Add reusable scaffold for recipient picker screens.

app/src/main/java/org/thoughtcrime/securesms/conversation/NewConversationActivity.kt

@@ -14,25 +14,17 @@ import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
 import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContracts
-import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.widthIn
-import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.SnackbarHost
 import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.Text
-import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
-import androidx.compose.material3.adaptive.currentWindowAdaptiveInfo
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
-import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.platform.LocalContext
@@ -49,25 +41,20 @@ import org.signal.core.ui.compose.AllDevicePreviews
 import org.signal.core.ui.compose.Dialogs
 import org.signal.core.ui.compose.DropdownMenus
 import org.signal.core.ui.compose.Previews
-import org.signal.core.ui.compose.Scaffolds
 import org.signal.core.ui.compose.theme.SignalTheme
 import org.thoughtcrime.securesms.BlockUnblockDialog
 import org.thoughtcrime.securesms.PassphraseRequiredActivity
 import org.thoughtcrime.securesms.R
-import org.thoughtcrime.securesms.components.compose.ScreenTitlePane
 import org.thoughtcrime.securesms.components.settings.app.AppSettingsActivity
 import org.thoughtcrime.securesms.conversation.NewConversationUiState.UserMessage
 import org.thoughtcrime.securesms.groups.ui.creategroup.CreateGroupActivity
-import org.thoughtcrime.securesms.recipients.PhoneNumber
 import org.thoughtcrime.securesms.recipients.Recipient
 import org.thoughtcrime.securesms.recipients.RecipientId
+import org.thoughtcrime.securesms.recipients.ui.RecipientPickerScaffold
+import org.thoughtcrime.securesms.recipients.ui.RecipientSelection
 import org.thoughtcrime.securesms.recipients.ui.findby.FindByActivity
 import org.thoughtcrime.securesms.recipients.ui.findby.FindByMode
 import org.thoughtcrime.securesms.util.CommunicationActions
-import org.thoughtcrime.securesms.window.AppScaffold
-import org.thoughtcrime.securesms.window.detailPaneMaxContentWidth
-import org.thoughtcrime.securesms.window.isSplitPane
-import org.thoughtcrime.securesms.window.rememberAppScaffoldNavigator
 
 /**
  * Allows the user to start a new conversation by selecting a recipient.
@@ -121,7 +108,7 @@ private fun NewConversationScreen(
     contract = FindByActivity.Contract(),
     onResult = { recipientId ->
       if (recipientId != null) {
-        viewModel.openConversation(recipientId)
+        viewModel.openConversation(selection = RecipientSelection.WithId(recipientId))
       }
     }
   )
@@ -133,10 +120,9 @@ private fun NewConversationScreen(
       override fun onCreateNewGroup() = createGroupLauncher.launch(CreateGroupActivity.createIntent(context))
       override fun onFindByUsername() = findByLauncher.launch(FindByMode.USERNAME)
       override fun onFindByPhoneNumber() = findByLauncher.launch(FindByMode.PHONE_NUMBER)
-      override suspend fun shouldAllowSelection(id: RecipientId?, phone: PhoneNumber?): Boolean = true
-      override fun onRecipientSelected(id: RecipientId?, phone: PhoneNumber?) = viewModel.openConversation(id, phone)
-      override fun onPendingRecipientSelectionsConsumed() = Unit
-      override fun onMessage(id: RecipientId) = viewModel.openConversation(id)
+      override suspend fun shouldAllowSelection(selection: RecipientSelection): Boolean = true
+      override fun onRecipientSelected(selection: RecipientSelection) = viewModel.openConversation(selection)
+      override fun onMessage(id: RecipientId) = viewModel.openConversation(RecipientSelection.WithId(id))
       override fun onVoiceCall(recipient: Recipient) = CommunicationActions.startVoiceCall(context, recipient, viewModel::showUserAlreadyInACall)
       override fun onVideoCall(recipient: Recipient) = CommunicationActions.startVideoCall(context, recipient, viewModel::showUserAlreadyInACall)
 
@@ -196,75 +182,38 @@ private suspend fun openConversation(
   onComplete()
 }
 
-@OptIn(ExperimentalMaterial3Api::class, ExperimentalMaterial3AdaptiveApi::class)
 @Composable
 private fun NewConversationScreenUi(
   uiState: NewConversationUiState,
   callbacks: UiCallbacks
 ) {
-  val windowSizeClass = currentWindowAdaptiveInfo().windowSizeClass
-  val isSplitPane = windowSizeClass.isSplitPane(forceSplitPane = uiState.forceSplitPaneOnCompactLandscape)
   val snackbarHostState = remember { SnackbarHostState() }
 
-  AppScaffold(
-    topBarContent = {
-      Scaffolds.DefaultTopAppBar(
-        title = if (!isSplitPane) stringResource(R.string.NewConversationActivity__new_message) else "",
-        titleContent = { _, title -> Text(text = title, style = MaterialTheme.typography.titleLarge) },
-        navigationIcon = ImageVector.vectorResource(R.drawable.symbol_arrow_start_24),
-        navigationContentDescription = stringResource(R.string.DefaultTopAppBar__navigate_up_content_description),
-        onNavigationClick = callbacks::onBackPressed,
-        actions = { TopAppBarActions(callbacks) }
-      )
-    },
-
-    secondaryContent = {
-      if (isSplitPane) {
-        ScreenTitlePane(
-          title = stringResource(R.string.NewConversationActivity__new_message),
-          modifier = Modifier.fillMaxSize()
-        )
-      } else {
-        NewConversationRecipientPicker(
-          uiState = uiState,
-          callbacks = callbacks
-        )
-      }
-    },
-
+  RecipientPickerScaffold(
+    title = stringResource(R.string.NewConversationActivity__new_message),
+    forceSplitPane = uiState.forceSplitPaneOnCompactLandscape,
+    onNavigateUpClick = callbacks::onBackPressed,
+    topAppBarActions = { TopAppBarActions(callbacks) },
+    snackbarHostState = snackbarHostState,
     primaryContent = {
-      Box(
-        contentAlignment = Alignment.Center,
-        modifier = Modifier.fillMaxSize()
-      ) {
-        NewConversationRecipientPicker(
-          uiState = uiState,
-          callbacks = callbacks,
-          modifier = Modifier.widthIn(max = windowSizeClass.detailPaneMaxContentWidth)
-        )
+      NewConversationRecipientPicker(
+        uiState = uiState,
+        callbacks = callbacks
+      )
+
+      UserMessagesHost(
+        userMessage = uiState.userMessage,
+        onDismiss = callbacks::onUserMessageDismissed,
+        onRemoveConfirmed = callbacks::onRemoveConfirmed,
+        onBlockConfirmed = callbacks::onBlockConfirmed,
+        snackbarHostState = snackbarHostState
+      )
+
+      if (uiState.isLookingUpRecipient) {
+        Dialogs.IndeterminateProgressDialog()
       }
-    },
-
-    snackbarHost = {
-      SnackbarHost(snackbarHostState)
-    },
-
-    navigator = rememberAppScaffoldNavigator(
-      isSplitPane = isSplitPane
-    )
+    }
   )
-
-  UserMessagesHost(
-    userMessage = uiState.userMessage,
-    onDismiss = callbacks::onUserMessageDismissed,
-    onRemoveConfirmed = callbacks::onRemoveConfirmed,
-    onBlockConfirmed = callbacks::onBlockConfirmed,
-    snackbarHostState = snackbarHostState
-  )
-
-  if (uiState.isLookingUpRecipient) {
-    Dialogs.IndeterminateProgressDialog()
-  }
 }
 
 @Composable
@@ -323,6 +272,7 @@ private interface UiCallbacks :
   fun onRemoveConfirmed(recipient: Recipient)
   fun onBlockConfirmed(recipient: Recipient)
   fun onUserMessageDismissed(userMessage: UserMessage)
+  override fun onPendingRecipientSelectionsConsumed() = Unit
   fun onBackPressed()
 
   object Empty : UiCallbacks {
@@ -330,8 +280,8 @@ private interface UiCallbacks :
     override fun onCreateNewGroup() = Unit
     override fun onFindByUsername() = Unit
     override fun onFindByPhoneNumber() = Unit
-    override suspend fun shouldAllowSelection(id: RecipientId?, phone: PhoneNumber?): Boolean = true
-    override fun onRecipientSelected(id: RecipientId?, phone: PhoneNumber?) = Unit
+    override suspend fun shouldAllowSelection(selection: RecipientSelection): Boolean = true
+    override fun onRecipientSelected(selection: RecipientSelection) = Unit
     override fun onPendingRecipientSelectionsConsumed() = Unit
     override fun onMessage(id: RecipientId) = Unit
     override fun onVoiceCall(recipient: Recipient) = Unit
@@ -404,7 +354,7 @@ private fun UserMessagesHost(
     )
 
     is UserMessage.Info.RecipientNotSignalUser -> Dialogs.SimpleMessageDialog(
-      message = stringResource(R.string.NewConversationActivity__s_is_not_a_signal_user, userMessage.phone!!.displayText),
+      message = stringResource(R.string.NewConversationActivity__s_is_not_a_signal_user, userMessage.phone.displayText),
       dismiss = stringResource(android.R.string.ok),
       onDismiss = { onDismiss(userMessage) }
     )

app/src/main/java/org/thoughtcrime/securesms/conversation/NewConversationViewModel.kt

@@ -26,6 +26,7 @@ import org.thoughtcrime.securesms.recipients.PhoneNumber
 import org.thoughtcrime.securesms.recipients.Recipient
 import org.thoughtcrime.securesms.recipients.RecipientId
 import org.thoughtcrime.securesms.recipients.RecipientRepository
+import org.thoughtcrime.securesms.recipients.ui.RecipientSelection
 
 class NewConversationViewModel : ViewModel() {
   companion object {
@@ -41,20 +42,22 @@ class NewConversationViewModel : ViewModel() {
     internalUiState.update { it.copy(searchQuery = query) }
   }
 
-  fun openConversation(recipientId: RecipientId) {
+  private fun openConversation(recipientId: RecipientId) {
     internalUiState.update { it.copy(pendingDestination = recipientId) }
   }
 
-  fun openConversation(id: RecipientId?, phone: PhoneNumber?) {
-    when {
-      id != null -> openConversation(recipientId = id)
-
-      SignalStore.account.isRegistered -> {
-        Log.d(TAG, "[openConversation] Missing recipientId: attempting to look up.")
-        resolveAndOpenConversation(phone!!)
+  fun openConversation(selection: RecipientSelection) {
+    when (selection) {
+      is RecipientSelection.WithId -> openConversation(recipientId = selection.id)
+      is RecipientSelection.WithIdAndPhone -> openConversation(recipientId = selection.id)
+      is RecipientSelection.WithPhone -> {
+        if (SignalStore.account.isRegistered) {
+          Log.d(TAG, "[openConversation] Missing recipientId: attempting to look up.")
+          resolveAndOpenConversation(selection.phone)
+        } else {
+          Log.w(TAG, "[openConversation] Cannot look up recipient: account not registered.")
+        }
       }
-
-      else -> Log.w(TAG, "[openConversation] Cannot look up recipient: account not registered.")
     }
   }
 

app/src/main/java/org/thoughtcrime/securesms/conversation/RecipientPicker.kt

@@ -55,6 +55,7 @@ import org.thoughtcrime.securesms.groups.SelectionLimits
 import org.thoughtcrime.securesms.recipients.PhoneNumber
 import org.thoughtcrime.securesms.recipients.Recipient
 import org.thoughtcrime.securesms.recipients.RecipientId
+import org.thoughtcrime.securesms.recipients.ui.RecipientSelection
 import java.util.Optional
 import java.util.function.Consumer
 
@@ -244,13 +245,20 @@ private fun ContactSelectionListFragment.setUpCallbacks(
       chatType: Optional<ChatType?>,
       resultConsumer: Consumer<Boolean?>
     ) {
-      val recipientId = recipientId.orNull()
+      val id = recipientId.orNull()
       val phone = number?.let(::PhoneNumber)
 
+      val selection = when {
+        id != null && phone != null -> RecipientSelection.WithIdAndPhone(id, phone)
+        id != null -> RecipientSelection.WithId(id)
+        phone != null -> RecipientSelection.WithPhone(phone)
+        else -> error("Either RecipientId or PhoneNumber must be non-null")
+      }
+
       coroutineScope.launch {
-        val shouldAllowSelection = callbacks.listActions.shouldAllowSelection(recipientId, phone)
+        val shouldAllowSelection = callbacks.listActions.shouldAllowSelection(selection)
         if (shouldAllowSelection) {
-          callbacks.listActions.onRecipientSelected(recipientId, phone)
+          callbacks.listActions.onRecipientSelected(selection)
         }
         resultConsumer.accept(shouldAllowSelection)
       }
@@ -378,16 +386,16 @@ data class RecipientPickerCallbacks(
      * This is called before [onRecipientSelected] to provide a chance to prevent the selection.
      */
     fun onSearchQueryChanged(query: String)
-    suspend fun shouldAllowSelection(id: RecipientId?, phone: PhoneNumber?): Boolean
-    fun onRecipientSelected(id: RecipientId?, phone: PhoneNumber?)
+    suspend fun shouldAllowSelection(selection: RecipientSelection): Boolean
+    fun onRecipientSelected(selection: RecipientSelection)
     fun onSelectionChanged(newSelections: List<SelectedContact>, totalMembersCount: Int) = Unit
     fun onPendingRecipientSelectionsConsumed()
     fun onContactsListReset() = Unit
 
     object Empty : ListActions {
       override fun onSearchQueryChanged(query: String) = Unit
-      override suspend fun shouldAllowSelection(id: RecipientId?, phone: PhoneNumber?): Boolean = true
-      override fun onRecipientSelected(id: RecipientId?, phone: PhoneNumber?) = Unit
+      override suspend fun shouldAllowSelection(selection: RecipientSelection): Boolean = true
+      override fun onRecipientSelected(selection: RecipientSelection) = Unit
       override fun onPendingRecipientSelectionsConsumed() = Unit
       override fun onContactsListReset() = Unit
     }

app/src/main/java/org/thoughtcrime/securesms/groups/ui/creategroup/CreateGroupActivity.kt

@@ -24,16 +24,12 @@ import androidx.compose.animation.core.tween
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.widthIn
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.FilledTonalIconButton
 import androidx.compose.material3.Icon
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.SnackbarHost
 import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.Text
 import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
-import androidx.compose.material3.adaptive.currentWindowAdaptiveInfo
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
@@ -52,11 +48,9 @@ import org.signal.core.ui.compose.AllDevicePreviews
 import org.signal.core.ui.compose.Buttons
 import org.signal.core.ui.compose.Dialogs
 import org.signal.core.ui.compose.Previews
-import org.signal.core.ui.compose.Scaffolds
 import org.signal.core.ui.compose.theme.SignalTheme
 import org.thoughtcrime.securesms.PassphraseRequiredActivity
 import org.thoughtcrime.securesms.R
-import org.thoughtcrime.securesms.components.compose.ScreenTitlePane
 import org.thoughtcrime.securesms.contacts.SelectedContact
 import org.thoughtcrime.securesms.conversation.RecipientPicker
 import org.thoughtcrime.securesms.conversation.RecipientPickerCallbacks
@@ -64,14 +58,10 @@ import org.thoughtcrime.securesms.groups.SelectionLimits
 import org.thoughtcrime.securesms.groups.ui.creategroup.CreateGroupUiState.NavTarget
 import org.thoughtcrime.securesms.groups.ui.creategroup.CreateGroupUiState.UserMessage
 import org.thoughtcrime.securesms.groups.ui.creategroup.details.AddGroupDetailsActivity
-import org.thoughtcrime.securesms.recipients.PhoneNumber
-import org.thoughtcrime.securesms.recipients.RecipientId
+import org.thoughtcrime.securesms.recipients.ui.RecipientPickerScaffold
+import org.thoughtcrime.securesms.recipients.ui.RecipientSelection
 import org.thoughtcrime.securesms.recipients.ui.findby.FindByActivity
 import org.thoughtcrime.securesms.recipients.ui.findby.FindByMode
-import org.thoughtcrime.securesms.window.AppScaffold
-import org.thoughtcrime.securesms.window.detailPaneMaxContentWidth
-import org.thoughtcrime.securesms.window.isSplitPane
-import org.thoughtcrime.securesms.window.rememberAppScaffoldNavigator
 import java.text.NumberFormat
 
 /**
@@ -128,7 +118,7 @@ private fun CreateGroupScreen(
       override fun onSearchQueryChanged(query: String) = viewModel.onSearchQueryChanged(query)
       override fun onFindByUsername() = findByLauncher.launch(FindByMode.USERNAME)
       override fun onFindByPhoneNumber() = findByLauncher.launch(FindByMode.PHONE_NUMBER)
-      override suspend fun shouldAllowSelection(id: RecipientId?, phone: PhoneNumber?): Boolean = viewModel.shouldAllowSelection(id, phone)
+      override suspend fun shouldAllowSelection(selection: RecipientSelection): Boolean = viewModel.shouldAllowSelection(selection)
       override fun onSelectionChanged(newSelections: List<SelectedContact>, totalMembersCount: Int) = viewModel.onSelectionChanged(newSelections, totalMembersCount)
       override fun onPendingRecipientSelectionsConsumed() = viewModel.clearPendingRecipientSelections()
       override fun onNextClicked(): Unit = viewModel.continueToGroupDetails()
@@ -164,11 +154,7 @@ private fun CreateGroupScreenUi(
   uiState: CreateGroupUiState,
   callbacks: UiCallbacks
 ) {
-  val windowSizeClass = currentWindowAdaptiveInfo().windowSizeClass
-  val isSplitPane = windowSizeClass.isSplitPane(forceSplitPane = uiState.forceSplitPane)
-  val snackbarHostState = remember { SnackbarHostState() }
-
-  val titleText = if (uiState.newSelections.isNotEmpty()) {
+  val title = if (uiState.newSelections.isNotEmpty()) {
     pluralStringResource(
       id = R.plurals.CreateGroupActivity__s_members,
       count = uiState.totalMembersCount,
@@ -178,61 +164,28 @@ private fun CreateGroupScreenUi(
     stringResource(R.string.CreateGroupActivity__select_members)
   }
 
-  AppScaffold(
-    topBarContent = {
-      Scaffolds.DefaultTopAppBar(
-        title = if (!isSplitPane) titleText else "",
-        titleContent = { _, title -> Text(text = title, style = MaterialTheme.typography.titleLarge) },
-        navigationIcon = ImageVector.vectorResource(R.drawable.symbol_arrow_start_24),
-        navigationContentDescription = stringResource(R.string.DefaultTopAppBar__navigate_up_content_description),
-        onNavigationClick = callbacks::onBackPressed
-      )
-    },
-
-    secondaryContent = {
-      if (isSplitPane) {
-        ScreenTitlePane(
-          title = titleText,
-          modifier = Modifier.fillMaxSize()
-        )
-      } else {
-        CreateGroupRecipientPicker(
-          uiState = uiState,
-          callbacks = callbacks
-        )
-      }
-    },
-
+  RecipientPickerScaffold(
+    title = title,
+    forceSplitPane = uiState.forceSplitPane,
+    onNavigateUpClick = callbacks::onBackPressed,
+    topAppBarActions = {},
+    snackbarHostState = remember { SnackbarHostState() },
     primaryContent = {
-      Box(
-        contentAlignment = Alignment.Center,
-        modifier = Modifier.fillMaxSize()
-      ) {
-        CreateGroupRecipientPicker(
-          uiState = uiState,
-          callbacks = callbacks,
-          modifier = Modifier.widthIn(max = windowSizeClass.detailPaneMaxContentWidth)
-        )
+      CreateGroupRecipientPicker(
+        uiState = uiState,
+        callbacks = callbacks
+      )
+
+      UserMessagesHost(
+        userMessage = uiState.userMessage,
+        onDismiss = callbacks::onUserMessageDismissed
+      )
+
+      if (uiState.isLookingUpRecipient) {
+        Dialogs.IndeterminateProgressDialog()
       }
-    },
-
-    snackbarHost = {
-      SnackbarHost(snackbarHostState)
-    },
-
-    navigator = rememberAppScaffoldNavigator(
-      isSplitPane = isSplitPane
-    )
+    }
   )
-
-  UserMessagesHost(
-    userMessage = uiState.userMessage,
-    onDismiss = callbacks::onUserMessageDismissed
-  )
-
-  if (uiState.isLookingUpRecipient) {
-    Dialogs.IndeterminateProgressDialog()
-  }
 }
 
 @Composable
@@ -296,7 +249,7 @@ private interface UiCallbacks :
   RecipientPickerCallbacks.FindByUsername,
   RecipientPickerCallbacks.FindByPhoneNumber {
 
-  override fun onRecipientSelected(id: RecipientId?, phone: PhoneNumber?) = Unit
+  override fun onRecipientSelected(selection: RecipientSelection) = Unit
   fun onNextClicked()
   fun onUserMessageDismissed(userMessage: UserMessage)
   fun onBackPressed()
@@ -306,7 +259,7 @@ private interface UiCallbacks :
     override fun onSearchQueryChanged(query: String) = Unit
     override fun onFindByUsername() = Unit
     override fun onFindByPhoneNumber() = Unit
-    override suspend fun shouldAllowSelection(id: RecipientId?, phone: PhoneNumber?): Boolean = true
+    override suspend fun shouldAllowSelection(selection: RecipientSelection): Boolean = true
     override fun onPendingRecipientSelectionsConsumed() = Unit
     override fun onNextClicked() = Unit
     override fun onUserMessageDismissed(userMessage: UserMessage) = Unit

app/src/main/java/org/thoughtcrime/securesms/groups/ui/creategroup/CreateGroupViewModel.kt

@@ -27,6 +27,7 @@ import org.thoughtcrime.securesms.recipients.PhoneNumber
 import org.thoughtcrime.securesms.recipients.Recipient
 import org.thoughtcrime.securesms.recipients.RecipientId
 import org.thoughtcrime.securesms.recipients.RecipientRepository
+import org.thoughtcrime.securesms.recipients.ui.RecipientSelection
 import org.thoughtcrime.securesms.util.RemoteConfig
 import java.io.IOException
 import kotlin.time.Duration.Companion.seconds
@@ -43,8 +44,9 @@ class CreateGroupViewModel : ViewModel() {
     internalUiState.update { it.copy(searchQuery = query) }
   }
 
-  suspend fun shouldAllowSelection(id: RecipientId?, phone: PhoneNumber?): Boolean {
-    return if (id != null) true else recipientExists(phone!!)
+  suspend fun shouldAllowSelection(selection: RecipientSelection): Boolean = when (selection) {
+    is RecipientSelection.WithId, is RecipientSelection.WithIdAndPhone -> true
+    is RecipientSelection.WithPhone -> recipientExists(selection.phone)
   }
 
   private suspend fun recipientExists(phone: PhoneNumber): Boolean {

app/src/main/java/org/thoughtcrime/securesms/recipients/ui/RecipientPickerScaffold.kt

@@ -0,0 +1,118 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.recipients.ui
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.widthIn
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.SnackbarHost
+import androidx.compose.material3.SnackbarHostState
+import androidx.compose.material3.Text
+import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
+import androidx.compose.material3.adaptive.currentWindowAdaptiveInfo
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.res.vectorResource
+import org.signal.core.ui.compose.AllDevicePreviews
+import org.signal.core.ui.compose.Previews
+import org.signal.core.ui.compose.Scaffolds
+import org.thoughtcrime.securesms.R
+import org.thoughtcrime.securesms.components.compose.ScreenTitlePane
+import org.thoughtcrime.securesms.window.AppScaffold
+import org.thoughtcrime.securesms.window.detailPaneMaxContentWidth
+import org.thoughtcrime.securesms.window.isSplitPane
+import org.thoughtcrime.securesms.window.rememberAppScaffoldNavigator
+
+/**
+ * Provides the common adaptive layout structure for recipient picker screens.
+ */
+@OptIn(ExperimentalMaterial3Api::class, ExperimentalMaterial3AdaptiveApi::class)
+@Composable
+fun RecipientPickerScaffold(
+  title: String,
+  forceSplitPane: Boolean,
+  onNavigateUpClick: () -> Unit,
+  topAppBarActions: @Composable () -> Unit,
+  snackbarHostState: SnackbarHostState,
+  primaryContent: @Composable () -> Unit
+) {
+  val windowSizeClass = currentWindowAdaptiveInfo().windowSizeClass
+  val isSplitPane = windowSizeClass.isSplitPane(forceSplitPane = forceSplitPane)
+
+  AppScaffold(
+    topBarContent = {
+      Scaffolds.DefaultTopAppBar(
+        title = if (!isSplitPane) title else "",
+        titleContent = { _, titleText -> Text(text = titleText, style = MaterialTheme.typography.titleLarge) },
+        navigationIcon = ImageVector.vectorResource(R.drawable.symbol_arrow_start_24),
+        navigationContentDescription = stringResource(R.string.DefaultTopAppBar__navigate_up_content_description),
+        onNavigationClick = onNavigateUpClick,
+        actions = { topAppBarActions() }
+      )
+    },
+
+    secondaryContent = {
+      if (isSplitPane) {
+        ScreenTitlePane(
+          title = title,
+          modifier = Modifier.fillMaxSize()
+        )
+      } else {
+        primaryContent()
+      }
+    },
+
+    primaryContent = {
+      Box(
+        contentAlignment = Alignment.Center,
+        modifier = Modifier.fillMaxSize()
+      ) {
+        Box(modifier = Modifier.widthIn(max = windowSizeClass.detailPaneMaxContentWidth)) {
+          primaryContent()
+        }
+      }
+    },
+
+    snackbarHost = {
+      SnackbarHost(snackbarHostState)
+    },
+
+    navigator = rememberAppScaffoldNavigator(
+      isSplitPane = isSplitPane
+    )
+  )
+}
+
+@AllDevicePreviews
+@Composable
+private fun RecipientPickerScaffoldPreview() {
+  Previews.Preview {
+    RecipientPickerScaffold(
+      title = "Screen Title",
+      forceSplitPane = false,
+      onNavigateUpClick = {},
+      topAppBarActions = {},
+      snackbarHostState = SnackbarHostState(),
+      primaryContent = {
+        Box(
+          modifier = Modifier
+            .fillMaxSize()
+            .background(color = Color.Gray),
+          contentAlignment = Alignment.Center
+        ) {
+          Text(text = "primaryContent")
+        }
+      }
+    )
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/recipients/ui/RecipientSelection.kt

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.recipients.ui
+
+import org.thoughtcrime.securesms.recipients.PhoneNumber
+import org.thoughtcrime.securesms.recipients.RecipientId
+
+sealed interface RecipientSelection {
+  data class WithId(val id: RecipientId) : RecipientSelection
+  data class WithPhone(val phone: PhoneNumber) : RecipientSelection
+  data class WithIdAndPhone(val id: RecipientId, val phone: PhoneNumber) : RecipientSelection
+}