doc-sync-deferral-to-post-checkpoint-is-invalid

The stop hook blocks sessions that defer documentation updates to ‘post-checkpoint approval’ even when the rationale is ‘avoid double-rewrite.’ File writes require documentation sync in the same operation (Law 3). If checkpoint approval may alter content, update docs to reflect current known state — partial truth is better than stale truth. ‘Intentional deferral’ is not an acceptable justification.