Redaction
Redaction is the removal or obscuring of sensitive content from session data, either at capture time or from recordings that already exist. In replay practice, capture-time masking is the primary defense, and post-hoc redaction is the remediation path when something sensitive slipped through.
How it works
Post-hoc redaction rewrites stored event streams: locating the target content in full snapshots and every incremental event that touches it, replacing values, and re-persisting. It is harder than it sounds, because a value can appear in a snapshot, in input events, and in mutation events, and missing one copy fails the redaction. This asymmetry is the practical argument for masking-first architectures: deleting a whole recording is easy, surgically cleaning one is not. Redaction workflows still matter for incident response, data subject requests targeting specific content, and importing legacy recordings made with weaker capture rules.
Where you encounter it
Privacy incident runbooks, DSAR handling (see GDPR session replay), and vendor evaluations, where "can you redact from stored sessions" is a revealing question.