Merge pull request #3586 from vitorpamplona/claude/nip29-message-pinning-elzck9

NIP-29 message pinning: UI bar, moderation events, and relay group integration

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/nip29RelayGroups/RelayGroupChannel.kt

@@ -31,6 +31,7 @@ import com.vitorpamplona.quartz.nip29RelayGroups.GroupId
 import com.vitorpamplona.quartz.nip29RelayGroups.metadata.GroupAdminsEvent
 import com.vitorpamplona.quartz.nip29RelayGroups.metadata.GroupMembersEvent
 import com.vitorpamplona.quartz.nip29RelayGroups.metadata.GroupMetadataEvent
+import com.vitorpamplona.quartz.nip29RelayGroups.metadata.GroupPinnedEvent
 import com.vitorpamplona.quartz.nip29RelayGroups.tags.GroupAdminTag
 import com.vitorpamplona.quartz.utils.cache.LargeCache
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -70,6 +71,14 @@ class RelayGroupChannel(
         private set
     private var adminsUpdatedAt: Long = 0
 
+    /**
+     * Relay-signed pinned message ids (kind 39005), in the relay's display order.
+     * Pinning replaces the whole list, so this is always the full current set.
+     */
+    var pinnedEventIds: List<HexKey> = emptyList()
+        private set
+    private var pinnedUpdatedAt: Long = 0
+
     /**
      * Members ∪ admins, recomputed only when a roster event lands. [memberCount] and the discovery
      * feed read this per note / per recomposition, so caching it avoids rebuilding the set each read.
@@ -158,6 +167,17 @@ class RelayGroupChannel(
         updateChannelInfo()
     }
 
+    fun updatePinned(event: GroupPinnedEvent) {
+        // Only newer lists supersede; equal-or-older is dropped so a duplicate
+        // arrival isn't reprocessed (no redundant emit).
+        if (event.createdAt <= pinnedUpdatedAt) return
+        pinnedEventIds = event.pinnedEventIds()
+        pinnedUpdatedAt = event.createdAt
+        updateChannelInfo()
+    }
+
+    fun isPinned(eventId: HexKey): Boolean = eventId in pinnedEventIds
+
     /**
      * The shareable NIP-19 `naddr` coordinate for this group's metadata (kind
      * 39000, authored by the relay's own key, with the host relay as a hint), or