HTTP intake, buffered

Do the Fly.io setup first.

Devices POST JSON, one reading or a list. The web process keeps readings in memory and appends them every 10 seconds, so a thousand devices sending once a second still make one commit every 10 seconds. A reading is visible to queries at most 10 seconds after it arrives.

The cost is that readings in memory are lost if the Machine crashes or its host fails: up to FLUSH_SECONDS of data. A normal stop flushes them. auto_stop_machines = "off" keeps the Machine running so the buffer isn't emptied and refilled with each idle period; "stop" also works, because a stop sends kill_signal first.

This is the default (INTAKE=memory). Try it:

curl -X POST https://$APP.fly.dev/readings -H "authorization: Bearer $INGEST_TOKEN" \
  -d '[{"time": "2026-01-05T10:00:00Z", "device_id": "pump-1", "temp": 61.2, "humidity": 40},
       {"time": "2026-01-05T10:00:00Z", "device_id": "pump-2", "temp": 58.9, "humidity": 42}]'
sleep 10
timelake latest iot.readings