Add explicit no-prune retention mode for archived local sessions #37435

What variant of Codex are you using?

CLI

What feature would you like to see?

Add an explicit retention policy for local session rollouts, including a disabled/unlimited mode that guarantees Codex will not automatically delete or prune archived or old session files. The policy should keep lightweight history.jsonl retention separate from full rollout retention under $CODEX_HOME/sessions and $CODEX_HOME/archived_sessions. If cleanup is opt-in, document the scope clearly and make age/size-based cleanup explicit and reversible where possible.

Additional information

Observed on Codex CLI 0.147.0 on macOS. The documented history settings cover history.jsonl (history.persistence and history.max_bytes), but there is no documented setting for full archived rollout retention. codex doctor reports active and archived rollout stores separately. Affected thread ID: 019fdbfa-01d9-7811-ab79-14669e54f3a2. Related issues: #6015, #28187, and #37216.