The release gate's own output caught this: every test brain printed
"[VFS] old-root sweep complete in 1ms and recorded" — hundreds of lines — and
a consumer would get two of them on the first open of every store.
They were emitted on the always-visible channel, which a production log level
deliberately CANNOT silence. That channel exists so an operator can always
learn why a database is slow; a 0ms no-op on a fresh store is not that, and
announcing it there trains people to ignore the one channel built to be
impossible to ignore. It was also inconsistent with every other narration in
this work, all of which is silent under a threshold.
The sweep now speaks when it has something to say — duplicate roots removed, or
a wall over a second that a person watching a slow first open deserves
explained — and otherwise does its work, records its marker, and stays quiet.
cleanupOldRoots() reports what it removed so the decision rests on a fact
rather than on a guess.
Pin: a fresh store's sweep emits nothing on the channel and still records its
marker, so the silence can never be mistaken for the work being skipped.
MEASURED on a 14,056-noun / 72,679-verb production-shaped store, measured
solo under an exclusive lock: the vfs-bootstrap phase cost 43,021 ms of a cold open and 52,696 ms of
a WARM REOPEN. What dominates it is a migration sweep — a filtered find() over
the whole store hunting for root directories created before the fixed root id
existed. A store either carries such duplicates or never will, and the sweep
ran on every open, forever, in the foreground.
It is now caused by the store's state instead of by the open count: a durable
marker under _system/ records that the sweep has run, and a store carrying it
never sweeps again. A store without one sweeps in the BACKGROUND — the sweep
only removes duplicate roots, nothing serves from them, and it was already
declared non-critical — narrated at both ends, with whenRootSweepSettled() for
anyone who needs to observe rather than race it. An adapter with no raw-object
door keeps the old behaviour: correctness over cost, never a silent skip.
Pins: tests/integration/vfs-root-sweep-once.test.ts — the sweep runs on the
first open and never on the second or third; a sweep slowed to 4s does not
delay the open.
