Fix request sync duplicate public messages (#707)

Co-authored-by: CC <cc@ggg.local>

app/src/main/java/com/bitchat/android/mesh/MessageHandler.kt

@@ -7,6 +7,7 @@ import com.bitchat.android.model.IdentityAnnouncement
 import com.bitchat.android.model.RoutedPacket
 import com.bitchat.android.protocol.BitchatPacket
 import com.bitchat.android.protocol.MessageType
+import com.bitchat.android.sync.PacketIdUtil
 import com.bitchat.android.util.toHexString
 import kotlinx.coroutines.*
 import java.util.*
@@ -400,7 +401,7 @@ class MessageHandler(private val myPeerID: String, private val appContext: andro
                 }
                 val savedPath = com.bitchat.android.features.file.FileUtils.saveIncomingFile(appContext, file)
                 val message = BitchatMessage(
-                    id = java.util.UUID.randomUUID().toString().uppercase(),
+                    id = PacketIdUtil.computeIdHex(packet).uppercase(),
                     sender = delegate?.getPeerNickname(peerID) ?: "unknown",
                     content = savedPath,
                     type = com.bitchat.android.features.file.FileUtils.messageTypeForMime(file.mimeType),
@@ -416,6 +417,7 @@ class MessageHandler(private val myPeerID: String, private val appContext: andro
 
             // Fallback: plain text
             val message = BitchatMessage(
+                id = PacketIdUtil.computeIdHex(packet).uppercase(),
                 sender = delegate?.getPeerNickname(peerID) ?: "unknown",
                 content = String(packet.payload, Charsets.UTF_8),
                 senderPeerID = peerID,

app/src/main/java/com/bitchat/android/protocol/BinaryProtocol.kt

@@ -36,7 +36,7 @@ object SpecialRecipients {
 /**
  * Binary packet format - 100% backward compatible with iOS version
  *
- * Header (13 bytes for v1, 15 bytes for v2):
+ * Header (14 bytes for v1, 16 bytes for v2):
  * - Version: 1 byte
  * - Type: 1 byte
  * - TTL: 1 byte
@@ -178,8 +178,8 @@ data class BitchatPacket(
  * Binary Protocol implementation - supports v1 and v2, backward compatible
  */
 object BinaryProtocol {
-    private const val HEADER_SIZE_V1 = 13
-    private const val HEADER_SIZE_V2 = 15
+    private const val HEADER_SIZE_V1 = 14
+    private const val HEADER_SIZE_V2 = 16
     private const val SENDER_ID_SIZE = 8
     private const val RECIPIENT_ID_SIZE = 8
     private const val SIGNATURE_SIZE = 64

app/src/main/java/com/bitchat/android/services/AppStateStore.kt

@@ -13,6 +13,7 @@ import kotlinx.coroutines.flow.asStateFlow
 object AppStateStore {
     // Global de-dup set by message id to avoid duplicate keys in Compose lists
     private val seenMessageIds = mutableSetOf<String>()
+    private val seenPublicMessageKeys = mutableSetOf<String>()
     // Connected peer IDs (mesh ephemeral IDs)
     private val _peers = MutableStateFlow<List<String>>(emptyList())
     val peers: StateFlow<List<String>> = _peers.asStateFlow()
@@ -35,8 +36,10 @@ object AppStateStore {
 
     fun addPublicMessage(msg: BitchatMessage) {
         synchronized(this) {
-            if (seenMessageIds.contains(msg.id)) return
+            val publicKey = publicMessageKey(msg)
+            if (seenMessageIds.contains(msg.id) || seenPublicMessageKeys.contains(publicKey)) return
             seenMessageIds.add(msg.id)
+            seenPublicMessageKeys.add(publicKey)
             _publicMessages.value = _publicMessages.value + msg
         }
     }
@@ -100,10 +103,22 @@ object AppStateStore {
     fun clear() {
         synchronized(this) {
             seenMessageIds.clear()
+            seenPublicMessageKeys.clear()
             _peers.value = emptyList()
             _publicMessages.value = emptyList()
             _privateMessages.value = emptyMap()
             _channelMessages.value = emptyMap()
         }
     }
+
+    private fun publicMessageKey(msg: BitchatMessage): String {
+        val sender = msg.senderPeerID ?: msg.sender
+        return listOf(
+            sender,
+            msg.timestamp.time.toString(),
+            msg.type.name,
+            msg.channel ?: "",
+            msg.content
+        ).joinToString("\u001F")
+    }
 }

app/src/test/kotlin/com/bitchat/android/services/AppStateStoreTest.kt

@@ -0,0 +1,58 @@
+package com.bitchat.android.services
+
+import com.bitchat.android.model.BitchatMessage
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Before
+import org.junit.Test
+import java.util.Date
+
+class AppStateStoreTest {
+    @Before
+    fun setUp() {
+        AppStateStore.clear()
+    }
+
+    @After
+    fun tearDown() {
+        AppStateStore.clear()
+    }
+
+    @Test
+    fun `public timeline collapses request sync replay even when android message ids differ`() {
+        val timestamp = Date(1_700_000_000_000L)
+        val originalDelivery = BitchatMessage(
+            id = "random-id-from-first-delivery",
+            sender = "alice",
+            content = "hello from sync",
+            timestamp = timestamp,
+            senderPeerID = "1122334455667788"
+        )
+        val requestSyncReplay = originalDelivery.copy(id = "different-random-id-from-replay")
+
+        AppStateStore.addPublicMessage(originalDelivery)
+        AppStateStore.addPublicMessage(requestSyncReplay)
+
+        assertEquals(listOf(originalDelivery), AppStateStore.publicMessages.value)
+    }
+
+    @Test
+    fun `public timeline still keeps same content sent at different packet timestamps`() {
+        val first = BitchatMessage(
+            id = "first-packet-id",
+            sender = "alice",
+            content = "same text",
+            timestamp = Date(1_700_000_000_000L),
+            senderPeerID = "1122334455667788"
+        )
+        val second = first.copy(
+            id = "second-packet-id",
+            timestamp = Date(first.timestamp.time + 1_000L)
+        )
+
+        AppStateStore.addPublicMessage(first)
+        AppStateStore.addPublicMessage(second)
+
+        assertEquals(listOf(first, second), AppStateStore.publicMessages.value)
+    }
+}