Backport-of: c590a01f33
Protect the existing release-line repair d33f81709e for candidate regression #1882 across repeated registry rebuilds and SQLite close/reopen. No runtime or product scope change.
Validation: focused test passes; restoring rebuild timestamps fails with 18 samples instead of 3; lifecycle and canonical-storage tests pass three race repetitions.
Contract-Neutral: regression coverage for existing observation-time behaviour.
Change-source: pulse-maintainer
pulse-triage[bot]
141d578535