The full path a strength session takes to land on Garmin as a real activity — pipeline, the auth/session model, and the failure modes — at the level of detail you'd need to build it yourself.
A working, open-source integration with real users. This is exactly how it's put together, end to end, for anyone who wants to understand it or build their own.
The upload is ~20% of the work. This is the 80% — and none of it is in Garmin's docs.
The clean way to build this at scale
Everything here is reverse-engineered against Garmin's mobile endpoints. At production scale, the sanctioned route is Garmin's Connect Developer / Health API partner program: real, authorised write access, no cloud-IP problem, and no login proxy to keep alive. The reverse-engineered version is the map; the partner API is the road.
If there's one takeaway: the integration is 20% "upload a workout" and 80% the auth/session lifecycle, the exercise taxonomy, the merge-vs-duplicate decision, heart-rate backfill, and graceful partial failure. That's where the real engineering is.