Three §7a.1 run-1 lessons (kernel-scale 2c/6GB: EXIT=137, WAL 22.2GB with
the backpressure hook DEPLOYED):
1. TRUNCATE at parked barriers: a completed passive backfill bounds the
un-checkpointed backlog but the FILE only stops growing when a commit
finds zero readers holding WAL marks — rare while pool workers cycle
(dubbo debug baseline: file climbed monotonically through six completed
pass-1 backfills). At a parked barrier the no-reader window is
guaranteed, so chop the file there with wal_checkpoint(TRUNCATE)
(off-thread, 2s busy_timeout — a racing reader degrades it to a no-op).
2. Futility latch: when backfill gives up (pinned reader), parking again at
every over-cap boundary burns a 20-pass checkpoint attempt — each a
worker thread + fresh connection against a multi-GB DB — per batch. Two
consecutive give-ups now disable parking for 60s; a pinned phase degrades
to pre-valve behavior instead of OOM-amplifying.
3. CODEGRAPH_WAL_VALVE_DEBUG=1 surfaces valve decisions without the
caller's verbose plumbing, and give-up lines print under
CODEGRAPH_SYNTH_TIMINGS — run 1 failed silently because give-ups were
verbose-gated.
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
8c1e821495