feat: NCS-25 Add linters to keep quality up

modules/io/src/main/scala/de/nowchess/io/fen/FenExporter.scala

@@ -15,28 +15,22 @@ object FenExporter extends GameContextExport:
   /** Build the FEN representation for a single rank. */
   private def buildRankString(board: Board, rank: Rank): String =
     val rankSquares = File.values.map(file => Square(file, rank))
-    val rankChars = scala.collection.mutable.ListBuffer[Char]()
-    var emptyCount = 0
-
-    for square <- rankSquares do
-      board.pieceAt(square) match
-        case Some(piece) =>
-          if emptyCount > 0 then
-            rankChars += emptyCount.toString.charAt(0)
-            emptyCount = 0
-          rankChars += pieceToFenChar(piece)
-        case None =>
-          emptyCount += 1
-
-    if emptyCount > 0 then rankChars += emptyCount.toString.charAt(0)
-    rankChars.mkString
+    val (result, emptyCount) = rankSquares.foldLeft(("", 0)):
+      case ((acc, empty), square) =>
+        board.pieceAt(square) match
+          case Some(piece) =>
+            val flushed = if empty > 0 then acc + empty.toString else acc
+            (flushed + pieceToFenChar(piece), 0)
+          case None =>
+            (acc, empty + 1)
+    if emptyCount > 0 then result + emptyCount.toString else result
 
   /** Convert a GameContext to a complete FEN string. */
   def gameContextToFen(context: GameContext): String =
     val piecePlacement = boardToFen(context.board)
-    val activeColor = if context.turn == Color.White then "w" else "b"
-    val castling = castlingString(context.castlingRights)
-    val enPassant = context.enPassantSquare.map(_.toString).getOrElse("-")
+    val activeColor    = if context.turn == Color.White then "w" else "b"
+    val castling       = castlingString(context.castlingRights)
+    val enPassant      = context.enPassantSquare.map(_.toString).getOrElse("-")
     val fullMoveNumber = 1 + (context.moves.length / 2)
     s"$piecePlacement $activeColor $castling $enPassant ${context.halfMoveClock} $fullMoveNumber"
 
@@ -44,10 +38,10 @@ object FenExporter extends GameContextExport:
 
   /** Convert castling rights to FEN notation. */
   private def castlingString(rights: CastlingRights): String =
-    val wk = if rights.whiteKingSide then "K" else ""
-    val wq = if rights.whiteQueenSide then "Q" else ""
-    val bk = if rights.blackKingSide then "k" else ""
-    val bq = if rights.blackQueenSide then "q" else ""
+    val wk     = if rights.whiteKingSide then "K" else ""
+    val wq     = if rights.whiteQueenSide then "Q" else ""
+    val bk     = if rights.blackKingSide then "k" else ""
+    val bq     = if rights.blackQueenSide then "q" else ""
     val result = s"$wk$wq$bk$bq"
     if result.isEmpty then "-" else result
 
@@ -61,4 +55,3 @@ object FenExporter extends GameContextExport:
       case PieceType.Queen  => 'q'
       case PieceType.King   => 'k'
     if piece.color == Color.White then base.toUpper else base
-

modules/io/src/main/scala/de/nowchess/io/fen/FenParser.scala

@@ -6,28 +6,27 @@ import de.nowchess.io.GameContextImport
 
 object FenParser extends GameContextImport:
 
-  /** Parse a complete FEN string into a GameContext.
-   *  Returns Left with error message if the format is invalid. */
+  /** Parse a complete FEN string into a GameContext. Returns Left with error message if the format is invalid.
+    */
   def parseFen(fen: String): Either[String, GameContext] =
     val parts = fen.trim.split("\\s+")
-    if parts.length != 6 then
-      Left(s"Invalid FEN: expected 6 space-separated fields, got ${parts.length}")
+    if parts.length != 6 then Left(s"Invalid FEN: expected 6 space-separated fields, got ${parts.length}")
     else
       for
-        board <- parseBoard(parts(0)).toRight("Invalid FEN: invalid board position")
-        activeColor <- parseColor(parts(1)).toRight("Invalid FEN: invalid active color (expected 'w' or 'b')")
+        board          <- parseBoard(parts(0)).toRight("Invalid FEN: invalid board position")
+        activeColor    <- parseColor(parts(1)).toRight("Invalid FEN: invalid active color (expected 'w' or 'b')")
         castlingRights <- parseCastling(parts(2)).toRight("Invalid FEN: invalid castling rights")
-        enPassant <- parseEnPassant(parts(3)).toRight("Invalid FEN: invalid en passant square")
-        halfMoveClock <- parts(4).toIntOption.toRight("Invalid FEN: invalid half-move clock (expected integer)")
+        enPassant      <- parseEnPassant(parts(3)).toRight("Invalid FEN: invalid en passant square")
+        halfMoveClock  <- parts(4).toIntOption.toRight("Invalid FEN: invalid half-move clock (expected integer)")
         fullMoveNumber <- parts(5).toIntOption.toRight("Invalid FEN: invalid full move number (expected integer)")
-        _ <- Either.cond(halfMoveClock >= 0 && fullMoveNumber >= 1, (), "Invalid FEN: invalid move counts")
+        _              <- Either.cond(halfMoveClock >= 0 && fullMoveNumber >= 1, (), "Invalid FEN: invalid move counts")
       yield GameContext(
         board = board,
         turn = activeColor,
         castlingRights = castlingRights,
         enPassantSquare = enPassant,
         halfMoveClock = halfMoveClock,
-        moves = List.empty
+        moves = List.empty,
       )
 
   def importGameContext(input: String): Either[String, GameContext] =
@@ -41,25 +40,26 @@ object FenParser extends GameContextImport:
 
   /** Parse castling rights string (e.g. "KQkq", "K", "-") into unified castling rights. */
   private def parseCastling(s: String): Option[CastlingRights] =
-    if s == "-" then
-      Some(CastlingRights.None)
+    if s == "-" then Some(CastlingRights.None)
     else if s.length <= 4 && s.forall(c => "KQkq".contains(c)) then
-      Some(CastlingRights(
-        whiteKingSide = s.contains('K'),
-        whiteQueenSide = s.contains('Q'),
-        blackKingSide = s.contains('k'),
-        blackQueenSide = s.contains('q')
-      ))
-    else
-      None
+      Some(
+        CastlingRights(
+          whiteKingSide = s.contains('K'),
+          whiteQueenSide = s.contains('Q'),
+          blackKingSide = s.contains('k'),
+          blackQueenSide = s.contains('q'),
+        ),
+      )
+    else None
 
   /** Parse en passant target square ("-" for none, or algebraic like "e3"). */
   private def parseEnPassant(s: String): Option[Option[Square]] =
     if s == "-" then Some(None)
     else Square.fromAlgebraic(s).map(Some(_))
 
-  /** Parses a FEN piece-placement string (rank 8 to rank 1, separated by '/') into a Board.
-   *  Returns None if the format is invalid. */
+  /** Parses a FEN piece-placement string (rank 8 to rank 1, separated by '/') into a Board. Returns None if the format
+    * is invalid.
+    */
   def parseBoard(fen: String): Option[Board] =
     val rankStrings = fen.split("/", -1)
     if rankStrings.length != 8 then None
@@ -73,28 +73,22 @@ object FenParser extends GameContextImport:
             parsePieceRank(rankStr, rank).map(squares => acc :+ squares)
       parsedRanks.map(ranks => Board(ranks.flatten.toMap))
 
-  /** Parse a single rank string (e.g. "rnbqkbnr" or "p3p3") into a list of (Square, Piece) pairs.
-   *  Returns None if the rank string contains invalid characters or the wrong number of files. */
+  /** Parse a single rank string (e.g. "rnbqkbnr" or "p3p3") into a list of (Square, Piece) pairs. Returns None if the
+    * rank string contains invalid characters or the wrong number of files.
+    */
   private def parsePieceRank(rankStr: String, rank: Rank): Option[List[(Square, Piece)]] =
-    var fileIdx = 0
-    val squares = scala.collection.mutable.ListBuffer[(Square, Piece)]()
-    var failed = false
-
-    for c <- rankStr if !failed do
-      if fileIdx > 7 then
-        failed = true
-      else if c.isDigit then
-        fileIdx += c.asDigit
-      else
-        charToPiece(c) match
-          case None => failed = true
-          case Some(piece) =>
-            val file = File.values(fileIdx)
-            squares += (Square(file, rank) -> piece)
-            fileIdx += 1
-
+    val (fileIdx, failed, squares) = rankStr.foldLeft((0, false, List.empty[(Square, Piece)])):
+      case ((idx, true, acc), _) => (idx, true, acc)
+      case ((idx, false, acc), c) =>
+        if idx > 7 then (idx, true, acc)
+        else if c.isDigit then (idx + c.asDigit, false, acc)
+        else
+          charToPiece(c) match
+            case None => (idx, true, acc)
+            case Some(piece) =>
+              (idx + 1, false, acc :+ (Square(File.values(idx), rank) -> piece))
     if failed || fileIdx != 8 then None
-    else Some(squares.toList)
+    else Some(squares)
 
   /** Convert a FEN piece character to a Piece. Uppercase = White, lowercase = Black. */
   private def charToPiece(c: Char): Option[Piece] =
@@ -108,4 +102,3 @@ object FenParser extends GameContextImport:
       case 'k' => Some(PieceType.King)
       case _   => None
     pieceTypeOpt.map(pt => Piece(color, pt))
-

modules/io/src/main/scala/de/nowchess/io/fen/FenParserCombinators.scala

@@ -14,7 +14,7 @@ object FenParserCombinators extends RegexParsers with GameContextImport:
 
   private def pieceChar: Parser[Piece] =
     "[prnbqkPRNBQK]".r ^^ { s =>
-      val c = s.head
+      val c     = s.head
       val color = if c.isUpper then Color.White else Color.Black
       Piece(color, charToPieceType(c.toLower))
     }
@@ -29,8 +29,9 @@ object FenParserCombinators extends RegexParsers with GameContextImport:
 
   private def rankTokens: Parser[List[RankToken]] = rep1(rankToken)
 
-  /** Parse rank string for a given Rank, producing (Square, Piece) pairs.
-   *  Fails if total file count != 8 or any piece placement exceeds board bounds. */
+  /** Parse rank string for a given Rank, producing (Square, Piece) pairs. Fails if total file count != 8 or any piece
+    * placement exceeds board bounds.
+    */
   private def rankParser(rank: Rank): Parser[List[(Square, Piece)]] =
     rankTokens >> { tokens =>
       buildSquares(rank, tokens) match
@@ -45,16 +46,15 @@ object FenParserCombinators extends RegexParsers with GameContextImport:
   /** Parse all 8 rank strings separated by '/', rank 8 down to rank 1. */
   private def boardParser: Parser[Board] =
     rankParser(Rank.R8) ~
-    (rankSep ~> rankParser(Rank.R7)) ~
-    (rankSep ~> rankParser(Rank.R6)) ~
-    (rankSep ~> rankParser(Rank.R5)) ~
-    (rankSep ~> rankParser(Rank.R4)) ~
-    (rankSep ~> rankParser(Rank.R3)) ~
-    (rankSep ~> rankParser(Rank.R2)) ~
-    (rankSep ~> rankParser(Rank.R1)) ^^ {
-      case r8 ~ r7 ~ r6 ~ r5 ~ r4 ~ r3 ~ r2 ~ r1 =>
+      (rankSep ~> rankParser(Rank.R7)) ~
+      (rankSep ~> rankParser(Rank.R6)) ~
+      (rankSep ~> rankParser(Rank.R5)) ~
+      (rankSep ~> rankParser(Rank.R4)) ~
+      (rankSep ~> rankParser(Rank.R3)) ~
+      (rankSep ~> rankParser(Rank.R2)) ~
+      (rankSep ~> rankParser(Rank.R1)) ^^ { case r8 ~ r7 ~ r6 ~ r5 ~ r4 ~ r3 ~ r2 ~ r1 =>
         Board((r8 ++ r7 ++ r6 ++ r5 ++ r4 ++ r3 ++ r2 ++ r1).toMap)
-    }
+      }
 
   // ── Color parser ─────────────────────────────────────────────────────────
 
@@ -68,20 +68,20 @@ object FenParserCombinators extends RegexParsers with GameContextImport:
 
   private def castlingParser: Parser[CastlingRights] =
     "-" ^^^ CastlingRights.None |
-    "[KQkq]{1,4}".r ^^ { s =>
-      CastlingRights(
-        whiteKingSide  = s.contains('K'),
-        whiteQueenSide = s.contains('Q'),
-        blackKingSide  = s.contains('k'),
-        blackQueenSide = s.contains('q')
-      )
-    }
+      "[KQkq]{1,4}".r ^^ { s =>
+        CastlingRights(
+          whiteKingSide = s.contains('K'),
+          whiteQueenSide = s.contains('Q'),
+          blackKingSide = s.contains('k'),
+          blackQueenSide = s.contains('q'),
+        )
+      }
 
   // ── En passant parser ────────────────────────────────────────────────────
 
   private def enPassantParser: Parser[Option[Square]] =
     "-" ^^^ Option.empty[Square] |
-    "[a-h][1-8]".r ^^ { s => Square.fromAlgebraic(s) }
+      "[a-h][1-8]".r ^^ { s => Square.fromAlgebraic(s) }
 
   // ── Clock parser ─────────────────────────────────────────────────────────
 
@@ -92,17 +92,17 @@ object FenParserCombinators extends RegexParsers with GameContextImport:
 
   private def fenParser: Parser[GameContext] =
     boardParser ~ (" " ~> colorParser) ~ (" " ~> castlingParser) ~
-    (" " ~> enPassantParser) ~ (" " ~> clockParser) ~ (" " ~> clockParser) ^^ {
-      case board ~ color ~ castling ~ ep ~ halfMove ~ _ =>
-        GameContext(
-          board          = board,
-          turn           = color,
-          castlingRights = castling,
-          enPassantSquare = ep,
-          halfMoveClock  = halfMove,
-          moves          = List.empty
-        )
-    }
+      (" " ~> enPassantParser) ~ (" " ~> clockParser) ~ (" " ~> clockParser) ^^ {
+        case board ~ color ~ castling ~ ep ~ halfMove ~ _ =>
+          GameContext(
+            board = board,
+            turn = color,
+            castlingRights = castling,
+            enPassantSquare = ep,
+            halfMoveClock = halfMove,
+            moves = List.empty,
+          )
+      }
 
   // ── Public API ───────────────────────────────────────────────────────────
 

modules/io/src/main/scala/de/nowchess/io/fen/FenParserFastParse.scala

@@ -13,7 +13,7 @@ object FenParserFastParse extends GameContextImport:
 
   private def pieceChar(using P[Any]): P[Piece] =
     CharIn("prnbqkPRNBQK").!.map { s =>
-      val c = s.head
+      val c     = s.head
       val color = if c.isUpper then Color.White else Color.Black
       Piece(color, charToPieceType(c.toLower))
     }
@@ -39,13 +39,13 @@ object FenParserFastParse extends GameContextImport:
 
   private def boardParser(using P[Any]): P[Board] =
     (rankParser(Rank.R8) ~ sep ~
-     rankParser(Rank.R7) ~ sep ~
-     rankParser(Rank.R6) ~ sep ~
-     rankParser(Rank.R5) ~ sep ~
-     rankParser(Rank.R4) ~ sep ~
-     rankParser(Rank.R3) ~ sep ~
-     rankParser(Rank.R2) ~ sep ~
-     rankParser(Rank.R1)).map { case (r8, r7, r6, r5, r4, r3, r2, r1) =>
+      rankParser(Rank.R7) ~ sep ~
+      rankParser(Rank.R6) ~ sep ~
+      rankParser(Rank.R5) ~ sep ~
+      rankParser(Rank.R4) ~ sep ~
+      rankParser(Rank.R3) ~ sep ~
+      rankParser(Rank.R2) ~ sep ~
+      rankParser(Rank.R1)).map { case (r8, r7, r6, r5, r4, r3, r2, r1) =>
       Board((r8 ++ r7 ++ r6 ++ r5 ++ r4 ++ r3 ++ r2 ++ r1).toMap)
     }
 
@@ -61,20 +61,20 @@ object FenParserFastParse extends GameContextImport:
 
   private def castlingParser(using P[Any]): P[CastlingRights] =
     LiteralStr("-").map(_ => CastlingRights.None) |
-    CharsWhileIn("KQkq").!.map { s =>
-      CastlingRights(
-        whiteKingSide  = s.contains('K'),
-        whiteQueenSide = s.contains('Q'),
-        blackKingSide  = s.contains('k'),
-        blackQueenSide = s.contains('q')
-      )
-    }
+      CharsWhileIn("KQkq").!.map { s =>
+        CastlingRights(
+          whiteKingSide = s.contains('K'),
+          whiteQueenSide = s.contains('Q'),
+          blackKingSide = s.contains('k'),
+          blackQueenSide = s.contains('q'),
+        )
+      }
 
   // ── En passant parser ────────────────────────────────────────────────────
 
   private def enPassantParser(using P[Any]): P[Option[Square]] =
     LiteralStr("-").map(_ => Option.empty[Square]) |
-    (CharIn("a-h") ~ CharIn("1-8")).!.map(s => Square.fromAlgebraic(s))
+      (CharIn("a-h") ~ CharIn("1-8")).!.map(s => Square.fromAlgebraic(s))
 
   // ── Clock parser ─────────────────────────────────────────────────────────
 
@@ -89,15 +89,15 @@ object FenParserFastParse extends GameContextImport:
 
   private def fenParser(using P[Any]): P[GameContext] =
     (boardParser ~ sp ~ colorParser ~ sp ~ castlingParser ~ sp ~
-     enPassantParser ~ sp ~ clockParser ~ sp ~ clockParser ~ End).map {
+      enPassantParser ~ sp ~ clockParser ~ sp ~ clockParser ~ End).map {
       case (board, color, castling, ep, halfMove, _) =>
         GameContext(
-          board           = board,
-          turn            = color,
-          castlingRights  = castling,
+          board = board,
+          turn = color,
+          castlingRights = castling,
           enPassantSquare = ep,
-          halfMoveClock   = halfMove,
-          moves           = List.empty
+          halfMoveClock = halfMove,
+          moves = List.empty,
         )
     }
 

modules/io/src/main/scala/de/nowchess/io/fen/FenParserSupport.scala

@@ -14,19 +14,20 @@ private[fen] object FenParserSupport:
     'n' -> PieceType.Knight,
     'b' -> PieceType.Bishop,
     'q' -> PieceType.Queen,
-    'k' -> PieceType.King
+    'k' -> PieceType.King,
   )
 
   def buildSquares(rank: Rank, tokens: Seq[RankToken]): Option[List[(Square, Piece)]] =
-    tokens.foldLeft(Option((List.empty[(Square, Piece)], 0))):
-      case (None, _) => None
-      case (Some((acc, fileIdx)), PieceToken(piece)) =>
-        if fileIdx > 7 then None
-        else
-          val sq = Square(File.values(fileIdx), rank)
-          Some((acc :+ (sq -> piece), fileIdx + 1))
-      case (Some((acc, fileIdx)), EmptyToken(n)) =>
-        val next = fileIdx + n
-        if next > 8 then None
-        else Some((acc, next))
-    .flatMap { case (squares, total) => if total == 8 then Some(squares) else None }
+    tokens
+      .foldLeft(Option((List.empty[(Square, Piece)], 0))):
+        case (None, _) => None
+        case (Some((acc, fileIdx)), PieceToken(piece)) =>
+          if fileIdx > 7 then None
+          else
+            val sq = Square(File.values(fileIdx), rank)
+            Some((acc :+ (sq -> piece), fileIdx + 1))
+        case (Some((acc, fileIdx)), EmptyToken(n)) =>
+          val next = fileIdx + n
+          if next > 8 then None
+          else Some((acc, next))
+      .flatMap { case (squares, total) => if total == 8 then Some(squares) else None }

modules/io/src/main/scala/de/nowchess/io/pgn/PgnExporter.scala

@@ -11,39 +11,38 @@ object PgnExporter extends GameContextExport:
   /** Export a GameContext to PGN format. */
   def exportGameContext(context: GameContext): String =
     val headers = Map(
-      "Event" -> "?",
-      "White" -> "?",
-      "Black" -> "?",
-      "Result" -> "*"
+      "Event"  -> "?",
+      "White"  -> "?",
+      "Black"  -> "?",
+      "Result" -> "*",
     )
 
     exportGame(headers, context.moves)
 
   /** Export a game with headers and moves to PGN format. */
   def exportGame(headers: Map[String, String], moves: List[Move]): String =
-    val headerLines = headers.map { case (key, value) =>
-      s"""[$key "$value"]"""
-    }.mkString("\n")
-
-    val moveText = if moves.isEmpty then ""
-    else
-      var ctx = GameContext.initial
-      val sanMoves = moves.map { move =>
-        val algebraic = moveToAlgebraic(move, ctx.board)
-        ctx = DefaultRules.applyMove(ctx)(move)
-        algebraic
+    val headerLines = headers
+      .map { case (key, value) =>
+        s"""[$key "$value"]"""
       }
+      .mkString("\n")
 
-      val groupedMoves = sanMoves.zipWithIndex.groupBy(_._2 / 2)
-      val moveLines = for (moveNumber, movePairs) <- groupedMoves.toList.sortBy(_._1) yield
-        val moveNum = moveNumber + 1
-        val whiteMoveStr = movePairs.find(_._2 % 2 == 0).map(_._1).getOrElse("")
-        val blackMoveStr = movePairs.find(_._2 % 2 == 1).map(_._1).getOrElse("")
-        if blackMoveStr.isEmpty then s"$moveNum. $whiteMoveStr"
-        else s"$moveNum. $whiteMoveStr $blackMoveStr"
+    val moveText =
+      if moves.isEmpty then ""
+      else
+        val contexts = moves.scanLeft(GameContext.initial)((ctx, move) => DefaultRules.applyMove(ctx)(move))
+        val sanMoves = moves.zip(contexts).map { case (move, ctx) => moveToAlgebraic(move, ctx.board) }
 
-      val termination = headers.getOrElse("Result", "*")
-      moveLines.mkString(" ") + s" $termination"
+        val groupedMoves = sanMoves.zipWithIndex.groupBy(_._2 / 2)
+        val moveLines = for (moveNumber, movePairs) <- groupedMoves.toList.sortBy(_._1) yield
+          val moveNum      = moveNumber + 1
+          val whiteMoveStr = movePairs.find(_._2 % 2 == 0).map(_._1).getOrElse("")
+          val blackMoveStr = movePairs.find(_._2 % 2 == 1).map(_._1).getOrElse("")
+          if blackMoveStr.isEmpty then s"$moveNum. $whiteMoveStr"
+          else s"$moveNum. $whiteMoveStr $blackMoveStr"
+
+        val termination = headers.getOrElse("Result", "*")
+        moveLines.mkString(" ") + s" $termination"
 
     if headerLines.isEmpty then moveText
     else if moveText.isEmpty then headerLines
@@ -55,7 +54,7 @@ object PgnExporter extends GameContextExport:
       case MoveType.CastleKingside  => "O-O"
       case MoveType.CastleQueenside => "O-O-O"
       case MoveType.EnPassant       => s"${move.from.file.toString.toLowerCase}x${move.to}"
-      case MoveType.Promotion(pp)   =>
+      case MoveType.Promotion(pp) =>
         val promSuffix = pp match
           case PromotionPiece.Queen  => "=Q"
           case PromotionPiece.Rook   => "=R"
@@ -76,5 +75,3 @@ object PgnExporter extends GameContextExport:
           case PieceType.Rook   => s"R$capStr$dest"
           case PieceType.Queen  => s"Q$capStr$dest"
           case PieceType.King   => s"K$capStr$dest"
-
-

modules/io/src/main/scala/de/nowchess/io/pgn/PgnParser.scala

@@ -8,38 +8,40 @@ import de.nowchess.rules.sets.DefaultRules
 
 /** A parsed PGN game containing headers and the resolved move list. */
 case class PgnGame(
-  headers: Map[String, String],
-  moves: List[Move]
+    headers: Map[String, String],
+    moves: List[Move],
 )
 
 object PgnParser extends GameContextImport:
 
-  /** Strictly validate a PGN text.
-   *  Returns Right(PgnGame) if every move token is a legal move in the evolving position.
-   *  Returns Left(error message) on the first illegal or impossible move, or any unrecognised token. */
+  /** Strictly validate a PGN text. Returns Right(PgnGame) if every move token is a legal move in the evolving position.
+    * Returns Left(error message) on the first illegal or impossible move, or any unrecognised token.
+    */
   def validatePgn(pgn: String): Either[String, PgnGame] =
-    val lines = pgn.split("\n").map(_.trim)
+    val lines               = pgn.split("\n").map(_.trim)
     val (headerLines, rest) = lines.span(_.startsWith("["))
-    val headers  = parseHeaders(headerLines)
-    val moveText = rest.mkString(" ")
+    val headers             = parseHeaders(headerLines)
+    val moveText            = rest.mkString(" ")
     validateMovesText(moveText).map(moves => PgnGame(headers, moves))
 
-  /** Import a PGN text into a GameContext by validating and replaying all moves.
-   *  Returns Right(GameContext) with all moves applied and .moves populated.
-   *  Returns Left(error message) if validation fails or move replay encounters an issue. */
+  /** Import a PGN text into a GameContext by validating and replaying all moves. Returns Right(GameContext) with all
+    * moves applied and .moves populated. Returns Left(error message) if validation fails or move replay encounters an
+    * issue.
+    */
   def importGameContext(input: String): Either[String, GameContext] =
     validatePgn(input).flatMap { game =>
       Right(game.moves.foldLeft(GameContext.initial)((ctx, move) => DefaultRules.applyMove(ctx)(move)))
     }
 
-  /** Parse a complete PGN text into a PgnGame with headers and moves.
-   *  Always succeeds (returns Some); malformed tokens are silently skipped. */
+  /** Parse a complete PGN text into a PgnGame with headers and moves. Always succeeds (returns Some); malformed tokens
+    * are silently skipped.
+    */
   def parsePgn(pgn: String): Option[PgnGame] =
-    val lines = pgn.split("\n").map(_.trim)
+    val lines               = pgn.split("\n").map(_.trim)
     val (headerLines, rest) = lines.span(_.startsWith("["))
-    val headers  = parseHeaders(headerLines)
-    val moveText = rest.mkString(" ")
-    val moves    = parseMovesText(moveText)
+    val headers             = parseHeaders(headerLines)
+    val moveText            = rest.mkString(" ")
+    val moves               = parseMovesText(moveText)
     Some(PgnGame(headers, moves))
 
   /** Parse PGN header lines of the form [Key "Value"]. */
@@ -51,25 +53,25 @@ object PgnParser extends GameContextImport:
   private def parseMovesText(moveText: String): List[Move] =
     val tokens = moveText.split("\\s+").filter(_.nonEmpty)
     val (_, _, moves) = tokens.foldLeft(
-      (GameContext.initial, Color.White, List.empty[Move])
+      (GameContext.initial, Color.White, List.empty[Move]),
     ):
       case (state @ (ctx, color, acc), token) =>
         if isMoveNumberOrResult(token) then state
         else
           parseAlgebraicMove(token, ctx, color) match
-            case None       => state
+            case None => state
             case Some(move) =>
-              val nextCtx    = DefaultRules.applyMove(ctx)(move)
+              val nextCtx = DefaultRules.applyMove(ctx)(move)
               (nextCtx, color.opposite, acc :+ move)
     moves
 
   /** True for move-number tokens ("1.", "12.") and PGN result tokens. */
   private def isMoveNumberOrResult(token: String): Boolean =
     token.matches("""\d+\.""") ||
-    token == "*"               ||
-    token == "1-0"             ||
-    token == "0-1"             ||
-    token == "1/2-1/2"
+      token == "*" ||
+      token == "1-0" ||
+      token == "0-1" ||
+      token == "1/2-1/2"
 
   /** Parse a single algebraic notation token into a Move, given the current game context. */
   def parseAlgebraicMove(notation: String, ctx: GameContext, color: Color): Option[Move] =
@@ -98,47 +100,52 @@ object PgnParser extends GameContextImport:
     if clean.length < 2 then None
     else
       val destStr = clean.takeRight(2)
-      Square.fromAlgebraic(destStr).flatMap: toSquare =>
-        val disambig = clean.dropRight(2)
+      Square
+        .fromAlgebraic(destStr)
+        .flatMap: toSquare =>
+          val disambig = clean.dropRight(2)
 
-        val requiredPieceType: Option[PieceType] =
-          if disambig.nonEmpty && disambig.head.isUpper then charToPieceType(disambig.head)
-          else if clean.head.isUpper then charToPieceType(clean.head)
-          else Some(PieceType.Pawn)
+          val requiredPieceType: Option[PieceType] =
+            if disambig.nonEmpty && disambig.head.isUpper then charToPieceType(disambig.head)
+            else if clean.head.isUpper then charToPieceType(clean.head)
+            else Some(PieceType.Pawn)
 
-        val hint =
-          if disambig.nonEmpty && disambig.head.isUpper then disambig.tail
-          else disambig
+          val hint =
+            if disambig.nonEmpty && disambig.head.isUpper then disambig.tail
+            else disambig
 
-        val promotion = extractPromotion(notation)
+          val promotion = extractPromotion(notation)
 
-        // Get all legal moves for this color that reach toSquare
-        val allLegal = DefaultRules.allLegalMoves(ctx)
-        val candidates = allLegal.filter { move =>
-          move.to == toSquare &&
-          ctx.board.pieceAt(move.from).exists(p =>
-            p.color == color &&
-            requiredPieceType.forall(_ == p.pieceType)
-          ) &&
-          (hint.isEmpty || matchesHint(move.from, hint)) &&
-          promotionMatches(move, promotion)
-        }
+          // Get all legal moves for this color that reach toSquare
+          val allLegal = DefaultRules.allLegalMoves(ctx)
+          val candidates = allLegal.filter { move =>
+            move.to == toSquare &&
+            ctx.board
+              .pieceAt(move.from)
+              .exists(p =>
+                p.color == color &&
+                  requiredPieceType.forall(_ == p.pieceType),
+              ) &&
+            (hint.isEmpty || matchesHint(move.from, hint)) &&
+            promotionMatches(move, promotion)
+          }
 
-        candidates.headOption
+          candidates.headOption
 
   /** True if `sq` matches a disambiguation hint (file letter, rank digit, or both). */
   private def matchesHint(sq: Square, hint: String): Boolean =
     hint.forall(c =>
       if c >= 'a' && c <= 'h' then sq.file.toString.equalsIgnoreCase(c.toString)
       else if c >= '1' && c <= '8' then sq.rank.ordinal == (c - '1')
-      else true
+      else true,
     )
 
   private def promotionMatches(move: Move, promotion: Option[PromotionPiece]): Boolean =
     promotion match
-      case None     => move.moveType match
-                         case MoveType.Normal(_) | MoveType.EnPassant | MoveType.CastleKingside | MoveType.CastleQueenside => true
-                         case _ => false
+      case None =>
+        move.moveType match
+          case MoveType.Normal(_) | MoveType.EnPassant | MoveType.CastleKingside | MoveType.CastleQueenside => true
+          case _                                                                                            => false
       case Some(pp) => move.moveType == MoveType.Promotion(pp)
 
   /** Extract a promotion piece from a notation string containing =Q/=R/=B/=N. */
@@ -168,17 +175,18 @@ object PgnParser extends GameContextImport:
   /** Walk all move tokens, failing immediately on any unresolvable or illegal move. */
   private def validateMovesText(moveText: String): Either[String, List[Move]] =
     val tokens = moveText.split("\\s+").filter(_.nonEmpty)
-    tokens.foldLeft(Right((GameContext.initial, Color.White, List.empty[Move])): Either[String, (GameContext, Color, List[Move])]) {
-      case (acc, token) =>
+    tokens
+      .foldLeft(
+        Right((GameContext.initial, Color.White, List.empty[Move])): Either[String, (GameContext, Color, List[Move])],
+      ) { case (acc, token) =>
         acc.flatMap { case (ctx, color, moves) =>
           if isMoveNumberOrResult(token) then Right((ctx, color, moves))
           else
             parseAlgebraicMove(token, ctx, color) match
-              case None       => Left(s"Illegal or impossible move: '$token'")
+              case None => Left(s"Illegal or impossible move: '$token'")
               case Some(move) =>
-                val nextCtx  = DefaultRules.applyMove(ctx)(move)
+                val nextCtx = DefaultRules.applyMove(ctx)(move)
                 Right((nextCtx, color.opposite, moves :+ move))
         }
-    }.map(_._3)
-
-
+      }
+      .map(_._3)

modules/io/src/test/scala/de/nowchess/io/fen/FenExporterTest.scala

@@ -9,16 +9,18 @@ import org.scalatest.matchers.should.Matchers
 class FenExporterTest extends AnyFunSuite with Matchers:
 
   private def context(
-    piecePlacement: String,
-    turn: Color,
-    castlingRights: CastlingRights,
-    enPassantSquare: Option[Square],
-    halfMoveClock: Int,
-    moveCount: Int
+      piecePlacement: String,
+      turn: Color,
+      castlingRights: CastlingRights,
+      enPassantSquare: Option[Square],
+      halfMoveClock: Int,
+      moveCount: Int,
   ): GameContext =
-    val board = FenParser.parseBoard(piecePlacement).getOrElse(
-      fail(s"Invalid test board FEN: $piecePlacement")
-    )
+    val board = FenParser
+      .parseBoard(piecePlacement)
+      .getOrElse(
+        fail(s"Invalid test board FEN: $piecePlacement"),
+      )
     val dummyMove = Move(Square(File.A, Rank.R2), Square(File.A, Rank.R3))
     GameContext(
       board = board,
@@ -26,7 +28,7 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       castlingRights = castlingRights,
       enPassantSquare = enPassantSquare,
       halfMoveClock = halfMoveClock,
-      moves = List.fill(moveCount)(dummyMove)
+      moves = List.fill(moveCount)(dummyMove),
     )
 
   test("exportGameContextToFen handles initial and typical developed position"):
@@ -39,7 +41,7 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       castlingRights = CastlingRights.All,
       enPassantSquare = Some(Square(File.E, Rank.R3)),
       halfMoveClock = 0,
-      moveCount = 0
+      moveCount = 0,
     )
     FenExporter.gameContextToFen(gameContext) shouldBe
       "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1"
@@ -51,7 +53,7 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       castlingRights = CastlingRights.None,
       enPassantSquare = None,
       halfMoveClock = 0,
-      moveCount = 0
+      moveCount = 0,
     )
     FenExporter.gameContextToFen(noCastling) shouldBe
       "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1"
@@ -63,11 +65,11 @@ class FenExporterTest extends AnyFunSuite with Matchers:
         whiteKingSide = true,
         whiteQueenSide = false,
         blackKingSide = false,
-        blackQueenSide = true
+        blackQueenSide = true,
       ),
       enPassantSquare = None,
       halfMoveClock = 5,
-      moveCount = 4
+      moveCount = 4,
     )
     FenExporter.gameContextToFen(partialCastling) shouldBe
       "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w Kq - 5 3"
@@ -78,7 +80,7 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       castlingRights = CastlingRights.All,
       enPassantSquare = Some(Square(File.C, Rank.R6)),
       halfMoveClock = 2,
-      moveCount = 4
+      moveCount = 4,
     )
     FenExporter.gameContextToFen(withEnPassant) shouldBe
       "rnbqkbnr/pp1ppppp/8/2pP4/8/8/PPPP1PPP/RNBQKBNR w KQkq c6 2 3"
@@ -90,7 +92,7 @@ class FenExporterTest extends AnyFunSuite with Matchers:
       castlingRights = CastlingRights.All,
       enPassantSquare = None,
       halfMoveClock = 42,
-      moves = List.empty
+      moves = List.empty,
     )
     val fen = FenExporter.gameContextToFen(gameContext)
     FenParser.parseFen(fen) match
@@ -101,4 +103,3 @@ class FenExporterTest extends AnyFunSuite with Matchers:
     val ctx = GameContext.initial
 
     FenExporter.exportGameContext(ctx) shouldBe FenExporter.gameContextToFen(ctx)
-

modules/io/src/test/scala/de/nowchess/io/fen/FenParserCombinatorsTest.scala

@@ -8,34 +8,52 @@ class FenParserCombinatorsTest extends AnyFunSuite with Matchers:
 
   test("parseBoard parses canonical positions and supports round-trip"):
     val initial = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"
-    val empty = "8/8/8/8/8/8/8/8"
+    val empty   = "8/8/8/8/8/8/8/8"
     val partial = "8/8/4k3/8/4K3/8/8/8"
 
-    FenParserCombinators.parseBoard(initial).map(_.pieceAt(Square(File.E, Rank.R2))) shouldBe Some(Some(Piece.WhitePawn))
-    FenParserCombinators.parseBoard(initial).map(_.pieceAt(Square(File.E, Rank.R8))) shouldBe Some(Some(Piece.BlackKing))
+    FenParserCombinators.parseBoard(initial).map(_.pieceAt(Square(File.E, Rank.R2))) shouldBe Some(
+      Some(Piece.WhitePawn),
+    )
+    FenParserCombinators.parseBoard(initial).map(_.pieceAt(Square(File.E, Rank.R8))) shouldBe Some(
+      Some(Piece.BlackKing),
+    )
     FenParserCombinators.parseBoard(empty).map(_.pieces.size) shouldBe Some(0)
-    FenParserCombinators.parseBoard(partial).map(_.pieceAt(Square(File.E, Rank.R6))) shouldBe Some(Some(Piece.BlackKing))
+    FenParserCombinators.parseBoard(partial).map(_.pieceAt(Square(File.E, Rank.R6))) shouldBe Some(
+      Some(Piece.BlackKing),
+    )
 
     FenParserCombinators.parseBoard(initial).map(FenExporter.boardToFen) shouldBe Some(initial)
     FenParserCombinators.parseBoard(empty).map(FenExporter.boardToFen) shouldBe Some(empty)
 
   test("parseFen parses full state for common valid inputs"):
-    FenParserCombinators.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1").fold(_ => fail(), ctx =>
-      ctx.turn shouldBe Color.White
-      ctx.castlingRights.whiteKingSide shouldBe true
-      ctx.enPassantSquare shouldBe None
-      ctx.halfMoveClock shouldBe 0
-    )
+    FenParserCombinators
+      .parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1")
+      .fold(
+        _ => fail(),
+        ctx =>
+          ctx.turn shouldBe Color.White
+          ctx.castlingRights.whiteKingSide shouldBe true
+          ctx.enPassantSquare shouldBe None
+          ctx.halfMoveClock shouldBe 0,
+      )
 
-    FenParserCombinators.parseFen("rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1").fold(_ => fail(), ctx =>
-      ctx.turn shouldBe Color.Black
-      ctx.enPassantSquare shouldBe Some(Square(File.E, Rank.R3))
-    )
+    FenParserCombinators
+      .parseFen("rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1")
+      .fold(
+        _ => fail(),
+        ctx =>
+          ctx.turn shouldBe Color.Black
+          ctx.enPassantSquare shouldBe Some(Square(File.E, Rank.R3)),
+      )
 
-    FenParserCombinators.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1").fold(_ => fail(), ctx =>
-      ctx.castlingRights.whiteKingSide shouldBe false
-      ctx.castlingRights.blackQueenSide shouldBe false
-    )
+    FenParserCombinators
+      .parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1")
+      .fold(
+        _ => fail(),
+        ctx =>
+          ctx.castlingRights.whiteKingSide shouldBe false
+          ctx.castlingRights.blackQueenSide shouldBe false,
+      )
 
   test("parseFen rejects invalid color and castling tokens"):
     FenParserCombinators.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR x KQkq - 0 1").isLeft shouldBe true

modules/io/src/test/scala/de/nowchess/io/fen/FenParserFastParseTest.scala

@@ -8,7 +8,7 @@ class FenParserFastParseTest extends AnyFunSuite with Matchers:
 
   test("parseBoard parses canonical positions and supports round-trip"):
     val initial = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"
-    val empty = "8/8/8/8/8/8/8/8"
+    val empty   = "8/8/8/8/8/8/8/8"
     val partial = "8/8/4k3/8/4K3/8/8/8"
 
     FenParserFastParse.parseBoard(initial).map(_.pieceAt(Square(File.E, Rank.R2))) shouldBe Some(Some(Piece.WhitePawn))
@@ -20,22 +20,34 @@ class FenParserFastParseTest extends AnyFunSuite with Matchers:
     FenParserFastParse.parseBoard(empty).map(FenExporter.boardToFen) shouldBe Some(empty)
 
   test("parseFen parses full state for common valid inputs"):
-    FenParserFastParse.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1").fold(_ => fail(), ctx =>
-      ctx.turn shouldBe Color.White
-      ctx.castlingRights.whiteKingSide shouldBe true
-      ctx.enPassantSquare shouldBe None
-      ctx.halfMoveClock shouldBe 0
-    )
+    FenParserFastParse
+      .parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1")
+      .fold(
+        _ => fail(),
+        ctx =>
+          ctx.turn shouldBe Color.White
+          ctx.castlingRights.whiteKingSide shouldBe true
+          ctx.enPassantSquare shouldBe None
+          ctx.halfMoveClock shouldBe 0,
+      )
 
-    FenParserFastParse.parseFen("rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1").fold(_ => fail(), ctx =>
-      ctx.turn shouldBe Color.Black
-      ctx.enPassantSquare shouldBe Some(Square(File.E, Rank.R3))
-    )
+    FenParserFastParse
+      .parseFen("rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1")
+      .fold(
+        _ => fail(),
+        ctx =>
+          ctx.turn shouldBe Color.Black
+          ctx.enPassantSquare shouldBe Some(Square(File.E, Rank.R3)),
+      )
 
-    FenParserFastParse.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1").fold(_ => fail(), ctx =>
-      ctx.castlingRights.whiteKingSide shouldBe false
-      ctx.castlingRights.blackQueenSide shouldBe false
-    )
+    FenParserFastParse
+      .parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1")
+      .fold(
+        _ => fail(),
+        ctx =>
+          ctx.castlingRights.whiteKingSide shouldBe false
+          ctx.castlingRights.blackQueenSide shouldBe false,
+      )
 
   test("parseFen rejects invalid color and castling tokens"):
     FenParserFastParse.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR x KQkq - 0 1").isLeft shouldBe true

modules/io/src/test/scala/de/nowchess/io/fen/FenParserTest.scala

@@ -8,7 +8,7 @@ class FenParserTest extends AnyFunSuite with Matchers:
 
   test("parseBoard parses canonical positions and supports round-trip"):
     val initial = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"
-    val empty = "8/8/8/8/8/8/8/8"
+    val empty   = "8/8/8/8/8/8/8/8"
     val partial = "8/8/4k3/8/4K3/8/8/8"
 
     FenParser.parseBoard(initial).map(_.pieceAt(Square(File.E, Rank.R2))) shouldBe Some(Some(Piece.WhitePawn))
@@ -20,22 +20,34 @@ class FenParserTest extends AnyFunSuite with Matchers:
     FenParser.parseBoard(empty).map(FenExporter.boardToFen) shouldBe Some(empty)
 
   test("parseFen parses full state for common valid inputs"):
-    FenParser.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1").fold(_ => fail(), ctx =>
-      ctx.turn shouldBe Color.White
-      ctx.castlingRights.whiteKingSide shouldBe true
-      ctx.enPassantSquare shouldBe None
-      ctx.halfMoveClock shouldBe 0
-    )
+    FenParser
+      .parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1")
+      .fold(
+        _ => fail(),
+        ctx =>
+          ctx.turn shouldBe Color.White
+          ctx.castlingRights.whiteKingSide shouldBe true
+          ctx.enPassantSquare shouldBe None
+          ctx.halfMoveClock shouldBe 0,
+      )
 
-    FenParser.parseFen("rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1").fold(_ => fail(), ctx =>
-      ctx.turn shouldBe Color.Black
-      ctx.enPassantSquare shouldBe Some(Square(File.E, Rank.R3))
-    )
+    FenParser
+      .parseFen("rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1")
+      .fold(
+        _ => fail(),
+        ctx =>
+          ctx.turn shouldBe Color.Black
+          ctx.enPassantSquare shouldBe Some(Square(File.E, Rank.R3)),
+      )
 
-    FenParser.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1").fold(_ => fail(), ctx =>
-      ctx.castlingRights.whiteKingSide shouldBe false
-      ctx.castlingRights.blackQueenSide shouldBe false
-    )
+    FenParser
+      .parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1")
+      .fold(
+        _ => fail(),
+        ctx =>
+          ctx.castlingRights.whiteKingSide shouldBe false
+          ctx.castlingRights.blackQueenSide shouldBe false,
+      )
 
   test("parseFen rejects invalid color and castling tokens"):
     FenParser.parseFen("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR x KQkq - 0 1").isLeft shouldBe true
@@ -52,4 +64,3 @@ class FenParserTest extends AnyFunSuite with Matchers:
     FenParser.parseBoard("8p/8/8/8/8/8/8/8") shouldBe None
     FenParser.parseBoard("7/8/8/8/8/8/8/8") shouldBe None
     FenParser.parseBoard("8/8/8/8/8/8/8/7X") shouldBe None
-

modules/io/src/test/scala/de/nowchess/io/pgn/PgnExporterTest.scala

@@ -9,7 +9,7 @@ import org.scalatest.matchers.should.Matchers
 class PgnExporterTest extends AnyFunSuite with Matchers:
 
   test("exportGame renders headers and basic move text"):
-    val headers = Map("Event" -> "Test", "White" -> "A", "Black" -> "B")
+    val headers  = Map("Event" -> "Test", "White" -> "A", "Black" -> "B")
     val emptyPgn = PgnExporter.exportGame(headers, List.empty)
     emptyPgn.contains("[Event \"Test\"]") shouldBe true
     emptyPgn.contains("[White \"A\"]") shouldBe true
@@ -19,13 +19,19 @@ class PgnExporterTest extends AnyFunSuite with Matchers:
     PgnExporter.exportGame(headers, moves).contains("1. e4") shouldBe true
 
   test("exportGame renders castling grouping and result markers"):
-    PgnExporter.exportGame(Map("Event" -> "Test"), List(Move(Square(File.E, Rank.R1), Square(File.G, Rank.R1), MoveType.CastleKingside))) should include("O-O")
-    PgnExporter.exportGame(Map("Event" -> "Test"), List(Move(Square(File.E, Rank.R1), Square(File.C, Rank.R1), MoveType.CastleQueenside))) should include("O-O-O")
+    PgnExporter.exportGame(
+      Map("Event" -> "Test"),
+      List(Move(Square(File.E, Rank.R1), Square(File.G, Rank.R1), MoveType.CastleKingside)),
+    ) should include("O-O")
+    PgnExporter.exportGame(
+      Map("Event" -> "Test"),
+      List(Move(Square(File.E, Rank.R1), Square(File.C, Rank.R1), MoveType.CastleQueenside)),
+    ) should include("O-O-O")
 
     val seq = List(
       Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal()),
       Move(Square(File.C, Rank.R7), Square(File.C, Rank.R5), MoveType.Normal()),
-      Move(Square(File.G, Rank.R1), Square(File.F, Rank.R3), MoveType.Normal())
+      Move(Square(File.G, Rank.R1), Square(File.F, Rank.R3), MoveType.Normal()),
     )
     val grouped = PgnExporter.exportGame(Map("Result" -> "1-0"), seq)
     grouped should include("1. e4 c5")
@@ -37,23 +43,24 @@ class PgnExporterTest extends AnyFunSuite with Matchers:
 
   test("exportGame handles promotion suffixes and normal move formatting"):
     List(
-      PromotionPiece.Queen -> "=Q",
-      PromotionPiece.Rook -> "=R",
+      PromotionPiece.Queen  -> "=Q",
+      PromotionPiece.Rook   -> "=R",
       PromotionPiece.Bishop -> "=B",
-      PromotionPiece.Knight -> "=N"
+      PromotionPiece.Knight -> "=N",
     ).foreach { (piece, suffix) =>
       val move = Move(Square(File.E, Rank.R7), Square(File.E, Rank.R8), MoveType.Promotion(piece))
       PgnExporter.exportGame(Map.empty, List(move)) should include(s"e8$suffix")
     }
 
-    val normal = PgnExporter.exportGame(Map.empty, List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal())))
+    val normal =
+      PgnExporter.exportGame(Map.empty, List(Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal())))
     normal should include("e4")
     normal should not include "="
 
   test("exportGameContext preserves moves and default headers"):
     val moves = List(
       Move(Square(File.E, Rank.R2), Square(File.E, Rank.R4), MoveType.Normal()),
-      Move(Square(File.E, Rank.R7), Square(File.E, Rank.R5), MoveType.Normal())
+      Move(Square(File.E, Rank.R7), Square(File.E, Rank.R5), MoveType.Normal()),
     )
     val withMoves = PgnExporter.exportGameContext(GameContext.initial.copy(moves = moves))
     withMoves.contains("e4") shouldBe true
@@ -78,7 +85,7 @@ class PgnExporterTest extends AnyFunSuite with Matchers:
       Move(sq("c7"), sq("c6")),
       Move(sq("d1"), sq("d7"), MoveType.Normal(true)),
       Move(sq("d8"), sq("d7"), MoveType.Normal(true)),
-      Move(sq("e1"), sq("e2"), MoveType.Normal(true))
+      Move(sq("e1"), sq("e2"), MoveType.Normal(true)),
     )
 
     val pgn = PgnExporter.exportGame(Map("Result" -> "*"), moves)
@@ -91,18 +98,17 @@ class PgnExporterTest extends AnyFunSuite with Matchers:
     pgn should include("Kxe2")
 
   test("exportGame emits en-passant and promotion capture notation"):
-    val enPassant = Move(sq("e2"), sq("d3"), MoveType.EnPassant)
-    val promotionCapture = Move(sq("e7"), sq("f8"), MoveType.Promotion(PromotionPiece.Queen))
-    val pawnCapture = Move(sq("e2"), sq("d3"), MoveType.Normal(isCapture = true))
+    val enPassant           = Move(sq("e2"), sq("d3"), MoveType.EnPassant)
+    val promotionCapture    = Move(sq("e7"), sq("f8"), MoveType.Promotion(PromotionPiece.Queen))
+    val pawnCapture         = Move(sq("e2"), sq("d3"), MoveType.Normal(isCapture = true))
     val promotionQuietSetup = Move(sq("e8"), sq("e7"))
-    val promotionQuiet = Move(sq("e2"), sq("e8"), MoveType.Promotion(PromotionPiece.Queen))
+    val promotionQuiet      = Move(sq("e2"), sq("e8"), MoveType.Promotion(PromotionPiece.Queen))
 
-    val pgn = PgnExporter.exportGame(Map.empty, List(enPassant, promotionCapture))
-    val pawnCapturePgn = PgnExporter.exportGame(Map.empty, List(pawnCapture))
+    val pgn               = PgnExporter.exportGame(Map.empty, List(enPassant, promotionCapture))
+    val pawnCapturePgn    = PgnExporter.exportGame(Map.empty, List(pawnCapture))
     val quietPromotionPgn = PgnExporter.exportGame(Map.empty, List(promotionQuietSetup, promotionQuiet))
 
     pgn should include("exd3")
     pgn should include("exf8=Q")
     pawnCapturePgn should include("exd3")
     quietPromotionPgn should include("e8=Q")
-

modules/io/src/test/scala/de/nowchess/io/pgn/PgnParserTest.scala

@@ -10,7 +10,7 @@ import org.scalatest.matchers.should.Matchers
 class PgnParserTest extends AnyFunSuite with Matchers:
 
   test("parsePgn handles headers standard sequences captures castling and skipped tokens"):
-    val headerOnly = """[Event "Test Game"]
+    val headerOnly  = """[Event "Test Game"]
 [White "Alice"]
 [Black "Bob"]
 [Result "1-0"]"""
@@ -30,72 +30,116 @@ class PgnParserTest extends AnyFunSuite with Matchers:
     capture.map(_.moves.length) shouldBe Some(3)
     capture.get.moves(2).to shouldBe Square(File.E, Rank.R5)
 
-    val whiteKs = PgnParser.parsePgn("""[Event "Test"]
+    val whiteKs = PgnParser
+      .parsePgn("""[Event "Test"]
 
-1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. O-O""").get.moves.last
+1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. O-O""")
+      .get
+      .moves
+      .last
     whiteKs.moveType shouldBe MoveType.CastleKingside
     whiteKs.from shouldBe Square(File.E, Rank.R1)
     whiteKs.to shouldBe Square(File.G, Rank.R1)
 
-    val whiteQs = PgnParser.parsePgn("""[Event "Test"]
+    val whiteQs = PgnParser
+      .parsePgn("""[Event "Test"]
 
-1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O""").get.moves.last
+1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O""")
+      .get
+      .moves
+      .last
     whiteQs.moveType shouldBe MoveType.CastleQueenside
     whiteQs.from shouldBe Square(File.E, Rank.R1)
     whiteQs.to shouldBe Square(File.C, Rank.R1)
 
-    val blackKs = PgnParser.parsePgn("""[Event "Test"]
+    val blackKs = PgnParser
+      .parsePgn("""[Event "Test"]
 
-1. e4 e5 2. Nf3 Nf6 3. Bc4 Be7 4. O-O O-O""").get.moves.last
+1. e4 e5 2. Nf3 Nf6 3. Bc4 Be7 4. O-O O-O""")
+      .get
+      .moves
+      .last
     blackKs.moveType shouldBe MoveType.CastleKingside
     blackKs.from shouldBe Square(File.E, Rank.R8)
 
-    val blackQs = PgnParser.parsePgn("""[Event "Test"]
+    val blackQs = PgnParser
+      .parsePgn("""[Event "Test"]
 
-1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O O-O-O""").get.moves.last
+1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O O-O-O""")
+      .get
+      .moves
+      .last
     blackQs.moveType shouldBe MoveType.CastleQueenside
     blackQs.from shouldBe Square(File.E, Rank.R8)
     blackQs.to shouldBe Square(File.C, Rank.R8)
 
-    PgnParser.parsePgn("""[Event "Test"]
+    PgnParser
+      .parsePgn("""[Event "Test"]
 
-1. e4 e5 1-0""").map(_.moves.length) shouldBe Some(2)
-    PgnParser.parsePgn("""[Event "Test"]
+1. e4 e5 1-0""")
+      .map(_.moves.length) shouldBe Some(2)
+    PgnParser
+      .parsePgn("""[Event "Test"]
 
-1. e4 INVALID e5""").map(_.moves.length) shouldBe Some(2)
+1. e4 INVALID e5""")
+      .map(_.moves.length) shouldBe Some(2)
 
   test("parseAlgebraicMove resolves pawn knight king and disambiguation cases"):
     val board = Board.initial
-    PgnParser.parseAlgebraicMove("e4", GameContext.initial.withBoard(board), Color.White).get.to shouldBe Square(File.E, Rank.R4)
-    PgnParser.parseAlgebraicMove("Nf3", GameContext.initial.withBoard(board), Color.White).get.to shouldBe Square(File.F, Rank.R3)
+    PgnParser.parseAlgebraicMove("e4", GameContext.initial.withBoard(board), Color.White).get.to shouldBe Square(
+      File.E,
+      Rank.R4,
+    )
+    PgnParser.parseAlgebraicMove("Nf3", GameContext.initial.withBoard(board), Color.White).get.to shouldBe Square(
+      File.F,
+      Rank.R3,
+    )
 
     val rookPieces: Map[Square, Piece] = Map(
       Square(File.A, Rank.R1) -> Piece(Color.White, PieceType.Rook),
       Square(File.H, Rank.R1) -> Piece(Color.White, PieceType.Rook),
       Square(File.E, Rank.R1) -> Piece(Color.White, PieceType.King),
-      Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King)
+      Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King),
     )
     val rankPieces: Map[Square, Piece] = Map(
       Square(File.A, Rank.R1) -> Piece(Color.White, PieceType.Rook),
       Square(File.A, Rank.R4) -> Piece(Color.White, PieceType.Rook),
       Square(File.E, Rank.R1) -> Piece(Color.White, PieceType.King),
-      Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King)
+      Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King),
     )
-    PgnParser.parseAlgebraicMove("Rad1", GameContext.initial.withBoard(Board(rookPieces)), Color.White).get.from shouldBe Square(File.A, Rank.R1)
-    PgnParser.parseAlgebraicMove("R1a3", GameContext.initial.withBoard(Board(rankPieces)), Color.White).get.from shouldBe Square(File.A, Rank.R1)
+    PgnParser
+      .parseAlgebraicMove("Rad1", GameContext.initial.withBoard(Board(rookPieces)), Color.White)
+      .get
+      .from shouldBe Square(File.A, Rank.R1)
+    PgnParser
+      .parseAlgebraicMove("R1a3", GameContext.initial.withBoard(Board(rankPieces)), Color.White)
+      .get
+      .from shouldBe Square(File.A, Rank.R1)
 
     val kingBoard = FenParser.parseBoard("4k3/8/8/8/8/8/8/4K3").get
-    val king = PgnParser.parseAlgebraicMove("Ke2", GameContext.initial.withBoard(kingBoard), Color.White)
+    val king      = PgnParser.parseAlgebraicMove("Ke2", GameContext.initial.withBoard(kingBoard), Color.White)
     king.isDefined shouldBe true
     king.get.from shouldBe Square(File.E, Rank.R1)
     king.get.to shouldBe Square(File.E, Rank.R2)
 
   test("parseAlgebraicMove handles all promotion targets"):
     val board = FenParser.parseBoard("8/4P3/4k3/8/8/8/8/8").get
-    PgnParser.parseAlgebraicMove("e7e8=Q", GameContext.initial.withBoard(board), Color.White).get.moveType shouldBe MoveType.Promotion(PromotionPiece.Queen)
-    PgnParser.parseAlgebraicMove("e7e8=R", GameContext.initial.withBoard(board), Color.White).get.moveType shouldBe MoveType.Promotion(PromotionPiece.Rook)
-    PgnParser.parseAlgebraicMove("e7e8=B", GameContext.initial.withBoard(board), Color.White).get.moveType shouldBe MoveType.Promotion(PromotionPiece.Bishop)
-    PgnParser.parseAlgebraicMove("e7e8=N", GameContext.initial.withBoard(board), Color.White).get.moveType shouldBe MoveType.Promotion(PromotionPiece.Knight)
+    PgnParser
+      .parseAlgebraicMove("e7e8=Q", GameContext.initial.withBoard(board), Color.White)
+      .get
+      .moveType shouldBe MoveType.Promotion(PromotionPiece.Queen)
+    PgnParser
+      .parseAlgebraicMove("e7e8=R", GameContext.initial.withBoard(board), Color.White)
+      .get
+      .moveType shouldBe MoveType.Promotion(PromotionPiece.Rook)
+    PgnParser
+      .parseAlgebraicMove("e7e8=B", GameContext.initial.withBoard(board), Color.White)
+      .get
+      .moveType shouldBe MoveType.Promotion(PromotionPiece.Bishop)
+    PgnParser
+      .parseAlgebraicMove("e7e8=N", GameContext.initial.withBoard(board), Color.White)
+      .get
+      .moveType shouldBe MoveType.Promotion(PromotionPiece.Knight)
 
   test("importGameContext accepts valid and empty PGN"):
     val pgn = """[Event "Test"]
@@ -119,7 +163,7 @@ class PgnParserTest extends AnyFunSuite with Matchers:
     PgnParser.parseAlgebraicMove("Xe5", initial, Color.White) shouldBe None
 
   test("parseAlgebraicMove rejects notation with invalid promotion piece"):
-    val board = FenParser.parseBoard("8/4P3/4k3/8/8/8/8/8").getOrElse(fail("valid board expected"))
+    val board   = FenParser.parseBoard("8/4P3/4k3/8/8/8/8/8").getOrElse(fail("valid board expected"))
     val context = GameContext.initial.withBoard(board)
 
     PgnParser.parseAlgebraicMove("e7e8=X", context, Color.White) shouldBe None
@@ -128,4 +172,3 @@ class PgnParserTest extends AnyFunSuite with Matchers:
     val parsed = PgnParser.parsePgn("1. e4 ??? e5")
 
     parsed.map(_.moves.size) shouldBe Some(2)
-

modules/io/src/test/scala/de/nowchess/io/pgn/PgnValidatorTest.scala

@@ -37,17 +37,20 @@ class PgnValidatorTest extends AnyFunSuite with Matchers:
     qCastle.map(_.moves.last.moveType) shouldBe Right(MoveType.CastleQueenside)
 
   test("validatePgn rejects impossible illegal and garbage tokens"):
-    PgnParser.validatePgn("""[Event "Test"]
+    PgnParser
+      .validatePgn("""[Event "Test"]
 
 1. Qd4
 """).isLeft shouldBe true
 
-    PgnParser.validatePgn("""[Event "Test"]
+    PgnParser
+      .validatePgn("""[Event "Test"]
 
 1. O-O
 """).isLeft shouldBe true
 
-    PgnParser.validatePgn("""[Event "Test"]
+    PgnParser
+      .validatePgn("""[Event "Test"]
 
 1. e4 GARBAGE e5
 """).isLeft shouldBe true
@@ -55,4 +58,3 @@ class PgnValidatorTest extends AnyFunSuite with Matchers:
   test("validatePgn accepts empty move text and minimal valid header"):
     PgnParser.validatePgn("[Event \"Test\"]\n[White \"A\"]\n[Black \"B\"]\n").map(_.moves) shouldBe Right(List.empty)
     PgnParser.validatePgn("[Event \"T\"]\n\n1. e4").isRight shouldBe true
-