understanding-billing
Installation
SKILL.md
Phase 0: Intent
Tell the user: "I will orient you to Google Play Billing's three pillars, map your goal to the right pillar, and point you at the concrete skill to run next."
Phase 1: Discovery
Before touching code, confirm the developer understands the three pillars and the four actors. Each pillar owns a different slice of the system:
| Pillar | Surface | Role |
|---|---|---|
| Play Billing Library (PBL) | Android client, Gradle dep com.android.billingclient:billing-ktx |
Query products, launch purchase dialog, receive results on device |
| Google Play Developer API | Server REST API at androidpublisher.googleapis.com |
Verify purchases, manage subscriptions, manage catalog. Source of truth |
| Google Play Console | Web dashboard | Create products, set prices, configure RTDNs and API access |
A fourth piece, Cloud Pub/Sub, carries Real Time Developer Notifications (RTDNs) from Google to your backend when purchase or subscription state changes.
The four actors in every transaction: