to the default worker model (or another available model) when the requested model is not accessible in the account context

Additional information

• Workaround: manually retry with the default worker model and continue locally in parallel
• The model picker / worker model config does not appear to validate whether the selected model is actually available for the user's subscription tier