All packsPlay Billing MachinerySolve
rtdn subscriptionnotification no subscriptionid field training data
Most tutorials show a subscriptionId field that no longer exists
subscriptionNotification is {version, notificationType, purchaseToken} -- there is no subscriptionId field any more, though most training data and tutorials still show one (decision 9).
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?
Code written to read notification.subscriptionNotification.subscriptionId compiles, types, and looks correct against most existing tutorials and sample code -- and reads undefined against the actual current payload shape, because that field doesn't exist. oneTimeProductNotification has the same trap in the other direction: it names the product sku, not productId.
Why this one is easy to get wrong
The field existed in the older RTDN shape, and a large share of indexed tutorials and sample repositories still show it, so training data reflects a payload Google has since simplified. Nothing about the field's absence throws an error -- it's just missing, and TypeScript won't catch a field name that was never in the type to begin with unless the type is written from the current reference.
What you get instead
The adapter is written against the current, verified shape: DeveloperNotification = {version, packageName, eventTimeMillis, <one of>} where the one-of is subscriptionNotification | oneTimeProductNotification | voidedPurchaseNotification | pendingRefundReviewNotification | testNotification -- the fifth member most integrations have never heard of. purchaseToken, not subscriptionId, is what every downstream lookup joins on.
Source: ARCHITECTURE.md decision 9 — 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 →