diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt
index ae6d013ef..9dee631e8 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt
@@ -2241,6 +2241,11 @@ object LocalCache : ILocalCache, ICacheProvider {
         }
     }
 
+    // 2× the 10-min `PRESENCE_FRESHNESS_WINDOW_SECONDS` used by
+    // `NestsFeedFilter` so a presence still inside any feed's window
+    // can never be pruned.
+    private val PRESENCE_PRUNE_AGE_SECONDS = 20L * 60L
+
     fun pruneOldMessagesChannel(channel: Channel) {
         val toBeRemoved = channel.pruneOldMessages()
 
@@ -2254,6 +2259,14 @@ object LocalCache : ILocalCache, ICacheProvider {
 
         removeFromCache(childrenToBeRemoved)
 
+        // Audio-room presence is keyed separately from `notes` and
+        // never gets reaped by the top-N rule. Drop entries older
+        // than 2× the 10-min freshness window so the index doesn't
+        // grow unbounded with every author who ever heartbeat here.
+        if (channel is LiveActivitiesChannel) {
+            channel.pruneStalePresence(TimeUtils.now() - PRESENCE_PRUNE_AGE_SECONDS)
+        }
+
         if (toBeRemoved.size > 100 || channel.notes.size() > 100) {
             println(
                 "PRUNE: ${toBeRemoved.size} old messages removed from ${channel.toBestDisplayName()}. ${channel.notes.size()} kept",
diff --git a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/nip53LiveActivities/LiveActivitiesChannel.kt b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/nip53LiveActivities/LiveActivitiesChannel.kt
index 75b202dae..1638b54d6 100644
--- a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/nip53LiveActivities/LiveActivitiesChannel.kt
+++ b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/nip53LiveActivities/LiveActivitiesChannel.kt
@@ -80,6 +80,27 @@ class LiveActivitiesChannel(
         flowSet?.notes?.invalidateData()
     }
 
+    /**
+     * Drop presence entries older than [cutoff]. Without this, every
+     * author who ever heartbeats in this room would leave an entry
+     * here forever, even though the freshness check in
+     * `NestsFeedFilter` already treats anything past
+     * `PRESENCE_FRESHNESS_WINDOW_SECONDS` (10 min) as dead. Run on the
+     * same schedule as [pruneOldMessages] with a generous cutoff (2×
+     * the freshness window) so a presence still inside any feed's
+     * window can never be pruned.
+     */
+    fun pruneStalePresence(cutoff: Long): Int {
+        val toRemove = mutableListOf<HexKey>()
+        presenceNotes.forEach { author, note ->
+            val createdAt = note.event?.createdAt
+            if (createdAt == null || createdAt < cutoff) toRemove.add(author)
+        }
+        toRemove.forEach { presenceNotes.remove(it) }
+        if (toRemove.isNotEmpty()) flowSet?.notes?.invalidateData()
+        return toRemove.size
+    }
+
     fun address() = address
 
     override fun relays() = info?.allRelayUrls()?.toSet()?.ifEmpty { null } ?: super.relays()