`integrations/sync-kit/after-write.ts` is the tail every provider write
ends in: the arrivals go out, the touched days are refolded, the read
caches are marked stale back to the earliest touched reading, and the
touched status cards are re-warmed (through `afterMeasurementMutation`,
shared with the interactive routes); Withings also evicts the dashboard
snapshot. A full-history backfill refolds its whole touched range once
through `afterProviderBackfill`.
Withings, WHOOP, Polar, Nightscout, Google Health, Fitbit and Oura drop
their hand-written tails, and no provider module imports the comprehensive
insight generator any more; a guard holds the provider folders to that.
Differences from the copies: the status cards are re-warmed even when the
fold failed, and the caches are marked stale back to the earliest touched
reading instead of wholesale, so older closed blocks survive a sync.
Several provider unit tests mocked an export the old tails never reached
(their failures were caught and only logged); the mocks now name what the
code calls.
