The 2026-07-18 storage migration reset every row's system Timestamp,
exposing that AuditLogs, OpsEvents and Events displayed, filtered and
retention-swept on it (custom "Timestamp" writes were silent no-ops —
reserved system property). All migrated rows read as 2026-07-18.
- New Helpers/BusinessTimestamp: RowKey decoders (audit !revtick_guid,
ops bare revtick, event yyyyMMddHHmmssfff_seq), RowKey-range OData
clause builders (tick-exact, with the mandatory RowKey lt '"' guard
so no lower bound can ever match legacy bare-GUID audit rows), and
dual DateTimeOffset/DateTime column reads.
- Writes in all three tables now persist OccurredUtc (custom column,
copied verbatim by future migrations); no-op ["Timestamp"] removed.
- Read mappers resolve OccurredUtc -> RowKey decode -> system Timestamp;
GetEarliestSessionEventTimestampAsync uses the same resolution so
StartedAt/Duration reconciliation can no longer absorb the migration
date on migrated sessions.
- Date-window filters and retention moved off the system Timestamp onto
RowKey ranges; ops retention loses its full-table scan and the
post-migration mass-delete cliff; audit retention runs a temporary
second pass for legacy GUID rows (TODO: remove after 2027-03-01).
- New GlobalAdmin backfill endpoint POST /api/maintenance/
backfill-occurred-utc (dry-run by default, batched, idempotent MERGE
of only OccurredUtc, table=audit|ops) — Events rows are deliberately
never mutated; their read path decodes the RowKey instead.
- Tests: decoders, clause boundary proofs incl. GUID-safety pins,
mapper precedence, backfill row decisions (Functions.Tests 3078).
- Docs: docs/backend/business-timestamps.md (system Timestamp is never
authoritative; migration checklist rule).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Oliver Kieselbach