Each of the 4 stage workers (library walk, MBID backfill, cover
enrich, artist art enrich) gains a progressCb parameter that
receives a snapshot of the current running state per item processed.
The orchestrator stores the snapshot in a local var that the
publisher's marshal closure reads at flush time.
scanrun.go's 4 stage blocks are rewritten to construct one publisher
per stage, pass a Tick-firing closure to the worker as progressCb,
and call Flush() after the worker returns (routing any persist error
to captureErr — preserves today's diagnostic behavior).
The previous post-stage UpdateScanRun* calls are removed; the
publisher's Flush handles the final write. Cadence: every 500 items
OR every 1s, whichever fires first.
Outside-orchestrator callers (scanner_test.go, enricher_test.go)
pass nil for progressCb — no-op behavior preserved for tests that
don't need progress observability.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
bvandeusen
3e9e46f190