Oura, Polar, WHOOP and Strava each keep the transport and endpoints in
`client.ts` and gain `wire-types.ts` (the record shapes) and `map.ts` (the
pure record-to-row mappers, no I/O). Google Health's 1,600-line client
becomes `budget.ts` (slice budget and outcome tally), `request.ts` (error
detail, retry, rate limits), `data-points.ts` (the paginated walker) and a
small `client.ts` for the profile and roll-up reads; its `export * from
"./mappers"` facade is gone and its importers name the module that defines
what they use.
The code moved verbatim; the mapper goldens written before the move and
the provider integration tests pass unchanged.
A full-history backfill read every heart-rate point of an account into one
array, mapped it into a second, and wrote the lot in one call; the cycle's
deferred-rollup ledger then kept one entry per written reading. On a watch
that records a reading a minute that is over a million points, and the
backfill ran a 1 GB heap out of memory within seconds, restarting the
instance it shares with the app (#1023).
The metric walk now hands each page to its write before requesting the
next, and both the Google Health and Fitbit ledgers collapse to one key per
touched type-day as they record. The heart-rate walk's page ceiling rises
from 1000 to 10000: at one point a minute the old ceiling is under two
years, a longer history always ended truncated, and the backfill retried
the whole walk on every attempt and every boot without completing.
Marc-André Bombeck