Optional persistent Codex session per GitHub pull request

[enesoz]

Problem

Each new @codex mention on a pull request starts a new Codex task/session. During an iterative review cycle, this fragments context and creates repeated tasks.

Proposal

Add an optional “one persistent session per pull request” mode for Codex GitHub code review:

• Key the session by repository + PR number.
• Reuse the same Codex task for subsequent @codex comments on that PR.
• Serialize concurrent events for the same PR and deduplicate repeated webhook/comment events.
• Refresh the PR head SHA, review threads, and CI status on each turn.
• Archive the task when the PR is closed or merged, and create a replacement only when the original expires or is archived.
• Make the behavior configurable per repository/workspace, with an opt-out if needed.

Benefit

This would preserve context across review iterations, reduce duplicated setup and token overhead, and make the review → fix → re-review workflow more coherent.

Using the same comment thread or enabling Automatic reviews can help, but neither provides one persistent conversational task for the PR.

Could this be considered for Codex GitHub integration? If there is an existing setting, related discussion, or tracking item, please link it.