Roll back a Core cutover

Core meaning

Capability purpose: Return to a known governed operating state without hiding partial destination effects or creating dual authority.
Meaningful outcome: The canonical side and client path are restored or explicitly stabilized, partial effects are reconciled, and the rollback evidence is durable.
Boundaries — includes: rollback trigger, authority, write fencing, client reversion, delta reconciliation, destination disposition, unresolved effects, and rollback receipt.
Boundaries — excludes: normal cutover, source decommissioning, destructive cleanup of evidence, and pretending failed destination writes never occurred.
Terms and concepts: rollback is a governed transition outcome, not automatic deletion of the destination.

Actor: An authorized owner or transition coordinator.
Command / intent: Abort or reverse the cutover and restore the approved prior path.
Current state: A cutover is in progress or completed within an allowed rollback boundary, and rollback authority exists.
Policies / invariants: Only one canonical writer is active per governed flow; accepted writes are reconciled; partial destination effects remain traceable; rollback scope and data-loss risk are explicit.
Transition: Fence writes, reconcile deltas, restore client routing and canonical authority, and record destination state.
Result: A completed, partial, failed, or blocked rollback record.
Events / effects: May create remediation work and a renewed parity/cutover plan.
Unknowns: Rollback-window duration and automatic trigger conditions are profile-specific.

Conflict handling for writes accepted only by the destination requires implementation-specific policy.

Statement	Semantic class	Evidence status	Source / note
Rollback is an explicit governed alternative to cutover and preserves transition evidence.	rule/invariant	sourced	C20.