Offline computer by veloce · Pull Request #2585 · lichess-org/mobile

veloce · 2026-01-29T11:25:57Z

This pull request introduces the offline "Play vs Computer" mode, allowing users to play chess games against a local Stockfish engine.

Copilot

Pull request overview

This pull request introduces an offline "Play vs Computer" mode that allows users to play chess games against a local Stockfish engine without requiring an internet connection. The implementation includes comprehensive game state management, hint system, takeback functionality, and game persistence.

Changes:

Implements offline computer game screen with UI controls for starting games, configuring Stockfish level (1-12), choosing sides, and managing casual/rated modes
Adds game controller with engine integration for move generation, hints computation using multi-PV evaluation, and game state management
Introduces game storage layer for persisting ongoing games and user preferences
Refactors MaterialDifferenceDisplay widget into a reusable component
Enhances engine work system with Elo-based multiPV and search time scaling for realistic difficulty levels

Reviewed changes

Copilot reviewed 16 out of 17 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
`test/view/offline_computer/offline_computer_game_screen_test.dart`	Comprehensive widget tests covering game flow, hints, casual mode, and saved game restoration
`test/model/engine/fake_stockfish.dart`	Adds LegalMoveFakeStockfish and MultiPvFakeStockfish for testing game progression and hints
`test/model/engine/evaluation_service_test.dart`	Updates tests to reflect new Elo-based multiPV and search time scaling
`lib/src/view/offline_computer/offline_computer_game_screen.dart`	Main game screen with board, player info, controls, and dialogs for game setup and results
`lib/src/model/offline_computer/offline_computer_game_controller.dart`	Game state controller managing moves, engine responses, hints computation, and takebacks
`lib/src/model/offline_computer/offline_computer_game_storage.dart`	JSON-based persistence for saving and loading ongoing games
`lib/src/model/offline_computer/offline_computer_game_preferences.dart`	User preferences for Stockfish level, side choice, and casual mode
`lib/src/model/game/offline_computer_game.dart`	Game model with 12 Stockfish levels mapping to Elo ratings (1320-3190)
`lib/src/widgets/material_diff.dart`	Extracted reusable widget for displaying material difference and captured pieces
`lib/src/view/game/game_player.dart`	Refactored to use extracted MaterialDifferenceDisplay widget
`lib/src/model/engine/work.dart`	Enhanced MoveWork with Elo-scaled multiPV (2-10) and search times (150-5000ms) for realistic strength levels
`lib/src/model/engine/evaluation_service.dart`	Removed redundant _isDisposed checks for cleaner code
`lib/src/model/engine/evaluation_mixin.dart`	Made EvalWork.path nullable to support contexts without position trees
`lib/src/view/play/play_menu.dart`	Adds "Play against computer" menu item
`lib/src/styles/lichess_icons.dart`	Minor whitespace cleanup
`lib/src/model/settings/preferences_storage.dart`	Adds offlineComputerGame preference category
`CLAUDE.md`	Documents Dart 3.10+ dot shorthand syntax conventions

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Copilot · 2026-01-30T15:12:52Z

lib/src/view/offline_computer/offline_computer_game_screen.dart

+              context: context,
+              builder: (context) => YesNoDialog(
+                title: Text(context.l10n.mobileAreYouSure),
+                content: const Text('No worries, your game will be saved.'),


The text 'No worries, your game will be saved.' is hardcoded and should use a localized string from context.l10n for internationalization consistency.

Suggested change

content: const Text('No worries, your game will be saved.'),

content: Text(context.l10n.mobileGameWillBeSaved),

Copilot · 2026-01-30T15:12:52Z

lib/src/view/offline_computer/offline_computer_game_screen.dart

+            const SizedBox(height: 16),
+            SwitchListTile.adaptive(
+              title: Text(context.l10n.casual),
+              subtitle: const Text('Allow takebacks and hints'),


The text 'Allow takebacks and hints' is hardcoded and should use a localized string from context.l10n for internationalization consistency.

Suggested change

subtitle: const Text('Allow takebacks and hints'),

subtitle: Text(context.l10n.allowTakebacksAndHints),

Copilot · 2026-01-30T15:12:52Z

lib/src/model/engine/evaluation_mixin.dart

  @override
  void runBuild() {
-    _evaluationService = ref.read(evaluationServiceProvider);
+    _evaluationService = ref.watch(evaluationServiceProvider);


Changing from ref.read to ref.watch means the mixin will now rebuild when the evaluationServiceProvider changes. This could cause unnecessary rebuilds if the service is mutated, as watching a provider typically means you want to rebuild when it changes. The original ref.read was likely intentional to avoid this. Please verify this change is necessary and doesn't cause performance issues or unexpected rebuilds.

Suggested change

_evaluationService = ref.watch(evaluationServiceProvider);

_evaluationService = ref.read(evaluationServiceProvider);

lib/src/model/engine/work.dart

Copilot · 2026-01-30T15:12:53Z

lib/src/view/offline_computer/offline_computer_game_screen.dart

+      mainAxisSize: .max,
+      mainAxisAlignment: .start,


The dot shorthand syntax (.max and .start) is not used elsewhere in the codebase. For consistency, use the full form MainAxisSize.max and MainAxisAlignment.start instead. While the CLAUDE.md document describes this syntax, the existing codebase consistently uses the full form throughout (see lib/src/view/game/game_player.dart:83, lib/src/view/analysis/analysis_layout.dart:208, and many other files).

we'd rather update the code little by little to use this new syntax

Copilot · 2026-01-30T15:12:53Z

test/view/offline_computer/offline_computer_game_screen_test.dart

+      // Verify side selection options (label is "Side")
+      expect(find.text('Side'), findsOneWidget);
+      expect(find.text('White'), findsOneWidget);
+      expect(find.text('Random side'), findsOneWidget);


The test expects the text 'Random side' but the UI code uses context.l10n.randomColor which, based on existing usage in lib/src/model/common/game.dart:11, would return a different localized string. The test should use the actual localized string that will be rendered, not a hardcoded value.

Suggested change

expect(find.text('Random side'), findsOneWidget);

expect(find.text('Random color'), findsOneWidget);

Copilot · 2026-01-30T15:12:53Z

lib/src/view/offline_computer/offline_computer_game_screen.dart

+            ref.read(_isBoardFlippedProvider.notifier).toggle();
+          },
+        ),
+        BottomSheetAction(makeLabel: (context) => const Text('New game'), onPressed: onNewGame),


The text 'New game' is hardcoded and should use a localized string from context.l10n. This is inconsistent with other menu items which properly use localization (e.g., flipBoard, analysis, resign).

Suggested change

BottomSheetAction(makeLabel: (context) => const Text('New game'), onPressed: onNewGame),

BottomSheetAction(

makeLabel: (context) => Text(context.l10n.newGame),

onPressed: onNewGame,

),

Copilot · 2026-01-30T15:12:54Z

lib/src/view/offline_computer/offline_computer_game_screen.dart

+      content: Text(subtitle),
+      actions: [
+        TextButton(onPressed: () => Navigator.pop(context), child: Text(context.l10n.close)),
+        TextButton(onPressed: onNewGame, child: const Text('New game')),


The text 'New game' is hardcoded and should use a localized string from context.l10n. This is inconsistent with other UI text which properly uses localization (e.g., close, victory, draw).

Suggested change

TextButton(onPressed: onNewGame, child: const Text('New game')),

TextButton(onPressed: onNewGame, child: Text(context.l10n.newGame)),

Co-authored-by: Copilot <[email protected]>

veloce added 17 commits January 30, 2026 14:16

WIP on offline computer

4f68436

Add tests for offline computer

b18bf17

Remove useless _isDisposed checks

051ae85

Update move calibration

17cceb2

Improve stockfish levels

d431ca0

Add game session id to provide context to engine

2b23d9c

Fix aligment

c6f1f06

Fix formatting

f5bf122

Translate screen name

4746fee

Tweak icon

86d0487

Add more translations

14a875c

Tweak level selector

886d9b7

Persist offline computer settings

d17d1ee

Update claude.md

77c33eb

Add flip board button

73ba577

Update search time distribution

8b27800

Implement hint feature

be29886

veloce force-pushed the computer_play branch from ca751d3 to be29886 Compare January 30, 2026 13:17

veloce added 5 commits January 30, 2026 15:08

Persist offline computer game

b17ba4b

Add the casual switch to offline computer setup

e1abfa9

Make default level 4

cc2a934

Update multipv distribution

a78da5d

Format

8221fec

veloce marked this pull request as ready for review January 30, 2026 15:05

veloce requested a review from Copilot January 30, 2026 15:05

Copilot started reviewing on behalf of veloce January 30, 2026 15:05 View session

Copilot AI reviewed Jan 30, 2026

View reviewed changes

veloce and others added 2 commits January 30, 2026 16:25

Update lib/src/model/engine/work.dart

fa2e749

Co-authored-by: Copilot <[email protected]>

Add play against computer quick action

bccdba3

veloce merged commit 0f8d893 into main Jan 30, 2026
1 check passed

veloce deleted the computer_play branch January 30, 2026 15:50

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Offline computer#2585

Offline computer#2585
veloce merged 24 commits intomainfrom
computer_play

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	content: const Text('No worries, your game will be saved.'),
	content: Text(context.l10n.mobileGameWillBeSaved),

	subtitle: const Text('Allow takebacks and hints'),
	subtitle: Text(context.l10n.allowTakebacksAndHints),

	_evaluationService = ref.watch(evaluationServiceProvider);
	_evaluationService = ref.read(evaluationServiceProvider);

	expect(find.text('Random side'), findsOneWidget);
	expect(find.text('Random color'), findsOneWidget);

	TextButton(onPressed: onNewGame, child: const Text('New game')),
	TextButton(onPressed: onNewGame, child: Text(context.l10n.newGame)),

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Pull request overview

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