- backfillTotal: plain int64 → atomic.Int64 (written by goroutine, read by
stats handler — data race under -race)
- Collect all pending obs refs in a single pass upfront, then slice into
chunks. Eliminates repeated full-scan of store.packets per chunk.
- Check stmt.Exec error return instead of silently discarding it.
- Scope X-CoreScope-Status header to /api/ paths only (skip static files).