Summary
- Added fastparse_3:3.0.2 dependency to modules/io
- Implemented FenParserFastParse as a second alternative FEN parser using FastParse, with the same public API as
FenParser and FenParserCombinators
- Parsers are built bottom-up using (using P[Any]) Scala 3 syntax with NoWhitespace.* to prevent implicit whitespace
skipping; rank sum validation uses Pass/Fail inside .flatMap
- Added FenParserFastParseTest mirroring FenParserCombinatorsTest to prove behavioural equivalence across all three
implementations
Test plan
- All existing tests pass — FenParser, FenParserCombinators, and all other modules untouched
- FenParserFastParseTest covers all cases: valid FEN, invalid color, invalid castling, invalid board shapes, en
passant, rank overflow, round-trip via FenExporter
- All parser logic branches genuinely covered — known scoverage gap documented in docs/unresolved.md (FastParse inline
macro generates synthetic proxy methods that scoverage instruments but that never execute at runtime)
Co-authored-by: LQ63 <lkhermann@web.de>
Reviewed-on: #22
Reviewed-by: Janis <janis-e@gmx.de>
Co-authored-by: Leon Hermann <lq@blackhole.local>
Co-committed-by: Leon Hermann <lq@blackhole.local>
Summary
- Added scala-parser-combinators_3:2.4.0 dependency to modules/io
- Implemented FenParserCombinators as an alternative FEN parser using RegexParsers, with the same public API as the
existing FenParser
- Parsers are built bottom-up: piece characters → rank tokens → rank → board, composed with explicit field separators
into a full FEN parser
- Added FenParserCombinatorsTest mirroring the existing FenParserTest to prove behavioural equivalence
Test plan
- All existing tests pass — FenParser and all other modules untouched
- FenParserCombinatorsTest covers all cases: valid FEN, invalid color, invalid castling, invalid board shapes, en
passant, round-trip via FenExporter
- 100% line/branch/method coverage on FenParserCombinators
Co-authored-by: LQ63 <lkhermann@web.de>
Reviewed-on: #21
Reviewed-by: Janis <janis-e@gmx.de>
Co-authored-by: Leon Hermann <lq@blackhole.local>
Co-committed-by: Leon Hermann <lq@blackhole.local>
Summary
- Curried candidateMoves, legalMoves, and applyMove in the RuleSet trait to separate (context) as the world being
operated on from the computation parameter
- Updated DefaultRules overrides and all internal call sites
- Updated all external call sites: GameEngine, PgnParser, PgnExporter, ChessBoardView, and all affected tests
Test plan
- All existing tests pass (./gradlew build)
- No behaviour changes — pure style refactoring, existing test suite is the regression guard
Co-authored-by: LQ63 <lkhermann@web.de>
Reviewed-on: #18
Reviewed-by: Janis <janis-e@gmx.de>
Co-authored-by: Leon Hermann <lq@blackhole.local>
Co-committed-by: Leon Hermann <lq@blackhole.local>
Summary
- Implements the FIDE 50-move draw rule: a player may claim a draw if no pawn move or capture has occurred in the last
50 full moves (100 half-moves)
- Draw is not automatic — the eligible player must claim it via a TUI menu shown at the start of their turn
- halfMoveClock: Int is threaded through processMove and gameLoop; resets on pawn move, capture, or en passant;
increments on all other moves
Changes
- GameController.scala: extended MoveResult.Moved and MoveResult.MovedInCheck with newHalfMoveClock: Int; added
MoveResult.DrawClaimed; added halfMoveClock parameter to processMove and gameLoop; TUI menu shown when clock ≥ 100
- Main.scala: initial gameLoop call passes halfMoveClock = 0
- GameControllerTest.scala: updated all existing pattern matches; added 10 new tests covering clock reset, clock
increment, draw claim, and TUI menu behaviour
Test plan
- processMove: 'draw' with halfMoveClock = 100 → DrawClaimed
- processMove: 'draw' with halfMoveClock = 99 → InvalidFormat
- Pawn move / capture / en passant → clock resets to 0
- Quiet piece move → clock increments by 1
- MovedInCheck carries updated clock
- TUI menu appears when clock ≥ 100; option 1 claims draw, option 2 continues
- No TUI menu when clock < 100
- All 197 tests passing
Co-authored-by: LQ63 <lkhermann@web.de>
Reviewed-on: #9
Co-authored-by: Leon Hermann <lq@blackhole.local>
Co-committed-by: Leon Hermann <lq@blackhole.local>
- Add EnPassantCalculator to derive the en passant target square from GameHistory, detect en passant captures, and
compute the captured pawn's square
- Extend MoveValidator.legalTargets to include the en passant diagonal square in pawn legal targets
- Extend GameController.processMove to remove the captured pawn from the board when an en passant capture is played
Details
En passant is derived purely from the last HistoryMove — no new state is introduced. If the last move was a double
pawn push, the target square is the square the pawn passed through. The board mutation follows the same pattern as
castling: board.withMove moves the capturing pawn, then board.removed removes the captured pawn from its actual square
(which differs from the destination square).
Test Plan
- EnPassantCalculatorTest — 14 unit tests covering target derivation, captured square calculation, and capture
detection for both colors
- MoveValidatorTest — 5 new tests: ep target included/excluded based on history, adjacency filter, both colors, case _
branch coverage
- GameControllerTest — 2 integration tests: white and black en passant capture removes pawn from board and returns
correct captured piece
- 100% scoverage (line/branch/method) confirmed
Co-authored-by: LQ63 <lkhermann@web.de>
Reviewed-on: #8
Reviewed-by: Janis <janis-e@gmx.de>
Co-authored-by: Leon Hermann <lq@blackhole.local>
Co-committed-by: Leon Hermann <lq@blackhole.local>
## Summary
- Introduces `GameContext` wrapper (board + castling rights) threading through the entire engine pipeline
- Extends `MoveValidator` with `castlingTargets`, context-aware `legalTargets`/`isLegal` overloads, and helpers (`isCastle`, `castleSide`)
- Updates `GameRules.legalMoves` and `gameStatus` to use `GameContext`, preventing false stalemate when castling is the only legal move
- Adds castle detection and atomic execution (`withCastle`) to `GameController.processMove`, plus full rights revocation via source- and
destination-square tables
## Test Plan
- [ ] 142 tests passing, 100% statement and branch coverage on `modules/core`
- [ ] White/Black kingside (e1g1/e8g8) and queenside (e1c1/e8c8) castling moves execute correctly
- [ ] All six legality conditions enforced (rights flags, home squares, empty transit, king not in check, transit/landing squares not attacked)
- [ ] Rights revoked on king moves, own rook moves, castle moves, and enemy rook captures
- [ ] False stalemate correctly prevented when castling is the only escape
Co-authored-by: LQ63 <lkhermann@web.de>
Co-authored-by: Janis <janis.e.20@gmx.de>
Reviewed-on: #1
Reviewed-by: Janis <janis-e@gmx.de>
Co-authored-by: Leon Hermann <lq@blackhole.local>
Co-committed-by: Leon Hermann <lq@blackhole.local>
- Add BlackKing/WhiteKing to capture board in 'legal capture returns Moved'
so the position is not treated as stalemate after the capture.
- Move WhiteKing from A3 to C3 in three MovedInCheck tests so it no
longer blocks the rook's path along file A.
- Remove Console.withOut(System.out) from withInput so it no longer
overrides the ByteArrayOutputStream installed by captureOutput.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Replace stub branches with GameRules.gameStatus dispatch in processMove
and fill in MovedInCheck/Checkmate/Stalemate cases in gameLoop.
Document 6 pre-existing test bugs in docs/unresolved.md.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
TeamCity
lq64
Janis
shosho996