Let failed messages be discarded

app/androidApp/src/main/kotlin/com/example/aiapp/PendingMessages.kt

@@ -65,6 +65,11 @@ internal fun markPendingAccepted(queued: List<QueuedMessage>, id: String): List<
         if (message.local && message.id == id) message.copy(serverAccepted = true) else message
     }
 
+internal fun discardPendingMessage(
+    queued: List<QueuedMessage>,
+    id: String,
+): List<QueuedMessage> = queued.filterNot { it.local && it.id == id }
+
 /** Restores sends for which this phone has not yet seen a durable server event. */
 internal fun loadPendingMessages(context: Context, key: String): List<QueuedMessage> {
     val encoded =

app/androidApp/src/main/kotlin/com/example/aiapp/SessionScreen.kt

@@ -373,6 +373,7 @@ fun SessionScreen(
     val pendingKey =
         remember(settings, address) { "${settings.host}:${settings.port}/${address.cachePath}" }
     var queued by remember(pendingKey) { mutableStateOf(loadPendingMessages(context, pendingKey)) }
+    var discardingMessage by remember(pendingKey) { mutableStateOf<QueuedMessage?>(null) }
 
     /**
      * Changes the visible outbox and keeps only its not-yet-durable part across a screen reopen.
@@ -1569,6 +1570,12 @@ fun SessionScreen(
                                             onTakeBack =
                                                 if (waiting.local) null
                                                 else ({ takeBack(waiting.id) }),
+                                            onDiscard =
+                                                if (waiting.local && waiting.refusal != null) {
+                                                    { discardingMessage = waiting }
+                                                } else {
+                                                    null
+                                                },
                                         )
                                     }
                                 }
@@ -2084,6 +2091,29 @@ fun SessionScreen(
             },
         )
     }
+    discardingMessage?.let { message ->
+        AlertDialog(
+            onDismissRequest = { discardingMessage = null },
+            title = { Text("Discard unsent message?") },
+            text = {
+                Text(
+                    "The server did not confirm this message. Discarding it removes this phone's " +
+                        "only copy and cannot be undone."
+                )
+            },
+            confirmButton = {
+                TextButton(
+                    onClick = {
+                        replaceQueued(discardPendingMessage(queued, message.id))
+                        discardingMessage = null
+                    }
+                ) {
+                    Text("Discard", color = MaterialTheme.colorScheme.error)
+                }
+            },
+            dismissButton = { TextButton(onClick = { discardingMessage = null }) { Text("Keep") } },
+        )
+    }
     if (settingsOpen) {
         // Measured when the dialog opens rather than kept up to date: what the reader is being told
         // is what pressing the button now would discard, and null until the walk of the directory
@@ -2202,6 +2232,7 @@ private fun UserChunkRow(
  * before the session reads it. A local one is not, because its request may still be in flight.
  * [refusal] is either that take-back refusal or the send's network failure. It is drawn here rather
  * than with the screen's other errors because this is the message the failure belongs to.
+ * [onDiscard] is confirmed by the screen because a failed local bubble is the phone's only copy.
  *
  * A settled message longer than [USER_SPLIT_CHARS] is drawn as [UserChunkRow] slices instead -- one
  * `Text` holding a pasted log is a hundred-thousand-pixel layout in the frame the row scrolls into.
@@ -2216,6 +2247,7 @@ private fun UserBubble(
     pending: Boolean = false,
     refusal: String? = null,
     onTakeBack: (() -> Unit)? = null,
+    onDiscard: (() -> Unit)? = null,
 ) {
     Box(Modifier.fillMaxWidth()) {
         Card(
@@ -2268,6 +2300,11 @@ private fun UserBubble(
                         color = MaterialTheme.colorScheme.error,
                     )
                 }
+                onDiscard?.let {
+                    TextButton(onClick = it, modifier = Modifier.align(Alignment.End)) {
+                        Text("Discard", color = MaterialTheme.colorScheme.error)
+                    }
+                }
             }
         }
     }

app/androidApp/src/test/kotlin/com/example/aiapp/PendingMessagesTest.kt

@@ -48,6 +48,16 @@ class PendingMessagesTest {
         assertTrue(queued.single().serverAccepted)
     }
 
+    @Test
+    fun discarding_a_failed_send_removes_only_that_local_copy() {
+        val server = QueuedMessage("server-1", "already accepted", emptyList())
+        val queued = listOf(local(), local("keep this one").copy(id = "local-2"), server)
+
+        val discarded = discardPendingMessage(queued, "local-1")
+
+        assertEquals(listOf("local-2", "server-1"), discarded.map { it.id })
+    }
+
     @Test
     fun identical_messages_are_reconciled_one_at_a_time() {
         val queued = listOf(local(), local().copy(id = "local-2"))