Purchase Flow

Implements the full client side purchase sequence: build BillingFlowParams, launch launchBillingFlow(), receive callbacks in PurchasesUpdatedListener, handle every response code, then verify, acknowledge, and grant access.

Phase 0: Intent

Use this skill when you need to:

• Launch a purchase from a "Buy" tap for a one time product or a subscription.
• Wire a PurchasesUpdatedListener and handle every BillingResponseCode.
• Decide where to verify, where to acknowledge, and how to grant entitlements idempotently.
• Support pending transactions (cash at convenience store, carrier billing, slow card auth).
• Bundle multiple items into a single transaction (PBL 7.0+).

Out of scope: connecting BillingClient, querying ProductDetails, subscription upgrades or downgrades, and retry or error taxonomy beyond the launch results listed below.

Phase 1: Discovery

Confirm the preconditions before you build params.