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

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.
Initial Compilation Test: Attempt to sync and build the project immediately.
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).
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.