> For the complete documentation index, see [llms.txt](https://docs.tryterra.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tryterra.co/faq/help-topics/data-api-sdk/historical-data-and-backfill/mobile-native-no-backfill-sdk-fetch.md).

# When is historical data available after connect?

[Mobile-native sources](https://docs.tryterra.co/health-and-fitness-api/mobile-only-sources) read from data stored on the user's phone, not a cloud history.

* **Apple Health** does not auto-backfill on connect. The app must call the SDK fetch methods (`getActivity`/`getDaily`/`getBody`/`getSleep`) with a date range, and a completion callback signals when history is pushed.
* **Samsung Health** likewise syncs forward from the link date. To pull older data, use the same SDK date-range methods at connection time, but reach is limited to the recent window Samsung Health still holds on the device, not the full lifetime.
* Each relink starts a fresh connection with a **new Terra user ID**, so older data sits under earlier connection instances.
* **Cloud providers** (Oura, Fitbit, Google Fit, WHOOP, Strava) backfill automatically, usually within an hour or two. Garmin is the exception, with no server-side backfill trigger.

The REST API returns what the device has already pushed, and `end_date` is **exclusive** (use the next day to capture a full day).