The upload loop previously always slept the full 30s UPLOAD_INTERVAL
between batches, even when a full batch was just sent (meaning more
rows were likely still queued). With GPS/OBD rows logged every 5s
locally, an offline/stale device could build up a large backlog that
took a very long time to drain at 100 rows/30s.
- Bump TRACKING_BATCH_SIZE 100 -> 500 (cuts round-trips per backlog).
- Only sleep the full UPLOAD_INTERVAL once actually caught up (a
short batch came back); while a full batch keeps coming back, drain
back-to-back with a short CATCHUP_INTERVAL (1s) instead.
- server/app.py: add a sane MAX_TRACKING_BATCH_POINTS (5000) cap on
the tracking/batch endpoint as a defensive guard against a runaway
client, independent of the Pi's own batch size.
Verified against the real deployed server: a simulated 1250-row
backlog now drains in 3 batches (~0.35s server round-trip time) instead
of 13 batches spread across ~6.5 minutes of idle sleeping.
Co-authored-by: Copilot <[email protected]>
