gossip works

app/src/main/java/com/bitchat/android/services/meshgraph/GossipTLV.kt

@@ -24,9 +24,10 @@ object GossipTLV {
     }
 
     /**
-     * Scan a TLV-encoded announce payload and extract neighbor peerIDs if present.
+     * Scan a TLV-encoded announce payload and extract neighbor peerIDs.
+     * Returns null if the TLV is not present at all; returns an empty list if present with length 0.
      */
-    fun decodeNeighborsFromAnnouncementPayload(payload: ByteArray): List<String> {
+    fun decodeNeighborsFromAnnouncementPayload(payload: ByteArray): List<String>? {
         val result = mutableListOf<String>()
         var offset = 0
         while (offset + 2 <= payload.size) {
@@ -45,10 +46,11 @@ object GossipTLV {
                     result.add(bytesToPeerIdHex(idBytes))
                     pos += 8
                 }
-                break // only one neighbors TLV expected
+                return result // present (possibly empty)
             }
         }
-        return result
+        // Not present
+        return null
     }
 
     private fun hexStringPeerIdTo8Bytes(hexString: String): ByteArray {
@@ -73,4 +75,3 @@ object GossipTLV {
         return sb.toString()
     }
 }
-

app/src/main/java/com/bitchat/android/services/meshgraph/MeshGraphService.kt

@@ -28,33 +28,40 @@ class MeshGraphService private constructor() {
      * Update graph from a verified announcement.
      * Replaces previous neighbors for origin if this is newer (by timestamp).
      */
-    fun updateFromAnnouncement(originPeerID: String, originNickname: String?, neighbors: List<String>, timestamp: ULong) {
-        // Newer-only replacement per origin
-        val prevTs = lastUpdate[originPeerID]
-        if (prevTs != null && prevTs >= timestamp) return
-        lastUpdate[originPeerID] = timestamp
-
+    fun updateFromAnnouncement(originPeerID: String, originNickname: String?, neighborsOrNull: List<String>?, timestamp: ULong) {
         synchronized(this) {
-            // Update nickname
+            // Always update nickname if provided
             if (originNickname != null) nicknames[originPeerID] = originNickname
 
+            // If no neighbors TLV present, do not modify edges or timestamps
+            if (neighborsOrNull == null) {
+                publishSnapshot()
+                return
+            }
+
+            // Newer-only replacement per origin (based on TLV-bearing announcements only)
+            val prevTs = lastUpdate[originPeerID]
+            if (prevTs != null && prevTs >= timestamp) {
+                // Older or equal TLV-bearing update: ignore
+                return
+            }
+            lastUpdate[originPeerID] = timestamp
+
             // Remove old symmetric edges contributed by this origin
             val prevNeighbors = adjacency[originPeerID]?.toSet().orEmpty()
             prevNeighbors.forEach { n ->
                 adjacency[n]?.remove(originPeerID)
             }
 
-            // Replace origin's adjacency with new set
-            val newSet = neighbors.distinct().take(10).filter { it != originPeerID }.toMutableSet()
+            // Replace origin's adjacency with new set (may be empty)
+            val newSet = neighborsOrNull.distinct().take(10).filter { it != originPeerID }.toMutableSet()
             adjacency[originPeerID] = newSet
-            // Ensure nodes exist for neighbors
+            // Ensure undirected edges
             newSet.forEach { n ->
                 adjacency.putIfAbsent(n, mutableSetOf())
-                // Add symmetric edge for undirected graph visualization
                 adjacency[n]?.add(originPeerID)
             }
 
-            // Compute snapshot
             publishSnapshot()
         }
     }
@@ -93,4 +100,3 @@ class MeshGraphService private constructor() {
         }
     }
 }
-