feat(chat): send back a DM's opening payment

apps/flipcash/app/src/main/kotlin/com/flipcash/app/inject/TransactionRouterModule.kt

@@ -0,0 +1,26 @@
+package com.flipcash.app.inject
+
+import com.flipcash.shared.chat.ChatCoordinator
+import com.flipcash.shared.chat.ChatHydration
+import com.flipcash.shared.transactionhistory.TransactionRouter
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+
+@Module
+@InstallIn(SingletonComponent::class)
+object TransactionRouterModule {
+    /**
+     * A send-back's activity row opens its DM only when the chat is stored or the server still has
+     * it. An absent or unreachable chat opens the details instead.
+     */
+    @Provides
+    fun providesTransactionRouter(chats: ChatCoordinator): TransactionRouter =
+        TransactionRouter.forChats { chatId ->
+            when (chats.hydrateChat(chatId)) {
+                ChatHydration.Stored, is ChatHydration.Fetched -> true
+                else -> false
+            }
+        }
+}

apps/flipcash/core/src/androidMain/res/values/strings.xml

@@ -2064,6 +2064,23 @@
         <item quantity="other">You and %1$d others received</item>
     </plurals>
     <string name="label_cashFrom">from %1$s</string>
+    <!-- Send Back: a DM's opening payment returned to its sender. The return's bubble, its sender's view. -->
+    <string name="subtitle_youSentBack">You sent back</string>
+    <!-- The return's bubble, read by the person it was returned to; also their activity row title. -->
+    <string name="subtitle_senderSentBack">%1$s sent back</string>
+    <!-- The return's foot line, read by the person it was returned to. Capital Y on return bubbles only. -->
+    <string name="label_cashReturnToYou">to You</string>
+    <!-- The action row under an opening payment its receiver can return. -->
+    <string name="action_sendBack">Send Back</string>
+    <!-- The footer under an opening payment once it has been returned. -->
+    <string name="label_sentBack">Sent Back</string>
+    <!-- The Send Back confirm sheet, under the currency. -->
+    <string name="label_sendBackTo">Send back to %1$s</string>
+    <string name="action_swipeToSendBack">Swipe to Send Back</string>
+    <string name="error_title_couldntSendBack">Couldn\'t Send Back</string>
+    <string name="error_description_couldntSendBack">Something went wrong. Please try again.</string>
+    <!-- Activity row title for a payment the viewer returned. -->
+    <string name="title_activitySentBackTo">Sent back to %1$s</string>
     <!-- What a cash bubble calls a sender or recipient whose name has not resolved. -->
     <string name="label_cashSomeone">Someone</string>
     <string name="label_cashDetails_sent">Sent</string>

apps/flipcash/features/balance/src/androidMain/kotlin/com/flipcash/app/balance/internal/HiltWalletViewModel.kt

@@ -8,6 +8,7 @@ import com.flipcash.app.userflags.UserFlagsCoordinator
 import com.flipcash.libs.coroutines.DispatcherProvider
 import com.flipcash.services.user.UserManager
 import com.flipcash.shared.transactionhistory.ActivityFeedCoordinator
+import com.flipcash.shared.transactionhistory.TransactionRouter
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 
@@ -22,6 +23,7 @@ internal class HiltWalletViewModel @Inject constructor(
     feedCoordinator: ActivityFeedCoordinator,
     tokenCoordinator: TokenCoordinator,
     walletReveal: WalletRevealCoordinator,
+    transactionRouter: TransactionRouter,
 ) : WalletViewModel(
     userManager = userManager,
     userFlags = userFlags,
@@ -31,4 +33,5 @@ internal class HiltWalletViewModel @Inject constructor(
     feedCoordinator = feedCoordinator,
     tokenCoordinator = tokenCoordinator,
     walletReveal = walletReveal,
+    transactionRouter = transactionRouter,
 )

apps/flipcash/features/balance/src/commonMain/kotlin/com/flipcash/app/balance/internal/WalletScreenContent.kt

@@ -288,9 +288,7 @@ internal fun WalletScreenContent(
                     }
                     .padding(top = grid.x4, bottom = grid.x1),
                 onItemClick = { item ->
-                    dispatchEvent(
-                        WalletViewModel.Event.OpenScreen(AppRoute.Sheets.TransactionDetails(item.messageId))
-                    )
+                    dispatchEvent(WalletViewModel.Event.OpenTransaction(item))
                 },
             )
         }

apps/flipcash/features/balance/src/commonMain/kotlin/com/flipcash/app/balance/internal/WalletViewModel.kt

@@ -8,6 +8,7 @@ import com.flipcash.app.core.AppRoute
 import com.flipcash.shared.transactionhistory.ActivityFeedCoordinator
 import com.flipcash.shared.transactionhistory.FeedSyncState
 import com.flipcash.shared.transactionhistory.TransactionListItem
+import com.flipcash.shared.transactionhistory.TransactionRouter
 import com.flipcash.app.funding.PurchaseMethodController
 import com.flipcash.app.tokens.TokenCoordinator
 import com.flipcash.app.tokens.WalletReveal
@@ -40,6 +41,7 @@ open class WalletViewModel @Inject constructor(
     feedCoordinator: ActivityFeedCoordinator,
     tokenCoordinator: TokenCoordinator,
     walletReveal: WalletRevealCoordinator,
+    transactionRouter: TransactionRouter = TransactionRouter.DetailsOnly,
 ) : BaseViewModel<WalletViewModel.State, WalletViewModel.Event>(
     initialState = State(),
     updateStateForEvent = updateStateForEvent,
@@ -117,6 +119,7 @@ open class WalletViewModel @Inject constructor(
         data object OpenCurrencySelection : Event
 
         data class OpenScreen(val screen: AppRoute) : Event
+        data class OpenTransaction(val item: TransactionListItem) : Event
         data object PresentDepositOptions: Event
     }
 
@@ -151,6 +154,11 @@ open class WalletViewModel @Inject constructor(
             .onEach { provider -> dispatchEvent(Event.OnPreferredOnRampProviderChanged(provider)) }
             .launchIn(viewModelScope)
 
+        eventFlow
+            .filterIsInstance<Event.OpenTransaction>()
+            .onEach { dispatchEvent(Event.OpenScreen(transactionRouter.routeFor(it.item))) }
+            .launchIn(viewModelScope)
+
         eventFlow
             .filterIsInstance<Event.PresentDepositOptions>()
             .mapNotNull {
@@ -211,6 +219,7 @@ open class WalletViewModel @Inject constructor(
                 }
                 Event.PresentDepositOptions -> { state -> state }
                 is Event.OpenScreen -> { state -> state }
+                is Event.OpenTransaction -> { state -> state }
             }
         }
     }

apps/flipcash/features/messenger/src/main/kotlin/com/flipcash/app/messenger/internal/ChatViewModel.kt

@@ -178,6 +178,9 @@ import com.flipcash.shared.payments.ContactPaymentDelegate
 import com.flipcash.shared.payments.group.GroupSendInsufficientBalance
 import com.flipcash.shared.payments.group.GroupSendPaymentDelegate
 import com.flipcash.shared.payments.TipPaymentDelegate
+import com.flipcash.shared.payments.sendback.SendBackPaymentDelegate
+import com.flipcash.services.controllers.ChatMessagingController
+import com.flipcash.app.messenger.internal.sendback.SendBackFlow
 import com.getcode.libs.emojis.reactions.EmojiCatalogLoader
 import com.getcode.libs.emojis.reactions.EmojiDrawability
 import com.getcode.libs.emojis.reactions.RecentReactions
@@ -327,6 +330,9 @@ internal class ChatViewModel @AssistedInject constructor(
     // Last and defaulted so the transcript tests, which hold no saved previews, need not supply one.
     linkCardMemory: LinkCardMemory? = null,
     private val composerLinkPreview: ComposerLinkPreview? = null,
+    // Defaulted for the same reason: only the Send Back tests supply them.
+    sendBackPayments: SendBackPaymentDelegate? = null,
+    chatMessagingController: ChatMessagingController? = null,
 ) : BaseViewModel<ChatViewModel.State, ChatViewModel.Event>(
     initialState = State(
         openingAtMessage = openAtMessageId != null,
@@ -1400,6 +1406,46 @@ internal class ChatViewModel @AssistedInject constructor(
         .flatMapLatest { chatCoordinator.observeChatReactions(it) }
         .stateIn(viewModelScope, SharingStarted.Eagerly, emptyMap())
 
+    /**
+     * Send Back: returning a DM's opening payment. The transcript notes each cash message to it as
+     * it maps them, and its rows join the built pages as an overlay, like [reactionOverlay]. Null
+     * where its collaborators are not supplied (tests that don't exercise it).
+     */
+    private val sendBack: SendBackFlow? =
+        if (sendBackPayments != null && chatMessagingController != null) {
+            SendBackFlow(
+                scope = viewModelScope,
+                payments = sendBackPayments,
+                returnStatus = chatMessagingController::getCashMessageReturnStatus,
+                payer = startChattingPayer,
+                tokenCoordinator = tokenCoordinator,
+                userManager = userManager,
+                resources = resources,
+                analytics = analytics,
+                chatId = { stateFlow.value.chatId },
+                peerName = { stateFlow.value.participant?.name },
+                openScreen = { route -> dispatchEvent(Event.OpenScreen(route)) },
+            )
+        } else {
+            null
+        }
+
+    /** The Send Back confirm sheet, or null when it is not up. */
+    val sendBackSheet: StateFlow<SendBackFlow.Sheet?> =
+        sendBack?.sheet ?: MutableStateFlow(null)
+
+    fun onSendBack(messageId: Long) {
+        sendBack?.tap(messageId)
+    }
+
+    fun confirmSendBack() {
+        sendBack?.confirm()
+    }
+
+    fun dismissSendBack() {
+        sendBack?.dismiss()
+    }
+
     /**
      * Null for a DM, a map for a group — the distinction the transcript needs, because a DM's
      * counterparty is already named in the title bar and attributing each of their bubbles would be
@@ -1708,6 +1754,10 @@ internal class ChatViewModel @AssistedInject constructor(
                         }
                     }
 
+                    (enriched as? MessageContent.Cash)?.let { cash ->
+                        sendBack?.note(message.messageId, cash, message.senderId, message.isFromSelf)
+                    }
+
                     ChatListItem.ContentBubble(
                         messageId = message.messageId,
                         contentIndex = index,
@@ -1804,7 +1854,22 @@ internal class ChatViewModel @AssistedInject constructor(
                     )
                 }
             }
-        }.cachedIn(pagingScope)
+        }
+        // Send Back's rows, the same way: an overlay on the built pages keyed by message id, so a
+        // status answer or a tap re-maps one field without re-running the pass above.
+        .let { pages ->
+            val rows = sendBack?.rows ?: return@let pages
+            combine(pages, rows) { data, overlay ->
+                if (overlay.isEmpty()) return@combine data
+                data.map { item ->
+                    if (item !is ChatListItem.ContentBubble || item.content !is MessageContent.Cash) {
+                        return@map item
+                    }
+                    overlay[item.messageId]?.let { item.copy(sendBack = it) } ?: item
+                }
+            }
+        }
+        .cachedIn(pagingScope)
 
     /**
      * The transcript as the list draws it: [mappedMessages] with date separators and the unread

apps/flipcash/features/messenger/src/main/kotlin/com/flipcash/app/messenger/internal/screens/MessengerScreen.kt

@@ -71,6 +71,7 @@ import com.flipcash.app.core.links.LocalTrustedWebsites
 import com.flipcash.app.core.tokens.TokenInfoEntry
 import com.flipcash.app.messenger.internal.ChatSubject
 import com.flipcash.app.messenger.internal.ChatViewModel
+import com.flipcash.app.messenger.internal.screens.cash.SendBackSheetHost
 import com.flipcash.app.messenger.internal.MemberModerationViewModel
 import com.flipcash.app.core.chat.ProfileOrigin
 import com.flipcash.app.messenger.internal.screens.profile.memberTapStep
@@ -464,6 +465,9 @@ internal fun MessengerScreen(viewModel: ChatViewModel) {
             is ChatAction.RefreshReactionIds -> {
                 viewModel.dispatchEvent(ChatViewModel.Event.RefreshReactionIds(action.messageIds))
             }
+
+            // Keyboard first, so the confirm sheet or the balance modal rises over a settled chat.
+            is ChatAction.SendBack -> keyboard.hideIfVisible { viewModel.onSendBack(action.messageId) }
         }
 
         Unit
@@ -796,6 +800,13 @@ internal fun MessengerScreen(viewModel: ChatViewModel) {
         }
     }
 
+    val sendBackSheet by viewModel.sendBackSheet.collectAsStateWithLifecycle()
+    SendBackSheetHost(
+        sheet = sendBackSheet,
+        onConfirm = viewModel::confirmSendBack,
+        onDismiss = viewModel::dismissSendBack,
+    )
+
     // In-window, over the conversation and the deck, so the bottom bar draws above it.
     RequestPaySheet(
         pay = requestPayState,

apps/flipcash/features/messenger/src/main/kotlin/com/flipcash/app/messenger/internal/screens/cash/SendBackSheet.kt

@@ -0,0 +1,128 @@
+package com.flipcash.app.messenger.internal.screens.cash
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.navigationBarsPadding
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.ModalBottomSheet
+import androidx.compose.material3.Text
+import androidx.compose.material3.rememberModalBottomSheetState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import com.flipcash.app.core.ui.TokenSelectionPill
+import com.flipcash.app.messenger.internal.sendback.SendBackFlow
+import com.flipcash.features.messenger.R
+import com.getcode.opencode.model.financial.Fiat
+import com.getcode.opencode.model.financial.Token
+import com.getcode.theme.CodeTheme
+import com.getcode.theme.White10
+import com.getcode.ui.components.SlideToConfirm
+
+/**
+ * The Send Back confirm sheet over the chat, held in-screen like the fee sheet. The sheet stays
+ * composed until it has slid away, so a dismissal from the flow (the swipe, or a balance that
+ * dropped meanwhile) animates out like a drag does.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+internal fun SendBackSheetHost(
+    sheet: SendBackFlow.Sheet?,
+    onConfirm: () -> Unit,
+    onDismiss: () -> Unit,
+) {
+    val sheetState = rememberModalBottomSheetState(skipPartiallyExpanded = true)
+    var shown by remember { mutableStateOf<SendBackFlow.Sheet?>(null) }
+    LaunchedEffect(sheet) {
+        if (sheet != null) {
+            shown = sheet
+        } else if (shown != null) {
+            sheetState.hide()
+            shown = null
+        }
+    }
+    val current = shown ?: return
+    ModalBottomSheet(
+        onDismissRequest = onDismiss,
+        sheetState = sheetState,
+        containerColor = CodeTheme.colors.background,
+    ) {
+        SendBackSheet(
+            amount = current.amount,
+            token = current.token,
+            recipientName = current.recipientName,
+            onConfirm = onConfirm,
+        )
+    }
+}
+
+/**
+ * Returning a DM's opening payment: the original's amount, its currency read-only (the contract
+ * fixes currency and mint), who it goes back to, and the swipe. [ChatInitPaymentSheet]'s layout
+ * with the picker taken out.
+ */
+@Composable
+internal fun SendBackSheet(
+    amount: Fiat,
+    token: Token?,
+    recipientName: String?,
+    onConfirm: () -> Unit,
+) {
+    Column(
+        modifier = Modifier
+            .fillMaxWidth()
+            .navigationBarsPadding()
+            .padding(horizontal = CodeTheme.dimens.inset)
+            .padding(top = CodeTheme.dimens.grid.x6, bottom = CodeTheme.dimens.grid.x2),
+        horizontalAlignment = Alignment.CenterHorizontally,
+        verticalArrangement = Arrangement.spacedBy(CodeTheme.dimens.inset),
+    ) {
+        Column(
+            horizontalAlignment = Alignment.CenterHorizontally,
+            verticalArrangement = Arrangement.spacedBy(CodeTheme.dimens.grid.x2),
+        ) {
+            Text(
+                text = amount.formatted(),
+                style = CodeTheme.typography.displayLarge,
+                color = CodeTheme.colors.textMain,
+            )
+
+            TokenSelectionPill(
+                token = token,
+                background = White10,
+                textStyle = CodeTheme.typography.textMedium,
+                imageSize = CodeTheme.dimens.staticGrid.x3,
+                contentPadding = PaddingValues(
+                    horizontal = CodeTheme.dimens.grid.x2,
+                    vertical = CodeTheme.dimens.grid.x1,
+                ),
+                showsPicker = false,
+                onClick = {},
+            )
+
+            Text(
+                text = stringResource(
+                    R.string.label_sendBackTo,
+                    recipientName?.takeIf { it.isNotBlank() } ?: stringResource(R.string.title_unnamedUser),
+                ),
+                style = CodeTheme.typography.caption,
+                color = CodeTheme.colors.textSecondary,
+            )
+        }
+
+        SlideToConfirm(
+            onConfirm = onConfirm,
+            modifier = Modifier.fillMaxWidth(),
+            label = stringResource(R.string.action_swipeToSendBack),
+        )
+    }
+}