Allow configurable reasoning efforts for Review Mode

[voctory]

What feature would you like to see?

The reasoning effort for the /review command was hardcoded to Low in this PR: #3701

From the PR alone, it's not clear why the review mode reasoning effort was set to Low. Proposing to allow a user-configurable reasoning effort, either by:

1. Inheriting the current reasoning effort from the thread's config.model in codex-rs/core/src/codex.rs
2. Creating a user preference for review mode reasoning effort in config.toml
3. (if it's preferred to not allow configurability): At minimum, consider bumping the reasoning effort to Medium for more dynamic reasoning

From a local POC, it seems like approach 1 works well and creates much more comprehensive reviews than before (gpt-5.1-codex-max, xhigh effort inherited)

I'd be happy to raise a PR for this, seeking alignment first.

Additional information

No response

[rahul810050]

Hii @voctory !!

Proposed Approach

I’d like to implement this by removing the hard-coded Low reasoning effort in the review-thread setup and letting /review inherit the current session’s model_reasoning_effort from Config.

Implementation outline:

1. In codex-rs/core/src/codex.rs, inside the review-thread creation (spawn_review_thread),
   delete the line forcing:

per_turn_config.model_reasoning_effort = Some(ReasoningEffortConfig::Low);

2. Allow per_turn_config to keep whatever reasoning effort is already set in the session config (config.model_reasoning_effort).
3. Keep model_reasoning_summary = Detailed (current intended review UX).
4. Add a small test ensuring /review uses the inherited reasoning effort when present.

This approach maintains backward compatibility, avoids new config keys, and immediately enables higher-quality reviews for users who already configure higher reasoning efforts.

I’m happy to open a PR once confirmed.