Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add RevenueCat/play-billing-skills --skill rtdngit clone --depth 1 https://github.com/RevenueCat/play-billing-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/revenuecat/play-billing-skills/rtdn)<a href="https://agentmods.dev/skills/revenuecat/play-billing-skills/rtdn"><img src="https://agentmods.dev/badge/skills/revenuecat/play-billing-skills/rtdn/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/revenuecat/play-billing-skills/rtdn"><img src="https://agentmods.dev/badge/skills/revenuecat/play-billing-skills/rtdn.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00056 | $0.02585 |
| Opus 5 | $0.00028 | $0.01293 |
| Sonnet 5 | $0.00011 | $0.00517 |
| Haiku 4.5 | $0.00006 | $0.00259 |
Grade A, and why
rtdn scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 13d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 233 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Real Time Developer Notifications (RTDN)
RTDN pushes subscription and purchase state changes from Google Play to your backend within seconds. Use it as the primary signal for entitlement updates; polling the Play Developer API on a schedule is a fallback, not a substitute.
Phase 1: Understand
Pin down the following before you write code:
- What triggers a notification. Google Play publishes a message to a Cloud Pub/Sub topic you own every time a subscription or one time product changes state (renewal, cancellation, refund, hold, pause, revocation, price change confirmation, etc.).
- What the notification contains. A
DeveloperNotificationJSON object withpackageName,eventTimeMillis, and exactly one ofsubscriptionNotification,oneTimeProductNotification,voidedPurchaseNotification, ortestNotification. It carries apurchaseTokenand a type code, not the full purchase state. - Who owns what. You own the Pub/Sub topic and subscription in your own Google Cloud project. Google Play only has publish rights.
- Delivery semantics. Cloud Pub/Sub guarantees at least once delivery and does not guarantee ordering. Duplicates and out of order messages are normal.
- The golden rule. RTDNs are signals, not sources of truth. For every notification, call
purchases.subscriptionsv2.getorpurchases.products.getand update entitlements from the API response, not the notification type.
Decide push vs pull:
| Strategy | Pick when |
|---|---|
| Push subscription | You have a public HTTPS endpoint and want a webhook style integration with retries handled by Pub/Sub |
| Pull subscription | Your backend has no public URL, needs batch processing, or wants fine grained control over consumption rate |
Push is the simpler default. You can swap strategies later without changing the Play Console configuration.
Phase 2: Plan
Write the plan before provisioning anything.
Infrastructure checklist
- One Pub/Sub topic (example:
play-billing-notifications). One topic handles subscriptions, one time products, and voided purchases. - One subscription attached to the topic with an appropriate
ack-deadline(60s is a reasonable starting point). - IAM binding granting
roles/pubsub.publisherto[email protected]on the topic. - Play Console Monetization setup pointing at
projects/YOUR_PROJECT_ID/topics/play-billing-notifications. - A test notification fired from the Play Console to confirm end to end wiring.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 13d ago First seen · 233 lines · 56 tokens per session scan A b45bc8334dd3
rtdn is a skill published in the GitHub repository RevenueCat/play-billing-skills (53 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 56 tokens to every session and 2,585 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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