feat(broadcast): Add transparent event broadcasting feedback (#1682)

Phase 1 - Core infrastructure:
- BroadcastModels: BroadcastEvent, RelayResult, BroadcastStatus data classes
- BroadcastTracker: State management with live progress updates
- BroadcastBanner: Global progress indicator (animated)
- BroadcastSnackbar: Result notifications with actions
- BroadcastDetailsSheet: Relay status detail bottom sheet

Refs: #1682

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

amethyst/src/main/java/com/vitorpamplona/amethyst/service/broadcast/BroadcastModels.kt

@@ -0,0 +1,134 @@
+/**
+ * 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.service.broadcast
+
+import androidx.compose.runtime.Immutable
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+
+/**
+ * Result of a relay's response to an event publish.
+ */
+@Immutable
+sealed class RelayResult {
+    /** Relay accepted the event (OK message with success=true) */
+    data object Success : RelayResult()
+
+    /** Relay rejected the event (OK message with success=false) */
+    data class Error(
+        val code: String,
+        val message: String?,
+    ) : RelayResult()
+
+    /** Relay did not respond within timeout */
+    data object Timeout : RelayResult()
+
+    /** Waiting for relay response */
+    data object Pending : RelayResult()
+}
+
+/**
+ * Overall status of a broadcast operation.
+ */
+enum class BroadcastStatus {
+    /** Currently waiting for relay responses */
+    IN_PROGRESS,
+
+    /** All relays accepted the event */
+    SUCCESS,
+
+    /** Some relays accepted, some failed */
+    PARTIAL,
+
+    /** No relays accepted the event */
+    FAILED,
+}
+
+/**
+ * Tracks a single event broadcast to multiple relays.
+ */
+@Immutable
+data class BroadcastEvent(
+    val id: String,
+    val eventId: HexKey,
+    val eventName: String,
+    val kind: Int,
+    val targetRelays: List<NormalizedRelayUrl>,
+    val results: Map<NormalizedRelayUrl, RelayResult> = emptyMap(),
+    val status: BroadcastStatus = BroadcastStatus.IN_PROGRESS,
+    val startedAt: Long = System.currentTimeMillis(),
+) {
+    /** Number of relays that accepted the event */
+    val successCount: Int
+        get() = results.count { it.value is RelayResult.Success }
+
+    /** Number of relays that rejected or timed out */
+    val failureCount: Int
+        get() = results.count { it.value is RelayResult.Error || it.value is RelayResult.Timeout }
+
+    /** Number of relays still pending response */
+    val pendingCount: Int
+        get() = targetRelays.size - results.size
+
+    /** Total number of target relays */
+    val totalRelays: Int
+        get() = targetRelays.size
+
+    /** Progress as a fraction (0.0 to 1.0) */
+    val progress: Float
+        get() = if (totalRelays == 0) 0f else results.size.toFloat() / totalRelays
+
+    /** Whether all relays have responded */
+    val isComplete: Boolean
+        get() = results.size >= targetRelays.size
+
+    /** List of relays that failed (for retry) */
+    val failedRelays: List<NormalizedRelayUrl>
+        get() = results.filter { it.value is RelayResult.Error || it.value is RelayResult.Timeout }.keys.toList()
+
+    /** Creates a copy with an updated relay result */
+    fun withResult(
+        relay: NormalizedRelayUrl,
+        result: RelayResult,
+    ): BroadcastEvent {
+        val newResults = results + (relay to result)
+        val newStatus =
+            when {
+                newResults.size < targetRelays.size -> BroadcastStatus.IN_PROGRESS
+                newResults.all { it.value is RelayResult.Success } -> BroadcastStatus.SUCCESS
+                newResults.none { it.value is RelayResult.Success } -> BroadcastStatus.FAILED
+                else -> BroadcastStatus.PARTIAL
+            }
+        return copy(results = newResults, status = newStatus)
+    }
+}
+
+/**
+ * Result of a broadcast operation, returned after all relays respond or timeout.
+ */
+@Immutable
+data class BroadcastResult(
+    val broadcast: BroadcastEvent,
+    val isSuccess: Boolean,
+) {
+    val successCount: Int get() = broadcast.successCount
+    val totalRelays: Int get() = broadcast.totalRelays
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/service/broadcast/BroadcastTracker.kt

@@ -0,0 +1,271 @@
+/**
+ * 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.service.broadcast
+
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.relay.client.INostrClient
+import com.vitorpamplona.quartz.nip01Core.relay.client.listeners.IRelayClientListener
+import com.vitorpamplona.quartz.nip01Core.relay.client.single.IRelayClient
+import com.vitorpamplona.quartz.nip01Core.relay.commands.toClient.Message
+import com.vitorpamplona.quartz.nip01Core.relay.commands.toClient.OkMessage
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+import com.vitorpamplona.quartz.utils.Log
+import kotlinx.coroutines.DelicateCoroutinesApi
+import kotlinx.coroutines.async
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.channels.Channel.Factory.UNLIMITED
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharedFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asSharedFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.withTimeoutOrNull
+import java.util.UUID
+
+/**
+ * Tracks event broadcasts to relays with live progress updates.
+ *
+ * Provides:
+ * - Real-time progress as relays respond
+ * - Detailed per-relay success/error information
+ * - Retry functionality for failed relays
+ */
+class BroadcastTracker {
+    companion object {
+        private const val TAG = "BroadcastTracker"
+        private const val TIMEOUT_SECONDS = 15L
+    }
+
+    private val _activeBroadcasts = MutableStateFlow<List<BroadcastEvent>>(emptyList())
+    val activeBroadcasts: StateFlow<List<BroadcastEvent>> = _activeBroadcasts.asStateFlow()
+
+    private val _completedBroadcast = MutableSharedFlow<BroadcastEvent>(extraBufferCapacity = 10)
+    val completedBroadcast: SharedFlow<BroadcastEvent> = _completedBroadcast.asSharedFlow()
+
+    /**
+     * Tracks an event broadcast to relays with live progress updates.
+     *
+     * @param event The Nostr event to broadcast
+     * @param eventName Human-readable name (e.g., "Boost", "Reaction")
+     * @param relays Target relays to send to
+     * @param client The Nostr client for sending
+     * @return BroadcastResult with final status
+     */
+    @OptIn(DelicateCoroutinesApi::class)
+    suspend fun trackBroadcast(
+        event: Event,
+        eventName: String,
+        relays: Set<NormalizedRelayUrl>,
+        client: INostrClient,
+    ): BroadcastResult {
+        val trackingId = UUID.randomUUID().toString()
+
+        val broadcast =
+            BroadcastEvent(
+                id = trackingId,
+                eventId = event.id,
+                eventName = eventName,
+                kind = event.kind,
+                targetRelays = relays.toList(),
+            )
+
+        // Add to active broadcasts
+        _activeBroadcasts.update { it + broadcast }
+
+        Log.d(TAG, "Starting broadcast $trackingId: $eventName (kind ${event.kind}) to ${relays.size} relays")
+
+        val resultChannel = Channel<RelayResponse>(UNLIMITED)
+
+        val subscription =
+            object : IRelayClientListener {
+                override fun onCannotConnect(
+                    relay: IRelayClient,
+                    errorMessage: String,
+                ) {
+                    if (relay.url in relays) {
+                        resultChannel.trySend(
+                            RelayResponse(
+                                relay = relay.url,
+                                result = RelayResult.Error("CONNECTION_ERROR", errorMessage),
+                            ),
+                        )
+                        Log.d(TAG, "[$trackingId] Cannot connect to ${relay.url}: $errorMessage")
+                    }
+                }
+
+                override fun onDisconnected(relay: IRelayClient) {
+                    if (relay.url in relays) {
+                        resultChannel.trySend(
+                            RelayResponse(
+                                relay = relay.url,
+                                result = RelayResult.Error("DISCONNECTED", "Relay disconnected"),
+                            ),
+                        )
+                        Log.d(TAG, "[$trackingId] Disconnected from ${relay.url}")
+                    }
+                }
+
+                override fun onIncomingMessage(
+                    relay: IRelayClient,
+                    msgStr: String,
+                    msg: Message,
+                ) {
+                    super.onIncomingMessage(relay, msgStr, msg)
+
+                    when (msg) {
+                        is OkMessage -> {
+                            if (msg.eventId == event.id) {
+                                val result =
+                                    if (msg.success) {
+                                        RelayResult.Success
+                                    } else {
+                                        val (code, message) = parseOkError(msg.message)
+                                        RelayResult.Error(code, message)
+                                    }
+                                resultChannel.trySend(RelayResponse(relay.url, result))
+                                Log.d(TAG, "[$trackingId] Response from ${relay.url}: success=${msg.success} message=${msg.message}")
+                            }
+                        }
+                    }
+                }
+            }
+
+        client.subscribe(subscription)
+
+        val finalBroadcast =
+            coroutineScope {
+                val resultCollector =
+                    async {
+                        val receivedRelays = mutableSetOf<NormalizedRelayUrl>()
+                        var currentBroadcast = broadcast
+
+                        withTimeoutOrNull(TIMEOUT_SECONDS * 1000) {
+                            while (receivedRelays.size < relays.size) {
+                                val response = resultChannel.receive()
+
+                                // Skip if already received (don't override success)
+                                if (response.relay in receivedRelays) continue
+
+                                receivedRelays.add(response.relay)
+                                currentBroadcast = currentBroadcast.withResult(response.relay, response.result)
+
+                                // Update active broadcasts with new progress
+                                _activeBroadcasts.update { list ->
+                                    list.map { if (it.id == trackingId) currentBroadcast else it }
+                                }
+                            }
+                        }
+
+                        // Mark remaining relays as timeout
+                        relays.filter { it !in receivedRelays }.forEach { relay ->
+                            currentBroadcast = currentBroadcast.withResult(relay, RelayResult.Timeout)
+                        }
+
+                        currentBroadcast
+                    }
+
+                // Send after setting up listener
+                client.send(event, relays)
+
+                resultCollector.await()
+            }
+
+        client.unsubscribe(subscription)
+        resultChannel.close()
+
+        // Remove from active, emit to completed
+        _activeBroadcasts.update { list -> list.filter { it.id != trackingId } }
+        _completedBroadcast.emit(finalBroadcast)
+
+        Log.d(TAG, "Broadcast $trackingId complete: ${finalBroadcast.successCount}/${finalBroadcast.totalRelays} success")
+
+        return BroadcastResult(
+            broadcast = finalBroadcast,
+            isSuccess = finalBroadcast.successCount > 0,
+        )
+    }
+
+    /**
+     * Retries sending an event to failed relays.
+     *
+     * @param originalBroadcast The original broadcast with failures
+     * @param event The original event to resend
+     * @param client The Nostr client
+     * @param specificRelay Optional specific relay to retry (null = all failed)
+     */
+    suspend fun retry(
+        originalBroadcast: BroadcastEvent,
+        event: Event,
+        client: INostrClient,
+        specificRelay: NormalizedRelayUrl? = null,
+    ): BroadcastResult {
+        val relaysToRetry =
+            if (specificRelay != null) {
+                setOf(specificRelay)
+            } else {
+                originalBroadcast.failedRelays.toSet()
+            }
+
+        if (relaysToRetry.isEmpty()) {
+            return BroadcastResult(originalBroadcast, originalBroadcast.successCount > 0)
+        }
+
+        return trackBroadcast(
+            event = event,
+            eventName = "${originalBroadcast.eventName} (retry)",
+            relays = relaysToRetry,
+            client = client,
+        )
+    }
+
+    /**
+     * Gets details for a specific broadcast by tracking ID.
+     */
+    fun getActiveBroadcast(trackingId: String): BroadcastEvent? = _activeBroadcasts.value.find { it.id == trackingId }
+
+    /**
+     * Clears all active broadcasts (e.g., on logout).
+     */
+    fun clear() {
+        _activeBroadcasts.update { emptyList() }
+    }
+
+    /**
+     * Parses NIP-20 OK error message into code and description.
+     * Format: "prefix: message" or just "message"
+     */
+    private fun parseOkError(message: String): Pair<String, String?> {
+        val parts = message.split(":", limit = 2)
+        return if (parts.size == 2) {
+            parts[0].trim().uppercase() to parts[1].trim()
+        } else {
+            "ERROR" to message.takeIf { it.isNotBlank() }
+        }
+    }
+
+    private data class RelayResponse(
+        val relay: NormalizedRelayUrl,
+        val result: RelayResult,
+    )
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/broadcast/BroadcastBanner.kt

@@ -0,0 +1,203 @@
+/**
+ * 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.broadcast
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.animateContentSize
+import androidx.compose.animation.core.animateFloatAsState
+import androidx.compose.animation.core.tween
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.animation.slideInVertically
+import androidx.compose.animation.slideOutVertically
+import androidx.compose.foundation.clickable
+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.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Sync
+import androidx.compose.material3.Icon
+import androidx.compose.material3.LinearProgressIndicator
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.service.broadcast.BroadcastEvent
+
+/**
+ * Banner showing active broadcast progress.
+ * Displayed above bottom navigation when events are being sent to relays.
+ */
+@Composable
+fun BroadcastBanner(
+    broadcasts: List<BroadcastEvent>,
+    onTap: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    AnimatedVisibility(
+        visible = broadcasts.isNotEmpty(),
+        enter = slideInVertically(initialOffsetY = { it }) + fadeIn(tween(200)),
+        exit = slideOutVertically(targetOffsetY = { it }) + fadeOut(tween(150)),
+        modifier = modifier,
+    ) {
+        Surface(
+            color = MaterialTheme.colorScheme.surfaceContainer,
+            tonalElevation = 2.dp,
+            modifier =
+                Modifier
+                    .fillMaxWidth()
+                    .clickable(onClick = onTap),
+        ) {
+            Column(
+                modifier =
+                    Modifier
+                        .padding(horizontal = 16.dp, vertical = 8.dp)
+                        .animateContentSize(),
+            ) {
+                if (broadcasts.size == 1) {
+                    SingleBroadcastContent(broadcasts.first())
+                } else {
+                    MultipleBroadcastsContent(broadcasts)
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun SingleBroadcastContent(broadcast: BroadcastEvent) {
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+        modifier = Modifier.fillMaxWidth(),
+    ) {
+        Icon(
+            imageVector = Icons.Default.Sync,
+            contentDescription = "Broadcasting",
+            tint = MaterialTheme.colorScheme.primary,
+            modifier = Modifier.size(18.dp),
+        )
+
+        Column(modifier = Modifier.weight(1f)) {
+            Row(
+                horizontalArrangement = Arrangement.SpaceBetween,
+                modifier = Modifier.fillMaxWidth(),
+            ) {
+                Text(
+                    text = "Broadcasting ${broadcast.eventName} (kind ${broadcast.kind})",
+                    style = MaterialTheme.typography.bodySmall,
+                    color = MaterialTheme.colorScheme.onSurface,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                    modifier = Modifier.weight(1f),
+                )
+
+                Spacer(Modifier.width(8.dp))
+
+                Text(
+                    text = "[${broadcast.results.size}/${broadcast.totalRelays}]",
+                    style = MaterialTheme.typography.labelMedium,
+                    color = MaterialTheme.colorScheme.primary,
+                )
+            }
+
+            Spacer(Modifier.height(4.dp))
+
+            val animatedProgress by animateFloatAsState(
+                targetValue = broadcast.progress,
+                animationSpec = tween(300),
+                label = "progress",
+            )
+
+            LinearProgressIndicator(
+                progress = { animatedProgress },
+                modifier = Modifier.fillMaxWidth(),
+                color = MaterialTheme.colorScheme.primary,
+                trackColor = MaterialTheme.colorScheme.surfaceVariant,
+            )
+        }
+    }
+}
+
+@Composable
+private fun MultipleBroadcastsContent(broadcasts: List<BroadcastEvent>) {
+    val totalRelays = broadcasts.sumOf { it.totalRelays }
+    val completedResponses = broadcasts.sumOf { it.results.size }
+
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+        modifier = Modifier.fillMaxWidth(),
+    ) {
+        Icon(
+            imageVector = Icons.Default.Sync,
+            contentDescription = "Broadcasting",
+            tint = MaterialTheme.colorScheme.primary,
+            modifier = Modifier.size(18.dp),
+        )
+
+        Column(modifier = Modifier.weight(1f)) {
+            Row(
+                horizontalArrangement = Arrangement.SpaceBetween,
+                modifier = Modifier.fillMaxWidth(),
+            ) {
+                Text(
+                    text = "Broadcasting ${broadcasts.size} events...",
+                    style = MaterialTheme.typography.bodySmall,
+                    color = MaterialTheme.colorScheme.onSurface,
+                )
+
+                Text(
+                    text = "[$completedResponses/$totalRelays]",
+                    style = MaterialTheme.typography.labelMedium,
+                    color = MaterialTheme.colorScheme.primary,
+                )
+            }
+
+            Spacer(Modifier.height(4.dp))
+
+            val progress = if (totalRelays > 0) completedResponses.toFloat() / totalRelays else 0f
+            val animatedProgress by animateFloatAsState(
+                targetValue = progress,
+                animationSpec = tween(300),
+                label = "progress",
+            )
+
+            LinearProgressIndicator(
+                progress = { animatedProgress },
+                modifier = Modifier.fillMaxWidth(),
+                color = MaterialTheme.colorScheme.primary,
+                trackColor = MaterialTheme.colorScheme.surfaceVariant,
+            )
+        }
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/broadcast/BroadcastDetailsSheet.kt

@@ -0,0 +1,277 @@
+/**
+ * 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.broadcast
+
+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.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.CheckCircle
+import androidx.compose.material.icons.filled.Error
+import androidx.compose.material.icons.filled.HourglassEmpty
+import androidx.compose.material.icons.filled.Refresh
+import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.ModalBottomSheet
+import androidx.compose.material3.OutlinedButton
+import androidx.compose.material3.SheetState
+import androidx.compose.material3.Text
+import androidx.compose.material3.rememberModalBottomSheetState
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.service.broadcast.BroadcastEvent
+import com.vitorpamplona.amethyst.service.broadcast.BroadcastStatus
+import com.vitorpamplona.amethyst.service.broadcast.RelayResult
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.displayUrl
+
+/**
+ * Modal bottom sheet showing detailed relay results for a broadcast.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun BroadcastDetailsSheet(
+    broadcast: BroadcastEvent,
+    onDismiss: () -> Unit,
+    onRetryRelay: (NormalizedRelayUrl) -> Unit,
+    onRetryAllFailed: () -> Unit,
+    sheetState: SheetState = rememberModalBottomSheetState(),
+) {
+    ModalBottomSheet(
+        onDismissRequest = onDismiss,
+        sheetState = sheetState,
+    ) {
+        Column(
+            modifier =
+                Modifier
+                    .fillMaxWidth()
+                    .padding(horizontal = 16.dp)
+                    .padding(bottom = 32.dp),
+        ) {
+            // Header
+            Text(
+                text = "Broadcast Results",
+                style = MaterialTheme.typography.titleLarge,
+                color = MaterialTheme.colorScheme.onSurface,
+            )
+
+            Spacer(Modifier.height(8.dp))
+
+            // Summary
+            Row(
+                verticalAlignment = Alignment.CenterVertically,
+                horizontalArrangement = Arrangement.spacedBy(8.dp),
+            ) {
+                StatusIcon(broadcast.status)
+
+                Text(
+                    text = "${broadcast.eventName} (kind ${broadcast.kind})",
+                    style = MaterialTheme.typography.bodyLarge,
+                    color = MaterialTheme.colorScheme.onSurface,
+                )
+
+                Spacer(Modifier.weight(1f))
+
+                Text(
+                    text = "${broadcast.successCount}/${broadcast.totalRelays} relays",
+                    style = MaterialTheme.typography.labelLarge,
+                    color =
+                        when (broadcast.status) {
+                            BroadcastStatus.SUCCESS -> Color(0xFF22C55E)
+                            BroadcastStatus.PARTIAL -> Color(0xFFF59E0B)
+                            BroadcastStatus.FAILED -> Color(0xFFEF4444)
+                            BroadcastStatus.IN_PROGRESS -> MaterialTheme.colorScheme.primary
+                        },
+                )
+            }
+
+            Spacer(Modifier.height(16.dp))
+            HorizontalDivider()
+            Spacer(Modifier.height(8.dp))
+
+            // Relay list
+            LazyColumn(
+                verticalArrangement = Arrangement.spacedBy(4.dp),
+                modifier = Modifier.weight(1f, fill = false),
+            ) {
+                items(broadcast.targetRelays) { relay ->
+                    val result = broadcast.results[relay] ?: RelayResult.Pending
+                    RelayResultRow(
+                        relay = relay,
+                        result = result,
+                        onRetry = { onRetryRelay(relay) },
+                    )
+                }
+            }
+
+            Spacer(Modifier.height(16.dp))
+
+            // Action buttons
+            Row(
+                modifier = Modifier.fillMaxWidth(),
+                horizontalArrangement = Arrangement.spacedBy(12.dp),
+            ) {
+                OutlinedButton(
+                    onClick = onDismiss,
+                    modifier = Modifier.weight(1f),
+                ) {
+                    Text("Dismiss")
+                }
+
+                if (broadcast.failedRelays.isNotEmpty()) {
+                    Button(
+                        onClick = onRetryAllFailed,
+                        modifier = Modifier.weight(1f),
+                        colors =
+                            ButtonDefaults.buttonColors(
+                                containerColor = MaterialTheme.colorScheme.primary,
+                            ),
+                    ) {
+                        Icon(
+                            imageVector = Icons.Default.Refresh,
+                            contentDescription = null,
+                            modifier = Modifier.size(18.dp),
+                        )
+                        Spacer(Modifier.width(4.dp))
+                        Text("Retry Failed (${broadcast.failedRelays.size})")
+                    }
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun StatusIcon(status: BroadcastStatus) {
+    val (icon, tint) =
+        when (status) {
+            BroadcastStatus.SUCCESS -> Icons.Default.CheckCircle to Color(0xFF22C55E)
+            BroadcastStatus.PARTIAL -> Icons.Default.Error to Color(0xFFF59E0B)
+            BroadcastStatus.FAILED -> Icons.Default.Error to Color(0xFFEF4444)
+            BroadcastStatus.IN_PROGRESS -> Icons.Default.HourglassEmpty to MaterialTheme.colorScheme.primary
+        }
+
+    Icon(
+        imageVector = icon,
+        contentDescription = status.name,
+        tint = tint,
+        modifier = Modifier.size(24.dp),
+    )
+}
+
+@Composable
+private fun RelayResultRow(
+    relay: NormalizedRelayUrl,
+    result: RelayResult,
+    onRetry: () -> Unit,
+) {
+    Row(
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .padding(vertical = 8.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        // Status icon
+        val (icon, tint) =
+            when (result) {
+                is RelayResult.Success -> Icons.Default.CheckCircle to Color(0xFF22C55E)
+                is RelayResult.Error -> Icons.Default.Error to Color(0xFFEF4444)
+                is RelayResult.Timeout -> Icons.Default.HourglassEmpty to Color(0xFFF59E0B)
+                is RelayResult.Pending -> Icons.Default.HourglassEmpty to MaterialTheme.colorScheme.onSurfaceVariant
+            }
+
+        Icon(
+            imageVector = icon,
+            contentDescription = null,
+            tint = tint,
+            modifier = Modifier.size(20.dp),
+        )
+
+        Spacer(Modifier.width(12.dp))
+
+        // Relay URL
+        Column(modifier = Modifier.weight(1f)) {
+            Text(
+                text = relay.displayUrl(),
+                style = MaterialTheme.typography.bodyMedium,
+                color = MaterialTheme.colorScheme.onSurface,
+                maxLines = 1,
+                overflow = TextOverflow.Ellipsis,
+            )
+
+            // Error message if present
+            when (result) {
+                is RelayResult.Error -> {
+                    Text(
+                        text = "[${result.code}]${result.message?.let { " $it" } ?: ""}",
+                        style = MaterialTheme.typography.bodySmall,
+                        fontFamily = FontFamily.Monospace,
+                        color = Color(0xFFEF4444),
+                        maxLines = 1,
+                        overflow = TextOverflow.Ellipsis,
+                    )
+                }
+                is RelayResult.Timeout -> {
+                    Text(
+                        text = "Timeout",
+                        style = MaterialTheme.typography.bodySmall,
+                        color = Color(0xFFF59E0B),
+                    )
+                }
+                else -> {}
+            }
+        }
+
+        // Retry button for failed relays
+        if (result is RelayResult.Error || result is RelayResult.Timeout) {
+            IconButton(
+                onClick = onRetry,
+                modifier = Modifier.size(32.dp),
+            ) {
+                Icon(
+                    imageVector = Icons.Default.Refresh,
+                    contentDescription = "Retry",
+                    tint = MaterialTheme.colorScheme.primary,
+                    modifier = Modifier.size(18.dp),
+                )
+            }
+        }
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/broadcast/BroadcastSnackbar.kt

@@ -0,0 +1,140 @@
+/**
+ * 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.broadcast
+
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Snackbar
+import androidx.compose.material3.SnackbarData
+import androidx.compose.material3.SnackbarDuration
+import androidx.compose.material3.SnackbarHost
+import androidx.compose.material3.SnackbarHostState
+import androidx.compose.material3.SnackbarResult
+import androidx.compose.material3.SnackbarVisuals
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.service.broadcast.BroadcastEvent
+import com.vitorpamplona.amethyst.service.broadcast.BroadcastStatus
+import kotlinx.coroutines.flow.SharedFlow
+
+/**
+ * Custom snackbar visuals for broadcast results.
+ */
+data class BroadcastSnackbarVisuals(
+    val broadcast: BroadcastEvent,
+    override val actionLabel: String? = "View",
+    override val duration: SnackbarDuration = SnackbarDuration.Short,
+    override val withDismissAction: Boolean = true,
+) : SnackbarVisuals {
+    override val message: String
+        get() =
+            when (broadcast.status) {
+                BroadcastStatus.SUCCESS -> "${broadcast.eventName} sent to ${broadcast.successCount}/${broadcast.totalRelays} relays"
+                BroadcastStatus.PARTIAL -> "${broadcast.eventName} sent to ${broadcast.successCount}/${broadcast.totalRelays} relays"
+                BroadcastStatus.FAILED -> "${broadcast.eventName} failed - 0/${broadcast.totalRelays} relays"
+                BroadcastStatus.IN_PROGRESS -> "Broadcasting ${broadcast.eventName}..."
+            }
+}
+
+/**
+ * Snackbar host that listens to completed broadcasts and shows result notifications.
+ */
+@Composable
+fun BroadcastSnackbarHost(
+    completedBroadcast: SharedFlow<BroadcastEvent>,
+    onViewDetails: (BroadcastEvent) -> Unit,
+    onRetry: (BroadcastEvent) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val snackbarHostState = remember { SnackbarHostState() }
+
+    LaunchedEffect(completedBroadcast) {
+        completedBroadcast.collect { broadcast ->
+            val visuals = BroadcastSnackbarVisuals(broadcast)
+            val result = snackbarHostState.showSnackbar(visuals)
+
+            when (result) {
+                SnackbarResult.ActionPerformed -> {
+                    if (broadcast.status == BroadcastStatus.FAILED) {
+                        onRetry(broadcast)
+                    } else {
+                        onViewDetails(broadcast)
+                    }
+                }
+                SnackbarResult.Dismissed -> { /* No action */ }
+            }
+        }
+    }
+
+    SnackbarHost(
+        hostState = snackbarHostState,
+        modifier = modifier.padding(bottom = 8.dp),
+    ) { snackbarData ->
+        BroadcastSnackbarContent(snackbarData)
+    }
+}
+
+@Composable
+private fun BroadcastSnackbarContent(snackbarData: SnackbarData) {
+    val visuals = snackbarData.visuals
+    val broadcastVisuals = visuals as? BroadcastSnackbarVisuals
+
+    val containerColor =
+        when (broadcastVisuals?.broadcast?.status) {
+            BroadcastStatus.FAILED -> Color(0xFF7F1D1D) // Dark red
+            BroadcastStatus.PARTIAL -> Color(0xFF78350F) // Dark amber
+            else -> Color(0xFF1E3A5F) // Dark blue (default)
+        }
+
+    val actionLabel =
+        when (broadcastVisuals?.broadcast?.status) {
+            BroadcastStatus.FAILED -> "Retry"
+            else -> "View"
+        }
+
+    Snackbar(
+        action = {
+            snackbarData.visuals.actionLabel?.let {
+                TextButton(onClick = { snackbarData.performAction() }) {
+                    Text(actionLabel)
+                }
+            }
+        },
+        dismissAction =
+            if (visuals.withDismissAction) {
+                {
+                    TextButton(onClick = { snackbarData.dismiss() }) {
+                        Text("Dismiss")
+                    }
+                }
+            } else {
+                null
+            },
+        containerColor = containerColor,
+    ) {
+        Text(visuals.message)
+    }
+}