fix(replace_by_fee): reject sub-minimum bumps under congestion

RBF validated custom bumps against the static 0.1 floor while send/swap track the live mempool minimumFee — its custom-fee field carries no presets, so FeeOptions.minRelay was unavailable. Thread minRelay from ReplaceByFeeCubit (already fetched, previously discarded) into CustomFeeListItem via a dedicated minRelay param that takes precedence over feePresets and falls back to 0.1 until the fetch completes. An RBF bump below the network's current minimum is now rejected at the keystroke gate, matching send/swap. Adds regression tests for the override floor and the RBF commit gate.

Author: ethicnology

lib/core/widgets/fees/custom_fee_list_item.dart

@@ -49,6 +49,7 @@ class CustomFeeListItem extends StatefulWidget {
     required this.tileShadowColor,
     required this.unselectedIconColor,
     required this.onCommit,
+    this.minRelay,
     this.onArm,
     this.onDisarm,
     this.onPreview,
@@ -69,8 +70,16 @@ class CustomFeeListItem extends StatefulWidget {
 
   /// The preset fees, used to label the "Estimated delivery" subtitle by
   /// comparing the user's value against fastest/economic/slow thresholds.
+  /// Also supplies the relay floor via [FeeOptions.minRelay] in modal mode.
   final FeeOptions? feePresets;
 
+  /// Explicit relay floor (the live mempool `minimumFee`, clamped to 0.1)
+  /// for callers that don't carry a full [feePresets] — i.e. RBF, which
+  /// has no preset tiers but still must reject sub-minimum bumps under
+  /// congestion. Takes precedence over [feePresets]'s `minRelay`; falls
+  /// back to the static 0.1 floor when neither is supplied.
+  final RelativeFee? minRelay;
+
   /// Estimated tx vsize (vbytes). Used to convert relative → absolute for
   /// the preview line, and to convert absolute → rate for the sub-1 sat/vB
   /// warning logic.
@@ -270,7 +279,8 @@ class _CustomFeeListItemState extends State<CustomFeeListItem> {
         // [TransferBloc._onCustomFeeFinalized] via aboveMinRelay.
         if (!fee.aboveMinRelay(
           txSize: widget.txSize,
-          floorSatPerKwu: widget.feePresets?.minRelay.satPerKwu,
+          floorSatPerKwu:
+              (widget.minRelay ?? widget.feePresets?.minRelay)?.satPerKwu,
         )) {
           return;
         }
@@ -369,9 +379,9 @@ class _CustomFeeListItemState extends State<CustomFeeListItem> {
     // Falls back to the static 0.1 when no presets are loaded yet (e.g. RBF).
     // Below 1 sat/vByte (but at/above the floor) we still warn the tx may
     // take longer to confirm and may not propagate to every node.
+    final RelativeFee? floor = widget.minRelay ?? feeOptions?.minRelay;
     final double floorSatPerVbyte =
-        feeOptions?.minRelay.satPerVbyte ??
-        NetworkFeeRelayPolicy.minRelaySatPerVbyte;
+        floor?.satPerVbyte ?? NetworkFeeRelayPolicy.minRelaySatPerVbyte;
     final bool belowFloor = customRate != null && customRate < floorSatPerVbyte;
     final bool subOneSatPerVbyte =
         customRate != null && customRate < 1.0 && !belowFloor;

lib/features/replace_by_fee/presentation/cubit.dart

@@ -52,6 +52,7 @@ class ReplaceByFeeCubit extends Cubit<ReplaceByFeeState> {
       state.copyWith(
         fastestFeeRate: fastestFeeRate,
         newFeeRate: recommendedBumpRate,
+        minRelay: fees.minRelay,
       ),
     );
   }

lib/features/replace_by_fee/presentation/state.dart

@@ -1,3 +1,4 @@
+import 'package:bb_mobile/core/fees/domain/fees_entity.dart';
 import 'package:bb_mobile/features/replace_by_fee/domain/fee_entity.dart';
 import 'package:bb_mobile/features/replace_by_fee/errors.dart';
 import 'package:freezed_annotation/freezed_annotation.dart';
@@ -11,6 +12,12 @@ sealed class ReplaceByFeeState with _$ReplaceByFeeState {
     @Default(null) FeeEntity? fastestFeeRate,
     @Default(null) FeeEntity? newFeeRate,
     @Default(null) String? txid,
+
+    /// Live relay floor (mempool `minimumFee`, clamped to 0.1) so the custom
+    /// bump field rejects sub-minimum rates under congestion. Null until the
+    /// initial fee fetch completes → custom field falls back to the static
+    /// 0.1 floor.
+    @Default(null) RelativeFee? minRelay,
   }) = _ReplaceByFeeState;
 
   const ReplaceByFeeState._();

lib/features/replace_by_fee/ui/fee_selector_widget.dart

@@ -15,6 +15,7 @@ class BumpFeeSelectorWidget extends StatelessWidget {
     required this.txSize,
     required this.onChanged,
     required this.focusNode,
+    this.minRelay,
   });
 
   final FeeEntity fastestFeeRate;
@@ -23,6 +24,9 @@ class BumpFeeSelectorWidget extends StatelessWidget {
   final void Function(FeeEntity fee) onChanged;
   final FocusNode focusNode;
 
+  /// Live relay floor for the custom bump field (null → static 0.1).
+  final RelativeFee? minRelay;
+
   @override
   Widget build(BuildContext context) {
     return SafeArea(
@@ -44,6 +48,7 @@ class BumpFeeSelectorWidget extends StatelessWidget {
               initialFee: selected.feeRate,
               isCommittedAsCustom: selected.type == FeeType.custom,
               feePresets: null,
+              minRelay: minRelay,
               txSize: txSize,
               exchangeRate: 0.0,
               fiatCurrencyCode: '',

lib/features/replace_by_fee/ui/home_page.dart

@@ -66,6 +66,7 @@ class _ReplaceByFeeHomePageState extends State<ReplaceByFeeHomePage> {
                       txSize: widget.tx.vsize,
                       onChanged: cubit.onChangeFee,
                       focusNode: _feeNode,
+                      minRelay: state.minRelay,
                     ),
                     if (state.error != null) ...[
                       const Gap(16),

test/core_test/widgets/fees/custom_fee_list_item_test.dart

@@ -26,6 +26,7 @@ void main() {
     int txSize = 140,
     int? previewFeeSat,
     bool previewLoading = false,
+    RelativeFee? minRelay,
     void Function(NetworkFee fee)? onArm,
     VoidCallback? onDisarm,
     void Function(NetworkFee fee)? onPreview,
@@ -52,6 +53,7 @@ void main() {
             onDisarm: onDisarm,
             onPreview: onPreview,
             onCommit: onCommit ?? (_) async {},
+            minRelay: minRelay,
             allowAbsoluteToggle: allowAbsoluteToggle,
             commitOnChange: commitOnChange,
             previewFeeSat: previewFeeSat,
@@ -379,6 +381,50 @@ void main() {
     });
   });
 
+  group('CustomFeeListItem — dynamic floor (minRelay override)', () {
+    testWidgets('blocks a rate above 0.1 but below the live minimum', (
+      tester,
+    ) async {
+      // Congested floor = 0.5 sat/vB (125 sat/kwu). 0.3 clears the static
+      // 0.1 floor but not the live minimum → below-floor error shows. This
+      // is the RBF path, which carries minRelay but no feePresets.
+      await pumpTile(tester, minRelay: const RelativeFee(125));
+      await tester.enterText(find.byType(TextFormField), '0.3');
+      await tester.pumpAndSettle();
+      expect(find.textContaining('must be at least'), findsOneWidget);
+    });
+
+    testWidgets('accepts the same rate with no override (static 0.1)', (
+      tester,
+    ) async {
+      await pumpTile(tester);
+      await tester.enterText(find.byType(TextFormField), '0.3');
+      await tester.pumpAndSettle();
+      expect(find.textContaining('must be at least'), findsNothing);
+    });
+
+    testWidgets('RBF commit-on-change is gated by the override floor', (
+      tester,
+    ) async {
+      NetworkFee? committed;
+      await pumpTile(
+        tester,
+        commitOnChange: true,
+        allowAbsoluteToggle: false,
+        minRelay: const RelativeFee(125),
+        onCommit: (fee) async => committed = fee,
+      );
+      // 0.3 > static 0.1 but < live 0.5 → must not commit.
+      await tester.enterText(find.byType(TextFormField), '0.3');
+      await tester.pumpAndSettle();
+      expect(committed, isNull);
+      // 0.6 ≥ live floor → commits.
+      await tester.enterText(find.byType(TextFormField), '0.6');
+      await tester.pumpAndSettle();
+      expect(committed, isNotNull);
+    });
+  });
+
   group('CustomFeeListItem — keyboard dismissal', () {
     testWidgets('Enter / Done pops the modal in modal mode', (tester) async {
       late BuildContext routeContext;