REPORTED from the field: a process holding many stores, with no writes for ten
minutes, printed "All indexes flushed to disk in 216-601ms" per store every
~35 seconds and burned over a core at idle. Every one of those flushes re-persisted
state identical to what was already on disk — the provider flushes, the
watermark stamps, the generation counter, the entity-tree stamp — because
flush() never asked whether anything had changed.
- flush() over a clean brain is now O(1) and silent: a dirty witness is set by
every committed write (both commit paths end at noteWriteForPersistence, and
the deferred-embed worker lands through the single-op path) and cleared by a
flush that runs. A write landing DURING a flush sets it again, so no write's
work is ever skipped — it is done by the next flush. Set before the policy
check, so a `'manual'` consumer's explicit flush is never a no-op it didn't
ask for.
- An explicit flush now tells the cadence it happened. It didn't, so the very
next write saw "30s since the last flush" and kicked a background flush with
nothing to do, and the idle timer fired two seconds later over writes the
explicit flush had already persisted.
- The graph adjacency index's auto-flush asks before it acts: two O(1) reads
of the LSM MemTables, and a tick over a quiet index returns without calling
into the trees at all.
assessProviderHealth is NOT timer-driven — it is a synchronous O(1) read of a
provider's own healthReport(), called on the read gate, so it costs nothing on
an idle brain. No change needed there.
Pins: tests/integration/idle-costs-nothing.test.ts — 90 idle seconds produce
zero flushes, zero provider calls and zero log lines; three explicit flushes
over a clean brain call no provider; one write earns exactly one flush.
David Snelling
f5a6cb3f61