lichess-org · veloce · Apr 22, 2025 · Apr 21, 2025 · Apr 22, 2025 · Apr 22, 2025
diff --git a/lib/src/model/analysis/analysis_controller.dart b/lib/src/model/analysis/analysis_controller.dart
@@ -710,15 +710,12 @@ class AnalysisState with _$AnalysisState implements EvaluationMixinState {
     IList<PgnComment>? pgnRootComments,
   }) = _AnalysisState;
 
+  @override
+  bool get alwaysRequestCloudEval => currentPosition.ply < 15;
+
   /// Whether the analysis is for a lichess game.
   bool get isLichessGameAnalysis => gameId != null;
 
-  /// Whether to delay the local engine evaluation.
-  ///
-  /// Cloud evaluations are most likely available for the opening moves.
-  @override
-  bool get delayLocalEngine => variant != Variant.fromPosition && currentPosition.ply < 20;
-
   /// Whether the user can request server analysis.
   ///
   /// It must be a lichess game, which is finished and not already analyzed.

diff --git a/lib/src/model/broadcast/broadcast_analysis_controller.dart b/lib/src/model/broadcast/broadcast_analysis_controller.dart
@@ -590,10 +590,9 @@ class BroadcastAnalysisState with _$BroadcastAnalysisState implements Evaluation
   /// If the game is new the path will be empty.
   UciPath? get broadcastLivePath => isNewOrOngoing ? broadcastPath : null;
 
-  /// In a broadcast analysis, the cloud evals are most likely available, so we always want to delay
-  /// the local engine evaluation to save battery.
+  /// In a broadcast analysis, the cloud evals are most likely available.
   @override
-  bool get delayLocalEngine => true;
+  bool get alwaysRequestCloudEval => true;
 
   /// Whether an evaluation can be available
   bool hasAvailableEval(EngineEvaluationPrefState prefs) =>

diff --git a/lib/src/model/common/chess.dart b/lib/src/model/common/chess.dart
@@ -21,6 +21,14 @@ class SanMove with _$SanMove {
 
   bool get isCheck => san.contains('+');
   bool get isCapture => san.contains('x');
+
+  bool isIrreversible(Variant variant) {
+    if (isCheck) return true;
+    if (variant == Variant.crazyhouse) return false;
+    if (isCapture) return true;
+    if (san[0].toLowerCase() == san[0]) return true; // pawn move
+    return variant == Variant.threeCheck && isCheck;
+  }
 }
 
 class MoveConverter implements JsonConverter<Move, String> {
@@ -45,6 +53,11 @@ bool isPromotionPawnMove(Position position, NormalMove move) {
           (move.to.rank == Rank.eighth && position.turn == Side.white));
 }
 
+String fenToEpd(String fen) {
+  // EPD is FEN without the halfmove clock and fullmove number
+  return fen.split(' ').take(4).join(' ');
+}
+
 /// Set of supported variants for reading a game (not playing).
 const ISet<Variant> readSupportedVariants = ISetConst({
   Variant.standard,

diff --git a/lib/src/model/engine/evaluation_mixin.dart b/lib/src/model/engine/evaluation_mixin.dart
@@ -4,6 +4,7 @@ import 'package:dartchess/dartchess.dart';
 import 'package:deep_pick/deep_pick.dart';
 import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:lichess_mobile/src/model/common/chess.dart';
 import 'package:lichess_mobile/src/model/common/eval.dart';
 import 'package:lichess_mobile/src/model/common/node.dart';
 import 'package:lichess_mobile/src/model/common/socket.dart';
@@ -23,13 +24,11 @@ import 'package:meta/meta.dart';
 const kRequestEvalDebounceDelay = Duration(milliseconds: 250);
 
 /// The debounce delay for starting the local engine evaluation in case we assume the cloud eval
-/// will be available.
+/// will be available (broadcasts).
 ///
-/// This is superior to the `kRequestEvalDebounceDelay` to avoid running the local engine
-/// when the cloud evaluation is available. The delay is thus increased to ensure that the socket
-/// 'evalGet/evalHit' round trip gets a chance to complete before starting the local engine, even
-/// with reasonably high network latency.
-const kStartLocalEngineDebounceDelay = Duration(milliseconds: 600);
+/// This is superior to the `kRequestEvalDebounceDelay` to avoid running the local engine too soon
+/// to get a chance to get the cloud eval first.
+const kLocalEngineAfterCloudEvalDelay = Duration(milliseconds: 500);
 
 /// Interface for Notifiers's State that uses [EngineEvaluationMixin].
 abstract class EvaluationMixinState {
@@ -48,20 +47,8 @@ abstract class EvaluationMixinState {
   /// found in studies.
   Position? get currentPosition;
 
-  /// Whether to delay the local engine evaluation to give time to get the cloud eval.
-  ///
-  /// By default, this should be `false`, which means the local engine evaluation is started at the
-  /// same time as the cloud evaluation is requested, after a debounce delay.
-  ///
-  /// This is the most common use case, because most of the time the cloud eval is not available
-  /// except on opening positions.
-  ///
-  /// However, on some cases, we know the cloud evaluations are available, as for instance in a broadcast.
-  /// So this can be set to `true` to delay the local engine evaluation in order to save battery.
-  /// The local engine will be started with a higher delay which gives time to get the cloud
-  /// eval during a socket round trip. If the cloud eval is available the [EvaluationService] will
-  /// detect it and not run the local engine.
-  bool get delayLocalEngine;
+  /// Whether to always request a cloud evaluation, regardless of the current ply.
+  bool get alwaysRequestCloudEval;
 }
 
 /// A mixin to provide engine evaluation functionality to an [AsyncNotifier].
@@ -95,7 +82,7 @@ mixin EngineEvaluationMixin {
   Node get positionTree;
 
   final _cloudEvalGetDebounce = Debouncer(kRequestEvalDebounceDelay);
-  final _engineEvalDebounce = Debouncer(kStartLocalEngineDebounceDelay);
+  final _engineEvalDebounce = Debouncer(kLocalEngineAfterCloudEvalDelay);
 
   StreamSubscription<SocketEvent>? _subscription;
 
@@ -177,7 +164,7 @@ mixin EngineEvaluationMixin {
   /// This sends an `evalGet` event to the server to get the cloud evaluation and starts the local
   /// engine evaluation.
   ///
-  /// If [EvaluationMixinState.delayLocalEngine] is `true`, the local engine evaluation will be
+  /// If [EvaluationMixinState.alwaysRequestCloudEval] is `true`, the local engine evaluation will be
   /// delayed to give time to get the cloud eval.
   ///
   /// The evaluation will not be requested if the engine is not available by the context or the
@@ -191,12 +178,12 @@ mixin EngineEvaluationMixin {
 
     _cloudEvalGetDebounce(() {
       _sendEvalGetEvent();
-      if (!evaluationState.delayLocalEngine) {
+      if (!evaluationState.alwaysRequestCloudEval) {
         _startEngineEval();
       }
     });
 
-    if (evaluationState.delayLocalEngine) {
+    if (evaluationState.alwaysRequestCloudEval) {
       _engineEvalDebounce(() {
         _startEngineEval();
       });
@@ -214,6 +201,7 @@ mixin EngineEvaluationMixin {
   void _handleEvalHitEvent(SocketEvent event) {
     final path = pick(event.data, 'path').asUciPathOrThrow();
     final depth = pick(event.data, 'depth').asIntOrThrow();
+
     final pvs =
         pick(event.data, 'pvs')
             .asListOrThrow(
@@ -228,6 +216,11 @@ mixin EngineEvaluationMixin {
     bool isSameEvalString = true;
     positionTree.updateAt(path, (node) {
       final eval = CloudEval(depth: depth, pvs: pvs, position: node.position);
+      final nodeDepth = node.eval?.depth;
+      if (nodeDepth != null && nodeDepth >= depth) {
+        // don't override the local eval if it's deeper than the cloud eval
+        return;
+      }
       isSameEvalString = eval.evalString == node.eval?.evalString;
       node.eval = eval;
     });
@@ -237,11 +230,33 @@ mixin EngineEvaluationMixin {
     }
   }
 
+  bool _canCloudEval() {
+    if (evaluationState.currentPosition!.ply >= 15 && !evaluationState.alwaysRequestCloudEval) {
+      return false;
+    }
+    if (positionTree.nodeAt(evaluationState.currentPath).eval is CloudEval) return false;
+
+    // cloud eval does not support threefold repetition
+    final Set<String> fens = <String>{};
+    final nodeList = positionTree.branchesOn(evaluationState.currentPath).toList();
+    for (var i = nodeList.length - 1; i >= 0; i--) {
+      final node = nodeList[i];
+      final epd = fenToEpd(node.position.fen);
+      if (fens.contains(epd)) return false;
+      if (node.sanMove.isIrreversible(evaluationState.evaluationContext.variant)) {
+        return true;
+      }
+      fens.add(epd);
+    }
+
+    return true;
+  }
+
   void _sendEvalGetEvent() {
     if (!evaluationState.isEngineAvailable(evaluationPrefs)) return;
+    if (!_canCloudEval()) return;
     final curPosition = evaluationState.currentPosition;
     if (curPosition == null) return;
-
     final numEvalLines = evaluationPrefs.numEvalLines;
 
     socketClient?.send('evalGet', {
@@ -270,11 +285,13 @@ mixin EngineEvaluationMixin {
           final (work, eval) = tuple;
           bool isSameEvalString = true;
           positionTree.updateAt(work.path, (node) {
-            if (node.eval is CloudEval) {
-              // in case of high network latency, the cloud eval may arrive after the local eval
-              // in this case, we should not override the cloud eval with the local eval
-              _stopEngineEval();
-              return;
+            // don't override the cloud eval if it's deeper than the local eval
+            // unless the engineSearchTime pref is set to kMaxEngineSearchTime (infinity)
+            if (node.eval is CloudEval &&
+                evaluationPrefs.engineSearchTime != kMaxEngineSearchTime) {
+              if (node.eval?.depth != null && node.eval!.depth >= eval.depth) {
+                return;
+              }
             }
             isSameEvalString = eval.evalString == node.eval?.evalString;
             node.eval = eval;
@@ -284,8 +301,4 @@ mixin EngineEvaluationMixin {
           }
         });
   }
-
-  void _stopEngineEval() {
-    _evaluationService?.stop();
-  }
 }
diff --git a/lib/src/model/engine/evaluation_preferences.dart b/lib/src/model/engine/evaluation_preferences.dart
@@ -106,5 +106,7 @@ const kAvailableEngineSearchTimes = [
   Duration(seconds: 30),
 
   /// Displayed as infinity in the UI.
-  Duration(hours: 1),
+  kMaxEngineSearchTime,
 ];
+
+const kMaxEngineSearchTime = Duration(hours: 1);
diff --git a/lib/src/model/puzzle/puzzle_controller.dart b/lib/src/model/puzzle/puzzle_controller.dart
@@ -430,7 +430,7 @@ class PuzzleState with _$PuzzleState implements EvaluationMixinState {
   }) = _PuzzleState;
 
   @override
-  bool get delayLocalEngine => false;
+  bool get alwaysRequestCloudEval => false;
 
   @override
   bool isEngineAvailable(EngineEvaluationPrefState _) =>

diff --git a/lib/src/model/study/study_controller.dart b/lib/src/model/study/study_controller.dart
@@ -504,7 +504,7 @@ class StudyState with _$StudyState implements EvaluationMixinState {
   }) = _StudyState;
 
   @override
-  bool get delayLocalEngine => false;
+  bool get alwaysRequestCloudEval => false;
 
   /// Whether the engine is available for evaluation
   @override

diff --git a/lib/src/view/analysis/analysis_settings_screen.dart b/lib/src/view/analysis/analysis_settings_screen.dart
@@ -4,7 +4,7 @@ import 'package:lichess_mobile/src/model/analysis/analysis_controller.dart';
 import 'package:lichess_mobile/src/model/analysis/analysis_preferences.dart';
 import 'package:lichess_mobile/src/utils/l10n_context.dart';
 import 'package:lichess_mobile/src/utils/navigation.dart';
-import 'package:lichess_mobile/src/view/analysis/stockfish_settings.dart';
+import 'package:lichess_mobile/src/view/analysis/engine_settings_widget.dart';
 import 'package:lichess_mobile/src/view/opening_explorer/opening_explorer_settings.dart';
 import 'package:lichess_mobile/src/widgets/adaptive_bottom_sheet.dart';
 import 'package:lichess_mobile/src/widgets/feedback.dart';
@@ -119,7 +119,7 @@ class AnalysisSettingsScreen extends ConsumerWidget {
                         ? CrossFadeState.showSecond
                         : CrossFadeState.showFirst,
                 firstChild: const SizedBox.shrink(),
-                secondChild: StockfishSettingsWidget(
+                secondChild: EngineSettingsWidget(
                   onSetEngineSearchTime: (value) {
                     ref.read(ctrlProvider.notifier).setEngineSearchTime(value);
                   },

diff --git a/...src/view/analysis/stockfish_settings.dart → ...view/analysis/engine_settings_widget.dart b/...src/view/analysis/stockfish_settings.dart → ...view/analysis/engine_settings_widget.dart
@@ -7,8 +7,8 @@ import 'package:lichess_mobile/src/widgets/list.dart';
 import 'package:lichess_mobile/src/widgets/non_linear_slider.dart';
 import 'package:lichess_mobile/src/widgets/settings.dart';
 
-class StockfishSettingsWidget extends ConsumerWidget {
-  const StockfishSettingsWidget({
+class EngineSettingsWidget extends ConsumerWidget {
+  const EngineSettingsWidget({
     this.onToggleLocalEvaluation,
     required this.onSetEngineSearchTime,
     required this.onSetNumEvalLines,

diff --git a/lib/src/view/broadcast/broadcast_game_settings_screen.dart b/lib/src/view/broadcast/broadcast_game_settings_screen.dart
@@ -5,7 +5,7 @@ import 'package:lichess_mobile/src/model/broadcast/broadcast_analysis_controller
 import 'package:lichess_mobile/src/model/common/id.dart';
 import 'package:lichess_mobile/src/utils/l10n_context.dart';
 import 'package:lichess_mobile/src/utils/navigation.dart';
-import 'package:lichess_mobile/src/view/analysis/stockfish_settings.dart';
+import 'package:lichess_mobile/src/view/analysis/engine_settings_widget.dart';
 import 'package:lichess_mobile/src/view/opening_explorer/opening_explorer_settings.dart';
 import 'package:lichess_mobile/src/widgets/adaptive_bottom_sheet.dart';
 import 'package:lichess_mobile/src/widgets/list.dart';
@@ -114,7 +114,7 @@ class BroadcastGameSettingsScreen extends ConsumerWidget {
                     ? CrossFadeState.showSecond
                     : CrossFadeState.showFirst,
             firstChild: const SizedBox.shrink(),
-            secondChild: StockfishSettingsWidget(
+            secondChild: EngineSettingsWidget(
               onSetEngineSearchTime:
                   (value) => ref.read(controller.notifier).setEngineSearchTime(value),
               onSetNumEvalLines: (value) => ref.read(controller.notifier).setNumEvalLines(value),

diff --git a/lib/src/view/settings/engine_settings_screen.dart b/lib/src/view/settings/engine_settings_screen.dart
@@ -2,7 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:lichess_mobile/src/model/engine/evaluation_preferences.dart';
 import 'package:lichess_mobile/src/utils/navigation.dart';
-import 'package:lichess_mobile/src/view/analysis/stockfish_settings.dart';
+import 'package:lichess_mobile/src/view/analysis/engine_settings_widget.dart';
 
 class EngineSettingsScreen extends StatelessWidget {
   const EngineSettingsScreen({super.key});
@@ -22,7 +22,7 @@ class _Body extends ConsumerWidget {
   Widget build(BuildContext context, WidgetRef ref) {
     return ListView(
       children: [
-        StockfishSettingsWidget(
+        EngineSettingsWidget(
           onSetEngineSearchTime: (value) {
             ref.read(engineEvaluationPreferencesProvider.notifier).setEngineSearchTime(value);
           },

diff --git a/lib/src/view/study/study_settings.dart b/lib/src/view/study/study_settings.dart
@@ -7,7 +7,7 @@ import 'package:lichess_mobile/src/model/study/study_controller.dart';
 import 'package:lichess_mobile/src/model/study/study_preferences.dart';
 import 'package:lichess_mobile/src/utils/l10n_context.dart';
 import 'package:lichess_mobile/src/utils/navigation.dart';
-import 'package:lichess_mobile/src/view/analysis/stockfish_settings.dart';
+import 'package:lichess_mobile/src/view/analysis/engine_settings_widget.dart';
 import 'package:lichess_mobile/src/view/opening_explorer/opening_explorer_settings.dart';
 import 'package:lichess_mobile/src/widgets/adaptive_bottom_sheet.dart';
 import 'package:lichess_mobile/src/widgets/list.dart';
@@ -72,7 +72,7 @@ class StudySettingsScreen extends ConsumerWidget {
             ],
           ),
           if (isComputerAnalysisAllowed)
-            StockfishSettingsWidget(
+            EngineSettingsWidget(
               onToggleLocalEvaluation: () => ref.read(studyController.notifier).toggleEngine(),
               onSetEngineSearchTime:
                   (value) => ref.read(studyController.notifier).setEngineSearchTime(value),

diff --git a/test/view/analysis/analysis_screen_test.dart b/test/view/analysis/analysis_screen_test.dart
@@ -475,10 +475,10 @@ void main() {
         await makeEngineTestApp(tester, isCloudEvalEnabled: false);
         await playMove(tester, 'e2', 'e4');
         expect(find.byType(InlineMove), findsOne);
-        await tester.pump(kStartLocalEngineDebounceDelay + kEngineEvalEmissionThrottleDelay);
+        await tester.pump(kLocalEngineAfterCloudEvalDelay + kEngineEvalEmissionThrottleDelay);
         expect(find.widgetWithText(InlineMove, '+0.2'), findsOne);
         await playMove(tester, 'e7', 'e5');
-        await tester.pump(kStartLocalEngineDebounceDelay + kEngineEvalEmissionThrottleDelay);
+        await tester.pump(kLocalEngineAfterCloudEvalDelay + kEngineEvalEmissionThrottleDelay);
         expect(find.widgetWithText(InlineMove, '+0.2'), findsNWidgets(2));
       });
     });

diff --git a/test/view/engine/engine_depth_test.dart b/test/view/engine/engine_depth_test.dart
@@ -43,7 +43,7 @@ void main() {
       expect(find.widgetWithText(EngineDepth, '36'), findsOne);
 
       // Wait for local engine delay
-      await tester.pump(kStartLocalEngineDebounceDelay + kEngineEvalEmissionThrottleDelay);
+      await tester.pump(kLocalEngineAfterCloudEvalDelay + kEngineEvalEmissionThrottleDelay);
       // Local engine has not even started
       expect(find.widgetWithText(EngineDepth, '36'), findsOne);
     });
@@ -66,20 +66,20 @@ void main() {
       expect(isCloudEvalDisplayed(), isFalse);
 
       // Now wait for local engine
-      await tester.pump(kStartLocalEngineDebounceDelay + kEngineEvalEmissionThrottleDelay);
+      await tester.pump(kLocalEngineAfterCloudEvalDelay + kEngineEvalEmissionThrottleDelay);
       expect(find.widgetWithText(EngineDepth, '16'), findsOne);
     });
 
     testWidgets('Cloud eval will override local engine eval', (tester) async {
       // Simulates a connection lag that will make the cloud eval come 300ms after the local engine
       final connectionLag =
-          kStartLocalEngineDebounceDelay -
+          kLocalEngineAfterCloudEvalDelay -
           kRequestEvalDebounceDelay +
           const Duration(milliseconds: 300);
       await makeEngineTestApp(tester, connectionLag: connectionLag);
 
       // Wait for local engine eval
-      await tester.pump(kStartLocalEngineDebounceDelay);
+      await tester.pump(kLocalEngineAfterCloudEvalDelay);
       expect(find.widgetWithText(EngineDepth, '15'), findsOne);
 
       // cloud eval will be available 300ms after the local engine eval
@@ -88,16 +88,16 @@ void main() {
       expect(find.widgetWithText(EngineDepth, '36'), findsOne);
     });
 
-    testWidgets('Local engine will not override cloud eval', (tester) async {
+    testWidgets('Local engine will not override cloud eval with greater depth', (tester) async {
       // Simulates a connection lag that will make the local engine come 100ms after the cloud eval
       final connectionLag =
-          kStartLocalEngineDebounceDelay -
+          kLocalEngineAfterCloudEvalDelay -
           kRequestEvalDebounceDelay +
           const Duration(milliseconds: 100);
       await makeEngineTestApp(tester, connectionLag: connectionLag);
 
       // Wait for local engine eval
-      await tester.pump(kStartLocalEngineDebounceDelay);
+      await tester.pump(kLocalEngineAfterCloudEvalDelay);
       expect(find.widgetWithText(EngineDepth, '15'), findsOne);
 
       // Cloud eval will be available 100ms after the first local engine eval emission