Skill v1.0.1

version: "1.0.1" name: play-billing-library-version-upgrade description: 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. license: Complete terms in LICENSE.txt metadata: author: Google LLC last-updated: '2026-10-06' keywords:

• android
• play billing
• play billing library
• pbl
• upgrade
• migration
• deprecation
• google play

Phase 0: Intent Message

Reporting Action: Before proceeding, immediately tell the user: "I will upgrade Play Billing Library to the latest version."

Phase 1: Discovery \& Situational Awareness

1. Primary Check (Build Version) : Locate the project's billing dependency (e.g., com.android.billingclient:billing) in build.gradle, build.gradle.kts, or libs.versions.toml.
2. Initial Compilation Test: Attempt to sync and build the project immediately.
3. Fallback Discovery (Effective Version) :

• Trigger: Only if the build fails immediately, scan the source code for deprecated artifacts.
• Logic : The presence of deprecated APIs indicates the **"Effective

Version" ---defined as the version where those specific APIs were last available**, not when they were introduced.

• Example : If SkuDetails is present, treat the baseline as PBL v7 or earlier (regardless of the version string in build.gradle).

1. Identify Target \& Path : Access the version tool or release notes to find the latest stable version and calculate a \[Direct/Stepped\] migration path based on the Effective Version baseline.

• Calculate Migration Path :
• If the Effective Version is within 2 major versions of the target: Plan a Direct Migration.
• If it is more than 2 major versions behind: Plan a **Stepped

Migration**. Migrate by two major versions at a time (e.g., v4 -\> v6 -\> v8) until you are within two versions of the target.

• Reporting Action: Before proceeding, tell the user: "I've detected you are effectively on PBL \[Current\] and the latest is \[Target\]. I am planning a \[direct/stepped\] migration path."

Phase 2: Contextual Document Mapping \& Planning

For every major version jump identified in your path, you MUST synthesize instructions from:

• [Migration Guide](https://developer.android.com/google/play/billing/migrate-gpblv%5BX%5D) (where [X] is the target major version).
• Release Highlights : The "Deprecations" and "Breaking Changes" sections of the relevant Release Notes.
• Developer Documentation: Consult your knowledge of the Google Play Billing documentation regarding the relevant features used in this app (e.g., Subscriptions, One-Time Products).
• Develop the Plan: Identify every specific code change required (API removals, class replacements, logic shifts) and print this out as a checklist.

Phase 3: Instructions for Execution

Reporting Action: For each of the following steps, give a brief explanation of what you will be doing prior to execution, and a brief summary of what you accomplished afterwards.

Step 1: SDK \& Environment Alignment

• Action : Update build.gradle to meet SDK requirements (e.g., "PBL 9 requires compileSdk 35").
• Gradle Version: Verify if the new library requires a newer Android Gradle Plugin (AGP) or Kotlin version.

Step 2: Intent-based Refactoring

Analyze the intent of the existing code rather than performing purely textual string replacement.

• Action : You MUST follow all deprecation instructions and refactor patterns from both the references/migration-logic.md section, the official migration guides, and the general documentation pages identified in Phase 2.
• Verification : Verify you are doing all steps from all documentation and then making sure you follow the specific directions from the checklist in the references.

Step 3: Sequential Verification (Only applicable for Stepped Migrations)

1. Upgrade to the first major intermediate version in your path.
2. Run `./gradlew assembleDebug` to verify no intermediate breaking changes were missed.
3. Repeat until you reach the final target version.

Step 4: Final Validation Checklist

1. Smart Checklist Verification:
2. Open references/version-checklist.md and locate the Smart Version-Specific Checklist.
3. Action: For every version between your \[Detected Effective Version\] and \[Detected New Version\], verify that every item has been addressed in the code using "Find in Files" or structural analysis.
4. Tests : Run all unit and implementation tests (./gradlew test).
5. Clean Build : Verify the project completes a full clean build: ./gradlew clean assembleDebug. Then, run ./gradlew sync and ./gradlew build so that the user can immediately test the new version manually.

Final Report

Explain the "Why" to the developer:

• "I updated your SDK to \[Version\] because PBL \[Version\] requires it for \[Reason from docs\]."
• "I removed your custom retryConnection() logic because it is now handled natively by the library using enableAutoServiceReconnection()."
• "Successfully upgraded from PBL \[Old\] to PBL \[New\] and verified with unit tests. Based on an analysis of features in the latest library and this application's current feature set, I suggest exploring \[New Feature\] (e.g., Prepaid Plans or Installments) from the latest release because it is now available but not yet implemented."