Wear Compose M3

Prerequisites and compatibility

1. Current Wear OS Compose version in-use: To find the installed library version, read gradle/libs.versions.toml or build.gradle.kts directly. Don't run ./gradlew dependencies or other shell commands to resolve versions.

2. Wear OS Compose Material3 version: If an internal tool is available to establish the latest stable version {VERSION} of androidx.wear.compose:compose-material3, use that tool.

   • Otherwise, fetch the official Maven metadata XML to identify {VERSION} (highest number, ignoring -alpha, -beta, or -rc).

3. Strict compliance: If a version is listed as stable, you MUST use it, unless overridden by the user. Do not downgrade based on initial "Unresolved reference" errors in the editor or outdated web search results.

4. Kotlin & Compose compiler: Use Kotlin 2.0.0+ with the org.jetbrains.kotlin.plugin.compose Gradle plugin.

5. Min SDK: Ensure minSdk is at least 25.

6. Compile SDK & AGP: Ensure compileSdk and AGP meet the library's AAR metadata floors (compileSdk >= 35 and AGP >= 8.6.0 for 1.6.x; compileSdk >= 37 and AGP >= 9.1.0 for 1.7.x).

Gotchas

1. Mandatory sync and validation: After updating versions in libs.versions.toml or build.gradle.kts, perform a Gradle sync (or ./gradlew assembleDebug) before refactoring, and run ./gradlew assembleDebug after refactoring to verify the build.

2. Prohibition of guessing (error protocol): If you encounter an 'Unresolved Reference' or API mismatch after a successful sync, do not attempt to 'fix' it by downgrading the library version.

Capabilities and tools

Capability 1: Migration, updates, and adding features

Use this guidance when migrating from an older version of Wear OS Compose or Horologist, updating an existing Wear Compose Material3 project, or adding features.

1. Unless otherwise indicated by the developer, use the latest stable version of Wear Compose Material3 from {VERSION} (superseding any literal version strings in the migration guide).

2. When migrating from Material 2.5 or Horologist, read the migration guide and use its official component mappings.

3. Before refactoring any component (for example, Chip -> Button), check the parameter names, slot types, and "Expressive" design tokens.

4. Do not use the Horologist Composables, Compose Layout, or Compose Material libraries; replace Horologist components with Wear Compose M3 equivalents (AppScaffold -> M3 AppScaffold, ScreenScaffold -> M3 ScreenScaffold, ScalingLazyColumn -> TransformingLazyColumn, ResponsiveListHeader -> ListHeader, PagerScreen -> HorizontalPagerScaffold, Chip -> Button, Confirmation -> ConfirmationDialog).

5. Always check against the component guidance in Capability 3.

6. Expect screenshot tests to fail when migrating or updating components: expected defaults for padding and positioning will have changed. Do not seek to artificially match the previous screenshot, but give preference to the Material3 defaults.

Capability 2: Component samples

Use this table of reference to find canonical samples for Wear Compose components. When working with a Wear Compose component, you must use the samples linked from the table to ensure you know how to correctly use it.

Important: Symbols marked with [alpha], [beta], or [rc] are only available in that pre-release track and are not in stable {VERSION}. Do not use them unless the project explicitly targets that pre-release version.

Material 3 components in androidx.wear.compose.material3.*

Foundation components in androidx.wear.compose.foundation.*

Navigation 3 components in androidx.wear.compose.navigation3.*

Capability 3: Component guidance

Mandatory: Use this capability as a checklist against any component use. It provides more holistic guidance on how to use each component in practice, beyond the component syntax.

1. AppScaffold and ScreenScaffold

   • [ ] Use AppScaffold as the outer container, with ScreenScaffold children.

   • [ ] Use only ONE AppScaffold and any number of ScreenScaffold.

2. ScalingLazyColumn - Use TransformingLazyColumn instead.

3. TransformingLazyColumn - You will need the following imports:

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   import androidx.wear.compose.foundation.lazy.TransformingLazyColumn
   import androidx.wear.compose.foundation.lazy.TransformingLazyColumnDefaults
   import androidx.wear.compose.foundation.lazy.rememberTransformingLazyColumnState
   // ...
   import androidx.wear.compose.material3.lazy.rememberTransformationSpec
   import androidx.wear.compose.material3.lazy.transformedHeight

   <br />

   Canonical example:

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   val columnState = rememberTransformingLazyColumnState()
   val transformationSpec = rememberTransformationSpec()
   ScreenScaffold(
       scrollState = columnState
   ) { contentPadding ->
       TransformingLazyColumn(
           state = columnState,
           contentPadding = contentPadding
       ) {
           item {
               ListHeader(
                   modifier = Modifier
                       .fillMaxWidth()
                       .transformedHeight(this, transformationSpec)
                       .minimumVerticalContentPadding(ListHeaderDefaults.minimumTopListContentPadding),
                   transformation = SurfaceTransformation(transformationSpec)
               ) {
                   Text(text = "Header")
               }
           }
           // ... other items
           item {
               Button(
                   modifier = Modifier
                       .fillMaxWidth()
                       .transformedHeight(this, transformationSpec)
                       .minimumVerticalContentPadding(ButtonDefaults.minimumVerticalListContentPadding),
                   transformation = SurfaceTransformation(transformationSpec),
                   onClick = { /* ... */ },
                   icon = {
                       Icon(
                           imageVector = Icons.Default.Build,
                           contentDescription = "build",
                       )
                   },
               ) {
                   Text(
                       text = "Build",
                       maxLines = 1,
                       overflow = TextOverflow.Ellipsis,
                   )
               }
           }
       }
   }

   <br />

   • [ ] Use TransformingLazyColumn instead of ScalingLazyColumn.

   • [ ] You must pass the contentPadding parameter from ScreenScaffold to the TransformingLazyColumn.

   • [ ] Use the minimumVerticalContentPadding modifier to achieve required padding top and bottom.

     • This expects a value from defaults, such as ButtonDefaults, CardDefaults, ListHeaderDefaults.

     • Note: This is a scoped modifier available within TransformingLazyColumnItemScope.

   • [ ] Ensure items morph and scale (apply to components within TransformingLazyColumn, not the list itself):

     • [ ] Use Modifier.transformedHeight(this, transformationSpec).

     • [ ] Use transformation = SurfaceTransformation(transformationSpec).

   • [ ] If configuring a list for snapping, use flingBehavior and rotaryScrollableBehavior together:

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   val columnState = rememberTransformingLazyColumnState()
   ScreenScaffold(scrollState = columnState) { contentPadding ->
       TransformingLazyColumn(
           state = columnState,
           flingBehavior = TransformingLazyColumnDefaults.snapFlingBehavior(columnState),
           rotaryScrollableBehavior = RotaryScrollableDefaults.snapBehavior(columnState)
       ) {
           // ...
           // ...
       }
   }

   <br />

4. ScreenScaffold

   • [ ] Guard the scrollIndicator with !LocalScrollCaptureInProgress.current (androidx.compose.ui.platform).

5. EdgeButton

   • [ ] Do NOT use as the final item within a TransformingLazyColumn. Instead, use the slot in ScreenScaffold.

   • [ ] When used in a TransformingLazyColumn, add the required overscroll behavior:

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   val columnState = rememberTransformingLazyColumnState()
   ScreenScaffold(
       scrollState = columnState,
       edgeButton = {
           EdgeButton(
               onClick = { /* TODO */ },
               modifier = Modifier.scrollable(
                   columnState,
                   orientation = Orientation.Vertical,
                   reverseDirection = true,
                   // Apply overscroll to the EdgeButton for proper scrolling behavior.
                   overscrollEffect = rememberOverscrollEffect(),
               )
           ) {
               Text("More")
           }
       }
   ) { contentPadding ->
       TransformingLazyColumn(
           contentPadding = contentPadding,
           state = columnState,
       ) {
           // ...
           // ...
       }
   }

   <br />

6. Column

   • [ ] USE as a direct child of ScreenScaffold if the screen will never scroll, even with the largest system font.

   • [ ] Use TransformingLazyColumn instead for all other cases.

7. Styles

   • [ ] Do NOT hard-code text sizes, use typography from MaterialTheme.

   • [ ] Do NOT hard-code colors, use colorScheme from MaterialTheme.

8. Use component defaults:

   • [ ] Components such as Button have a corresponding ButtonDefaults object.

   • [ ] Check for and use the *Defaults object for any component when working with padding and styling values, in preference to hard-coded values.

9. Use Wear-specific preview annotations (androidx.wear.compose.ui.tooling.preview):

   • [ ] @WearPreviewDevices

   • [ ] @WearPreviewFontScales

   • [ ] Ensure the androidx.wear.compose:compose-ui-tooling dependency is included.

10. Ambient mode

    • [ ] Use LocalAmbientModeManager (provided by CompositionLocalProvider and rememberAmbientModeManager()) instead of AmbientLifecycleObserver.

11. Navigation

    • [ ] When adding navigation fresh, use Navigation3 (androidx.wear.compose:compose-navigation3).

    • [ ] Use rememberSwipeDismissableSceneStrategy() / SwipeDismissableSceneStrategy (androidx.wear.compose.navigation3).

12. Comments

    • [ ] Where any Kotlin file has been modified, ensure that the existing comments are up to date and accurately reflect any changes to the implementation.

13. HorizontalPager or VerticalPager

    • [ ] Use the Composable hierarchy in this order: AppScaffold, HorizontalPagerScaffold, HorizontalPager, AnimatedPage, ScreenScaffold. Or similarly for VerticalPager.