feat(notifications): notify on replies (NIP-10) and comments (NIP-22)

Adds a dedicated "Replies" notification channel that fires when someone
replies to one of the user's posts. Handled on two kinds:

- TextNoteEvent (kind 1): notifies only when the reply target
  (`replyingTo()`) is authored by the current account, so plain p-tag
  mentions are not routed through this channel.

- CommentEvent (kind 1111): notifies when the current account is the
  NIP-22 reply author or root author of the parent scope.

The channel uses its own group key and summary so users can disable it
independently from OS-level notification settings, just like Zaps,
Reactions, DMs, and Chess.

https://claude.ai/code/session_01GQDJxiHPogdzCNhUBN7Pjc

amethyst/src/main/java/com/vitorpamplona/amethyst/service/notifications/EventNotificationConsumer.kt

@@ -41,6 +41,7 @@ import com.vitorpamplona.amethyst.service.call.notification.CallNotifier
 import com.vitorpamplona.amethyst.service.notifications.NotificationUtils.sendChessNotification
 import com.vitorpamplona.amethyst.service.notifications.NotificationUtils.sendDMNotification
 import com.vitorpamplona.amethyst.service.notifications.NotificationUtils.sendReactionNotification
+import com.vitorpamplona.amethyst.service.notifications.NotificationUtils.sendReplyNotification
 import com.vitorpamplona.amethyst.service.notifications.NotificationUtils.sendZapNotification
 import com.vitorpamplona.amethyst.service.relayClient.authCommand.model.ScreenAuthAccount
 import com.vitorpamplona.amethyst.service.relayClient.reqCommand.event.EventFinderQueryState
@@ -56,10 +57,12 @@ import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
 import com.vitorpamplona.quartz.nip01Core.tags.people.isTaggedUser
 import com.vitorpamplona.quartz.nip01Core.tags.people.taggedUserIds
 import com.vitorpamplona.quartz.nip04Dm.messages.PrivateDmEvent
+import com.vitorpamplona.quartz.nip10Notes.TextNoteEvent
 import com.vitorpamplona.quartz.nip17Dm.files.ChatMessageEncryptedFileHeaderEvent
 import com.vitorpamplona.quartz.nip17Dm.messages.ChatMessageEvent
 import com.vitorpamplona.quartz.nip19Bech32.toNpub
 import com.vitorpamplona.quartz.nip21UriScheme.toNostrUri
+import com.vitorpamplona.quartz.nip22Comments.CommentEvent
 import com.vitorpamplona.quartz.nip25Reactions.ReactionEvent
 import com.vitorpamplona.quartz.nip57Zaps.LnZapEvent
 import com.vitorpamplona.quartz.nip57Zaps.LnZapRequestEvent
@@ -176,6 +179,8 @@ class EventNotificationConsumer(
             is ChatMessageEvent -> notify(event, account)
             is ChatMessageEncryptedFileHeaderEvent -> notify(event, account)
             is ReactionEvent -> notify(event, account)
+            is TextNoteEvent -> notify(event, account)
+            is CommentEvent -> notify(event, account)
             is LiveChessGameAcceptEvent -> notifyChessEvent(event, account, R.string.app_notification_chess_challenge_accepted)
             is LiveChessMoveEvent -> notifyChessEvent(event, account, R.string.app_notification_chess_your_turn)
             // WelcomeEvent is dispatched directly from processMarmotWelcomeFlow
@@ -648,6 +653,110 @@ class EventNotificationConsumer(
             )
     }
 
+    private suspend fun notify(
+        event: TextNoteEvent,
+        account: Account,
+    ) {
+        Log.d(TAG, "New TextNote to Notify")
+
+        // old event being re-broadcast
+        if (event.createdAt < TimeUtils.fifteenMinutesAgo()) return
+
+        // don't notify for own notes
+        if (event.pubKey == account.signer.pubKey) return
+
+        // must be a reply (NIP-10) — plain mentions are not handled on this channel.
+        val replyTargetId = event.replyingTo() ?: return
+
+        // only notify when the reply targets a note authored by the current account.
+        val repliedNote = LocalCache.getNoteIfExists(replyTargetId) ?: return
+        if (repliedNote.author?.pubkeyHex != account.signer.pubKey) return
+
+        notifyReply(event, account, repliedNote.event?.content)
+    }
+
+    private suspend fun notify(
+        event: CommentEvent,
+        account: Account,
+    ) {
+        Log.d(TAG, "New NIP-22 Comment to Notify")
+
+        // old event being re-broadcast
+        if (event.createdAt < TimeUtils.fifteenMinutesAgo()) return
+
+        // don't notify for own comments
+        if (event.pubKey == account.signer.pubKey) return
+
+        // NIP-22 marks direct-reply and root authors. Notify when the current
+        // account is either (someone commenting on our post, or replying to our comment).
+        val pubKey = account.signer.pubKey
+        val isTarget = event.replyAuthorKeys().contains(pubKey) || event.rootAuthorKeys().contains(pubKey)
+        if (!isTarget) return
+
+        val parentContent =
+            event
+                .replyingTo()
+                ?.let { LocalCache.getNoteIfExists(it)?.event?.content }
+
+        notifyReply(event, account, parentContent)
+    }
+
+    private suspend fun notifyReply(
+        event: Event,
+        account: Account,
+        parentContent: String?,
+    ) {
+        val replyNote = LocalCache.getNoteIfExists(event.id) ?: return
+
+        val author = LocalCache.getOrCreateUser(event.pubKey)
+        val user = author.toBestDisplayName()
+        val userPicture = author.profilePicture()
+
+        val title = stringRes(applicationContext, R.string.app_notification_replies_channel_message, user)
+
+        val replyExcerpt =
+            event.content
+                .split("\n")
+                .firstOrNull { it.isNotBlank() }
+                ?.take(280)
+                ?: ""
+
+        val parentExcerpt =
+            parentContent
+                ?.split("\n")
+                ?.firstOrNull { it.isNotBlank() }
+                ?.take(140)
+
+        val content =
+            if (!parentExcerpt.isNullOrBlank()) {
+                replyExcerpt + "\n\n" +
+                    stringRes(
+                        applicationContext,
+                        R.string.app_notification_replies_channel_message_for,
+                        parentExcerpt,
+                    )
+            } else {
+                replyExcerpt
+            }
+
+        val accountNpub =
+            account.signer.pubKey
+                .hexToByteArray()
+                .toNpub()
+        val noteUri = replyNote.toNEvent() + ACCOUNT_QUERY_PARAM + accountNpub
+
+        notificationManager()
+            .sendReplyNotification(
+                event.id,
+                content,
+                title,
+                event.createdAt,
+                userPicture,
+                noteUri,
+                applicationContext,
+            )
+    }
+
     private suspend fun notifyChessEvent(
         event: BaseChessEvent,
         account: Account,

amethyst/src/main/java/com/vitorpamplona/amethyst/service/notifications/NotificationDispatcher.kt

@@ -28,8 +28,10 @@ import com.vitorpamplona.quartz.marmot.mip02Welcome.WelcomeEvent
 import com.vitorpamplona.quartz.nip01Core.core.Event
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip04Dm.messages.PrivateDmEvent
+import com.vitorpamplona.quartz.nip10Notes.TextNoteEvent
 import com.vitorpamplona.quartz.nip17Dm.files.ChatMessageEncryptedFileHeaderEvent
 import com.vitorpamplona.quartz.nip17Dm.messages.ChatMessageEvent
+import com.vitorpamplona.quartz.nip22Comments.CommentEvent
 import com.vitorpamplona.quartz.nip25Reactions.ReactionEvent
 import com.vitorpamplona.quartz.nip57Zaps.LnZapEvent
 import com.vitorpamplona.quartz.nip64Chess.challenge.accept.LiveChessGameAcceptEvent
@@ -75,6 +77,8 @@ class NotificationDispatcher(
                 PrivateDmEvent.KIND,
                 LnZapEvent.KIND,
                 ReactionEvent.KIND,
+                TextNoteEvent.KIND,
+                CommentEvent.KIND,
                 LiveChessGameAcceptEvent.KIND,
                 LiveChessMoveEvent.KIND,
                 WakeUpEvent.KIND,

amethyst/src/main/java/com/vitorpamplona/amethyst/service/notifications/NotificationUtils.kt

@@ -48,11 +48,13 @@ object NotificationUtils {
     private var zapChannel: NotificationChannel? = null
     private var reactionChannel: NotificationChannel? = null
     private var chessChannel: NotificationChannel? = null
+    private var replyChannel: NotificationChannel? = null
 
     private const val DM_GROUP_KEY = "com.vitorpamplona.amethyst.DM_NOTIFICATION"
     private const val ZAP_GROUP_KEY = "com.vitorpamplona.amethyst.ZAP_NOTIFICATION"
     private const val REACTION_GROUP_KEY = "com.vitorpamplona.amethyst.REACTION_NOTIFICATION"
     private const val CHESS_GROUP_KEY = "com.vitorpamplona.amethyst.CHESS_NOTIFICATION"
+    private const val REPLY_GROUP_KEY = "com.vitorpamplona.amethyst.REPLY_NOTIFICATION"
 
     const val REPLY_ACTION = "com.vitorpamplona.amethyst.REPLY_ACTION"
     const val MARK_READ_ACTION = "com.vitorpamplona.amethyst.MARK_READ_ACTION"
@@ -65,6 +67,7 @@ object NotificationUtils {
     private const val ZAP_SUMMARY_ID = 0x20000
     private const val REACTION_SUMMARY_ID = 0x40000
     private const val CHESS_SUMMARY_ID = 0x30000
+    private const val REPLY_SUMMARY_ID = 0x50000
 
     fun getOrCreateDMChannel(applicationContext: Context): NotificationChannel {
         if (dmChannel != null) return dmChannel!!
@@ -150,6 +153,27 @@ object NotificationUtils {
         return chessChannel!!
     }
 
+    fun getOrCreateReplyChannel(applicationContext: Context): NotificationChannel {
+        if (replyChannel != null) return replyChannel!!
+
+        replyChannel =
+            NotificationChannel(
+                stringRes(applicationContext, R.string.app_notification_replies_channel_id),
+                stringRes(applicationContext, R.string.app_notification_replies_channel_name),
+                NotificationManager.IMPORTANCE_DEFAULT,
+            ).apply {
+                description =
+                    stringRes(applicationContext, R.string.app_notification_replies_channel_description)
+            }
+
+        val notificationManager: NotificationManager =
+            applicationContext.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+
+        notificationManager.createNotificationChannel(replyChannel!!)
+
+        return replyChannel!!
+    }
+
     suspend fun NotificationManager.sendReactionNotification(
         id: String,
         messageBody: String,
@@ -206,6 +230,34 @@ object NotificationUtils {
         )
     }
 
+    suspend fun NotificationManager.sendReplyNotification(
+        id: String,
+        messageBody: String,
+        messageTitle: String,
+        time: Long,
+        pictureUrl: String?,
+        uri: String,
+        applicationContext: Context,
+    ) {
+        getOrCreateReplyChannel(applicationContext)
+        val channelId = stringRes(applicationContext, R.string.app_notification_replies_channel_id)
+
+        sendNotification(
+            id = id,
+            messageBody = messageBody,
+            messageTitle = messageTitle,
+            time = time,
+            pictureUrl = pictureUrl,
+            uri = uri,
+            channelId = channelId,
+            notificationGroupKey = REPLY_GROUP_KEY,
+            category = NotificationCompat.CATEGORY_SOCIAL,
+            summaryId = REPLY_SUMMARY_ID,
+            summaryText = stringRes(applicationContext, R.string.app_notification_replies_summary),
+            applicationContext = applicationContext,
+        )
+    }
+
     suspend fun NotificationManager.sendZapNotification(
         id: String,
         messageBody: String,

amethyst/src/main/res/values/strings.xml

@@ -876,6 +876,12 @@
     <string name="app_notification_chess_challenge_accepted">%1$s accepted your chess challenge</string>
     <string name="app_notification_chess_your_turn">%1$s moved — your turn</string>
     <string name="app_notification_chess_summary">Chess updates</string>
+    <string name="app_notification_replies_channel_id" translatable="false">RepliesID</string>
+    <string name="app_notification_replies_channel_name">Replies</string>
+    <string name="app_notification_replies_channel_description">Notifies you when somebody replies to your post</string>
+    <string name="app_notification_replies_channel_message">%1$s replied</string>
+    <string name="app_notification_replies_channel_message_for">on: %1$s</string>
+    <string name="app_notification_replies_summary">New replies</string>
 
     <!-- Call notifications and UI -->
     <string name="app_notification_calls_channel_name">Incoming calls</string>