feat: share an order through the system share sheet

lib/features/order/screens/take_order_screen.dart

@@ -108,6 +108,8 @@ class _TakeOrderScreenState extends ConsumerState<TakeOrderScreen> {
                   const SizedBox(height: 16),
                   _buildOrderId(context),
                   const SizedBox(height: 16),
+                  _buildOrderLink(context),
+                  const SizedBox(height: 16),
                   _buildCreatorReputation(order),
                   const SizedBox(height: 24),
                   if (order.status == Status.pending)
@@ -211,6 +213,10 @@ class _TakeOrderScreenState extends ConsumerState<TakeOrderScreen> {
     return OrderIdCard(orderId: widget.orderId);
   }
 
+  Widget _buildOrderLink(BuildContext context) {
+    return OrderShareLinkCard(orderId: widget.orderId);
+  }
+
   Widget _buildPaymentMethod(BuildContext context, NostrEvent order) {
     final methods = order.paymentMethods.isNotEmpty
         ? order.paymentMethods.join(', ')

lib/features/trades/screens/trade_detail_screen.dart

@@ -76,6 +76,12 @@ class TradeDetailScreen extends ConsumerWidget {
                 const SizedBox(height: 16),
                 _buildOrderId(context),
                 const SizedBox(height: 16),
+                // Only while the order can still be taken: sharing a link to a
+                // trade already under way is of no use to whoever opens it.
+                if (isPending) ...[
+                  OrderShareLinkCard(orderId: orderId),
+                  const SizedBox(height: 16),
+                ],
                 // For pending orders created by the user, show creator's reputation
                 if (isPending && isCreator) ...[
                   // TODO: Change this to use `orderPayload` after Order model is updated

lib/l10n/intl_de.arb

@@ -313,6 +313,7 @@
     "paymentMethodLabel": "Zahlungsmethode",
     "createdOnLabel": "Erstellt am",
     "orderIdLabel": "Order-ID",
+    "orderLinkLabel": "Order-Link",
     "creatorReputationLabel": "Reputation des Erstellers",
     "buyerReputationLabel": "Reputation des Käufers",
     "sellerReputationLabel": "Reputation des Verkäufers",
@@ -369,6 +370,16 @@
     "cooperativeCancelDialogMessage": "Wenn du bestätigst, leitest du eine kooperative Stornierung mit deinem Handelspartner ein.",
     "acceptCancelDialogMessage": "Wenn du bestätigst, akzeptierst du die von deinem Handelspartner eingeleitete kooperative Stornierung.",
     "orderIdCopiedMessage": "Order-ID in die Zwischenablage kopiert",
+    "orderLinkCopiedMessage": "Order-Link in die Zwischenablage kopiert",
+    "orderShareMessage": "Nimm diese Order auf Mostro: {link}",
+    "@orderShareMessage": {
+        "placeholders": {
+            "link": {
+                "type": "String"
+            }
+        }
+    },
+    "failedToShareOrder": "Order konnte nicht geteilt werden. Versuche stattdessen zu kopieren.",
     "disputeTradeDialogTitle": "Streitfall starten",
     "disputeTradeDialogContent": "Du bist dabei, einen Streitfall mit deinem Handelspartner zu eröffnen. Möchtest du fortfahren?",
     "disputeCreatedSuccessfully": "Streitfall erfolgreich erstellt",

lib/l10n/intl_en.arb

@@ -313,6 +313,7 @@
     "paymentMethodLabel": "Payment Method",
     "createdOnLabel": "Created On",
     "orderIdLabel": "Order ID",
+    "orderLinkLabel": "Order link",
     "creatorReputationLabel": "Creator's Reputation",
     "buyerReputationLabel": "Buyer's Reputation",
     "sellerReputationLabel": "Seller's Reputation",
@@ -369,6 +370,16 @@
     "cooperativeCancelDialogMessage": "If you confirm, you will start a cooperative cancellation with your counterparty.",
     "acceptCancelDialogMessage": "If you confirm, you will accept the cooperative cancellation initiated by your counterparty.",
     "orderIdCopiedMessage": "Order ID copied to clipboard",
+    "orderLinkCopiedMessage": "Order link copied to clipboard",
+    "orderShareMessage": "Take this order on Mostro: {link}",
+    "@orderShareMessage": {
+        "placeholders": {
+            "link": {
+                "type": "String"
+            }
+        }
+    },
+    "failedToShareOrder": "Failed to share order. Please try copying instead.",
     "disputeTradeDialogTitle": "Start Dispute",
     "disputeTradeDialogContent": "You are about to start a dispute with your counterparty. Do you want to continue?",
     "disputeCreatedSuccessfully": "Dispute created successfully",

lib/l10n/intl_es.arb

@@ -749,6 +749,7 @@
     "paymentMethodLabel": "Método de Pago",
     "createdOnLabel": "Creado el",
     "orderIdLabel": "ID de la orden",
+    "orderLinkLabel": "Enlace de la orden",
     "creatorReputationLabel": "Reputación del Creador",
     "buyerReputationLabel": "Reputación del Comprador",
     "sellerReputationLabel": "Reputación del Vendedor",
@@ -805,6 +806,16 @@
     "cooperativeCancelDialogMessage": "Si confirmas, iniciarás una cancelación cooperativa con tu contraparte.",
     "acceptCancelDialogMessage": "Si confirmas, aceptarás la cancelación cooperativa iniciada por tu contraparte.",
     "orderIdCopiedMessage": "ID de orden copiado al portapapeles",
+    "orderLinkCopiedMessage": "Enlace de la orden copiado al portapapeles",
+    "orderShareMessage": "Toma esta orden en Mostro: {link}",
+    "@orderShareMessage": {
+        "placeholders": {
+            "link": {
+                "type": "String"
+            }
+        }
+    },
+    "failedToShareOrder": "No se pudo compartir la orden. Prueba a copiarla.",
     "disputeTradeDialogTitle": "Iniciar Disputa",
     "disputeTradeDialogContent": "Estás a punto de iniciar una disputa con tu contraparte. ¿Deseas continuar?",
     "disputeCreatedSuccessfully": "Disputa creada exitosamente",

lib/l10n/intl_fr.arb

@@ -313,6 +313,7 @@
     "paymentMethodLabel": "Méthode de paiement",
     "createdOnLabel": "Créé le",
     "orderIdLabel": "ID de commande",
+    "orderLinkLabel": "Lien de commande",
     "creatorReputationLabel": "Réputation du créateur",
     "buyerReputationLabel": "Réputation de l'acheteur",
     "sellerReputationLabel": "Réputation du vendeur",
@@ -369,6 +370,16 @@
     "cooperativeCancelDialogMessage": "Si vous confirmez, vous allez initier une annulation coopérative avec votre contrepartie.",
     "acceptCancelDialogMessage": "Si vous confirmez, vous allez accepter l'annulation coopérative initiée par votre contrepartie.",
     "orderIdCopiedMessage": "ID de commande copié dans le presse-papiers",
+    "orderLinkCopiedMessage": "Lien de commande copié dans le presse-papiers",
+    "orderShareMessage": "Prends cet ordre sur Mostro : {link}",
+    "@orderShareMessage": {
+        "placeholders": {
+            "link": {
+                "type": "String"
+            }
+        }
+    },
+    "failedToShareOrder": "Impossible de partager l'ordre. Essaie de le copier.",
     "disputeTradeDialogTitle": "Démarrer un différend",
     "disputeTradeDialogContent": "Vous êtes sur le point de démarrer un différend avec votre contrepartie. Voulez-vous continuer ?",
     "disputeCreatedSuccessfully": "Différend créé avec succès",

lib/l10n/intl_it.arb

@@ -822,6 +822,7 @@
     "paymentMethodLabel": "Metodo di Pagamento",
     "createdOnLabel": "Creato il",
     "orderIdLabel": "ID Ordine",
+    "orderLinkLabel": "Link Ordine",
     "creatorReputationLabel": "Reputazione del Creatore",
     "buyerReputationLabel": "Reputazione dell'Acquirente",
     "sellerReputationLabel": "Reputazione del Venditore",
@@ -878,6 +879,16 @@
     "cooperativeCancelDialogMessage": "Se confermi, inizierai un annullamento cooperativo con la tua controparte.",
     "acceptCancelDialogMessage": "Se confermi, accetterai l'annullamento cooperativo iniziato dalla tua controparte.",
     "orderIdCopiedMessage": "ID ordine copiato negli appunti",
+    "orderLinkCopiedMessage": "Link ordine copiato negli appunti",
+    "orderShareMessage": "Prendi questo ordine su Mostro: {link}",
+    "@orderShareMessage": {
+        "placeholders": {
+            "link": {
+                "type": "String"
+            }
+        }
+    },
+    "failedToShareOrder": "Impossibile condividere l'ordine. Prova a copiarlo.",
     "disputeTradeDialogTitle": "Inizia Disputa",
     "disputeTradeDialogContent": "Stai per iniziare una disputa con la tua controparte. Vuoi continuare?",
     "disputeCreatedSuccessfully": "Disputa creata con successo",

lib/l10n/intl_pt.arb

@@ -313,6 +313,7 @@
     "paymentMethodLabel": "Método de Pagamento",
     "createdOnLabel": "Criada Em",
     "orderIdLabel": "ID da Ordem",
+    "orderLinkLabel": "Link da Ordem",
     "creatorReputationLabel": "Reputação do Criador",
     "buyerReputationLabel": "Reputação do Comprador",
     "sellerReputationLabel": "Reputação do Vendedor",
@@ -369,6 +370,16 @@
     "cooperativeCancelDialogMessage": "Se você confirmar, iniciará um cancelamento cooperativo com sua contraparte.",
     "acceptCancelDialogMessage": "Se você confirmar, aceitará o cancelamento cooperativo iniciado pela sua contraparte.",
     "orderIdCopiedMessage": "ID da ordem copiado para a área de transferência",
+    "orderLinkCopiedMessage": "Link da ordem copiado para a área de transferência",
+    "orderShareMessage": "Aceita esta ordem no Mostro: {link}",
+    "@orderShareMessage": {
+        "placeholders": {
+            "link": {
+                "type": "String"
+            }
+        }
+    },
+    "failedToShareOrder": "Não foi possível partilhar a ordem. Tenta copiá-la.",
     "disputeTradeDialogTitle": "Iniciar Disputa",
     "disputeTradeDialogContent": "Você está prestes a iniciar uma disputa com sua contraparte. Deseja continuar?",
     "disputeCreatedSuccessfully": "Disputa criada com sucesso",

lib/shared/utils/nostr_utils.dart

@@ -152,6 +152,51 @@ class NostrUtils {
     }
   }
 
+  /// Builds a shareable `mostro:` link for [orderId], in the same format
+  /// [parseMostroUrl] reads back.
+  ///
+  /// Relays that carry no WebSocket scheme are dropped and duplicates are
+  /// removed; at most [maxRelays] survive, so the link stays short enough to
+  /// paste into a chat. Returns null when none is left, since the format
+  /// requires at least one relay to resolve the order.
+  static String? buildMostroUrl({
+    required String orderId,
+    required List<String> relays,
+    String? mostroPubkey,
+    int maxRelays = 3,
+  }) {
+    final trimmedOrderId = orderId.trim();
+    if (trimmedOrderId.isEmpty) return null;
+
+    final usableRelays = <String>[];
+    for (final relay in relays) {
+      final trimmedRelay = relay.trim();
+      if (!trimmedRelay.startsWith('wss://') &&
+          !trimmedRelay.startsWith('ws://')) {
+        continue;
+      }
+      if (usableRelays.contains(trimmedRelay)) continue;
+      usableRelays.add(trimmedRelay);
+      if (usableRelays.length == maxRelays) break;
+    }
+    if (usableRelays.isEmpty) return null;
+
+    final buffer = StringBuffer('mostro:$trimmedOrderId?relays=')
+      ..write(usableRelays.join(','));
+
+    // Same shape parseMostroUrl accepts, so a link we build never carries a
+    // pubkey the reader would silently discard.
+    final normalizedPubkey =
+        mostroPubkey?.trim().toLowerCase().replaceFirst('0x', '');
+    if (normalizedPubkey != null &&
+        normalizedPubkey.length == 64 &&
+        RegExp(r'^[0-9a-f]{64}$').hasMatch(normalizedPubkey)) {
+      buffer.write('&mostro=$normalizedPubkey');
+    }
+
+    return buffer.toString();
+  }
+
   /// Parses a mostro: URL and returns order information
   /// Format: `mostro:order-id?relays=wss://relay1,wss://relay2&mostro=pubkey`
   /// Returns a map with 'orderId', 'relays', and optionally 'mostroPubkey' keys

lib/shared/widgets/order_cards.dart

@@ -1,10 +1,14 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:share_plus/share_plus.dart';
 import 'package:mostro_mobile/core/app_theme.dart';
 import 'package:mostro_mobile/core/automation/automation_id.dart';
 import 'package:mostro_mobile/core/automation/automation_ids.dart';
 import 'package:mostro_mobile/data/models/user_info.dart';
+import 'package:mostro_mobile/features/settings/settings_provider.dart';
+import 'package:mostro_mobile/services/logger_service.dart';
+import 'package:mostro_mobile/shared/utils/nostr_utils.dart';
 import 'package:mostro_mobile/shared/widgets/custom_card.dart';
 
 import 'package:mostro_mobile/shared/providers/exchange_service_provider.dart';
@@ -246,6 +250,120 @@ class OrderIdCard extends StatelessWidget {
   }
 }
 
+/// Card that displays the order's shareable `mostro:` link with a copy button.
+///
+/// The link carries the relays the order can be resolved from and the Mostro
+/// instance it lives on, so any client that understands the scheme can open the
+/// order directly. It renders nothing when no usable relay is configured.
+class OrderShareLinkCard extends ConsumerWidget {
+  final String orderId;
+
+  const OrderShareLinkCard({
+    super.key,
+    required this.orderId,
+  });
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final settings = ref.watch(settingsProvider);
+    final link = NostrUtils.buildMostroUrl(
+      orderId: orderId,
+      relays: settings.relays,
+      mostroPubkey: settings.mostroPublicKey,
+    );
+
+    if (link == null) return const SizedBox.shrink();
+
+    return CustomCard(
+      padding: const EdgeInsets.all(16),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Text(
+            S.of(context)!.orderLinkLabel,
+            style: TextStyle(
+              color: Colors.white70,
+              fontSize: 12,
+            ),
+          ),
+          const SizedBox(height: 8),
+          Row(
+            children: [
+              Expanded(
+                child: Text(
+                  link,
+                  style: const TextStyle(
+                    color: AppTheme.mostroGreen,
+                    fontSize: 14,
+                  ),
+                  maxLines: 2,
+                  overflow: TextOverflow.ellipsis,
+                ),
+              ),
+              IconButton(
+                icon: const Icon(
+                  Icons.copy,
+                  color: Colors.white70,
+                  size: 20,
+                ),
+                visualDensity: VisualDensity.compact,
+                onPressed: () {
+                  Clipboard.setData(ClipboardData(text: link));
+                  SnackBarHelper.showTopSnackBar(
+                    context,
+                    S.of(context)!.orderLinkCopiedMessage,
+                  );
+                },
+              ),
+              IconButton(
+                icon: const Icon(
+                  Icons.share,
+                  color: Colors.white70,
+                  size: 20,
+                ),
+                visualDensity: VisualDensity.compact,
+                tooltip: S.of(context)!.share,
+                onPressed: () => _share(context, link),
+              ),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+
+  /// Hands the link to the system share sheet, wrapped in a sentence so it
+  /// arrives as something the recipient can make sense of.
+  ///
+  /// Everything taken from [context] is read before the await: this is a
+  /// stateless widget, so there is no `mounted` to check afterwards.
+  Future<void> _share(BuildContext context, String link) async {
+    final messenger = ScaffoldMessenger.of(context);
+    final mediaQuery = MediaQuery.of(context);
+    final message = S.of(context)!.orderShareMessage(link);
+    final errorMessage = S.of(context)!.failedToShareOrder;
+    final box = context.findRenderObject() as RenderBox?;
+
+    try {
+      await Share.share(
+        message,
+        // iPads anchor the share sheet to the widget that raised it.
+        sharePositionOrigin: box == null
+            ? null
+            : box.localToGlobal(Offset.zero) & box.size,
+      );
+    } catch (e, stack) {
+      logger.e('Failed to share order link', error: e, stackTrace: stack);
+      SnackBarHelper.showTopSnackBarAsync(
+        messenger: messenger,
+        screenHeight: mediaQuery.size.height,
+        statusBarHeight: mediaQuery.padding.top,
+        message: errorMessage,
+      );
+    }
+  }
+}
+
 /// Card that displays the creator's reputation
 class CreatorReputationCard extends StatelessWidget {
   final double rating;