Review agent turns and keep or undo file changes with a cross-turn tracker and per-file diffs. Write modes: disabled (default), fixture (allowlist-scoped), or enabled (real projects). All write modes run the same safety gates: complete before/after capture, CAS/live-match, ambiguity, repo identity, writer-active. After a Deny the change can be restored and re-opened for accept/deny until the next turn. Resolved reviews, backups and ops are pruned by retention/per-project cap GC.
