refactor: use Option<String> for SendResult.transaction_id

lib/providers/wallet_provider.dart

@@ -987,15 +987,21 @@ class WalletProvider extends ChangeNotifier {
 
     // Save token metadata using the deterministic transaction ID returned by CDK
     // (SHA-256 of sorted proof Y values — no racy listTransactions needed)
-    if (result.transactionId.isNotEmpty) {
-      await _txMetaStorage.save(
-        result.transactionId,
-        TransactionMeta(
-          type: TransactionType.cashu,
-          token: result.token.encoded,
-        ),
-      );
-      debugPrint('Token guardado para tx ${result.transactionId}');
+    // Best-effort: don't fail the send if metadata persistence fails
+    final txId = result.transactionId;
+    if (txId != null && txId.isNotEmpty) {
+      try {
+        await _txMetaStorage.save(
+          txId,
+          TransactionMeta(
+            type: TransactionType.cashu,
+            token: result.token.encoded,
+          ),
+        );
+        debugPrint('Token guardado para tx $txId');
+      } catch (e) {
+        debugPrint('Error guardando send metadata: $e');
+      }
     }
 
     notifyListeners();
@@ -1124,7 +1130,7 @@ class WalletProvider extends ChangeNotifier {
       amount: amount,
       description: description,
     ).listen(
-      (quote) {
+      (quote) async {
         // Guardar invoice temprano en SharedPreferences
         if (quote.state == MintQuoteState.unpaid) {
           invoiceBolt11 = quote.request;
@@ -1133,8 +1139,10 @@ class WalletProvider extends ChangeNotifier {
 
         // Cuando se completa, guardar metadata, confetti, limpiar pending
         if (quote.state == MintQuoteState.issued && invoiceBolt11 != null) {
-          _saveMintMetadata(wallet, invoiceBolt11!, quote.transactionId);
-          _removePendingMintInvoice(quote.id);
+          final saved = await _saveMintMetadata(wallet, invoiceBolt11!, quote.transactionId);
+          // Only remove pending invoice if metadata was saved;
+          // otherwise _matchPendingMintInvoices can recover it on next startup
+          if (saved) _removePendingMintInvoice(quote.id);
         }
 
         // Reenviar a la UI (si sigue escuchando)
@@ -1368,8 +1376,8 @@ class WalletProvider extends ChangeNotifier {
   }
 
   /// Guarda metadata para una transacción de mint (Lightning deposit).
-  /// Uses the deterministic transaction ID from CDK when available.
-  Future<void> _saveMintMetadata(Wallet wallet, String invoice, String? transactionId) async {
+  /// Returns true if metadata was actually saved.
+  Future<bool> _saveMintMetadata(Wallet wallet, String invoice, String? transactionId) async {
     try {
       if (transactionId != null && transactionId.isNotEmpty) {
         await _txMetaStorage.save(
@@ -1380,13 +1388,18 @@ class WalletProvider extends ChangeNotifier {
           ),
         );
         debugPrint('Mint metadata guardada para tx $transactionId');
+        confettiController.fire();
+        notifyListeners();
+        return true;
       } else {
         debugPrint('Mint metadata: no transaction ID available');
+        confettiController.fire();
+        notifyListeners();
+        return false;
       }
-      confettiController.fire();
-      notifyListeners();
     } catch (e) {
       debugPrint('Error guardando mint metadata: $e');
+      return false;
     }
   }
 

lib/src/rust/api/wallet.dart

@@ -271,9 +271,11 @@ class SendOptions {
 /// listTransactions lookup.
 class SendResult {
   final Token token;
-  final String transactionId;
 
-  const SendResult({required this.token, required this.transactionId});
+  /// Deterministic transaction ID (None if computation failed)
+  final String? transactionId;
+
+  const SendResult({required this.token, this.transactionId});
 
   @override
   int get hashCode => token.hashCode ^ transactionId.hashCode;

lib/src/rust/frb_generated.dart

@@ -3298,7 +3298,7 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
       throw Exception('unexpected arr length: expect 2 but see ${arr.length}');
     return SendResult(
       token: dco_decode_token(arr[0]),
-      transactionId: dco_decode_String(arr[1]),
+      transactionId: dco_decode_opt_String(arr[1]),
     );
   }
 
@@ -4398,7 +4398,7 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
   SendResult sse_decode_send_result(SseDeserializer deserializer) {
     // Codec=Sse (Serialization based), see doc to use other codecs
     var var_token = sse_decode_token(deserializer);
-    var var_transactionId = sse_decode_String(deserializer);
+    var var_transactionId = sse_decode_opt_String(deserializer);
     return SendResult(token: var_token, transactionId: var_transactionId);
   }
 
@@ -5493,7 +5493,7 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
   void sse_encode_send_result(SendResult self, SseSerializer serializer) {
     // Codec=Sse (Serialization based), see doc to use other codecs
     sse_encode_token(self.token, serializer);
-    sse_encode_String(self.transactionId, serializer);
+    sse_encode_opt_String(self.transactionId, serializer);
   }
 
   @protected

rust/src/api/wallet.rs

@@ -158,7 +158,7 @@ impl Wallet {
         let proofs = cdk_token.proofs(&keysets)?;
         let tx_id = TransactionId::try_from(proofs)
             .map(|id| id.to_string())
-            .unwrap_or_default();
+            .ok();
 
         let token_str = cdk_token.to_string();
         self.update_balance_streams().await;
@@ -500,7 +500,8 @@ impl Wallet {
 /// listTransactions lookup.
 pub struct SendResult {
     pub token: Token,
-    pub transaction_id: String,
+    /// Deterministic transaction ID (None if computation failed)
+    pub transaction_id: Option<String>,
 }
 
 pub struct MintQuote {

rust/src/frb_generated.rs

@@ -3954,7 +3954,7 @@ impl SseDecode for crate::api::wallet::SendResult {
     // Codec=Sse (Serialization based), see doc to use other codecs
     fn sse_decode(deserializer: &mut flutter_rust_bridge::for_generated::SseDeserializer) -> Self {
         let mut var_token = <crate::api::token::Token>::sse_decode(deserializer);
-        let mut var_transactionId = <String>::sse_decode(deserializer);
+        let mut var_transactionId = <Option<String>>::sse_decode(deserializer);
         return crate::api::wallet::SendResult {
             token: var_token,
             transaction_id: var_transactionId,
@@ -5609,7 +5609,7 @@ impl SseEncode for crate::api::wallet::SendResult {
     // Codec=Sse (Serialization based), see doc to use other codecs
     fn sse_encode(self, serializer: &mut flutter_rust_bridge::for_generated::SseSerializer) {
         <crate::api::token::Token>::sse_encode(self.token, serializer);
-        <String>::sse_encode(self.transaction_id, serializer);
+        <Option<String>>::sse_encode(self.transaction_id, serializer);
     }
 }