core/achievement_sync_seam library

Classes

AchievementSyncCoordinator

Pulls remote progress, merges it into service with max(local, remote) per achievement, then pushes the merged map back. Progress only grows, so two devices converge without losing either side's data. Resetting or lowering progress is not supported by this merge.

AchievementSyncSeam

Platform-neutral achievement-sync seam — the package ships no Play Games / Game Center client. The consuming app registers its own adapter via Get.put<AchievementSyncSeam>(myAdapter, permanent: true), same pattern as LeaderboardSyncSeam-style seams. Progress is a plain achievementId -> progress map; thresholds stay in the app.