feat(orders): implement take-sell order flow with LN address support

lib/features/home/providers/home_order_providers.dart

@@ -3,6 +3,8 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:mostro/src/rust/api/orders.dart' as orders_api;
 import 'package:mostro/src/rust/api/types.dart';
 
+export 'package:mostro/src/rust/api/types.dart' show OrderStatus;
+
 // ── Order type ────────────────────────────────────────────────────────────────
 
 enum OrderType { buy, sell }
@@ -60,6 +62,8 @@ class OrderItem {
     this.rating = 0.0,
     this.tradeCount = 0,
     this.daysActive = 0,
+    this.status = OrderStatus.pending,
+    this.amountSats,
   }) {
     final isFixed = fiatAmount != null &&
         fiatAmountMin == null &&
@@ -89,6 +93,10 @@ class OrderItem {
   final double rating;
   final int tradeCount;
   final int daysActive;
+  /// Current order status from the Mostro protocol.
+  final OrderStatus status;
+  /// Sats amount resolved by Mostro (non-null once Mostro accepts the take).
+  final BigInt? amountSats;
 
   bool get isRange => fiatAmountMin != null && fiatAmountMax != null;
 
@@ -118,6 +126,8 @@ class OrderItem {
         expiresAt: info.expiresAt != null
             ? DateTime.fromMillisecondsSinceEpoch(info.expiresAt! * 1000)
             : null,
+        status: info.status,
+        amountSats: info.amountSats,
       );
 }
 

lib/features/order/providers/trade_state_provider.dart

@@ -0,0 +1,38 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:mostro/src/rust/api/orders.dart' as orders_api;
+import 'package:mostro/src/rust/api/types.dart';
+
+/// Maps `orderId` → whether the local user is the buyer in that trade.
+///
+/// Set this before navigating to [AddLightningInvoiceScreen] or
+/// [TradeDetailScreen] so those screens know the user's role.
+final tradeRoleProvider =
+    StateProvider<Map<String, bool>>((ref) => const {});
+
+/// Poll `getOrder()` every 2 s until `amountSats` is non-null, then stop.
+///
+/// Returns `null` while waiting.  Useful for the add-invoice screen which
+/// needs the sats amount before it can submit a Lightning invoice.
+final tradeAmountProvider =
+    StreamProvider.family.autoDispose<BigInt?, String>((ref, orderId) async* {
+  while (true) {
+    final info = await orders_api.getOrder(orderId: orderId);
+    final sats = info?.amountSats;
+    yield sats;
+    if (sats != null) return; // done — no need to keep polling
+    await Future.delayed(const Duration(seconds: 2));
+  }
+});
+
+/// Live order status for a single trade, polled from the order book every 2 s.
+///
+/// Returns [OrderStatus.pending] as the initial / fallback value while loading.
+final tradeStatusProvider =
+    StreamProvider.family.autoDispose<OrderStatus, String>((ref, orderId) async* {
+  yield OrderStatus.pending; // immediate first emission so UI doesn't hang
+  while (true) {
+    await Future.delayed(const Duration(seconds: 2));
+    final info = await orders_api.getOrder(orderId: orderId);
+    if (info != null) yield info.status;
+  }
+});

lib/features/order/screens/add_lightning_invoice_screen.dart

@@ -4,6 +4,7 @@ import 'package:go_router/go_router.dart';
 
 import 'package:mostro/core/app_routes.dart';
 import 'package:mostro/core/app_theme.dart';
+import 'package:mostro/features/order/providers/trade_state_provider.dart';
 import 'package:mostro/features/settings/providers/nwc_provider.dart';
 import 'package:mostro/shared/widgets/nwc_invoice_widget.dart';
 import 'package:mostro/src/rust/api/orders.dart' as orders_api;
@@ -41,20 +42,44 @@ class _AddLightningInvoiceScreenState
     super.dispose();
   }
 
-  bool get _isValid =>
-      _invoiceController.text.trim().isNotEmpty &&
-      widget.amountSats != null &&
-      widget.amountSats! > 0;
+  BigInt? _resolvedSats(WidgetRef ref) {
+    final fromProvider = ref.watch(tradeAmountProvider(widget.orderId)).valueOrNull;
+    if (fromProvider != null) return fromProvider;
+    final fallback = widget.amountSats;
+    return fallback != null ? BigInt.from(fallback) : null;
+  }
+
+  bool _isLnAddress(String text) => text.contains('@');
 
-  Future<void> _submit() async {
-    if (_submitting || !_isValid) return;
+  bool _isValid(WidgetRef ref) {
+    final text = _invoiceController.text.trim();
+    if (text.isEmpty) return false;
+    // Lightning Address requires a known sats amount before submission.
+    if (_isLnAddress(text) && _resolvedSats(ref) == null) return false;
+    return true;
+  }
+
+  Future<void> _submit(WidgetRef ref) async {
+    if (_submitting) return;
+    final input = _invoiceController.text.trim();
+    // For Lightning Addresses, the sats amount must be resolved before sending —
+    // the Rust side uses it to resolve the address. Bolt11 invoices encode
+    // their own amount so BigInt.one is an acceptable non-zero placeholder.
+    final resolvedSats = _resolvedSats(ref);
+    if (_isLnAddress(input) && resolvedSats == null) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('Waiting for trade amount — please try again shortly.')),
+      );
+      return;
+    }
+    final sats = resolvedSats ?? BigInt.one;
     setState(() => _submitting = true);
 
     try {
       await orders_api.sendInvoice(
         orderId: widget.orderId,
         invoiceOrAddress: _invoiceController.text.trim(),
-        amountSats: BigInt.from(widget.amountSats!),
+        amountSats: sats,
       );
 
       if (!mounted) return;
@@ -79,10 +104,12 @@ class _AddLightningInvoiceScreenState
 
     final isWalletConnected = ref.watch(isWalletConnectedProvider);
 
-    // Amount not yet resolved and user hasn't explicitly chosen manual mode:
-    // show a loading indicator while waiting for the trade provider.
-    final sats = widget.amountSats;
-    if (sats == null && !_manualMode) {
+    // Resolve sats: provider first (live polling), fall back to constructor param.
+    final sats = _resolvedSats(ref);
+
+    // When NWC is connected, we need the sats amount to auto-generate an invoice.
+    // Show a loading indicator only in that case. Manual entry is always available.
+    if (isWalletConnected && sats == null && !_manualMode) {
       return Scaffold(
         appBar: AppBar(title: const Text('Add Invoice')),
         body: Center(
@@ -95,6 +122,11 @@ class _AddLightningInvoiceScreenState
                 'Fetching trade amount…',
                 style: TextStyle(color: Theme.of(context).extension<AppColors>()?.textSecondary),
               ),
+              const SizedBox(height: AppSpacing.md),
+              TextButton(
+                onPressed: () => setState(() => _manualMode = true),
+                child: const Text('Enter invoice manually'),
+              ),
             ],
           ),
         ),
@@ -103,17 +135,17 @@ class _AddLightningInvoiceScreenState
 
     // If NWC wallet is connected, amount is known, and we haven't fallen back
     // to manual, show the auto-invoice widget instead of the manual form.
-    if (isWalletConnected && !_manualMode && sats != null && sats > 0) {
+    if (isWalletConnected && !_manualMode && sats != null && sats > BigInt.zero) {
       return Scaffold(
         appBar: AppBar(title: const Text('Add Invoice')),
         body: Padding(
           padding: const EdgeInsets.all(AppSpacing.lg),
           child: Center(
             child: NwcInvoiceWidget(
-              amountSats: sats,
+              amountSats: sats.toInt(),
               onInvoiceConfirmed: (invoice) {
                 _invoiceController.text = invoice;
-                _submit();
+                _submit(ref);
               },
               onFallbackToManual: () => setState(() => _manualMode = true),
             ),
@@ -196,7 +228,7 @@ class _AddLightningInvoiceScreenState
                 const SizedBox(width: AppSpacing.md),
                 Expanded(
                   child: FilledButton(
-                    onPressed: _isValid ? _submit : null,
+                    onPressed: _isValid(ref) ? () => _submit(ref) : null,
                     style: FilledButton.styleFrom(
                       backgroundColor: green,
                       foregroundColor: Colors.black,

lib/features/order/screens/take_order_screen.dart

@@ -9,8 +9,12 @@ import 'package:mostro/core/app_routes.dart';
 import 'package:mostro/core/app_theme.dart';
 import 'package:mostro/features/account/providers/privacy_mode_provider.dart';
 import 'package:mostro/features/home/providers/home_order_providers.dart';
+import 'package:mostro/features/order/providers/trade_state_provider.dart';
 import 'package:mostro/features/order/widgets/range_amount_modal.dart';
 import 'package:mostro/shared/utils/fiat_currencies.dart';
+import 'package:mostro/src/rust/api/orders.dart' as orders_api;
+import 'package:mostro/src/rust/api/settings.dart' as settings_api;
+import 'package:mostro/src/rust/api/types.dart';
 
 /// Take order screen — displays order details and allows the user
 /// to take (buy or sell) the order.
@@ -37,7 +41,6 @@ class _TakeOrderScreenState extends ConsumerState<TakeOrderScreen> {
   Timer? _countdownTimer;
   Duration _remaining = Duration.zero;
   bool _submitting = false;
-  // ignore: unused_field — used when Rust bridge take_order() is wired (Phase 8+).
   double? _selectedAmount;
 
   @override
@@ -110,15 +113,31 @@ class _TakeOrderScreenState extends ConsumerState<TakeOrderScreen> {
     setState(() => _submitting = true);
 
     try {
-      // TODO (Phase 8+): Call take_order(orderId, _selectedAmount) via Rust bridge.
-      await Future.delayed(const Duration(milliseconds: 500));
+      // Dispatch take-order to Mostro via the Rust bridge.
+      await orders_api.takeOrder(
+        orderId: widget.orderId,
+        role: widget.isBuying ? TradeRole.buyer : TradeRole.seller,
+        fiatAmount: _selectedAmount,
+      );
 
       if (!mounted) return;
 
-      // Navigate based on role:
-      // Buyer → add invoice screen; Seller → pay invoice screen.
+      // Record the user's role so TradeDetailScreen can read it.
+      ref.read(tradeRoleProvider.notifier).update(
+            (map) => {...map, widget.orderId: widget.isBuying},
+          );
+
       if (widget.isBuying) {
-        context.push(AppRoute.addInvoicePath(widget.orderId));
+        // Check whether a default LN address is configured. If yes, Mostro
+        // will pay it directly and the buyer can skip the add-invoice step.
+        final settings = await settings_api.getSettings();
+        if (!mounted) return;
+        if (settings.defaultLightningAddress != null) {
+          // LN address was included in take-sell payload — go straight to trade.
+          context.go(AppRoute.tradeDetailPath(widget.orderId));
+        } else {
+          context.push(AppRoute.addInvoicePath(widget.orderId));
+        }
       } else {
         context.push(AppRoute.payInvoicePath(widget.orderId));
       }