fix: MEDIUM/LOW bugs - validation, unread tracking, TLS bounds, KeyPackage checks

- H17: Add unread count tracking to MarmotGroupChatroom
- M8: Add MAX_OPAQUE_SIZE bounds check to TLS deserialization
- M13: Add version/ciphersuite validation on KeyPackage deserialization
- M24: Add logging before deleting corrupted group state in restoreAll
- L1: Add size limit to sentKeys map in MlsGroup
- Additional UI fixes: leave group cleanup, error handling improvements
- Fix MarmotSubscriptionManagerTest for updated API

https://claude.ai/code/session_018gVkmmYgMFtBH7G31pCk9N

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/marmot/MarmotManager.kt

@@ -121,6 +121,14 @@ class MarmotManager(
         welcomeEvent: WelcomeEvent,
         nostrGroupId: HexKey,
     ): WelcomeResult {
+        // Validate that the provided nostrGroupId matches the WelcomeEvent's h-tag if present
+        val eventGroupId = welcomeEvent.nostrGroupId()
+        if (eventGroupId != null && eventGroupId != nostrGroupId) {
+            return WelcomeResult.Error(
+                "nostrGroupId mismatch: expected $nostrGroupId but WelcomeEvent has $eventGroupId",
+            )
+        }
+
         val result = inboundProcessor.processWelcome(welcomeEvent, nostrGroupId)
 
         if (result is WelcomeResult.Joined) {
@@ -153,6 +161,20 @@ class MarmotManager(
         keyPackageEventId: HexKey,
         relays: List<NormalizedRelayUrl>,
     ): Pair<OutboundGroupEvent, WelcomeDelivery?> {
+        // Verify that the KeyPackage credential matches the expected member pubkey
+        val kp =
+            com.vitorpamplona.quartz.marmot.mls.messages.MlsKeyPackage.decodeTls(
+                com.vitorpamplona.quartz.marmot.mls.codec
+                    .TlsReader(keyPackageBytes),
+            )
+        val credential = kp.leafNode.credential
+        require(credential is Credential.Basic) {
+            "KeyPackage must use BasicCredential"
+        }
+        require(credential.identity.toHexKey() == memberPubKey) {
+            "KeyPackage credential identity does not match memberPubKey"
+        }
+
         val commitResult = groupManager.addMember(nostrGroupId, keyPackageBytes)
         val commitEvent = outboundProcessor.buildCommitEvent(nostrGroupId, commitResult.commitBytes)
 

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/marmotGroups/MarmotGroupChatroom.kt

@@ -47,6 +47,7 @@ class MarmotGroupChatroom(
     var relays = MutableStateFlow<List<String>>(emptyList())
     var memberCount = MutableStateFlow(0)
     var newestMessage: Note? = null
+    val unreadCount = MutableStateFlow(0)
 
     private var changesFlow: WeakReference<MutableSharedFlow<ListChange<Note>>> = WeakReference(null)
 
@@ -73,6 +74,7 @@ class MarmotGroupChatroom(
                 newestMessage = msg
             }
 
+            unreadCount.value += 1
             changesFlow.get()?.tryEmit(ListChange.Addition(msg))
             return true
         }
@@ -95,6 +97,10 @@ class MarmotGroupChatroom(
         return false
     }
 
+    fun markAsRead() {
+        unreadCount.value = 0
+    }
+
     fun pruneMessagesToTheLatestOnly(): Set<Note> {
         val sorted = messages.sortedWith(DefaultFeedOrder)
         val toKeep =