feat(live-chat): display zap receipts inline in live stream chat

Subscribe to kind 9735 alongside kind 1311 against the stream's #a tag,
route host-directed zaps into the LiveActivitiesChannel cache, and render
them as a centered, lightning-accented row with the zapper, amount, and
optional zap message. Matches zap.stream's chat behavior for
NIP-53 + NIP-57 interop.

https://claude.ai/code/session_01WJA5PvDABegBYUu6h42YZi

amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt

@@ -1541,6 +1541,8 @@ object LocalCache : ILocalCache, ICacheProvider {
 
             repliesTo.forEach { it.addZap(zapRequest, note) }
 
+            attachZapToLiveActivityChannel(event, note, relay)
+
             refreshNewNoteObservers(note)
 
             return true
@@ -1549,6 +1551,24 @@ object LocalCache : ILocalCache, ICacheProvider {
         return false
     }
 
+    private fun attachZapToLiveActivityChannel(
+        event: LnZapEvent,
+        note: Note,
+        relay: NormalizedRelayUrl?,
+    ) {
+        val address =
+            event.tags
+                .asSequence()
+                .mapNotNull(ATag::parseAddress)
+                .firstOrNull { it.kind == LiveActivitiesEvent.KIND }
+                ?: return
+
+        // Match zap.stream: only show zaps whose receiver is the live activity host
+        if (event.zappedAuthor().none { it == address.pubKeyHex }) return
+
+        getOrCreateLiveChannel(address).addNote(note, relay)
+    }
+
     fun consume(
         event: LnZapRequestEvent,
         relay: NormalizedRelayUrl?,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/feed/ChatMessageCompose.kt

@@ -61,6 +61,7 @@ import com.vitorpamplona.amethyst.ui.note.elements.DisplayPoW
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.layouts.ChatBubbleLayout
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.RenderChangeChannelMetadataNote
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.RenderChatZap
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.RenderCreateChannelNote
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.RenderDraftEvent
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.RenderEncryptedFile
@@ -84,6 +85,7 @@ import com.vitorpamplona.quartz.nip17Dm.files.ChatMessageEncryptedFileHeaderEven
 import com.vitorpamplona.quartz.nip28PublicChat.admin.ChannelCreateEvent
 import com.vitorpamplona.quartz.nip28PublicChat.admin.ChannelMetadataEvent
 import com.vitorpamplona.quartz.nip37Drafts.DraftWrapEvent
+import com.vitorpamplona.quartz.nip57Zaps.LnZapEvent
 import com.vitorpamplona.quartz.nip57Zaps.splits.hasZapSplitSetup
 import com.vitorpamplona.quartz.nip57Zaps.zapraiser.zapraiserAmount
 
@@ -109,20 +111,24 @@ fun ChatroomMessageCompose(
             accountViewModel = accountViewModel,
             nav = nav,
         ) { canPreview ->
-            NormalChatNote(
+            if (baseNote.event is LnZapEvent) {
-                baseNote,
+                RenderChatZap(baseNote, accountViewModel, nav)
-                routeForLastRead,
+            } else {
-                innerQuote,
+                NormalChatNote(
-                canPreview,
+                    baseNote,
-                parentBackgroundColor,
+                    routeForLastRead,
-                accountViewModel,
+                    innerQuote,
-                nav,
+                    canPreview,
-                onWantsToReply,
+                    parentBackgroundColor,
-                onWantsToEditDraft,
+                    accountViewModel,
-                onScrollToNote,
+                    nav,
-                shouldHighlight,
+                    onWantsToReply,
-                onHighlightFinished,
+                    onWantsToEditDraft,
-            )
+                    onScrollToNote,
+                    shouldHighlight,
+                    onHighlightFinished,
+                )
+            }
         }
     }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/feed/types/RenderChatZap.kt

@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.produceState
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.R
+import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.amethyst.ui.navigation.navs.INav
+import com.vitorpamplona.amethyst.ui.note.CrossfadeToDisplayComment
+import com.vitorpamplona.amethyst.ui.note.UserPicture
+import com.vitorpamplona.amethyst.ui.note.UsernameDisplay
+import com.vitorpamplona.amethyst.ui.note.ZapAmountCommentNotification
+import com.vitorpamplona.amethyst.ui.note.ZapIcon
+import com.vitorpamplona.amethyst.ui.note.showAmountInteger
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.amethyst.ui.stringRes
+import com.vitorpamplona.amethyst.ui.theme.BitcoinOrange
+import com.vitorpamplona.amethyst.ui.theme.Size20Modifier
+import com.vitorpamplona.amethyst.ui.theme.Size20dp
+import com.vitorpamplona.amethyst.ui.theme.Size24Modifier
+import com.vitorpamplona.amethyst.ui.theme.StdHorzSpacer
+import com.vitorpamplona.quartz.nip57Zaps.LnZapEvent
+
+private const val BIG_ZAP_THRESHOLD_SATS = 50_000L
+
+@Composable
+fun RenderChatZap(
+    baseNote: Note,
+    accountViewModel: AccountViewModel,
+    nav: INav,
+) {
+    val zapEvent = baseNote.event as? LnZapEvent ?: return
+
+    val card by produceState(
+        ZapAmountCommentNotification(user = null, comment = null, amount = null),
+        baseNote,
+    ) {
+        value = accountViewModel.innerDecryptAmountMessage(baseNote) ?: value
+    }
+
+    val isBigZap =
+        remember(zapEvent) {
+            (zapEvent.amount?.toLong() ?: 0L) >= BIG_ZAP_THRESHOLD_SATS
+        }
+
+    val containerColor =
+        if (isBigZap) {
+            BitcoinOrange.copy(alpha = 0.18f)
+        } else {
+            BitcoinOrange.copy(alpha = 0.08f)
+        }
+
+    val backgroundColor = remember(containerColor) { mutableStateOf(containerColor) }
+
+    val amountText = card.amount ?: showAmountInteger(zapEvent.amount)
+
+    Row(
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .padding(horizontal = 8.dp, vertical = 2.dp)
+                .clip(RoundedCornerShape(8.dp))
+                .background(containerColor)
+                .padding(horizontal = 10.dp, vertical = 6.dp),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(6.dp),
+    ) {
+        ZapIcon(
+            if (isBigZap) Size24Modifier else Size20Modifier,
+            BitcoinOrange,
+        )
+
+        Column(modifier = Modifier.weight(1f)) {
+            Row(verticalAlignment = Alignment.CenterVertically) {
+                val sender = card.user
+                if (sender != null) {
+                    UserPicture(sender, Size20dp, Modifier, accountViewModel, nav)
+                    Spacer(StdHorzSpacer)
+                    UsernameDisplay(
+                        baseUser = sender,
+                        fontWeight = FontWeight.Bold,
+                        accountViewModel = accountViewModel,
+                    )
+                } else {
+                    Text(
+                        text = stringRes(R.string.chat_zap_anonymous),
+                        fontWeight = FontWeight.Bold,
+                    )
+                }
+
+                Spacer(StdHorzSpacer)
+                Text(
+                    text = stringRes(R.string.chat_zap_amount_suffix, amountText),
+                    color = BitcoinOrange,
+                    fontWeight = if (isBigZap) FontWeight.Bold else FontWeight.Normal,
+                )
+            }
+
+            card.comment?.takeIf { it.isNotBlank() }?.let { comment ->
+                Spacer(Modifier.padding(top = 2.dp))
+                CrossfadeToDisplayComment(
+                    comment = comment,
+                    backgroundColor = backgroundColor,
+                    nav = nav,
+                    accountViewModel = accountViewModel,
+                )
+            }
+        }
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/publicChannels/datasource/subassemblies/FilterMessagesToLiveStream.kt

@@ -25,6 +25,7 @@ import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
 import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip53LiveActivities.chat.LiveActivitiesChatMessageEvent
+import com.vitorpamplona.quartz.nip57Zaps.LnZapEvent
 
 fun filterMessagesToLiveActivities(
     channel: LiveActivitiesChannel,
@@ -35,7 +36,7 @@ fun filterMessagesToLiveActivities(
             relay = it,
             filter =
                 Filter(
-                    kinds = listOf(LiveActivitiesChatMessageEvent.KIND),
+                    kinds = listOf(LiveActivitiesChatMessageEvent.KIND, LnZapEvent.KIND),
                     tags = mapOf("a" to listOfNotNull(channel.address.toValue())),
                     limit = 200,
                     since = since?.get(it)?.time,

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

@@ -53,6 +53,8 @@
     <string name="login_with_a_private_key_to_be_able_to_boost_posts">You are using a public key and public keys are read-only. Login with a Private key to be able to boost posts</string>
     <string name="login_with_a_private_key_to_like_posts">You are using a public key and public keys are read-only. Login with a Private key to like posts</string>
     <string name="no_zap_amount_setup_long_press_to_change">No Zap Amount Setup. Long Press to change</string>
+    <string name="chat_zap_amount_suffix">zapped %1$s sats</string>
+    <string name="chat_zap_anonymous">Anonymous</string>
     <string name="login_with_a_private_key_to_be_able_to_send_zaps">You are using a public key and public keys are read-only. Login with a Private key to be able to send zaps</string>
     <string name="login_with_a_private_key_to_be_able_to_follow">You are using a public key and public keys are read-only. Login with a Private key to be able to follow</string>
     <string name="login_with_a_private_key_to_be_able_to_unfollow">You are using a public key and public keys are read-only. Login with a Private key to be able to unfollow</string>