Codex App Fast Mode should be configurable per thread/session instead of globally

What variant of Codex are you using?

Codex App

What feature would you like to see?

Fast Mode in the Codex App currently behaves like a global setting, including for remote chats. I would like Fast Mode / priority to be configurable per thread or per session instead.

I am on a Pro 200 subscription, where Fast Mode/high-priority usage is useful but should be applied deliberately. The current global behavior is awkward when running multiple conversations at once. Some sessions should run at normal priority, while others should be high priority / Fast Mode. This is similar to how multiple Codex CLI sessions can be run with different priority/service-tier choices depending on the task.

A better behavior would be:

• Allow each new chat/thread to choose normal vs Fast Mode priority.
• Preserve that choice on the thread/session rather than applying it globally to all Codex App chats.
• Include remote chats in that per-thread behavior, so enabling Fast Mode for one remote chat does not force every other remote/local chat into Fast Mode.
• Optionally keep a global default, but let the user override it per thread/session.

Additional information

I searched for related issues before filing. The closest existing issue I found is #2916, which asks for OpenAI service tier support mostly around CLI/config. This request is specifically about Codex App Fast Mode being global across app chats, including remote chats, and needing per-thread/per-session control.

Other related but different issues:

• #18841 was about Fast Mode disappearing from settings/chat.
• #14593 is about token/usage burn rate.