feat: parse NIP-47 transaction metadata for sender/recipient display

Add NwcTransactionMetadata parser that extracts comment, payer_data,
recipient_data, and nostr zap data from the untyped metadata field.
The transaction list UI now shows the Nostr user profile picture and
name for zap senders/recipients, falls back to payer name/email or
lightning address, and displays comment when it differs from description.

https://claude.ai/code/session_01JFogiwyR4CPVP8cRznqahJ

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

@@ -59,7 +59,10 @@ import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
+import com.vitorpamplona.amethyst.ui.note.UserPicture
+import com.vitorpamplona.amethyst.ui.note.UsernameDisplay
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms.LoadUser
 import com.vitorpamplona.amethyst.ui.stringRes
 import com.vitorpamplona.quartz.nip47WalletConnect.NwcTransaction
 import com.vitorpamplona.quartz.nip47WalletConnect.NwcTransactionType
@@ -143,7 +146,7 @@ fun WalletTransactionsScreen(
                 modifier = Modifier.padding(padding),
             ) {
                 items(transactions) { tx ->
-                    TransactionItem(tx)
+                    TransactionItem(tx, accountViewModel, nav)
                     HorizontalDivider()
                 }
             }
@@ -152,7 +155,11 @@ fun WalletTransactionsScreen(
 }
 
 @Composable
-private fun TransactionItem(tx: NwcTransaction) {
+private fun TransactionItem(
+    tx: NwcTransaction,
+    accountViewModel: AccountViewModel,
+    nav: INav,
+) {
     val isIncoming = tx.type == NwcTransactionType.INCOMING
     val amountSats = (tx.amount ?: 0L) / 1000L
     val formattedAmount =
@@ -169,6 +176,36 @@ private fun TransactionItem(tx: NwcTransaction) {
             } ?: ""
         }
 
+    val parsed = remember(tx.metadata) { tx.parsedMetadata() }
+
+    // For incoming: show who sent it (nostr pubkey or payer name/email)
+    // For outgoing: show who received it (nostr recipient or recipient identifier)
+    val counterpartyPubkeyHex =
+        remember(parsed) {
+            if (isIncoming) parsed?.senderPubkeyHex() else parsed?.recipientPubkeyHex()
+        }
+
+    val counterpartyDisplayName =
+        remember(parsed) {
+            if (isIncoming) {
+                parsed?.senderDisplayName()
+            } else {
+                parsed?.recipientIdentifier()
+            }
+        }
+
+    // Show comment only if it differs from description
+    val commentText =
+        remember(parsed, tx.description) {
+            parsed?.comment?.let { comment ->
+                if (tx.description == null || !comment.equals(tx.description, ignoreCase = true)) {
+                    comment
+                } else {
+                    null
+                }
+            }
+        }
+
     Row(
         modifier =
             Modifier
@@ -176,6 +213,15 @@ private fun TransactionItem(tx: NwcTransaction) {
                 .padding(horizontal = 16.dp, vertical = 12.dp),
         verticalAlignment = Alignment.CenterVertically,
     ) {
+        if (counterpartyPubkeyHex != null) {
+            UserPicture(
+                userHex = counterpartyPubkeyHex,
+                size = 40.dp,
+                accountViewModel = accountViewModel,
+                nav = nav,
+            )
+            Spacer(modifier = Modifier.width(12.dp))
+        } else {
             Icon(
                 imageVector =
                     if (isIncoming) Icons.Filled.ArrowDownward else Icons.Filled.ArrowUpward,
@@ -193,10 +239,21 @@ private fun TransactionItem(tx: NwcTransaction) {
                         MaterialTheme.colorScheme.onSurfaceVariant
                     },
             )
-
             Spacer(modifier = Modifier.width(12.dp))
+        }
 
         Column(modifier = Modifier.weight(1f)) {
+            if (counterpartyPubkeyHex != null) {
+                TransactionUserName(counterpartyPubkeyHex, counterpartyDisplayName, accountViewModel)
+            } else if (counterpartyDisplayName != null) {
+                Text(
+                    text = counterpartyDisplayName,
+                    style = MaterialTheme.typography.bodyMedium,
+                    fontWeight = FontWeight.Medium,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                )
+            } else {
                 Text(
                     text = tx.description ?: if (isIncoming) stringRes(R.string.wallet_incoming) else stringRes(R.string.wallet_outgoing),
                     style = MaterialTheme.typography.bodyMedium,
@@ -204,6 +261,26 @@ private fun TransactionItem(tx: NwcTransaction) {
                     maxLines = 1,
                     overflow = TextOverflow.Ellipsis,
                 )
+            }
+
+            if (commentText != null) {
+                Text(
+                    text = commentText,
+                    style = MaterialTheme.typography.bodySmall,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                )
+            } else if (counterpartyPubkeyHex != null || counterpartyDisplayName != null) {
+                val descOrType = tx.description ?: if (isIncoming) stringRes(R.string.wallet_incoming) else stringRes(R.string.wallet_outgoing)
+                Text(
+                    text = descOrType,
+                    style = MaterialTheme.typography.bodySmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis,
+                )
+            }
+
             Text(
                 text = dateText,
                 style = MaterialTheme.typography.bodySmall,
@@ -224,3 +301,28 @@ private fun TransactionItem(tx: NwcTransaction) {
         )
     }
 }
+
+@Composable
+private fun TransactionUserName(
+    pubkeyHex: String,
+    fallbackName: String?,
+    accountViewModel: AccountViewModel,
+) {
+    LoadUser(baseUserHex = pubkeyHex, accountViewModel = accountViewModel) { user ->
+        if (user != null) {
+            UsernameDisplay(
+                baseUser = user,
+                fontWeight = FontWeight.Medium,
+                accountViewModel = accountViewModel,
+            )
+        } else {
+            Text(
+                text = fallbackName ?: pubkeyHex.take(8) + "...",
+                style = MaterialTheme.typography.bodyMedium,
+                fontWeight = FontWeight.Medium,
+                maxLines = 1,
+                overflow = TextOverflow.Ellipsis,
+            )
+        }
+    }
+}

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip47WalletConnect/NwcTransaction.kt

@@ -63,7 +63,9 @@ class NwcTransaction(
     var settled_at: Long? = null,
     var settle_deadline: Long? = null,
     var metadata: Any? = null,
-)
+) {
+    fun parsedMetadata(): NwcTransactionMetadata? = NwcTransactionMetadata.parse(metadata)
+}
 
 class TlvRecord(
     var type: Long? = null,

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip47WalletConnect/NwcTransactionMetadata.kt

@@ -0,0 +1,106 @@
+/*
+ * 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.quartz.nip47WalletConnect
+
+import com.vitorpamplona.quartz.nip19Bech32.decodePublicKeyAsHexOrNull
+
+class NwcTransactionMetadata(
+    val comment: String?,
+    val payerData: PayerData?,
+    val recipientData: RecipientData?,
+    val nostr: NostrZapData?,
+) {
+    class PayerData(
+        val name: String?,
+        val email: String?,
+        val pubkey: String?,
+    )
+
+    class RecipientData(
+        val identifier: String?,
+    )
+
+    class NostrZapData(
+        val pubkeyHex: String?,
+        val recipientPubkeyHex: String?,
+    )
+
+    fun senderPubkeyHex(): String? = nostr?.pubkeyHex ?: payerData?.pubkey?.let { decodePublicKeyAsHexOrNull(it) }
+
+    fun senderDisplayName(): String? = payerData?.name ?: payerData?.email
+
+    fun recipientIdentifier(): String? = recipientData?.identifier
+
+    fun recipientPubkeyHex(): String? = nostr?.recipientPubkeyHex
+
+    companion object {
+        fun parse(metadata: Any?): NwcTransactionMetadata? {
+            val map = metadata as? Map<*, *> ?: return null
+
+            val comment = map["comment"] as? String
+
+            val payerData = (map["payer_data"] as? Map<*, *>)?.let { pd ->
+                PayerData(
+                    name = pd["name"] as? String,
+                    email = pd["email"] as? String,
+                    pubkey = pd["pubkey"] as? String,
+                )
+            }
+
+            val recipientData = (map["recipient_data"] as? Map<*, *>)?.let { rd ->
+                RecipientData(
+                    identifier = rd["identifier"] as? String,
+                )
+            }
+
+            val nostr = (map["nostr"] as? Map<*, *>)?.let { n ->
+                val rawPubkey = n["pubkey"] as? String
+                val pubkeyHex = rawPubkey?.let { decodePublicKeyAsHexOrNull(it) }
+
+                val tags = n["tags"] as? List<*>
+                val recipientHex = tags?.firstNotNullOfOrNull { tag ->
+                    val tagList = tag as? List<*>
+                    if (tagList != null && tagList.size >= 2 && tagList[0] == "p") {
+                        tagList[1] as? String
+                    } else {
+                        null
+                    }
+                }
+
+                NostrZapData(
+                    pubkeyHex = pubkeyHex,
+                    recipientPubkeyHex = recipientHex,
+                )
+            }
+
+            if (comment == null && payerData == null && recipientData == null && nostr == null) {
+                return null
+            }
+
+            return NwcTransactionMetadata(
+                comment = comment,
+                payerData = payerData,
+                recipientData = recipientData,
+                nostr = nostr,
+            )
+        }
+    }
+}

quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/nip47WalletConnect/AlbyInteropTest.kt

@@ -500,6 +500,78 @@ class AlbyInteropTest {
         assertNotNull(response.result?.metadata)
     }
 
+    @Test
+    fun testMetadataParserComment() {
+        val json =
+            """{"result_type":"lookup_invoice","result":{"type":"incoming","state":"settled","invoice":"lnbc...","payment_hash":"hash","amount":5000,"created_at":1000,"settled_at":2000,"metadata":{"comment":"Great post!"}}}"""
+        val response = OptimizedJsonMapper.fromJsonTo<Response>(json)
+        assertIs<LookupInvoiceSuccessResponse>(response)
+        val parsed = response.result?.parsedMetadata()
+        assertNotNull(parsed)
+        assertEquals("Great post!", parsed.comment)
+        assertNull(parsed.payerData)
+        assertNull(parsed.nostr)
+    }
+
+    @Test
+    fun testMetadataParserPayerData() {
+        val json =
+            """{"result_type":"lookup_invoice","result":{"type":"incoming","state":"settled","invoice":"lnbc...","payment_hash":"hash","amount":5000,"created_at":1000,"settled_at":2000,"metadata":{"payer_data":{"name":"Alice","email":"alice@example.com","pubkey":"abc123"}}}}"""
+        val response = OptimizedJsonMapper.fromJsonTo<Response>(json)
+        assertIs<LookupInvoiceSuccessResponse>(response)
+        val parsed = response.result?.parsedMetadata()
+        assertNotNull(parsed)
+        assertEquals("Alice", parsed.payerData?.name)
+        assertEquals("alice@example.com", parsed.payerData?.email)
+        assertEquals("abc123", parsed.payerData?.pubkey)
+        assertEquals("Alice", parsed.senderDisplayName())
+    }
+
+    @Test
+    fun testMetadataParserNostrZap() {
+        val senderHex = "7e7e9c42a91bfef19fa929e5fda1b72e0ebc1a4c1141673e2794234d86addf4e"
+        val recipientHex = "460c25e682fda7832b52d1f22d3d22b3176d972f60dcdc3212ed8c92ef85065c"
+        val json =
+            """{"result_type":"lookup_invoice","result":{"type":"incoming","state":"settled","invoice":"lnbc...","payment_hash":"hash","amount":21000,"created_at":1000,"settled_at":2000,"metadata":{"nostr":{"pubkey":"$senderHex","tags":[["p","$recipientHex"],["amount","21000"]]}}}}"""
+        val response = OptimizedJsonMapper.fromJsonTo<Response>(json)
+        assertIs<LookupInvoiceSuccessResponse>(response)
+        val parsed = response.result?.parsedMetadata()
+        assertNotNull(parsed)
+        assertEquals(senderHex, parsed.senderPubkeyHex())
+        assertEquals(recipientHex, parsed.recipientPubkeyHex())
+    }
+
+    @Test
+    fun testMetadataParserRecipientData() {
+        val json =
+            """{"result_type":"lookup_invoice","result":{"type":"outgoing","state":"settled","invoice":"lnbc...","payment_hash":"hash","amount":5000,"created_at":1000,"settled_at":2000,"metadata":{"recipient_data":{"identifier":"alice@getalby.com"}}}}"""
+        val response = OptimizedJsonMapper.fromJsonTo<Response>(json)
+        assertIs<LookupInvoiceSuccessResponse>(response)
+        val parsed = response.result?.parsedMetadata()
+        assertNotNull(parsed)
+        assertEquals("alice@getalby.com", parsed.recipientIdentifier())
+    }
+
+    @Test
+    fun testMetadataParserNullForSimpleMetadata() {
+        val json =
+            """{"result_type":"lookup_invoice","result":{"type":"incoming","state":"settled","invoice":"lnbc...","payment_hash":"hash","amount":5000,"created_at":1000,"settled_at":2000,"metadata":{"a":123}}}"""
+        val response = OptimizedJsonMapper.fromJsonTo<Response>(json)
+        assertIs<LookupInvoiceSuccessResponse>(response)
+        val parsed = response.result?.parsedMetadata()
+        assertNull(parsed)
+    }
+
+    @Test
+    fun testMetadataParserNullMetadata() {
+        val json =
+            """{"result_type":"lookup_invoice","result":{"type":"incoming","state":"settled","invoice":"lnbc...","payment_hash":"hash","amount":5000,"created_at":1000,"settled_at":2000}}"""
+        val response = OptimizedJsonMapper.fromJsonTo<Response>(json)
+        assertIs<LookupInvoiceSuccessResponse>(response)
+        val parsed = response.result?.parsedMetadata()
+        assertNull(parsed)
+    }
+
     @Test
     fun testJsSdkGetInfoWithAllMethods() {
         // JS SDK advertises all 13 single methods + notifications