titooan · Sep 9, 2026 · Sep 4, 2026
diff --git a/app/src/androidTest/java/org/mozilla/tryfox/data/FakeUserDataRepository.kt b/app/src/androidTest/java/org/mozilla/tryfox/data/FakeUserDataRepository.kt
@@ -8,6 +8,7 @@ import org.mozilla.tryfox.data.SearchHistoryQueryType
 import org.mozilla.tryfox.data.repositories.UserDataRepository
 import org.mozilla.tryfox.lan.LanReceiveIdentity
 import org.mozilla.tryfox.model.HomeScreenLayout
+import org.mozilla.tryfox.util.DEFAULT_PREFERRED_ABI
 
 /**
  * A fake implementation of [org.mozilla.tryfox.data.repositories.UserDataRepository] for testing purposes.
@@ -22,6 +23,8 @@ class FakeUserDataRepository : UserDataRepository {
     override val lanReceiveIdentityFlow: Flow<LanReceiveIdentity?> = _lanReceiveIdentityFlow
     private val _homeScreenLayoutFlow = MutableStateFlow(HomeScreenLayout.OneCardPerApp)
     override val homeScreenLayoutFlow: Flow<HomeScreenLayout> = _homeScreenLayoutFlow
+    private val _preferredAbiFlow = MutableStateFlow(DEFAULT_PREFERRED_ABI)
+    override val preferredAbiFlow: Flow<String> = _preferredAbiFlow
 
     override suspend fun saveLastSearchedEmail(email: String) {
         recordSearch("try", email)
@@ -44,6 +47,10 @@ class FakeUserDataRepository : UserDataRepository {
         _homeScreenLayoutFlow.value = layout
     }
 
+    override suspend fun savePreferredAbi(abiName: String) {
+        _preferredAbiFlow.value = abiName
+    }
+
     // Helper method for tests to clear the stored email if needed
     fun clearLastSearchedEmail() {
         _lastSearchedEmailFlow.value = ""

diff --git a/app/src/main/java/org/mozilla/tryfox/data/DefaultMozillaPackageManager.kt b/app/src/main/java/org/mozilla/tryfox/data/DefaultMozillaPackageManager.kt
@@ -34,6 +34,7 @@ import org.mozilla.tryfox.util.REFERENCE_BROWSER
 import org.mozilla.tryfox.util.REFERENCE_BROWSER_PACKAGE
 import org.mozilla.tryfox.util.TRYFOX
 import org.mozilla.tryfox.util.TRYFOX_PACKAGE
+import org.mozilla.tryfox.util.abiFromNativeLibraryDir
 
 class DefaultMozillaPackageManager(private val context: Context) : MozillaPackageManager {
 
@@ -61,6 +62,7 @@ class DefaultMozillaPackageManager(private val context: Context) : MozillaPackag
             versionCode = packageInfo?.let { PackageInfoCompat.getLongVersionCode(it) },
             installDateMillis = packageInfo?.lastUpdateTime,
             installingPackageName = if (packageInfo != null) getInstallingPackageName(packageName) else null,
+            activeAbi = abiFromNativeLibraryDir(packageInfo?.applicationInfo?.nativeLibraryDir),
             splitNames = packageInfo?.applicationInfo?.splitNames?.toList() ?: emptyList(),
         )
     }

diff --git a/app/src/main/java/org/mozilla/tryfox/data/repositories/DefaultUserDataRepository.kt b/app/src/main/java/org/mozilla/tryfox/data/repositories/DefaultUserDataRepository.kt
@@ -16,6 +16,7 @@ import org.mozilla.tryfox.data.SearchHistoryEntry
 import org.mozilla.tryfox.data.SearchHistoryQueryType
 import org.mozilla.tryfox.lan.LanReceiveIdentity
 import org.mozilla.tryfox.model.HomeScreenLayout
+import org.mozilla.tryfox.util.DEFAULT_PREFERRED_ABI
 
 /**
  * A repository that stores the last searched email in a DataStore.
@@ -31,6 +32,7 @@ class DefaultUserDataRepository(private val appContext: Context) : UserDataRepos
         val LAN_DEVICE_NAME = stringPreferencesKey("lan_device_name")
         val LAN_SHARED_SECRET = stringPreferencesKey("lan_shared_secret")
         val HOME_SCREEN_LAYOUT = stringPreferencesKey("home_screen_layout")
+        val PREFERRED_ABI = stringPreferencesKey("preferred_abi")
     }
 
     override val searchHistoryFlow: Flow<List<SearchHistoryEntry>> = appContext.dataStore.data.map { preferences ->
@@ -66,6 +68,10 @@ class DefaultUserDataRepository(private val appContext: Context) : UserDataRepos
         homeScreenLayoutFromStoredValue(preferences[PreferenceKeys.HOME_SCREEN_LAYOUT])
     }
 
+    override val preferredAbiFlow: Flow<String> = appContext.dataStore.data.map { preferences ->
+        preferences[PreferenceKeys.PREFERRED_ABI]?.takeIf { it.isNotBlank() } ?: DEFAULT_PREFERRED_ABI
+    }
+
     override suspend fun saveLastSearchedEmail(email: String) {
         recordSearch(project = "try", query = email)
     }
@@ -102,6 +108,12 @@ class DefaultUserDataRepository(private val appContext: Context) : UserDataRepos
         }
     }
 
+    override suspend fun savePreferredAbi(abiName: String) {
+        appContext.dataStore.edit { preferences ->
+            preferences[PreferenceKeys.PREFERRED_ABI] = abiName
+        }
+    }
+
     private fun decodeSearchHistory(serializedHistory: String): List<SearchHistoryEntry> =
         runCatching { json.decodeFromString<List<SearchHistoryEntry>>(serializedHistory) }.getOrDefault(emptyList())
 

diff --git a/app/src/main/java/org/mozilla/tryfox/data/repositories/UserDataRepository.kt b/app/src/main/java/org/mozilla/tryfox/data/repositories/UserDataRepository.kt
@@ -18,6 +18,9 @@ interface UserDataRepository {
     val lanReceiveIdentityFlow: Flow<LanReceiveIdentity?>
     val homeScreenLayoutFlow: Flow<HomeScreenLayout>
 
+    /** The ABI variant to favour when a build offers several. Emits `universal` by default. */
+    val preferredAbiFlow: Flow<String>
+
     /**
      * Saves the last searched email.
      * @param email The email to save.
@@ -26,4 +29,5 @@ interface UserDataRepository {
     suspend fun recordSearch(project: String, query: String, searchedAt: Long = System.currentTimeMillis())
     suspend fun saveLanReceiveIdentity(identity: LanReceiveIdentity)
     suspend fun saveHomeScreenLayout(layout: HomeScreenLayout)
+    suspend fun savePreferredAbi(abiName: String)
 }
diff --git a/app/src/main/java/org/mozilla/tryfox/model/AppState.kt b/app/src/main/java/org/mozilla/tryfox/model/AppState.kt
@@ -11,6 +11,7 @@ data class AppState(
     val installDateMillis: Long?,
     val installingPackageName: String? = null,
     val versionCode: Long? = null,
+    val activeAbi: String? = null,
     val splitNames: List<String> = emptyList(),
 ) {
     val isInstalled: Boolean

diff --git a/app/src/main/java/org/mozilla/tryfox/ui/composables/ArchiveGroupCard.kt b/app/src/main/java/org/mozilla/tryfox/ui/composables/ArchiveGroupCard.kt
@@ -80,6 +80,8 @@ import org.mozilla.tryfox.install.InstallState
 import org.mozilla.tryfox.model.AppState
 import org.mozilla.tryfox.ui.models.ApkUiModel
 import org.mozilla.tryfox.ui.models.NightlyBuildOption
+import org.mozilla.tryfox.ui.models.preferredAbiApk
+import org.mozilla.tryfox.util.DEFAULT_PREFERRED_ABI
 import org.mozilla.tryfox.util.FENIX
 import org.mozilla.tryfox.util.FENIX_BETA
 import org.mozilla.tryfox.util.FENIX_RELEASE
@@ -124,6 +126,7 @@ fun ArchiveGroupCard(
     onDismissBuildPicker: () -> Unit = {},
     installStates: Map<String, InstallState> = emptyMap(),
     onOpenInstalledApp: (String) -> Unit = {},
+    preferredAbi: String = DEFAULT_PREFERRED_ABI,
 ) {
     if (pendingBuildOptions.isNotEmpty()) {
         NightlyBuildPickerDialog(
@@ -200,6 +203,7 @@ fun ArchiveGroupCard(
                         appState,
                         installStates,
                         onOpenInstalledApp,
+                        preferredAbi,
                     )
                 }
 
@@ -623,9 +627,13 @@ private fun ArchiveGroupAbiSelector(
     appState: AppState?,
     installStates: Map<String, InstallState>,
     onOpenInstalledApp: (String) -> Unit,
+    preferredAbi: String,
 ) {
-    val firstSupportedIndex = apks.indexOfFirst { it.abi.isSupported }.takeIf { it != -1 } ?: 0
-    var selectedIndex by remember { mutableStateOf(firstSupportedIndex) }
+    val preferredIndex = apks.preferredAbiApk(preferredAbi)
+        ?.let(apks::indexOf)
+        ?.takeIf { it != -1 }
+        ?: 0
+    var selectedIndex by remember { mutableStateOf(preferredIndex) }
 
     Column(
         horizontalAlignment = Alignment.CenterHorizontally,

diff --git a/app/src/main/java/org/mozilla/tryfox/ui/composables/CurrentInstallState.kt b/app/src/main/java/org/mozilla/tryfox/ui/composables/CurrentInstallState.kt
@@ -172,6 +172,13 @@ private fun InstallMetadataBottomSheet(
                 label = stringResource(id = R.string.install_metadata_source_label),
                 value = installSourceLabel(appState),
             )
+            InstallMetadataRow(
+                // The ABI Android selected at install time. A universal APK reports the single
+                // architecture the platform kept, so this does not identify the APK variant.
+                label = stringResource(id = R.string.install_metadata_abi_label),
+                value = appState.activeAbi
+                    ?: stringResource(id = R.string.install_metadata_abi_none),
+            )
             InstallMetadataBlock(
                 label = stringResource(id = R.string.install_metadata_splits_label),
                 // splitNames covers only the config splits; the base APK is always present but not
@@ -233,7 +240,7 @@ private fun InstallMetadataBlock(label: String, value: String) {
             text = value,
             style = MaterialTheme.typography.bodySmall,
             fontFamily = FontFamily.Monospace,
-            modifier = Modifier.padding(top = 2.dp),
+            modifier = Modifier.padding(start = 8.dp, top = 2.dp),
         )
     }
 }

diff --git a/app/src/main/java/org/mozilla/tryfox/ui/models/AbiUiModel.kt b/app/src/main/java/org/mozilla/tryfox/ui/models/AbiUiModel.kt
@@ -1,6 +1,21 @@
 package org.mozilla.tryfox.ui.models
 
+import org.mozilla.tryfox.util.isUniversalAbi
+
 data class AbiUiModel(
     val name: String?,
     val isSupported: Boolean,
-)
+) {
+    val isUniversal: Boolean get() = isUniversalAbi(name)
+}
+
+/**
+ * Picks the variant matching [preferredAbi], falling back to universal, then to anything the
+ * device can install, then to whatever came first. Nightly builds ship no universal variant, so
+ * an unmatched affinity still resolves to an installable APK.
+ */
+fun List<ApkUiModel>.preferredAbiApk(preferredAbi: String): ApkUiModel? =
+    firstOrNull { preferredAbi.equals(it.abi.name, ignoreCase = true) }
+        ?: firstOrNull { it.abi.isUniversal }
+        ?: firstOrNull { it.abi.isSupported }
+        ?: firstOrNull()
diff --git a/app/src/main/java/org/mozilla/tryfox/ui/models/AppUiModel.kt b/app/src/main/java/org/mozilla/tryfox/ui/models/AppUiModel.kt
@@ -27,6 +27,7 @@ data class AppUiModel(
     val installedDate: String?,
     val installingPackageName: String? = null,
     val splitNames: List<String> = emptyList(),
+    val activeAbi: String? = null,
     val installedTryBuild: InstalledTryBuild? = null,
     val apks: ApksResult,
     val userPickedDate: LocalDate? = null,

diff --git a/app/src/main/java/org/mozilla/tryfox/ui/screens/HomeAppCard.kt b/app/src/main/java/org/mozilla/tryfox/ui/screens/HomeAppCard.kt
@@ -67,6 +67,8 @@ import org.mozilla.tryfox.ui.models.ApkUiModel
 import org.mozilla.tryfox.ui.models.ApksResult
 import org.mozilla.tryfox.ui.models.AppUiModel
 import org.mozilla.tryfox.ui.models.NightlyBuildOption
+import org.mozilla.tryfox.ui.models.preferredAbiApk
+import org.mozilla.tryfox.util.DEFAULT_PREFERRED_ABI
 import org.mozilla.tryfox.util.FENIX
 import org.mozilla.tryfox.util.FENIX_BETA
 import org.mozilla.tryfox.util.FENIX_DEBUG
@@ -94,6 +96,7 @@ internal fun HomeAppCard(
     onBuildSelected: (String, String) -> Unit,
     onDismissBuildPicker: (String) -> Unit,
     modifier: Modifier = Modifier,
+    preferredAbi: String = DEFAULT_PREFERRED_ABI,
 ) {
     val app = card.selectedApp
     val appState = app.toAppState()
@@ -104,8 +107,7 @@ internal fun HomeAppCard(
     val isNightly = app.name == FENIX || app.name == FOCUS
     val isDebug = app.name == FENIX_DEBUG || app.name == FOCUS_DEBUG
     val isVersionSelectable = app.name in setOf(FENIX_RELEASE, FENIX_BETA, FOCUS_RELEASE, FOCUS_BETA)
-    val selectedApk = (app.apks as? ApksResult.Success)?.apks
-        ?.let { apks -> apks.firstOrNull { it.abi.isSupported } ?: apks.firstOrNull() }
+    val selectedApk = (app.apks as? ApksResult.Success)?.apks?.preferredAbiApk(preferredAbi)
 
     Card(
         modifier = modifier
@@ -340,6 +342,7 @@ private fun AppUiModel.toAppState(): AppState? = installedVersion?.let { version
         installDateMillis = installedDate?.let(::parseDateToMillis),
         installingPackageName = installingPackageName,
         versionCode = installedVersionCode,
+        activeAbi = activeAbi,
         splitNames = splitNames,
     )
 }

diff --git a/app/src/main/java/org/mozilla/tryfox/ui/screens/HomeScreen.kt b/app/src/main/java/org/mozilla/tryfox/ui/screens/HomeScreen.kt
@@ -221,6 +221,7 @@ fun HomeScreen(
                                 onDismissBuildPicker = { appName ->
                                     homeViewModel.onDismissBuildPicker(appName)
                                 },
+                                preferredAbi = currentScreenState.preferredAbi,
                             )
                         }
                     }

diff --git a/app/src/main/java/org/mozilla/tryfox/ui/screens/HomeScreenState.kt b/app/src/main/java/org/mozilla/tryfox/ui/screens/HomeScreenState.kt
@@ -3,6 +3,7 @@ package org.mozilla.tryfox.ui.screens
 import org.mozilla.tryfox.model.CacheManagementState
 import org.mozilla.tryfox.model.HomeScreenLayout
 import org.mozilla.tryfox.ui.models.AppUiModel
+import org.mozilla.tryfox.util.DEFAULT_PREFERRED_ABI
 
 /**
  * Represents the various states of the Home screen.
@@ -23,5 +24,6 @@ sealed class HomeScreenState {
         val isDownloadingAnyFile: Boolean,
         val selectedAppNames: Map<HomeAppFamily, String> = HomeAppFamily.entries.associateWith { it.defaultAppName },
         val homeScreenLayout: HomeScreenLayout = HomeScreenLayout.OneCardPerApp,
+        val preferredAbi: String = DEFAULT_PREFERRED_ABI,
     ) : HomeScreenState()
 }
diff --git a/app/src/main/java/org/mozilla/tryfox/ui/screens/HomeViewModel.kt b/app/src/main/java/org/mozilla/tryfox/ui/screens/HomeViewModel.kt
@@ -50,6 +50,7 @@ import org.mozilla.tryfox.ui.models.ApksResult
 import org.mozilla.tryfox.ui.models.AppUiModel
 import org.mozilla.tryfox.ui.models.NightlyBuildOption
 import org.mozilla.tryfox.ui.models.newVersionAvailable
+import org.mozilla.tryfox.util.DEFAULT_PREFERRED_ABI
 import org.mozilla.tryfox.util.FENIX
 import org.mozilla.tryfox.util.FENIX_BETA
 import org.mozilla.tryfox.util.FENIX_DEBUG
@@ -60,6 +61,8 @@ import org.mozilla.tryfox.util.FOCUS_DEBUG
 import org.mozilla.tryfox.util.FOCUS_RELEASE
 import org.mozilla.tryfox.util.REFERENCE_BROWSER
 import org.mozilla.tryfox.util.TRYFOX
+import org.mozilla.tryfox.util.isAbiSupported
+import org.mozilla.tryfox.util.resolvePreferredAbi
 import java.io.File
 
 /**
@@ -100,6 +103,9 @@ class HomeViewModel(
     private var tryFoxCardDismissed = false
     private var homeScreenLayout = HomeScreenLayout.OneCardPerApp
 
+    @Volatile
+    private var preferredAbi = DEFAULT_PREFERRED_ABI
+
     @Volatile
     private var selectedHomeAppNames = HomeAppFamily.entries.associateWith { it.defaultAppName }
     private val appMutationVersions = mutableMapOf<String, Long>()
@@ -139,6 +145,20 @@ class HomeViewModel(
             }
             ?.launchIn(viewModelScope)
 
+        userDataRepository?.preferredAbiFlow
+            ?.onEach { storedAbi ->
+                val resolvedAbi = resolvePreferredAbi(storedAbi, supportedAbis)
+                preferredAbi = resolvedAbi
+                _homeScreenState.update { currentState ->
+                    if (currentState is HomeScreenState.Loaded) {
+                        currentState.copy(preferredAbi = resolvedAbi)
+                    } else {
+                        currentState
+                    }
+                }
+            }
+            ?.launchIn(viewModelScope)
+
         mozillaPackageManager.appStates
             .onEach { appState ->
                 _homeScreenState.update { currentState ->
@@ -151,6 +171,7 @@ class HomeViewModel(
                                         installedVersionCode = appState.versionCode,
                                         installedDate = appState.formattedInstallDate,
                                         installingPackageName = appState.installingPackageName,
+                                        activeAbi = appState.activeAbi,
                                         splitNames = appState.splitNames,
                                         installedTryBuild = app.name.takeIf { it == FENIX_DEBUG }
                                             ?.let { matchingInstalledTryBuild(appState) },
@@ -327,6 +348,7 @@ class HomeViewModel(
         installedDate = appState?.formattedInstallDate,
         installingPackageName = appState?.installingPackageName,
         splitNames = appState?.splitNames ?: emptyList(),
+        activeAbi = appState?.activeAbi,
         installedTryBuild = appState?.takeIf { name == FENIX_DEBUG }
             ?.let { matchingInstalledTryBuild(it) },
     )
@@ -343,6 +365,7 @@ class HomeViewModel(
             isDownloadingAnyFile = false,
             selectedAppNames = selectedHomeAppNames,
             homeScreenLayout = homeScreenLayout,
+            preferredAbi = preferredAbi,
         ).applyDownloadStates(downloadStates.value)
     }
 
@@ -401,6 +424,7 @@ class HomeViewModel(
         installedDate = appState?.formattedInstallDate,
         installingPackageName = appState?.installingPackageName,
         splitNames = appState?.splitNames.orEmpty(),
+        activeAbi = appState?.activeAbi,
         installedTryBuild = appState?.takeIf { appName == FENIX_DEBUG }?.let(::matchingInstalledTryBuild),
         apks = ApksResult.Success(apks.map { it.toUiModel() }),
         selectedReleaseVersion = selectedReleaseVersion,
@@ -476,6 +500,7 @@ class HomeViewModel(
             installedDate = appState?.formattedInstallDate,
             installingPackageName = appState?.installingPackageName,
             splitNames = appState?.splitNames ?: emptyList(),
+            activeAbi = appState?.activeAbi,
             installedTryBuild = appState?.takeIf { repository.appName == FENIX_DEBUG }?.let(::matchingInstalledTryBuild),
             apks = apksResult,
             selectedReleaseVersion = selectedReleaseVersion,
@@ -487,12 +512,8 @@ class HomeViewModel(
         return parsedApks.map { parsedApk ->
             val buildDate = parsedApk.rawDateString?.rawNightlyBuildDate()
             val date = buildDate?.let { parsedApk.rawDateString?.formatNightlyBuildDate().orEmpty() }.orEmpty()
-            val isCompatible = supportedAbis.any { deviceAbi ->
-                deviceAbi.equals(
-                    parsedApk.abiName,
-                    ignoreCase = true,
-                )
-            }
+            // Universal APKs bundle every architecture, so they install anywhere.
+            val isCompatible = isAbiSupported(parsedApk.abiName, supportedAbis)
 
             // Key the cache dir / unique key by the full build timestamp (yyyy-MM-dd-HH-mm-ss) so
             // two Nightly builds from the same day don't collide on a date-only path. Releases have
-Original file line number
+Diff line change
@@ Expand Up / @@ -221,6 +221,7 @@ fun HomeScreen( @@
                                     onDismissBuildPicker = { appName ->
                                         homeViewModel.onDismissBuildPicker(appName)
                                     },
+                                    preferredAbi = currentScreenState.preferredAbi,
                                 )
                             }
                         }
@@ Expand Down @@