Add dedicated reasoning-depth hotkeys, non-semantic depth meter, and next-turn-safe switching

[oxysoft]

Summary

Codex should support dedicated reasoning-depth controls that are fast enough for frequent use, visually legible at a glance, and safe to use even while a turn is already in flight.

Problem

Right now, going through /models to change reasoning depth is too slow for something users may want to adjust constantly.

There are three related UX gaps:

1. no dedicated shortcut for changing reasoning depth quickly
2. the current semantic reasoning indicator is not the right mental shape for fast control/recognition
3. commands are blocked during inference, so model/reasoning changes cannot cleanly participate in a fast adjust -> abort -> resume workflow

Requested behavior

• add a dedicated shortcut for changing reasoning depth quickly, separate from the slower /models flow
• optionally keep model selection and reasoning-depth selection as distinct controls/keymaps
• add a non-semantic visual reasoning-depth indicator, for example:
  • [◉···]
  • [◉◉··]
  • [◉◉◉·]
  • [◉◉◉◉]
• make the control work as a fast "control room" lever rather than a menu-heavy flow

Inference-safe switching semantics

If the user changes model or reasoning depth while a prompt is already running:

• do not change the in-flight request mid-execution
• the active turn should keep the model/reasoning configuration it was started with
• the newly selected model/reasoning depth should be staged for the next turn

This implies the model/reasoning config is effectively cached/snapshotted when a prompt is sent.

Why this matters

This unlocks a much cleaner workflow:

• adjust depth/model quickly
• abort if needed
• resume/continue without retyping

The broader point is that model/reasoning controls should feel like immediate cockpit switches, not buried menu actions.

Success criteria

• users can change reasoning depth with a direct shortcut
• the visual indicator is quickly readable without parsing semantic labels
• changing depth/model during inference does not mutate the running request
• the next-turn behavior is deterministic and visible to the user

Related context

Existing shortcut requests:

• [FEATURE] Keyboard shortcut to switch models while composing prompt #9807
• Keyboard shortcut to switch models and thinking #12915

This issue broadens those requests with:

• a dedicated reasoning-depth UX
• a non-semantic indicator
• safe staging semantics for in-flight turns

[github-actions]

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

• Keyboard shortcut to switch models and thinking #12915
• Queue /fast while running #14081
• Add Fast Mode Status #14159

Powered by Codex Action

[oxysoft]

One more connection: this pairs very naturally with the continuation/resume UX discussed in #14041 and #14042.

If model/reasoning changes are next-turn-safe, then the control flow can become much cleaner:

• adjust model/depth quickly
• abort if needed
• resume/continue without retyping

That seems like a much stronger mental model than forcing users back through /models plus manual prompt editing every time they want to steer the current thread.