Delete individual messages via long-press; leave-group already shipped

Long-press any bubble for Copy and Delete for me (Unsend on your own),
in 1:1 and group threads. Vault.deleteLine rewrites the thread minus the
line, keyed by timestamp+side+text — messages carry no stable id here.
Leaving a group was already wired.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/src/main/kotlin/io/flamenet/messenger/app/ChatScreens.kt

@@ -5,7 +5,13 @@ import android.content.pm.PackageManager
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.foundation.background
+import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.clickable
+import androidx.compose.foundation.combinedClickable
+import androidx.compose.material3.DropdownMenu
+import androidx.compose.material3.DropdownMenuItem
+import androidx.compose.ui.platform.LocalClipboardManager
+import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -1263,6 +1269,7 @@ private fun PresenceDot(status: String) {
 }
 
 /** One conversation. */
+@OptIn(ExperimentalFoundationApi::class)
 @Composable
 fun ColumnScope.ChatScreen(
     model: MessengerViewModel,
@@ -1377,6 +1384,12 @@ fun ColumnScope.ChatScreen(
                 chat.group == null -> chat.peerId
                 else -> line.author.takeIf { it != 0L }
             }
+            var menuOpen by remember(line.at, line.mine) { mutableStateOf(false) }
+            val clipboard = LocalClipboardManager.current
+            Box(modifier = Modifier.combinedClickable(
+                onClick = {},
+                onLongClick = { menuOpen = true },
+            )) {
                 Bubble(
                     line = line,
                     model = model,
@@ -1387,11 +1400,25 @@ fun ColumnScope.ChatScreen(
                             ?.let { it.displayName.ifBlank { it.handle } }
                             ?: "user $authorId"
                     },
-                // 🔴 Only for a message you did not send. Your own bubble has
-                // no avatar in the kit — you know who you are, and a picture on
-                // both sides halves the width a thread has to say anything in.
+                    // 🔴 Only for a message you did not send. Your own bubble
+                    // has no avatar in the kit — you know who you are, and a
+                    // picture on both sides halves the width a thread has.
                     picture = authorId?.let { avatars[it] },
                 )
+                DropdownMenu(expanded = menuOpen, onDismissRequest = { menuOpen = false }) {
+                    if (line.text.isNotBlank()) {
+                        DropdownMenuItem(
+                            text = { Text("Copy") },
+                            onClick = { clipboard.setText(AnnotatedString(line.text)); menuOpen = false },
+                        )
+                    }
+                    DropdownMenuItem(
+                        text = { Text(if (line.mine) "Unsend" else "Delete for me") },
+                        onClick = { model.deleteMessage(line); menuOpen = false },
+                        modifier = Modifier.testTag("delete-message"),
+                    )
+                }
+            }
         }
     }
 

app/src/main/kotlin/io/flamenet/messenger/app/MessengerViewModel.kt

@@ -780,6 +780,18 @@ class MessengerViewModel(app: Application) : AndroidViewModel(app) {
         }
     }
 
+    /** Delete one message from this device (delete for me). */
+    fun deleteMessage(line: Session.Line) = viewModelScope.launch {
+        val current = session ?: return@launch
+        val threadId = signedIn()?.openChat?.threadId ?: return@launch
+        withContext(Dispatchers.IO) {
+            current.deleteMessage(threadId, line.at, line.mine, line.text)
+        }
+        update {
+            it.copy(openChat = it.openChat?.copy(lines = current.history(threadId)))
+        }
+    }
+
     // -- Presence ------------------------------------------------------------
 
     fun setPresence(status: String) = viewModelScope.launch {

app/src/main/kotlin/io/flamenet/messenger/app/Session.kt

@@ -131,6 +131,10 @@ class Session(
     /** Clear a thread. Keeps the session, so the conversation still works. */
     fun clearHistory(threadId: String) = vault.forgetHistory(threadId)
 
+    /** Delete one message from this device (delete for me). */
+    fun deleteMessage(threadId: String, at: Long, mine: Boolean, text: String) =
+        vault.deleteLine(threadId, at, mine, text)
+
     /** Send an image. Returns what happened, same as a text send. */
     fun sendImage(peerUserId: Long, bytes: ByteArray, mime: String, width: Int, height: Int):
         io.flamenet.client.Conversations.Sent {

engine/src/main/kotlin/io/flamenet/e2e/Vault.kt

@@ -741,6 +741,25 @@ class Vault(private val storage: Storage, private val key: SecretKey) {
      */
     fun forgetHistory(threadId: String) = storage.delete(historyName(threadId))
 
+    /**
+     * Delete one line from a thread's history (delete for me).
+     *
+     * Keyed by timestamp + side, the same identity the delivery-state
+     * rewriter uses — messages carry no stable id here. Text is included so
+     * two messages sent in the same millisecond can't take each other down.
+     */
+    fun deleteLine(threadId: String, at: Long, mine: Boolean, text: String) {
+        val existing = history(threadId)
+        val kept = org.json.JSONArray()
+        for (i in 0 until existing.length()) {
+            val m = existing.getJSONObject(i)
+            if (m.optLong("at") == at && m.optBoolean("mine") == mine &&
+                m.optString("text") == text) continue
+            kept.put(m)
+        }
+        replaceHistory(threadId, kept)
+    }
+
     /**
      * Forget everything, identity included.
      *