xml-to-compose-migration-pro

name	xml-to-compose-migration-pro
description	Reviews and assists migration from XML layouts + Fragments to Jetpack Compose. Covers incremental interop (AndroidView / ComposeView), layout translation (ConstraintLayout / LinearLayout / FrameLayout → Modifier), RecyclerView → LazyColumn with keys, Fragment → Composable, Navigation Component → Navigation-Compose, ViewModel bridging, and XML themes → MaterialTheme.
license	MIT
metadata	{"author":"AppBootstrapAI contributors","version":"1.0","grounded_in":"Android Developers Compose migration guide (https://developer.android.com/develop/ui/compose/migrate), Android Developers Compose docs"}

Review and assist the migration from XML-based Android UI (Fragments + layouts + RecyclerViews) to Jetpack Compose. Migration is incremental by default — ComposeView / AndroidView make it possible to ship a hybrid screen-by-screen without a big-bang rewrite. Report only genuine migration issues; don't nitpick the existing XML where it doesn't need to change.

Review process:

1. Frame the migration scope using references/interop-strategy.md — incremental vs all-at-once, where to put interop boundaries.
2. Translate layouts using references/layout-migration.md — LinearLayout / ConstraintLayout / FrameLayout / RelativeLayout to Compose equivalents.
3. Translate RecyclerViews using references/recyclerview-to-lazy.md — including stable keys, item-content separation, and DiffUtil → automatic recomposition.
4. Translate Fragments using references/fragment-to-composable.md — lifecycle ownership, ViewBinding → parameters, animations.
5. Translate Navigation Component using references/navigation-migration.md — NavGraph XML → NavHost Kotlin DSL.
6. Bridge ViewModels using references/viewmodel-bridge.md — existing ViewModels stay; only the View layer changes.
7. Translate themes using references/themes-styles.md — styles.xml → MaterialTheme(colorScheme, typography, shapes).

If doing a partial review, load only the relevant reference files.

Core Instructions

• Migrate incrementally. A full XML-to-Compose rewrite of a non-trivial app is months of work; an incremental screen-by-screen migration ships value continuously. ComposeView in an XML layout (or AndroidView in a Composable) makes it possible.
• Existing ViewModels stay. Compose works with ViewModel + StateFlow + LiveData without changes. The migration is a View-layer concern, not a state-layer one.
• Don't preserve XML idioms in Compose. A LinearLayout(orientation = horizontal) becomes a Row — not a Column with Modifier.fillMaxWidth().wrapContentHeight(). A literal translation produces awkward Compose.
• Test parity before deleting XML. Snapshot tests, manual QA, or feature-flag the new screen alongside the old. Don't delete the XML in the same PR that introduces the Composable.
• Use semantic testTag for tests, not preserved android:id values. XML view IDs (R.id.submit_button) don't carry over; Compose uses Modifier.testTag(...) and Modifier.semantics { contentDescription = ... }.
• AndroidView { factory: ... update: ... } is for one-way binding from Compose state to a View. Don't try to round-trip — if state needs to flow back, lift it.

Output Format

For migration reviews, organize findings by file. For each issue:

1. State the file and the XML element / Kotlin class.
2. Name the migration concern.
3. Show the XML/Fragment "before" and the Compose "after".

For migration work (rewriting a screen), make the changes directly and produce a final patch with the old XML deleted (or feature-flagged) and the new Composable + ViewModel wiring in place.

Example output:

res/layout/fragment_settings.xml + SettingsFragment.kt

Migrate to SettingsScreen Composable + Navigation-Compose route.

// Before (SettingsFragment.kt) — Fragment + ViewBinding + RecyclerView
class SettingsFragment : Fragment() {
    private var _binding: FragmentSettingsBinding? = null
    private val binding get() = _binding!!
    private val viewModel: SettingsViewModel by viewModels()

    override fun onCreateView(...): View {
        _binding = FragmentSettingsBinding.inflate(inflater, container, false)
        binding.recyclerView.adapter = SettingsAdapter { onClick(it) }
        viewModel.items.observe(viewLifecycleOwner) { /* ... */ }
        return binding.root
    }
}

// After
@Composable
fun SettingsScreen(
    onItemClick: (SettingsItem) -> Unit,
    viewModel: SettingsViewModel = hiltViewModel()
) {
    val state by viewModel.state.collectAsStateWithLifecycle()
    LazyColumn(modifier = Modifier.fillMaxSize()) {
        items(state.items, key = { it.id }) { item ->
            SettingsRow(item = item, onClick = { onItemClick(item) })
        }
    }
}

RecyclerView's DiffUtil is replaced by Compose's reference-equality-based recomposition. Provide a stable key (e.g., it.id) so Compose can match items across emissions.

Summary

1. State exposure (medium): SettingsViewModel.items is LiveData — migrate to StateFlow for collectAsStateWithLifecycle() consistency with other migrated screens.
2. Theme (low): New SettingsScreen references MaterialTheme.colorScheme.surface; ensure the host theme defines a non-default colorScheme.surface.

End of example.

References

• references/interop-strategy.md — incremental vs all-at-once, ComposeView in an XML layout, AndroidView in a Composable, choosing screen-level vs widget-level migration boundaries.
• references/layout-migration.md — XML layouts → Compose equivalents: LinearLayout → Row/Column, ConstraintLayout → Modifier constraints + ConstraintLayout Composable, FrameLayout → Box, ScrollView → Modifier.verticalScroll(). Padding/margin/weight translation.
• references/recyclerview-to-lazy.md — RecyclerView.Adapter → LazyColumn/LazyRow with stable keys; DiffUtil → reference-equality recomposition; pagination via paging-compose.
• references/fragment-to-composable.md — Fragment lifecycle → Composable lifecycle, ViewBinding → Composable parameters, fragment transactions → navigation route changes, ActivityResultLauncher / system permissions in Compose.
• references/navigation-migration.md — XML navigation/nav_graph.xml → Kotlin NavHost + composable("route"), type-safe arguments, deep links, navigation results.
• references/viewmodel-bridge.md — existing ViewModels carry over; viewModel() / hiltViewModel(), LiveData → observeAsState() (or migrate to StateFlow + collectAsStateWithLifecycle()), SavedStateHandle unchanged.
• references/themes-styles.md — styles.xml themes → MaterialTheme(colorScheme, typography, shapes), dark/light handling, dynamic color (dynamicColorScheme), per-screen theme overrides.