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 understanding-revenuecatgit 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/understanding-revenuecat)<a href="https://agentmods.dev/skills/revenuecat/play-billing-skills/understanding-revenuecat"><img src="https://agentmods.dev/badge/skills/revenuecat/play-billing-skills/understanding-revenuecat/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/understanding-revenuecat"><img src="https://agentmods.dev/badge/skills/revenuecat/play-billing-skills/understanding-revenuecat.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 | $0.00064 | $0.01531 |
| Opus 5 | $0.00032 | $0.00766 |
| Sonnet 5 | $0.00013 | $0.00306 |
| Haiku 4.5 | $0.00006 | $0.00153 |
Grade A, and why
understanding-revenuecat 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 12d 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.
This is a copy
91% identical to rc-understanding-revenuecat — 10 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 143 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Understanding RevenueCat
Phase 0: Intent
Use this skill before writing any RevenueCat code. It gives you the vocabulary and mental model you need so that downstream skills (setup, configuration, purchase flow, entitlements) make sense.
Start here if any of these apply:
- You are new to RevenueCat or coming from a raw Play Billing integration.
- You are unsure which concept maps to which dashboard object.
- You need to decide which downstream skill to invoke for a specific user goal.
Skip this skill if you already know the difference between an Offering, a Package, a Product, and an Entitlement, and you already know that Purchases.sharedInstance is the single entry point.
Phase 1: Orient
Raw Android in-app purchases require three separate systems. RevenueCat folds all three into one SDK plus one dashboard.
| Raw Google Play stack | RevenueCat replacement | Where it lives |
|---|---|---|
BillingClient on the client |
Purchases SDK |
Your Android app |
| Google Play Developer API on your server | RevenueCat backend | RevenueCat managed |
| Real Time Developer Notifications via Cloud Pub/Sub | RevenueCat webhooks | RevenueCat managed, delivered to your server |
The call path is:
Your App
-> Purchases SDK
-> RevenueCat Backend
-> Google Play Developer API
-> Google Play
Your app talks to the Purchases SDK. The SDK talks to Google Play for the purchase UI and to the RevenueCat backend for verification and entitlement storage. Your server side code talks to the RevenueCat backend, not to Google Play directly.
One consequence: RevenueCat sits in the purchase verification path. After a user completes a purchase, the SDK posts the token to RevenueCat before your app sees confirmation. You trade a network round trip for not having to build server side verification yourself.
The four concepts you must know
| Concept | What it is | Where you define it |
|---|---|---|
| Product | A subscription, base plan, or one time purchase | Google Play Console |
| Package | A Product wrapped with a type label (Monthly, Annual, Lifetime, custom). The unit your paywall displays | RevenueCat dashboard |
| Offering | A group of Packages. One Offering is marked Current and returned by offerings.current |
RevenueCat dashboard |
| Entitlement | A logical access level your app checks, such as "pro_access". Products are attached to Entitlements |
RevenueCat dashboard |
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.
- 12d ago First seen · 143 lines · 64 tokens per session scan A 848ad9c6a311
understanding-revenuecat is a skill published in the GitHub repository RevenueCat/play-billing-skills (53 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 64 tokens to every session and 1,531 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to rc-understanding-revenuecat, differing in 10 lines, and is treated as a copy.
Other skills, from other repositories
play-billing-library-version-upgrade
Use this skill when upgrading or migrating an Android project from any legacy Google Play Billing Library (PBL) version to the latest stable version of PBL.
asc-revenuecat-catalog-sync
Reconcile App Store Connect subscriptions and in-app purchases with RevenueCat products, entitlements, offerings, and packages using asc and RevenueCat MCP. Use when setting up or syncing subscription catalogs across ASC and RevenueCat.
axiom-implement-iap
Use when the user wants to add in-app purchases, implement StoreKit 2, or set up subscriptions.
google-play
Google Play Developer API (Android Publisher) integration with managed OAuth. Manage apps, subscriptions, in-app purchases, and reviews. Use this skill when users want to interact with Google Play Console programmatically. For other third party apps, use the api-gateway skill (https://clawhub.ai/byungkyu/api-gateway).
subscription-lifecycle
Generates StoreKit 2 subscription lifecycle management — grace periods, billing retry, offer codes, win-back offers, upgrade/downgrade paths, and subscription status monitoring. Use when user needs post-purchase subscription state handling beyond the initial paywall.
subscription-offers
Generates StoreKit 2 code for all subscription offer types — introductory, promotional, offer codes, and win-back. Includes eligibility checks, offer presentation, and the preferredSubscriptionOffer modifier. Use when adding subscription offers, free trials, or promotional pricing.