Atomic Lua-driven snapshot mutation for the burst-buffer entry hash.
Returns one of three result codes per Q3:
- applied_to_snapshot: entry was QUEUED + not materialised; the
drainer will see the patched payload on its next pop.
- not_found: no entry hash for this runId.
- busy: entry is DRAINING / FAILED / materialised — the caller
wait-and-bounces through PG (helper lands in B5).
Four patch types:
- append_tags: union-merges into payload.tags, dedupes against
existing values.
- set_metadata: replaces metadata + metadataType (last-write-wins).
- set_delay: replaces payload.delayUntil.
- mark_cancelled: stamps cancelledAt + cancelReason; the drainer
bifurcation in Q4 reads these on next pop.
10 new tests cover: not_found, all four patch types (success +
absent-field handling), each busy state (DRAINING, FAILED,
materialised), and per-runId atomicity under 50-way concurrent
appends.
Dan Sutton
08f20c65f3