Codex carves out a 'Guardian' review subsystem in four hours of merges and fixes a context-reset leak in it

GitHub·medium signalXBlueskyLinkedInCopy link

On 2026-09-14 Codex merged #45413, #45417, #45418 and #45420, pulling Guardian transcript selection into a codex-guardian-context crate, conversation bookkeeping into the reviewer crate, and sampler execution into its own module. #45413 fixes the substantive bug: a summary-free parent context reset could reuse a Guardian review session and carry forward rationale from before the reset, so destructive history replacements are now tracked with a reset_version that is part of the session reuse key while ordinary input and compaction preserve it. #45417 adds a TranscriptMode::select API that falls back to the full transcript when the history version changes or a saved cursor exceeds the collected entry count.