MEASURED on a production store: a metadata provider that had to rebuild made
init() pay the ENTIRE rebuild on the foreground — 641 seconds — with every
other family idle behind it. The cause is a missing distinction: a provider
reporting serving:false because it is BUSY BUILDING ITSELF and one reporting
serving:false because it is BROKEN looked identical through healthReport(),
and both were answered the same way — call rebuild(), and wait for it.
The contract that tells them apart is one optional, synchronous, O(1) hook:
`rebuildInProgress(): ProviderRebuildProgress | null`, reporting a phase name
and whatever the provider actually measures (done/total/startedAt) — never an
estimate dressed as a fact. A provider without the hook behaves exactly as
before.
With it, a provider owns its own rebuild:
- the open gate neither starts a second rebuild nor waits for the provider's,
and narrates that it is not waiting and what will refuse meanwhile;
- init() returns and every other family serves;
- that family's doors refuse BY NAME, carrying the provider's own progress,
and say plainly that the door opens by itself and no action is needed —
distinct from a broken index, which names repairIndex();
- the epoch stamp does not advance while any family is still being built.
Nothing is ever served empty: a not-serving family refuses, as it already did.
Pins: tests/integration/open-does-not-wait-for-a-rebuilding-provider.test.ts —
init() returns in milliseconds against a provider claiming a 6s rebuild, brainy
starts no rebuild of its own, a filtered read refuses naming the phase and the
4,096/14,056 progress, and the door answers once the provider reports serving.
The pin fails loudly rather than vacuously if its stub never installs.
David Snelling
06d9475998