feat(amethyst): NIP-BC onchain zap receive + display

Phase C of the onchain zaps plan (amethyst/plans/2026-05-14-onchain-zaps.md).
Plumbs the Quartz receive foundation from Phase A.1 into the Android app so
incoming kind 8333 zaps show up in note totals and the wallet screen.

Subscription / fetch path (kind 8333 rides existing zap filters, no new
assemblers per the plan):
- FilterRepliesAndReactionsToNotes: OnchainZapEvent.KIND in
  RepliesAndReactionsKinds (#e on notes)
- FilterUserProfileZapReceived: OnchainZapEvent.KIND in
  UserProfileZapReceiverKinds (#p on profiles)
- UserProfileZapsViewModel: kinds = LnZap + Onchain inline
- FilterNotificationsToPubkey: OnchainZapEvent.KIND in SummaryKinds
- NotificationFeedFilter / NotificationDispatcher: kind 8333 in
  NOTIFICATION_KINDS
- FilterMessagesToLiveStream / FilterGoalForLiveActivity: kind 8333
  alongside 9735

Display path (Note.zapsAmount fold-in — no UI changes needed downstream):
- commons/model/Note.kt: new `onchainZaps: Map<String, OnchainZapAmount>`
  (keyed by txid for `(txid, target)` dedup); `addOnchainZap(txid, sats,
  confirmed)` mutator; `updateZapTotal` now also sums confirmed onchain
  sats into `zapsAmount`. Pending entries are tracked but excluded from
  the aggregate total per the NIP-BC spec.
- commons/model/OnchainZapAmount.kt: new data class for per-tx state.
- LocalCache: new `onchainBackend: OnchainBackend?` slot; new
  `consume(OnchainZapEvent)` handler that runs the same sig-verify and
  computeReplyTo pipeline as `consume(LnZapEvent)`, then kicks off async
  verification on `applicationIOScope`. Self-zaps are rejected
  synchronously per the spec. Verification failures, mempool-only txs,
  and confirmed txs all route to `Note.addOnchainZap` with the correct
  flag. Without a backend wired, events are still cached (so subscriptions
  see them) but skip the total contribution.
- LocalCache.computeReplyTo: new `is OnchainZapEvent ->` branch that
  enumerates `e`/`a` targets — profile-only zaps return an empty list and
  flow through profile zap queries instead.

Wallet UI:
- Wallet screen now renders a "Bitcoin" Card above the existing NIP-47
  NWC wallet list. Single card (one onchain wallet per Nostr identity,
  derived from the pubkey). Shows the bc1p taproot address + Copy button.
  Balance, recent incoming zaps, and tap-to-detail come in later phases.

Settings + wiring:
- AccountSettings: new `onchainEsploraEndpoint: MutableStateFlow<String>`,
  default mempool.space, plumbed for a future settings UI.
- AppModules: builds a single shared `EsploraBackend` at app init using
  the role-based money-flavored OkHttp client (Tor-aware), installs it on
  `LocalCache.onchainBackend` so verification can run.

Secp256k1Instance: new `pubKeyTweakAdd` was added in Phase A.1.

No PSBT, no signing, no broadcasting — send-side (Phase A.2 + D) is still
pending.

amethyst/src/main/java/com/vitorpamplona/amethyst/AppModules.kt

@@ -28,6 +28,7 @@ import com.vitorpamplona.amethyst.commons.model.NoteState
 import com.vitorpamplona.amethyst.commons.robohash.CachedRobohash
 import com.vitorpamplona.amethyst.commons.tor.TorSettings
 import com.vitorpamplona.amethyst.model.Account
+import com.vitorpamplona.amethyst.model.DEFAULT_ESPLORA_ENDPOINT
 import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.model.UiSettings
 import com.vitorpamplona.amethyst.model.accountsCache.AccountCacheState
@@ -99,6 +100,7 @@ import com.vitorpamplona.quartz.nip05DnsIdentifiers.namecoin.ElectrumXClient
 import com.vitorpamplona.quartz.nip05DnsIdentifiers.namecoin.NamecoinNameResolver
 import com.vitorpamplona.quartz.nip05DnsIdentifiers.namecoin.TOR_ELECTRUMX_SERVERS
 import com.vitorpamplona.quartz.nipB7Blossom.BlossomServersEvent
+import com.vitorpamplona.quartz.nipBCOnchainZaps.chain.EsploraBackend
 import com.vitorpamplona.quartz.utils.Log
 import kotlinx.coroutines.CoroutineExceptionHandler
 import kotlinx.coroutines.CoroutineScope
@@ -330,6 +332,19 @@ class AppModules(
     // Caches all events in Memory
     val cache: LocalCache = LocalCache
 
+    // NIP-BC onchain zap verification backend. Wired up once at app init so
+    // LocalCache.consume(OnchainZapEvent) can sum the on-chain output values
+    // that pay the recipient's derived Taproot address. Endpoint is currently
+    // a fixed default; per-account override (AccountSettings.onchainEsploraEndpoint)
+    // is plumbed for a future Settings UI.
+    init {
+        cache.onchainBackend =
+            EsploraBackend(
+                baseUrl = { DEFAULT_ESPLORA_ENDPOINT },
+                client = roleBasedHttpClientBuilder.okHttpClientForMoney(DEFAULT_ESPLORA_ENDPOINT),
+            )
+    }
+
     // Provides a relay pool
     val client: INostrClient = NostrClient(websocketBuilder, applicationIOScope)
 

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

@@ -141,6 +141,9 @@ sealed class TopFilter(
     ) : TopFilter("InterestSet/${address.toValue()}")
 }
 
+/** Default Esplora-compatible Bitcoin chain backend for NIP-BC onchain zaps. */
+const val DEFAULT_ESPLORA_ENDPOINT = "https://mempool.space/api"
+
 @Stable
 class AccountSettings(
     val keyPair: KeyPair,
@@ -176,6 +179,8 @@ class AccountSettings(
     val defaultFollowPacksFollowList: MutableStateFlow<TopFilter> = MutableStateFlow(TopFilter.Global),
     val nwcWallets: MutableStateFlow<List<NwcWalletEntryNorm>> = MutableStateFlow(emptyList()),
     val defaultNwcWalletId: MutableStateFlow<String?> = MutableStateFlow(null),
+    // NIP-BC onchain zap configuration.
+    val onchainEsploraEndpoint: MutableStateFlow<String> = MutableStateFlow(DEFAULT_ESPLORA_ENDPOINT),
     var hideDeleteRequestDialog: Boolean = false,
     var hideBlockAlertDialog: Boolean = false,
     var hideNIP17WarningDialog: Boolean = false,

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

@@ -240,6 +240,10 @@ import com.vitorpamplona.quartz.nipACWebRtcCalls.events.CallRejectEvent
 import com.vitorpamplona.quartz.nipACWebRtcCalls.events.CallRenegotiateEvent
 import com.vitorpamplona.quartz.nipB0WebBookmarks.WebBookmarkEvent
 import com.vitorpamplona.quartz.nipB7Blossom.BlossomServersEvent
+import com.vitorpamplona.quartz.nipBCOnchainZaps.chain.OnchainBackend
+import com.vitorpamplona.quartz.nipBCOnchainZaps.verify.OnchainZapVerifier
+import com.vitorpamplona.quartz.nipBCOnchainZaps.verify.VerifiedOnchainZap
+import com.vitorpamplona.quartz.nipBCOnchainZaps.zap.OnchainZapEvent
 import com.vitorpamplona.quartz.nipC0CodeSnippets.CodeSnippetEvent
 import com.vitorpamplona.quartz.nipC7Chats.ChatEvent
 import com.vitorpamplona.quartz.utils.DualCase
@@ -286,6 +290,15 @@ object LocalCache : ILocalCache, ICacheProvider {
 
     val paymentTracker = NwcPaymentTracker()
 
+    /**
+     * Bitcoin chain backend used by [consume]`(OnchainZapEvent)` to verify NIP-BC zaps
+     * against the actual on-chain transaction. `null` disables verification (incoming
+     * onchain zap events still get cached, but no `Note.zapsAmount` contribution).
+     * Set during account init.
+     */
+    @Volatile
+    var onchainBackend: OnchainBackend? = null
+
     val relayHints = HintIndexer()
 
     val deletionIndex = DeletionIndex()
@@ -904,6 +917,18 @@ object LocalCache : ILocalCache, ICacheProvider {
                     (event.zapRequest?.taggedAddresses()?.map { getOrCreateAddressableNote(it) } ?: emptyList())
             }
 
+            is OnchainZapEvent -> {
+                // NIP-BC zaps can target an event id (e), an addressable event (a),
+                // or just the recipient profile (p). Profile-only zaps have no
+                // Note target and are surfaced through profile zap queries.
+                buildList {
+                    event.zappedEvent()?.let { checkGetOrCreateNote(it)?.let { add(it) } }
+                    event.zappedAddress()?.let { coord ->
+                        Address.parse(coord)?.let { add(getOrCreateAddressableNote(it)) }
+                    }
+                }
+            }
+
             is LnZapRequestEvent -> {
                 event.zappedPost().mapNotNull { checkGetOrCreateNote(it) } +
                     event.taggedAddresses().map { getOrCreateAddressableNote(it) }
@@ -1712,6 +1737,60 @@ object LocalCache : ILocalCache, ICacheProvider {
         return false
     }
 
+    fun consume(
+        event: OnchainZapEvent,
+        relay: NormalizedRelayUrl?,
+        wasVerified: Boolean,
+    ): Boolean {
+        val note = getOrCreateNote(event.id)
+        if (note.event != null) return false
+
+        if (!(wasVerified || justVerify(event))) return false
+
+        // Anti-spoofing: NIP-BC requires rejecting self-zaps.
+        val recipient = event.recipient() ?: return false
+        if (event.pubKey.equals(recipient, ignoreCase = true)) return false
+
+        val author = getOrCreateUser(event.pubKey)
+        val repliesTo = computeReplyTo(event)
+        note.loadEvent(event, author, repliesTo)
+        refreshNewNoteObservers(note)
+
+        // Verification needs a chain backend. Without one (e.g. before Account
+        // wires its EsploraBackend) the event is still cached so subscriptions
+        // and profile zap views see it, but it can't contribute to Note totals.
+        val backend = onchainBackend ?: return true
+        val verifier = OnchainZapVerifier(backend)
+
+        Amethyst.instance.applicationIOScope.launch {
+            try {
+                when (val result = verifier.verify(event)) {
+                    is VerifiedOnchainZap.Confirmed -> {
+                        repliesTo.forEach {
+                            it.addOnchainZap(result.txid, result.verifiedSats, confirmed = true)
+                        }
+                    }
+
+                    is VerifiedOnchainZap.Pending -> {
+                        repliesTo.forEach {
+                            it.addOnchainZap(result.txid, result.verifiedSats, confirmed = false)
+                        }
+                    }
+
+                    is VerifiedOnchainZap.Rejected -> {
+                        Log.d("OnchainZap") {
+                            "rejected ${result.txid}: ${result.reason}"
+                        }
+                    }
+                }
+            } catch (t: Throwable) {
+                Log.w("OnchainZap", "verification failed for ${event.id}", t)
+            }
+        }
+
+        return true
+    }
+
     private fun attachZapToLiveActivityChannel(
         event: LnZapEvent,
         note: Note,
@@ -3142,6 +3221,10 @@ object LocalCache : ILocalCache, ICacheProvider {
                     consume(event, relay, wasVerified)
                 }
 
+                is OnchainZapEvent -> {
+                    consume(event, relay, wasVerified)
+                }
+
                 is NIP90StatusEvent -> {
                     consumeRegularEvent(event, relay, wasVerified)
                 }

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

@@ -51,6 +51,7 @@ import com.vitorpamplona.quartz.nip71Video.VideoVerticalEvent
 import com.vitorpamplona.quartz.nip84Highlights.HighlightEvent
 import com.vitorpamplona.quartz.nip88Polls.poll.PollEvent
 import com.vitorpamplona.quartz.nipACWebRtcCalls.events.CallOfferEvent
+import com.vitorpamplona.quartz.nipBCOnchainZaps.zap.OnchainZapEvent
 import com.vitorpamplona.quartz.nipC7Chats.ChatEvent
 import com.vitorpamplona.quartz.utils.Log
 import com.vitorpamplona.quartz.utils.TimeUtils
@@ -96,6 +97,7 @@ class NotificationDispatcher(
                 // Direct-arrival
                 PrivateDmEvent.KIND,
                 LnZapEvent.KIND,
+                OnchainZapEvent.KIND,
                 ReactionEvent.KIND,
                 TextNoteEvent.KIND,
                 CommentEvent.KIND,

amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/reqCommand/account/nip01Notifications/FilterNotificationsToPubkey.kt

@@ -54,6 +54,7 @@ import com.vitorpamplona.quartz.nip84Highlights.HighlightEvent
 import com.vitorpamplona.quartz.nip88Polls.poll.PollEvent
 import com.vitorpamplona.quartz.nip88Polls.response.PollResponseEvent
 import com.vitorpamplona.quartz.nipA4PublicMessages.PublicMessageEvent
+import com.vitorpamplona.quartz.nipBCOnchainZaps.zap.OnchainZapEvent
 
 val SummaryKinds =
     listOf(
@@ -62,6 +63,7 @@ val SummaryKinds =
         RepostEvent.KIND,
         GenericRepostEvent.KIND,
         LnZapEvent.KIND,
+        OnchainZapEvent.KIND,
     )
 
 val NotificationsPerKeyKinds =

amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/reqCommand/event/watchers/FilterRepliesAndReactionsToNotes.kt

@@ -43,6 +43,7 @@ import com.vitorpamplona.quartz.nip57Zaps.LnZapEvent
 import com.vitorpamplona.quartz.nip88Polls.response.PollResponseEvent
 import com.vitorpamplona.quartz.nip90Dvms.contentDiscoveryResponse.NIP90ContentDiscoveryResponseEvent
 import com.vitorpamplona.quartz.nip90Dvms.status.NIP90StatusEvent
+import com.vitorpamplona.quartz.nipBCOnchainZaps.zap.OnchainZapEvent
 import com.vitorpamplona.quartz.utils.mapOfSet
 
 val RepliesAndReactionsKinds =
@@ -53,6 +54,7 @@ val RepliesAndReactionsKinds =
         GenericRepostEvent.KIND,
         ReportEvent.KIND,
         LnZapEvent.KIND,
+        OnchainZapEvent.KIND,
         OtsEvent.KIND,
         TextNoteModificationEvent.KIND,
         CommentEvent.KIND,

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

@@ -26,6 +26,7 @@ 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
+import com.vitorpamplona.quartz.nipBCOnchainZaps.zap.OnchainZapEvent
 
 /**
  * Fetches the NIP-75 zap goal referenced by a live stream plus the zap receipts
@@ -55,7 +56,7 @@ fun filterGoalForLiveActivities(
                 relay = relay,
                 filter =
                     Filter(
-                        kinds = listOf(LnZapEvent.KIND),
+                        kinds = listOf(LnZapEvent.KIND, OnchainZapEvent.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/datasource/subassemblies/FilterMessagesToLiveStream.kt

@@ -28,6 +28,7 @@ import com.vitorpamplona.quartz.nip53LiveActivities.chat.LiveActivitiesChatMessa
 import com.vitorpamplona.quartz.nip53LiveActivities.clip.LiveActivitiesClipEvent
 import com.vitorpamplona.quartz.nip53LiveActivities.raid.LiveActivitiesRaidEvent
 import com.vitorpamplona.quartz.nip57Zaps.LnZapEvent
+import com.vitorpamplona.quartz.nipBCOnchainZaps.zap.OnchainZapEvent
 
 fun filterMessagesToLiveActivities(
     channel: LiveActivitiesChannel,
@@ -44,6 +45,7 @@ fun filterMessagesToLiveActivities(
                             LiveActivitiesRaidEvent.KIND,
                             LiveActivitiesClipEvent.KIND,
                             LnZapEvent.KIND,
+                            OnchainZapEvent.KIND,
                         ),
                     tags = mapOf("a" to listOfNotNull(channel.address.toValue())),
                     limit = 200,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/notifications/dal/NotificationFeedFilter.kt

@@ -74,6 +74,7 @@ import com.vitorpamplona.quartz.nip99Classifieds.ClassifiedsEvent
 import com.vitorpamplona.quartz.nipA0VoiceMessages.VoiceEvent
 import com.vitorpamplona.quartz.nipA0VoiceMessages.VoiceReplyEvent
 import com.vitorpamplona.quartz.nipA4PublicMessages.PublicMessageEvent
+import com.vitorpamplona.quartz.nipBCOnchainZaps.zap.OnchainZapEvent
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 
@@ -121,6 +122,7 @@ class NotificationFeedFilter(
                 ReactionEvent.KIND,
                 RepostEvent.KIND,
                 LnZapEvent.KIND,
+                OnchainZapEvent.KIND,
                 LiveActivitiesChatMessageEvent.KIND,
                 PictureEvent.KIND,
                 PollEvent.KIND,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/profile/datasource/FilterUserProfileZapReceived.kt

@@ -26,8 +26,9 @@ 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.nipBCOnchainZaps.zap.OnchainZapEvent
 
-val UserProfileZapReceiverKinds = listOf(LnZapEvent.KIND)
+val UserProfileZapReceiverKinds = listOf(LnZapEvent.KIND, OnchainZapEvent.KIND)
 
 fun filterUserProfileZapsReceived(
     user: User,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/profile/zaps/dal/UserProfileZapsViewModel.kt

@@ -30,6 +30,7 @@ import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.model.User
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip57Zaps.LnZapEvent
+import com.vitorpamplona.quartz.nipBCOnchainZaps.zap.OnchainZapEvent
 import com.vitorpamplona.quartz.utils.BigDecimal
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.SharingStarted
@@ -52,7 +53,7 @@ class UserProfileZapsViewModel(
 ) : ViewModel() {
     val zapsToUser =
         Filter(
-            kinds = listOf(LnZapEvent.KIND),
+            kinds = listOf(LnZapEvent.KIND, OnchainZapEvent.KIND),
             tags = mapOf("p" to listOf(user.pubkeyHex)),
         )
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/wallet/OnchainSection.kt

@@ -0,0 +1,123 @@
+/*
+ * 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.wallet
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Card
+import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalClipboard
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.ui.components.util.setText
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.quartz.nipBCOnchainZaps.taproot.TaprootAddress
+import kotlinx.coroutines.launch
+
+/**
+ * "Bitcoin" section card on the wallet screen, shown above the lightning NWC
+ * wallet list. Every account has exactly one Taproot address (derived from
+ * its Nostr pubkey via NIP-BC / BIP-341), so this is always a single card —
+ * not a list.
+ *
+ * Phase C scope: derive + display + copy address. Balance, recent zaps, send,
+ * and tap-to-detail UI come in later phases.
+ */
+@Composable
+fun OnchainSection(
+    accountViewModel: AccountViewModel,
+    modifier: Modifier = Modifier,
+) {
+    val pubKey = accountViewModel.account.signer.pubKey
+
+    // Cache the derived address — bech32m + tap-tweak is cheap but pubkey doesn't
+    // change for the lifetime of the screen.
+    val address =
+        remember(pubKey) {
+            runCatching { TaprootAddress.fromPubKey(pubKey) }.getOrNull()
+        }
+
+    Card(
+        modifier = modifier.fillMaxWidth(),
+        elevation = CardDefaults.cardElevation(defaultElevation = 1.dp),
+    ) {
+        Column(
+            modifier = Modifier.padding(16.dp),
+            verticalArrangement = Arrangement.spacedBy(8.dp),
+        ) {
+            Text(
+                text = "Bitcoin",
+                style = MaterialTheme.typography.titleMedium,
+                fontWeight = FontWeight.SemiBold,
+            )
+            if (address == null) {
+                Text(
+                    text = "Address derivation unavailable for this account.",
+                    style = MaterialTheme.typography.bodySmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+            } else {
+                Text(
+                    text = "Your Taproot address",
+                    style = MaterialTheme.typography.labelMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+                Text(
+                    text = address,
+                    style = MaterialTheme.typography.bodyMedium,
+                    maxLines = 2,
+                    overflow = TextOverflow.Ellipsis,
+                )
+                CopyAddressRow(address)
+            }
+        }
+    }
+}
+
+@Composable
+private fun CopyAddressRow(address: String) {
+    val clipboard = LocalClipboard.current
+    val scope = rememberCoroutineScope()
+
+    Row(
+        modifier = Modifier.fillMaxWidth(),
+        horizontalArrangement = Arrangement.End,
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        OutlinedButton(onClick = {
+            scope.launch { clipboard.setText(address) }
+        }) {
+            Text("Copy address")
+        }
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/wallet/WalletScreen.kt

@@ -124,18 +124,24 @@ fun WalletScreen(
             }
         },
     ) { padding ->
-        if (!hasWallet) {
+        Column(modifier = Modifier.padding(padding)) {
-            NoWalletSetup(
+            OnchainSection(
-                modifier = Modifier.padding(padding),
+                accountViewModel = accountViewModel,
-                nav = nav,
+                modifier = Modifier.padding(horizontal = 16.dp, vertical = 8.dp),
-            )
-        } else {
-            MultiWalletHomeContent(
-                walletViewModel = walletViewModel,
-                modifier = Modifier.padding(padding),
-                listState = listState,
-                nav = nav,
             )
+            if (!hasWallet) {
+                NoWalletSetup(
+                    modifier = Modifier,
+                    nav = nav,
+                )
+            } else {
+                MultiWalletHomeContent(
+                    walletViewModel = walletViewModel,
+                    modifier = Modifier,
+                    listState = listState,
+                    nav = nav,
+                )
+            }
         }
     }
 }

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/Note.kt

@@ -156,6 +156,15 @@ open class Note(
 
     var zapsAmount: BigDecimal = BigDecimal.ZERO
 
+    /**
+     * NIP-BC verified onchain zaps targeting this note.
+     * Key: Bitcoin txid (lowercase 64-char hex). Value: verified satoshis paid to the recipient
+     * (NOT the sender-claimed amount). Confirmed and pending entries live here together;
+     * `updateZapTotal` only counts confirmed amounts.
+     */
+    var onchainZaps = mapOf<String, OnchainZapAmount>()
+        private set
+
     var zapPayments = mapOf<Note, Note?>()
         private set
 
@@ -318,6 +327,7 @@ open class Note(
         boosts = listOf()
         reports = mapOf()
         zaps = mapOf()
+        onchainZaps = mapOf()
         zapPayments = mapOf()
         zapsAmount = BigDecimal.ZERO
         relays = listOf()
@@ -417,6 +427,36 @@ open class Note(
         }
     }
 
+    @Synchronized
+    private fun innerAddOnchainZap(
+        txid: String,
+        amount: OnchainZapAmount,
+    ): Boolean {
+        val existing = onchainZaps[txid]
+        // Allow upgrading pending → confirmed but never reduce already-stored confirmations.
+        if (existing != null && existing.confirmed && !amount.confirmed) return false
+        if (existing == amount) return false
+        onchainZaps = onchainZaps + Pair(txid, amount)
+        return true
+    }
+
+    /**
+     * Register a NIP-BC verified onchain zap targeting this note. `verifiedSats` MUST come
+     * from on-chain verification (sum of outputs paying the recipient's derived Taproot
+     * address), not the sender-claimed `amount` tag.
+     */
+    fun addOnchainZap(
+        txid: String,
+        verifiedSats: Long,
+        confirmed: Boolean,
+    ) {
+        val inserted = innerAddOnchainZap(txid, OnchainZapAmount(verifiedSats, confirmed))
+        if (inserted) {
+            updateZapTotal()
+            flowSet?.zaps?.invalidateData()
+        }
+    }
+
     @Synchronized
     private fun innerAddZapPayment(
         zapPaymentRequest: Note,
@@ -629,6 +669,14 @@ open class Note(
             }
         }
 
+        // NIP-BC onchain zaps — verified amounts only, confirmed only.
+        // Pending/unconfirmed entries are tracked but excluded from the total per spec.
+        onchainZaps.values.forEach { entry ->
+            if (entry.confirmed) {
+                sumOfAmounts += BigDecimal.valueOf(entry.verifiedSats)
+            }
+        }
+
         zapsAmount = sumOfAmounts
     }
 

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/OnchainZapAmount.kt

@@ -0,0 +1,40 @@
+/*
+ * 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.commons.model
+
+import androidx.compose.runtime.Immutable
+
+/**
+ * Per-(note, txid) verified NIP-BC onchain zap state.
+ *
+ * @property verifiedSats Satoshis verified to have paid the recipient's derived Taproot
+ *                        address on chain. NEVER the sender-claimed `amount` tag.
+ * @property confirmed True when the transaction has at least one confirmation. Unconfirmed
+ *                     zaps are tracked but excluded from aggregate totals per the NIP-BC
+ *                     spec ("Unconfirmed transactions MAY be displayed as pending...
+ *                     SHOULD either exclude them from aggregate totals or clearly label
+ *                     them as pending").
+ */
+@Immutable
+data class OnchainZapAmount(
+    val verifiedSats: Long,
+    val confirmed: Boolean,
+)