All packsPlay Billing MachinerySolve
pub/sub push ack deadline 10 seconds retry storm
Respond in 10 seconds, reconcile after -- or trigger a retry storm
The push ack deadline defaults to 10 seconds and can't be modified per-message; a 500 on one bad payload turns into an exponential-backoff retry storm (decision 4).
This is one of the things Play Billing Machinery already handles. Sell subscriptions in your Android app on the Billing Library version Google requires from 31 August 2026.
Is this you?
A handler that does real work -- querying the Play API, writing entitlement -- before acknowledging the push can blow past Pub/Sub's 10-second ack deadline under any load spike, and a 500 on a single unparseable payload triggers redelivery with exponential backoff, turning one bad message into a self-inflicted flood of retries against the same broken code path.
Why this one is easy to get wrong
Doing the real work inline, then returning success, is the natural way to write a webhook-shaped handler -- it reads as more correct, not less, because the response only goes out once everything is actually done. Nothing about a working demo under light load reveals the deadline until real traffic or a slow Play API call pushes past it.
What you get instead
The handler persists the delivery and returns 2xx immediately, then reconciles asynchronously. Ack codes are pinned to 102/200/201/202/204; unknown notification types and testNotification also return 200 rather than erroring, and only a genuinely malformed envelope returns 400 -- so novelty in Google's own notification catalogue is never mistaken for a failure worth retrying.
Source: ARCHITECTURE.md decision 4 — checkable in the pack you receive
How you actually use this
You don’t install a library or wire up an SDK. Your own coding agent builds the code in your project, and you keep it — no runtime dependency on us.
Step 1
Download and unzip
You get a folder: the docs that tell an agent what to build, a starting skeleton, and the test suite that decides when it's done.
Step 2
Open it in Claude Code or Cursor
Point your coding agent at the folder. Nothing to install, no account with us, no API key.
Step 3
Paste one prompt
The pack contains the exact prompt. Paste it as your first message and leave it alone — it works through the build itself, choosing a cheaper or stronger model per task.
Step 4
Run ./verify.sh
One command. It prints a pass or fail for every check. Green means the build is done — the same script we ran to produce the receipt on this page.
Typical build: about 33 minutes of your agent working, mostly unattended. Then you integrate the working module into your app the way you would any code you’d written yourself.
Why you can believe this
3 of 3 runs passedWe ran this pack from an empty folder 3 times and published exactly what happened — every check, the model, the token cost, the wall time. Not a testimonial, and not our opinion: the same verify.sh you run yourself. Read the full receipt →