checkSyncFreshness now reports an actively-running sync via the live
per-source lock (names holder pid+host, counts as synced_recently) instead
of flagging it stale; loadOpCheckpoint gates the legacy union arm on
jsonb_typeof = 'array' so a scalar parent can't take down the whole load,
and migration v119's CHECK constraint makes the corruption class
structurally impossible. Reference docs describe current behavior only —
both entries updated in place, no release-clause appends. Guard + llms
freshness test green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>