feat(live-chat): show NIP-75 zap goal at top of live stream chat

Add a goalEventId() accessor on LiveActivitiesEvent that reads the
zap.stream `["goal", "<hex>"]` tag. When a stream channel's 30311 event
references a goal, fetch the kind 9041 event and its zap receipts
(#e=<goalId>) so the existing goal-progress aggregation works.

Render a compact LiveStreamGoalHeader above the chat feed showing the
goal title, the existing GoalProgressBar, and a one-tap ZapReaction
that targets the goal event so viewers can contribute directly to the
fundraiser without leaving the stream.

https://claude.ai/code/session_01WJA5PvDABegBYUu6h42YZi

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

@@ -39,10 +39,22 @@ class ChannelPublicFilterSubAssembler(
         since: SincePerRelayMap?,
     ): List<RelayBasedFilter>? =
         when (val channel = key.channel) {
-            is EphemeralChatChannel -> filterMessagesToEphemeralChat(channel, since)
+            is EphemeralChatChannel -> {
-            is PublicChatChannel -> filterMessagesToPublicChat(channel, since)
+                filterMessagesToEphemeralChat(channel, since)
-            is LiveActivitiesChannel -> filterMessagesToLiveActivities(channel, since)
+            }
-            else -> null
+
+            is PublicChatChannel -> {
+                filterMessagesToPublicChat(channel, since)
+            }
+
+            is LiveActivitiesChannel -> {
+                filterMessagesToLiveActivities(channel, since) +
+                    filterGoalForLiveActivities(channel, since)
+            }
+
+            else -> {
+                null
+            }
         }
 
     override fun id(key: ChannelQueryState) = key.channel

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

@@ -0,0 +1,66 @@
+/*
+ * 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.publicChannels.datasource.subassemblies
+
+import com.vitorpamplona.amethyst.commons.model.nip53LiveActivities.LiveActivitiesChannel
+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.nip57Zaps.LnZapEvent
+import com.vitorpamplona.quartz.nip75ZapGoals.GoalEvent
+
+/**
+ * Fetches the NIP-75 zap goal referenced by a live stream plus the zap receipts
+ * that count toward it.
+ *
+ * zap.stream attaches a goal to a 30311 event via `["goal", "<hex event id>"]`.
+ * We fetch the 9041 goal event by id and the 9735 zap receipts that `#e`-tag it.
+ */
+fun filterGoalForLiveActivities(
+    channel: LiveActivitiesChannel,
+    since: SincePerRelayMap?,
+): List<RelayBasedFilter> {
+    val goalId = channel.info?.goalEventId() ?: return emptyList()
+
+    return channel.relays().toSet().flatMap { relay ->
+        listOf(
+            RelayBasedFilter(
+                relay = relay,
+                filter =
+                    Filter(
+                        kinds = listOf(GoalEvent.KIND),
+                        ids = listOf(goalId),
+                        limit = 1,
+                    ),
+            ),
+            RelayBasedFilter(
+                relay = relay,
+                filter =
+                    Filter(
+                        kinds = listOf(LnZapEvent.KIND),
+                        tags = mapOf("e" to listOf(goalId)),
+                        limit = 200,
+                        since = since?.get(relay)?.time,
+                    ),
+            ),
+        )
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/publicChannels/nip53LiveActivities/ChannelView.kt

@@ -38,6 +38,7 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.RefreshingChatroomFeedView
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.dal.ChannelFeedViewModel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.datasource.ChannelFilterAssemblerSubscription
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.nip53LiveActivities.header.LiveStreamGoalHeader
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.send.ChannelNewMessageViewModel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.send.EditFieldRow
 import com.vitorpamplona.amethyst.ui.theme.DoubleVertSpacer
@@ -127,6 +128,7 @@ fun LiveActivityChannelView(
                     .weight(1f, true),
         ) {
             ShowVideoStreaming(channel, accountViewModel)
+            LiveStreamGoalHeader(channel, accountViewModel, nav)
             RefreshingChatroomFeedView(
                 feedContentState = feedViewModel.feedState,
                 accountViewModel = accountViewModel,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/publicChannels/nip53LiveActivities/header/LiveStreamGoalHeader.kt

@@ -0,0 +1,131 @@
+/*
+ * 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.publicChannels.nip53LiveActivities.header
+
+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.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.commons.model.nip53LiveActivities.LiveActivitiesChannel
+import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.amethyst.ui.components.LoadNote
+import com.vitorpamplona.amethyst.ui.navigation.navs.INav
+import com.vitorpamplona.amethyst.ui.note.ZapReaction
+import com.vitorpamplona.amethyst.ui.note.types.GoalProgressBar
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.amethyst.ui.theme.Size20Modifier
+import com.vitorpamplona.amethyst.ui.theme.Size20dp
+import com.vitorpamplona.amethyst.ui.theme.StdHorzSpacer
+import com.vitorpamplona.amethyst.ui.theme.placeholderText
+import com.vitorpamplona.quartz.nip75ZapGoals.GoalEvent
+
+/**
+ * Compact header rendered above the live-activity chat feed when the stream
+ * has a NIP-75 zap goal attached. Shows the goal title, a progress bar, and
+ * a one-tap zap button targeting the goal event.
+ */
+@Composable
+fun LiveStreamGoalHeader(
+    channel: LiveActivitiesChannel,
+    accountViewModel: AccountViewModel,
+    nav: INav,
+) {
+    val goalId = channel.info?.goalEventId() ?: return
+
+    LoadNote(baseNoteHex = goalId, accountViewModel = accountViewModel) { goalNote ->
+        if (goalNote != null) {
+            GoalHeaderContent(goalNote, accountViewModel, nav)
+        }
+    }
+}
+
+@Composable
+private fun GoalHeaderContent(
+    goalNote: Note,
+    accountViewModel: AccountViewModel,
+    nav: INav,
+) {
+    val goal = goalNote.event as? GoalEvent ?: return
+
+    val title =
+        remember(goal) {
+            goal.summary()?.ifBlank { null } ?: goal.content.take(120).ifBlank { null }
+        }
+    val goalAmountSats = remember(goal) { (goal.amount() ?: 0L) / 1000 }
+
+    if (goalAmountSats <= 0) return
+
+    Column(
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .padding(horizontal = 12.dp, vertical = 8.dp),
+        verticalArrangement = Arrangement.spacedBy(4.dp),
+    ) {
+        Row(verticalAlignment = Alignment.CenterVertically) {
+            if (title != null) {
+                Text(
+                    text = title,
+                    style = MaterialTheme.typography.bodyMedium,
+                    fontWeight = FontWeight.SemiBold,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                    modifier = Modifier.weight(1f),
+                )
+            } else {
+                Spacer(Modifier.weight(1f))
+            }
+
+            Spacer(StdHorzSpacer)
+            ZapReaction(
+                baseNote = goalNote,
+                grayTint = MaterialTheme.colorScheme.placeholderText,
+                accountViewModel = accountViewModel,
+                iconSize = Size20dp,
+                iconSizeModifier = Size20Modifier,
+                showCounter = false,
+                nav = nav,
+            )
+        }
+
+        GoalProgressBar(
+            note = goalNote,
+            goalAmountSats = goalAmountSats,
+            accountViewModel = accountViewModel,
+        )
+    }
+
+    HorizontalDivider(thickness = 0.5.dp)
+    Spacer(Modifier.height(2.dp))
+}

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip53LiveActivities/streaming/LiveActivitiesEvent.kt

@@ -117,6 +117,12 @@ class LiveActivitiesEvent(
 
     fun pinned() = tags.mapNotNull(PinnedEventTag::parse)
 
+    /**
+     * zap.stream convention: a NIP-75 zap goal (kind 9041) is attached to a live stream
+     * via a flat tag `["goal", "<hex event id>"]` on the 30311 event.
+     */
+    fun goalEventId(): HexKey? = tags.firstOrNull { it.size > 1 && it[0] == GOAL_TAG && it[1].isNotEmpty() }?.get(1)
+
     fun checkStatus(eventStatus: StatusTag.STATUS?): StatusTag.STATUS? =
         if (eventStatus == StatusTag.STATUS.LIVE && createdAt < TimeUtils.eightHoursAgo()) {
             StatusTag.STATUS.ENDED
@@ -139,6 +145,7 @@ class LiveActivitiesEvent(
     companion object {
         const val KIND = 30311
         const val ALT = "Live activity event"
+        const val GOAL_TAG = "goal"
 
         suspend fun create(
             signer: NostrSigner,