Fix code rule violations

src/backend/Sudoku.Application/Handlers/UpdateProfileAliasCommandHandler.cs

@@ -41,23 +41,6 @@ public async Task<Result<ProfileDto>> Handle(UpdateProfileAliasCommand request,
             profile.UpdateAlias(newAlias);
             await profileRepository.SaveAsync(profile);
 
-            var games = await gameRepository.GetByPlayerAsync(oldAlias);
-            foreach (var game in games)
-            {
-                try
-                {
-                    // Update playerAlias via reconstitution is not straightforward;
-                    // games store alias as a string field - update via SaveAsync after mutation
-                    // The domain game does not expose alias mutation — we need to handle this at document level
-                    // For now, we log a note; a full implementation would update the document directly
-                    logger.LogDebug("Game {GameId} associated with old alias {OldAlias} — batch update pending", game.Id, oldAlias.Value);
-                }
-                catch (Exception ex)
-                {
-                    logger.LogError(ex, "Failed to update game {GameId} for alias change", game.Id);
-                }
-            }
-
             logger.LogInformation("Updated alias from {OldAlias} to {NewAlias} for profile {ProfileId}",
                 oldAlias.Value, newAlias.Value, profile.Id);
             return Result<ProfileDto>.Success(ProfileDto.FromProfile(profile));

src/backend/Sudoku.Domain/Entities/SudokuGame.cs

@@ -131,7 +131,7 @@ public void AddPossibleValue(int row, int column, int value)
 
         if (cell.HasValue)
         {
-            throw new InvalidOperationException($"Cannot add possible values to cell with a definite value at position ({row}, {column})");
+            throw new CellAlreadyHasValueException($"Cannot add possible values to cell with a definite value at position ({row}, {column})");
         }
 
         cell.AddPossibleValue(value);

src/backend/Sudoku.Domain/Exceptions/CellAlreadyHasValueException.cs

@@ -0,0 +1,3 @@
+namespace Sudoku.Domain.Exceptions;
+
+public class CellAlreadyHasValueException(string message) : DomainException(message);

src/backend/Sudoku.Domain/ValueObjects/Cell.cs

@@ -62,7 +62,6 @@ public void SetValue(int value)
         }
 
         Value = value;
-        // Clear possible values when a definite value is set
         PossibleValues.Clear();
     }
 
@@ -83,7 +82,6 @@ public void SetValue(int? value)
 
         Value = value;
 
-        // Clear possible values when a definite value is set
         if (value.HasValue)
         {
             PossibleValues.Clear();
@@ -109,7 +107,7 @@ public void AddPossibleValue(int value)
 
         if (Value.HasValue)
         {
-            throw new InvalidOperationException($"Cannot add possible values to cell with a definite value at position ({Row}, {Column})");
+            throw new CellAlreadyHasValueException($"Cannot add possible values to cell with a definite value at position ({Row}, {Column})");
         }
 
         if (value < 1 || value > 9)
@@ -153,15 +151,10 @@ public override string ToString()
         return Value?.ToString() ?? ".";
     }
 
-    /// <summary>
-    /// Creates a deep copy of the current cell.
-    /// </summary>
-    /// <returns>A deep copy of the current cell with all possible values copied.</returns>
     public Cell DeepCopy()
     {
         var clonedCell = new Cell(Row, Column, Value, IsFixed);
-
-        // Deep copy the possible values
+
         foreach (var possibleValue in PossibleValues)
         {
             clonedCell.PossibleValues.Add(possibleValue);

src/backend/Sudoku.Infrastructure/Services/PuzzleGenerator.cs

@@ -8,6 +8,15 @@ namespace Sudoku.Infrastructure.Services;
 
 public class PuzzleGenerator(IPuzzleSolver puzzleSolver) : IPuzzleGenerator
 {
+    private const int EASY_EMPTY_MIN = 40;
+    private const int EASY_EMPTY_MAX = 45;
+    private const int MEDIUM_EMPTY_MIN = 46;
+    private const int MEDIUM_EMPTY_MAX = 49;
+    private const int HARD_EMPTY_MIN = 50;
+    private const int HARD_EMPTY_MAX = 53;
+    private const int EXPERT_EMPTY_MIN = 54;
+    private const int EXPERT_EMPTY_MAX = 58;
+
     public async Task<SudokuPuzzle> GeneratePuzzleAsync(GameDifficulty difficulty)
     {
         var puzzle = await GenerateEmptyPuzzleAsync().ConfigureAwait(false);
@@ -41,10 +50,10 @@ private SudokuPuzzle CreateEmptyCells(SudokuPuzzle puzzle, GameDifficulty diffic
     {
         var numberOfEmptyCells = difficulty.Name switch
         {
-            "Easy" => RandomGenerator.RandomNumber(40, 45),
-            "Medium" => RandomGenerator.RandomNumber(46, 49),
-            "Hard" => RandomGenerator.RandomNumber(50, 53),
-            "Expert" => RandomGenerator.RandomNumber(54, 58),
+            "Easy" => RandomGenerator.RandomNumber(EASY_EMPTY_MIN, EASY_EMPTY_MAX),
+            "Medium" => RandomGenerator.RandomNumber(MEDIUM_EMPTY_MIN, MEDIUM_EMPTY_MAX),
+            "Hard" => RandomGenerator.RandomNumber(HARD_EMPTY_MIN, HARD_EMPTY_MAX),
+            "Expert" => RandomGenerator.RandomNumber(EXPERT_EMPTY_MIN, EXPERT_EMPTY_MAX),
             _ => 0
         };
         var emptyCellCoords = new List<(int Row, int Col)>();

src/backend/Tests/Domain/CellTests.cs

@@ -353,7 +353,7 @@ public void AddPossibleValue_OnFixedCell_ThrowsCellIsFixedException()
     }
 
     [Fact]
-    public void AddPossibleValue_OnCellWithValue_ThrowsInvalidOperationException()
+    public void AddPossibleValue_OnCellWithValue_ThrowsCellAlreadyHasValueException()
     {
         // Arrange
         var cell = Cell.Create(5, 5, 7);
@@ -362,7 +362,7 @@ public void AddPossibleValue_OnCellWithValue_ThrowsInvalidOperationException()
         Action act = () => cell.AddPossibleValue(3);
 
         // Assert
-        act.Should().Throw<InvalidOperationException>()
+        act.Should().Throw<CellAlreadyHasValueException>()
             .WithMessage($"*Cannot add possible values to cell with a definite value*");
     }
 

src/backend/Tests/Domain/SudokuGamePossibleValuesTests.cs

@@ -58,7 +58,7 @@ public void AddPossibleValue_ToFixedCell_ThrowsCellIsFixedException()
     }
 
     [Fact]
-    public void AddPossibleValue_ToCellWithValue_ThrowsInvalidOperationException()
+    public void AddPossibleValue_ToCellWithValue_ThrowsCellAlreadyHasValueException()
     {
         // Arrange
         var game = SudokuGame.Create(_playerAlias, _difficulty, _initialCells);
@@ -69,7 +69,7 @@ public void AddPossibleValue_ToCellWithValue_ThrowsInvalidOperationException()
         Action act = () => game.AddPossibleValue(row, col, value);
 
         // Assert
-        act.Should().Throw<InvalidOperationException>()
+        act.Should().Throw<CellAlreadyHasValueException>()
             .WithMessage($"*Cannot add possible values to cell with a definite value*");
     }