# Rollback

Before the core boundary, R08 removes only the synthetic proof peer if present, restores the baseline lifecycle-library content and dynamic peer-state backup, and deliberately restores the library to canonical executable mode 0775 instead of recreating the known R01 mode residue. It reapplies selector/activity renderers and fail-closed verifies: baseline lifecycle-library SHA256, executable mode 0775, zero runtime/registry/selector membership, and a clean explicit HEAD-to-worktree Machine Git diff.

This rollback semantics is intentional: the incoming mode 0644 is proven to be residue from failed R20QZB R01, not the authoritative `c401f82...` baseline. A rollback must return to the authoritative baseline rather than preserve that known residue.

If postcheck succeeds, `CORE_CHANGE_COMPLETE=true`; later source/report publication failures must not roll back the proven lifecycle fix.

R09 rollback uses scripts/vm100-backup-restore.sh restore and returns the exact proven pre-state mode 0644; it does not partially repair mode on failed core.