feat(chat): open and join private groups from invite links

apps/flipcash/app/src/main/kotlin/com/flipcash/app/internal/ui/navigation/AppScreenContent.kt

@@ -46,6 +46,7 @@ import com.flipcash.app.invite.InviteContactScreen
 import com.flipcash.app.messenger.ChatFlowScreen
 import com.flipcash.app.tokens.internal.CommunityChatsScreen
 import com.flipcash.app.messenger.CurrencySendScreen
+import com.flipcash.app.messenger.internal.screens.profile.GroupInviteScreen
 import com.flipcash.app.messenger.E2eeLearnMoreScreen
 import com.flipcash.app.messenger.MuteChatScreen
 import com.flipcash.app.messenger.ProfileScreen
@@ -145,6 +146,7 @@ internal fun appEntryProvider(
             ChatFlowScreen(route = key, resultStateRegistry = resultStateRegistry)
         }
     }
+    annotatedEntry<AppRoute.Messaging.GroupInvite> { key -> GroupInviteScreen(key.secret) }
     annotatedEntry<AppRoute.Messaging.Profile> { key -> ProfileScreen(key.address, key.origin) }
     annotatedEntry<AppRoute.Messaging.NewChat> { NewChatScreen() }
     annotatedEntry<AppRoute.Messaging.ArchivedChats> { ArchivedChatsScreen() }

apps/flipcash/core/src/main/kotlin/com/flipcash/app/core/AppRoute.kt

@@ -421,6 +421,20 @@ sealed interface AppRoute : NavKey, Parcelable {
                 }
         }
 
+        /**
+         * A group invite link opened by the joiner (nodes 12846:59 to 12846:259). [secret] is the
+         * link's key material, so it is redacted from [toString]; null is a link with no valid
+         * secret, which shows the broken-link state rather than a chat.
+         */
+        @Serializable
+        @Parcelize
+        class GroupInvite(val secret: ByteArray?) : Messaging {
+            override fun equals(other: Any?): Boolean =
+                other is GroupInvite && secret.contentEquals(other.secret)
+            override fun hashCode(): Int = secret.contentHashCode()
+            override fun toString(): String = "GroupInvite(redacted)"
+        }
+
         /**
          * Node 10127:117987 — the two ways to start a chat, reached from the "+" on the Chats list.
          *

apps/flipcash/core/src/main/kotlin/com/flipcash/app/core/navigation/DeeplinkType.kt

@@ -32,6 +32,21 @@ sealed interface DeeplinkType: Parcelable {
      */
     @Serializable data class GroupChatInvite(val chatId: ChatId): DeeplinkType, Navigatable
 
+    /**
+     * A group invite link — `app.flipcash.com/chat/invite#s=<secret>`. The secret is the link's
+     * key material: it is held as bytes, never in [toString] or anything built from it, and no
+     * caller logs or reports it.
+     */
+    @Serializable
+    class GroupInvite(val secret: ByteArray) : DeeplinkType, Navigatable {
+        override fun equals(other: Any?): Boolean = other is GroupInvite && secret.contentEquals(other.secret)
+        override fun hashCode(): Int = secret.contentHashCode()
+        override fun toString(): String = "GroupInvite(redacted)"
+    }
+
+    /** `/chat/invite` whose fragment holds no valid secret: a broken link, shown as one. */
+    @Serializable data object InvalidGroupInvite : DeeplinkType, Navigatable
+
     /**
      * One message in a chat — `app.flipcash.com/chat/{chatId}/m/{seq}`.
      *
@@ -91,6 +106,8 @@ sealed interface DeeplinkType: Parcelable {
             is Profile,
             is GroupChatInvite,
             is ChatMessage,
+            is GroupInvite,
+            is InvalidGroupInvite,
             -> true
 
             is Login,

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

@@ -945,7 +945,7 @@
     <string name="action_leaveChat">Leave Chat</string>
     <string name="prompt_title_leaveChat">Leave %1$s?</string>
     <!-- A private group: coming back means a new request, not an invite link (node 11206:98). -->
-    <string name="prompt_description_leavePrivateChat">You’ll lose access to the conversation. To rejoin, you’ll need to request again and wait for the host to approve</string>
+    <string name="prompt_description_leavePrivateChat">You’ll lose access to the conversation. To rejoin, you’ll need an invite link or the host’s approval</string>
     <string name="prompt_description_leaveChat">You won’t receive messages from this group any more. You can join again with an invite link</string>
     <string name="error_title_failedToLeave">Something Went Wrong</string>
     <string name="error_description_failedToLeave">We were unable to leave this group. Please try again</string>
@@ -1008,6 +1008,9 @@
     <string name="label_chat_system_added">%1$s added %2$s</string>
     <string name="label_chat_system_addedSelf">%1$s added you</string>
     <string name="label_chat_system_selfAdded">You added %1$s</string>
+    <string name="label_chat_system_joinedViaInvite">%1$s joined with %2$s’s invite link</string>
+    <string name="label_chat_system_joinedSelfViaInvite">You joined with %1$s’s invite link</string>
+    <string name="label_chat_system_joinedViaYourInvite">%1$s joined with your invite link</string>
     <string name="label_chat_preview_sentCash_bySender">%1$s sent %2$s</string>
     <string name="label_chat_preview_tippedCash_bySender">%1$s tipped %2$s</string>
     <string name="label_chat_preview_sharedProfile">Shared a profile</string>
@@ -1211,6 +1214,9 @@
     <string name="label_linkCard_untitledGroup">Group Chat</string>
     <string name="action_linkCard_view">View</string>
     <string name="label_linkCard_groupUnavailable">Group Unavailable</string>
+    <string name="label_linkCard_privateGroupInvite">Private group · Invite link</string>
+    <!-- Stands in for an invite URL in a chat-list preview, a push and a reply citation: its fragment is the group's key. -->
+    <string name="label_inviteLinkPreview">Invite link</string>
     <string name="label_messageLink_kindPrivateGroup">Private group</string>
     <string name="label_messageLink_kindDirect">Direct message</string>
     <string name="label_messageLink_you">You</string>
@@ -1312,6 +1318,28 @@
     <string name="action_exploreCurrencies">Explore Currencies</string>
     <string name="title_newPrivateGroup">New Private Group</string>
     <string name="action_requestToJoin">Request to Join</string>
+    <!-- Opening a group invite link (nodes 12846:59, 12846:126, 12846:148, 12846:160, 12846:220, 12846:259). -->
+    <string name="subtitle_privateGroupInvited">Private group · You’ve been invited to join</string>
+    <string name="subtitle_inviteExhausted">This invite link has reached its limit.</string>
+    <string name="subtitle_inviteExpired">This invite link has expired.</string>
+    <string name="subtitle_inviteRevoked">This invite link was turned off by the host.</string>
+    <string name="action_joinGroup">Join Group</string>
+    <string name="action_leaveGroup">Leave Group</string>
+    <string name="title_inviteLinkNotFound">Link Not Found</string>
+    <string name="description_inviteLinkNotFound">This invite link isn’t valid. Ask whoever sent it for a new one.</string>
+    <string name="description_inviteGroupGone">This group no longer exists</string>
+    <string name="title_inviteBanned">You Can’t Join This Group</string>
+    <string name="description_inviteBanned">The host has removed you from this group.</string>
+    <string name="error_title_failedToJoinGroup">Couldn’t Join Group</string>
+    <string name="error_description_failedToJoinGroup">Check your connection and try again.</string>
+    <!-- Alert-bar copy: modals take no final period. The full-screen states above keep theirs. -->
+    <string name="description_inviteLinkNotFoundAlert">This invite link isn’t valid. Ask whoever sent it for a new one</string>
+    <string name="description_inviteBannedAlert">The host has removed you from this group</string>
+    <string name="error_description_failedToJoinGroupAlert">Check your connection and try again</string>
+    <string name="error_description_failedToJoinAlert">Something went wrong. Please try again</string>
+    <string name="title_cantReadGroup">Can’t read this group</string>
+    <string name="description_cantReadGroup">The invite link you used didn’t include a working key. Leave and ask the host to approve you.</string>
+    <string name="hint_cantSendHere">You can’t send messages here</string>
     <string name="action_requestSent">Request Sent</string>
     <string name="action_cancelRequest">Cancel Request</string>
     <string name="subtitle_privateGroupMembers">Private group · %1$s</string>

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

@@ -85,6 +85,7 @@ import com.flipcash.app.messenger.internal.screens.profile.privateGroupMembers
 import com.flipcash.services.models.TipAction
 import com.flipcash.services.models.TipOrigin
 import com.flipcash.services.models.UserProfile
+import com.flipcash.services.chat.WrongKeyChats
 import com.flipcash.services.models.chat.ChatId
 import com.flipcash.services.models.chat.LobbyMember
 import com.flipcash.services.models.chat.ChatMember
@@ -275,6 +276,7 @@ internal class ChatViewModel @AssistedInject constructor(
      */
     @Assisted private val linkedAsGroup: Boolean = false,
     private val chatCoordinator: ChatCoordinator,
+    private val wrongKeyChats: WrongKeyChats,
     private val mediaUploads: ChatMediaUploads,
     private val e2eePolicy: E2eePolicy,
     private val contactCoordinator: ContactCoordinator,
@@ -355,6 +357,11 @@ internal class ChatViewModel @AssistedInject constructor(
     }
 
     data class State(
+        /**
+         * Whether the key this group's invite link handed the viewer failed its checks, so the
+         * transcript cannot be read. The only repair is to leave and be admitted from the lobby.
+         */
+        val wrongKey: Boolean = false,
         val separatorConfig: SeparatorConfig = SeparatorConfig.Continuous(),
         val chatId: ChatId? = null,
         val subject: ChatSubject? = null,
@@ -868,6 +875,9 @@ internal class ChatViewModel @AssistedInject constructor(
         /** The chat this screen is showing turned out to be a group, with this metadata. */
         data class OnGroupResolved(val membership: ChatMembership) : Event
 
+        /** The wrong-key mark for this chat changed (see `WrongKeyChats`). */
+        data class OnWrongKey(val wrongKey: Boolean) : Event
+
         /** The token cache learned the currency behind the group's balance requirement. */
         data class OnRuleCurrencyResolved(val currency: RuleCurrency?) : Event
 
@@ -1353,9 +1363,14 @@ internal class ChatViewModel @AssistedInject constructor(
     /**
      * Follows a tapped message link inside the app. True when [uri] was one: a message in this
      * chat is jumped to in place, and one in another chat is pushed over this one with a chip back
-     * here. False leaves [uri] to the ordinary link handling.
+     * here. An invite link opens its landing over this chat, so its secret stays in the app. False
+     * leaves [uri] to the ordinary link handling.
      */
     fun followMessageLink(uri: String): Boolean {
+        linkCardClassifier.inviteRoute(uri)?.let { route ->
+            dispatchEvent(Event.OpenScreen(route))
+            return true
+        }
         val link = linkCardClassifier.messageLink(uri) ?: return false
         val state = stateFlow.value
         if (link.chatId == state.chatId) {
@@ -1916,6 +1931,7 @@ internal class ChatViewModel @AssistedInject constructor(
         initMentionHandlers()
         initDraftHandlers()
         initGroupAnalytics()
+        initWrongKey()
 
         viewModelScope.launch {
             // Yield to let the first frame render before setting up remaining collectors
@@ -2709,6 +2725,14 @@ internal class ChatViewModel @AssistedInject constructor(
             .launchIn(viewModelScope)
     }
 
+    /** Whether the key this account holds for the open chat is the wrong one (an invite join gone bad). */
+    private fun initWrongKey() {
+        stateFlow.map { it.chatId }.filterNotNull().distinctUntilChanged()
+            .flatMapLatest { wrongKeyChats.observe(it) }
+            .onEach { dispatchEvent(Event.OnWrongKey(it)) }
+            .launchIn(viewModelScope)
+    }
+
     /**
      * The group events that are not an RPC's answer: the gate appearing, and the taps on the
      * invite sheet, an invite card, the gate's funding button and the group profile. The screens report the taps
@@ -4140,6 +4164,7 @@ internal class ChatViewModel @AssistedInject constructor(
                     if (state.subject is ChatSubject.Group) state
                     else state.copy(chatType = ChatType.TIP_DM)
                 }
+                is Event.OnWrongKey -> { state -> state.copy(wrongKey = event.wrongKey) }
                 is Event.OnGroupResolved -> { state ->
                     val metadata = event.membership.metadata
                     val previous = state.subject as? ChatSubject.Group