/android-compose

name: android-compose
description: Build high-performance declarative UI with Jetpack Compose. Use when writing Composable functions, optimizing recomposition, hoisting state, or working with LazyColumn and side effects; defer deep-link and navigation routing to android-navigation.
metadata:
  triggers:
    files:
    - '**/*Screen.kt'
    - '**/*Composable*.kt'
    - '**/*Content.kt'
    keywords:
    - "@Composable"
    - Modifier
    - Column
    - Row
    - LazyColumn
    - setContent
    - recompose
    - remember
    - derivedStateOf
    - LaunchedEffect

Jetpack Compose Expert

**Priority: P0 (CRITICAL)**

**Role**: Android UI Performance Expert. Prioritize frame stability and state management.

1. Hoist State Correctly

• **Screen** (Stateful) -> **Content** (Stateless).
• Pass lambdas down (`onItemClick: (Id) -> Unit`).
• NEVER pass ViewModel to stateless composables.
• Use `MaterialTheme.colorScheme`, no hardcoded hex.

See [implementation examples](references/implementation.md) for state hoisting patterns.

2. Optimize Recomposition

• Annotate params with `@Stable` or `@Immutable`.
• Use `key` in `LazyColumn` items for stable identity.
• Reuse or make Modifiers static where possible.
• Use `derivedStateOf` for frequently updating derived values.

See [implementation examples](references/implementation.md) for `derivedStateOf` usage.

3. Handle Side Effects Properly

• Use `LaunchedEffect` for one-shot or keyed side effects — never run side effects in composition body.
• Move complex calculations to ViewModel or `remember`.

Anti-Patterns

• **No Side Effects in Composition Body**: Use `LaunchedEffect`, not raw coroutines.
• **No VM Deep Pass**: Hoist state; pass only data/callbacks.
• **No Heavy Computation in Composables**: Offload to ViewModel or `remember`.

Verification

• [ ] All stateless Composables have `@Preview`.
• [ ] `LazyColumn` items use `key` parameter.
• [ ] No ViewModel passed below Screen-level Composables.
• [ ] `./gradlew build` succeeds.

References

• [Optimization Patterns](references/implementation.md)