Fix geohash filtering (#376)

* fix(geohash): enforce client-side filter on subscription and validate 'g' tag in handler; move dedup after validation; avoid misrouting events across geohashes

* cleanup duplicate code block

* remove

app/src/main/java/com/bitchat/android/nostr/NostrGeohashService.kt

@@ -1167,7 +1167,7 @@ class NostrGeohashService(
     private fun handleUnifiedGeohashEvent(event: NostrEvent, geohash: String) {
         coroutineScope.launch(Dispatchers.Default) {
         try {
-            Log.v(TAG, "🔍 handleUnifiedGeohashEvent called - eventGeohash: $geohash, currentGeohash: $currentGeohash, eventKind: ${event.kind}, eventId: ${event.id.take(8)}...")
+            Log.v(TAG, "🔍 handleUnifiedGeohashEvent called - subGeohash: $geohash, currentGeohash: $currentGeohash, kind: ${event.kind}, id: ${event.id.take(8)}...")
             
             // Only handle ephemeral kind 20000 events
             if (event.kind != 20000) {
@@ -1175,6 +1175,17 @@ class NostrGeohashService(
                 return@launch
             }
 
+            // VALIDATE EVENT G TAG AGAINST SUBSCRIPTION GEOHASH
+            val eventGeohash = event.tags.firstOrNull { it.size >= 2 && it[0] == "g" }?.getOrNull(1)
+            if (eventGeohash == null) {
+                Log.w(TAG, "🚫 Dropping kind=20000 without 'g' tag id=${event.id.take(8)}")
+                return@launch
+            }
+            if (!eventGeohash.equals(geohash, ignoreCase = true)) {
+                Log.w(TAG, "🚫 Dropping mismatched geohash event: sub=$geohash eventTag=$eventGeohash id=${event.id.take(8)}")
+                return@launch
+            }
+            
             // Check Proof of Work validation BEFORE other processing
             val powSettings = PoWPreferenceManager.getCurrentSettings()
             if (powSettings.enabled && powSettings.difficulty > 0) {

app/src/main/java/com/bitchat/android/nostr/NostrRelayManager.kt

@@ -666,6 +666,16 @@ class NostrRelayManager private constructor() {
                     relay?.messagesReceived = (relay?.messagesReceived ?: 0) + 1
                     updateRelaysList()
                     
+                    // CLIENT-SIDE FILTER ENFORCEMENT: Ensure this event matches the subscription's filter
+                    activeSubscriptions[response.subscriptionId]?.let { subInfo ->
+                        val matches = try { subInfo.filter.matches(response.event) } catch (e: Exception) { true }
+                        if (!matches) {
+                            Log.v(TAG, "🚫 Dropping event ${response.event.id.take(16)}... not matching filter for sub=${response.subscriptionId}")
+                            // Do NOT call deduplicator here to allow the correct subscription to process it later
+                            return
+                        }
+                    }
+                    
                     // DEDUPLICATION: Check if we've already processed this event
                     val wasProcessed = eventDeduplicator.processEvent(response.event) { event ->
                         // Only log non-gift-wrap events to reduce noise