fix(messenger): head a solo group with its invite card, messages or not

The invite card only replaced the group's info card while the transcript
was empty, so a group whose only member had posted anything fell back to
the old header. iOS decides on who is in the chat instead: the card heads
the transcript while the viewer is a member and nobody else has joined
(ConversationScreen.showsGroupInvite).

State.showsGroupInviteCard now carries that rule and MessageList reads
it. Once someone joins, the header goes back to the info card and the
invite stays on the group's profile.

Author: bmc08gt

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

@@ -467,6 +467,16 @@ internal class ChatViewModel @Inject constructor(
             get() = (subject as? ChatSubject.Group)
                 ?.takeIf { it.isMember == true }
                 ?.let { Linkify.groupChatInvite(it.chatId) }
+
+        /**
+         * Whether the group's invite card heads the transcript in place of its info card: a group
+         * the viewer has joined that nobody else has (node 10330:19164). Decided by who is in the
+         * chat, not by whether it has messages, so posting into a solo group keeps the card. Once
+         * someone joins, the invite moves to the group's profile, as on iOS.
+         */
+        val showsGroupInviteCard: Boolean
+            get() = groupInviteUrl != null &&
+                (subject as? ChatSubject.Group)?.memberCount?.let { it <= 1 } == true
     }
 
     /**

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

@@ -421,13 +421,13 @@ internal fun MessageList(
                     }
                 }
 
-                // Chat start shows contact info container. An empty group the viewer can invite to
-                // shows its invite card there instead (node 10330:19164): inviting someone is the
-                // only thing to do with an empty group, and it is the same card a DM transcript
+                // Chat start shows contact info container. A group nobody else has joined shows its
+                // invite card there instead (node 10330:19164), whether or not it has messages:
+                // inviting someone is the thing left to do, and it is the same card a DM transcript
                 // renders for the link, with a different CTA and destination.
                 val inviteUrl = state.groupInviteUrl
                 val inviteGroup = state.subject as? ChatSubject.Group
-                if (messages.itemCount == 0 && inviteUrl != null && inviteGroup != null) {
+                if (state.showsGroupInviteCard && inviteUrl != null && inviteGroup != null) {
                     item(key = "group-invite-card") {
                         val card = remember(inviteGroup, inviteUrl, state.ruleCurrency) {
                             inviteGroup.toGroupInviteCard(

apps/flipcash/features/messenger/src/test/kotlin/com/flipcash/app/messenger/internal/ChatViewModelStateTest.kt

@@ -43,11 +43,15 @@ class ChatViewModelStateTest {
 
     private val gatedRules = ChatRules(listener = listOf(unmet), speaker = emptyList())
 
-    private fun group(isMember: Boolean?, rules: ChatRules? = gatedRules) = ChatSubject.Group(
+    private fun group(
+        isMember: Boolean?,
+        rules: ChatRules? = gatedRules,
+        memberCount: Long = 1L,
+    ) = ChatSubject.Group(
         chatId = groupChatId,
         groupTitle = "Ballers",
         picture = null,
-        memberCount = 1L,
+        memberCount = memberCount,
         rules = rules,
         isMember = isMember,
     )
@@ -239,6 +243,18 @@ class ChatViewModelStateTest {
         assertNull(ChatViewModel.State().groupInviteUrl)
     }
 
+    @Test
+    fun `the invite card heads a group only while the viewer is its only member`() {
+        // Messages have no say: a solo group the viewer has posted in still has nobody to talk to.
+        assertTrue(ChatViewModel.State(subject = group(isMember = true)).showsGroupInviteCard)
+        assertFalse(
+            ChatViewModel.State(subject = group(isMember = true, memberCount = 2L)).showsGroupInviteCard,
+        )
+        assertFalse(ChatViewModel.State(subject = group(isMember = false)).showsGroupInviteCard)
+        assertFalse(ChatViewModel.State(subject = group(isMember = null)).showsGroupInviteCard)
+        assertFalse(ChatViewModel.State(subject = dm).showsGroupInviteCard)
+    }
+
     @Test
     fun `a chat id with no uuid form yields no link rather than a malformed one`() {
         // A DM's id is a 32-byte hash. Reaching this through a Group subject is unreachable in the