desfazer-refazer-colaborativo-seletivo

Maintain a separate undo stack per client that logs local transactions with affected character IDs and vector clocks. On undo, generate an explicit counter-operation (delete inserted IDs or re-insert deleted IDs) and propagate it as a normal CRDT change rather than moving a global history pointer.

Tag AI-inserted transactions with an author-type metadata label such as AI_CO_WRITER. When the writer rejects a suggestion, scan the transaction log and issue counter-operations only against the character IDs of that AI block, preserving concurrent human edits.

This happens when the editor uses a single global undo stack on the server, so the last operation undone belongs to whoever typed most recently. The fix is isolating undo queues per client replica so each user's Ctrl+Z only affects their own client_id operations.

Yes, the Yjs UndoManager tracks local-origin transactions and can serve as the v1 fallback for linear per-client undo. Selective non-linear rollback of arbitrary AI blocks requires the custom counter-operation approach described in this skill.

Re-inserting deleted text while preserving original character IDs can cause complex interleaving behavior in late merges. The skill recommends falling back to simple linear local undo for v1 and notes it should not be used for LGPD permanent deletion or full-chapter version restores.