Configuring R8 for Compose — Trust Consumer Rules, Avoid Blanket Keeps

R8 is the only supported shrinker — ProGuard is deprecated. Compose ships consumer ProGuard rules, so most apps need no Compose-specific keep rules. The big modern wins come from R8 full mode (default since AGP 8.0): lambda grouping, sourceInformation() stripping, constant-folding of composable args, and ComposerImpl devirtualization. This skill teaches Claude to set R8 up minimally and refuse over-broad keeps that defeat those wins.

When to use this skill

• Setting up a new Compose app's release variant for the first time.
• A PR adds -keep class androidx.compose.** { *; } or any other Compose-wide keep — push back and apply this skill.
• A release build crashes after enabling minification — the cause is almost always a missing keep on a reflective consumer, not on Compose itself.
• APK size review surfaces a large classes.dex and the developer wants to know why.
• The first time isMinifyEnabled = true is being flipped on, before any release benchmark is run.
• Cross-link from ../../measurement/testing-compose-in-release-mode/SKILL.md whenever release measurement is being set up.

When NOT to use this skill

• The app is not yet ready to ship a release variant — wait until perf and crash budgets are in scope.
• The developer is debugging a code-level bug (logic error, race, wrong state). R8 issues manifest as ClassNotFoundException, NoSuchMethodError, or empty reflection results — not behavioral bugs.
• The release variant has been measured and is fine — do not pre-emptively add keep rules.
• The perf concern is recomposition, layout phase, or stability — see the relevant stability/ or recomposition/ skills.