refactor: update CLAUDE.md for improved structure and clarity

refactor: replace StringBuilder/for-loops in render with map/mkString
refactor: replace return/var in castlingTargets with functional style
2026-03-25 08:44:43 +01:00 · 2026-03-25 08:44:43 +01:00 · 2026-03-25 08:44:43 +01:00 · 2026-03-25 08:44:43 +01:00
63 changed files with 727 additions and 4381 deletions
@@ -12,7 +12,7 @@ You write tests for Scala 3 + Quarkus services.
 - Unit tests: `extends AnyFunSuite with Matchers` — use `test("description") { ... }` DSL, no `@Test` annotation, no `: Unit` return type needed.
 - Integration tests: `@QuarkusTest` with JUnit 5 — `@Test` methods MUST be explicitly typed `: Unit`.

-Target 100% conditional coverage if possible.
+Target 95%+ conditional coverage.

 When invoked BEFORE scala-implementer (no implementation exists yet):
  Use the contract-first-test-writing skill — write failing tests from docs/api/{service}.yaml.
@@ -1,9 +0,0 @@
-# Memory Index
-
-## Feedback
- [feedback_keep_structure_updated.md](feedback_keep_structure_updated.md) — Update structure memory files whenever source files are added, removed, or changed
-
-## Project Structure
- [project_structure_root.md](project_structure_root.md) — Top-level layout, modules list, VERSIONS map, navigation rules (skip `build/`, `.gradle/`, `.idea/`)
- [project_structure_api.md](project_structure_api.md) — `modules/api`: all files and types (Board, Piece, Square, GameState, Move, ApiResponse, PlayerInfo)
- [project_structure_core.md](project_structure_core.md) — `modules/core`: all files and types (GameContext, GameRules, MoveValidator, GameController, Parser, Renderer)
@@ -1,16 +0,0 @@
---
-name: keep-structure-memory-updated
-description: Always update the project structure memory files when adding, removing, or changing source files
-type: feedback
---
-
-After any change that adds, removes, renames, or significantly alters a source file, update the relevant structure memory file:
-
- New/renamed/deleted file in `modules/api` → update `project_structure_api.md`
- New/renamed/deleted file in `modules/core` → update `project_structure_core.md`
- New module, dependency version change, or new top-level directory → update `project_structure_root.md`
- New module added → create a new `project_structure_<module>.md` and add it to `MEMORY.md`
-
-**Why:** Structure memories are the primary navigation aid. Stale entries cause wasted exploration.
-
-**How to apply:** Treat the structure memory update as part of completing any implementation task — do it in the same session, not as a follow-up.
@@ -1,51 +0,0 @@
---
-name: module-api-structure
-description: File and type overview for the modules/api module (shared domain types)
-type: project
---
-
-# Module: `modules/api`
-
-**Purpose:** Shared domain model — pure data types with no game logic. Depended on by `modules/core`.
-
-**Gradle:** `id("scala")`, no `application` plugin. No Quarkus. Uses scoverage plugin.
-
-**Package root:** `de.nowchess.api`
-
-## Source files (`src/main/scala/de/nowchess/api/`)
-
-### `board/`
-| File | Contents |
-|------|----------|
-| `Board.scala` | `opaque type Board = Map[Square, Piece]` — extensions: `pieceAt`, `withMove`, `pieces`; `Board.initial` sets up start position |
-| `Color.scala` | `enum Color { White, Black }` — `.opposite`, `.label` |
-| `Piece.scala` | `case class Piece(color, pieceType)` — convenience vals `WhitePawn`…`BlackKing` |
-| `PieceType.scala` | `enum PieceType { Pawn, Knight, Bishop, Rook, Queen, King }` — `.label` |
-| `Square.scala` | `enum File { A–H }`, `enum Rank { R1–R8 }`, `case class Square(file, rank)` — `.toString` algebraic, `Square.fromAlgebraic(s)` |
-
-### `game/`
-| File | Contents |
-|------|----------|
-| `GameState.scala` | `case class CastlingRights(kingSide, queenSide)` + `.None`/`.Both`; `enum GameResult { WhiteWins, BlackWins, Draw }`; `enum GameStatus { NotStarted, InProgress, Finished(result) }`; `case class GameState(piecePlacement, activeColor, castlingWhite, castlingBlack, enPassantTarget, halfMoveClock, fullMoveNumber, status)` — FEN-compatible snapshot |
-
-### `move/`
-| File | Contents |
-|------|----------|
-| `Move.scala` | `enum PromotionPiece { Knight, Bishop, Rook, Queen }`; `enum MoveType { Normal, CastleKingside, CastleQueenside, EnPassant, Promotion(piece) }`; `case class Move(from, to, moveType = Normal)` |
-
-### `player/`
-| File | Contents |
-|------|----------|
-| `PlayerInfo.scala` | `opaque type PlayerId = String`; `case class PlayerInfo(id: PlayerId, displayName: String)` |
-
-### `response/`
-| File | Contents |
-|------|----------|
-| `ApiResponse.scala` | `sealed trait ApiResponse[+A]` → `Success[A](data)` / `Failure(errors)`; `case class ApiError(code, message, field?)`; `case class Pagination(page, pageSize, totalItems)` + `.totalPages`; `case class PagedResponse[A](items, pagination)` |
-
-## Test files (`src/test/scala/de/nowchess/api/`)
-Mirror of main structure — one `*Test.scala` per source file using `AnyFunSuite with Matchers`.
-
-## Notes
- `GameState` is FEN-style but `Board` (in `core`) is a `Map[Square,Piece]` — the two are separate representations
- `CastlingRights` is defined here in `api`; the castling logic lives in `core`
@@ -1,48 +0,0 @@
---
-name: module-core-structure
-description: File and type overview for the modules/core module (TUI chess engine)
-type: project
---
-
-# Module: `modules/core`
-
-**Purpose:** Standalone TUI chess application. All game logic, move validation, rendering. Depends on `modules/api`.
-
-**Gradle:** `id("scala")` + `application` plugin. Main class: `de.nowchess.chess.Main`. Uses scoverage plugin.
-
-**Package root:** `de.nowchess.chess`
-
-## Source files (`src/main/scala/de/nowchess/chess/`)
-
-### Root
-| File | Contents |
-|------|----------|
-| `Main.scala` | Entry point — prints welcome, starts `GameController.gameLoop(GameContext.initial, Color.White)` |
-
-### `controller/`
-| File | Contents |
-|------|----------|
-| `GameController.scala` | `sealed trait MoveResult` ADT: `Quit`, `InvalidFormat`, `NoPiece`, `WrongColor`, `IllegalMove`, `Moved`, `MovedInCheck`, `Checkmate`, `Stalemate`; `object GameController` — `processMove(ctx, turn, raw): MoveResult` (pure), `gameLoop(ctx, turn)` (I/O loop), `applyRightsRevocation(...)` (castling rights bookkeeping) |
-| `Parser.scala` | `object Parser` — `parseMove(input): Option[(Square, Square)]` parses coordinate notation e.g. `"e2e4"` |
-
-### `logic/`
-| File | Contents |
-|------|----------|
-| `GameContext.scala` | `enum CastleSide { Kingside, Queenside }`; `case class GameContext(board, whiteCastling, blackCastling)` — `.castlingFor(color)`, `.withUpdatedRights(color, rights)`; `GameContext.initial`; `extension (Board).withCastle(color, side)` moves king+rook atomically |
-| `GameRules.scala` | `enum PositionStatus { Normal, InCheck, Mated, Drawn }`; `object GameRules` — `isInCheck(board, color)`, `legalMoves(ctx, color): Set[(Square,Square)]`, `gameStatus(ctx, color): PositionStatus` |
-| `MoveValidator.scala` | `object MoveValidator` — `isLegal(board, from, to)`, `legalTargets(board, from): Set[Square]` (board-only, no castling), `legalTargets(ctx, from)` (context-aware, includes castling), `isCastle`, `castleSide`, `castlingTargets(ctx, color)` — full castling legality (empty squares, no check through transit) |
-
-### `view/`
-| File | Contents |
-|------|----------|
-| `Renderer.scala` | `object Renderer` — `render(board): String` outputs ANSI-colored board with file/rank labels |
-| `PieceUnicode.scala` | `extension (Piece).unicode: String` maps each piece to its Unicode chess symbol |
-
-## Test files (`src/test/scala/de/nowchess/chess/`)
-Mirror of main structure — one `*Test.scala` per source file using `AnyFunSuite with Matchers`.
-
-## Key design notes
- `MoveValidator` has two overloaded `legalTargets`: one takes `Board` (geometry only), one takes `GameContext` (adds castling)
- `GameRules.legalMoves` filters by check — it calls `MoveValidator.legalTargets(ctx, from)` then simulates each move
- Castling rights revocation is in `GameController.applyRightsRevocation`, triggered after every move
- No `@QuarkusTest` — this module is a plain Scala application, not a Quarkus service
@@ -1,55 +0,0 @@
---
-name: project-root-structure
-description: Top-level project structure, modules list, and navigation notes for NowChessSystems
-type: project
---
-
-# NowChessSystems — Root Structure
-
-## Directory layout (skip `build/`, `.gradle/`, `.idea/`)
-
-```
-NowChessSystems/
-├── build.gradle.kts          # Root: sonarqube plugin, VERSIONS map
-├── settings.gradle.kts       # include(":modules:core", ":modules:api")
-├── gradlew / gradlew.bat
-├── CLAUDE.md                 # Project instructions for Claude Code
-├── .claude/
-│   ├── CLAUDE.MD             # Working agreement (plan/verify/unresolved)
-│   ├── settings.json
-│   └── agents/               # architect, code-reviewer, gradle-builder, scala-implementer, test-writer
-├── docs/
-│   ├── Claude-Skills.md
-│   ├── Security.md
-│   └── unresolved.md
-├── jacoco-reporter/          # Python scripts for coverage gap reporting
-└── modules/
-    ├── api/                  # Shared domain types (no logic)
-    └── core/                 # TUI chess engine + game logic
-```
-
-## Modules
-
-| Module | Gradle path | Purpose |
-|--------|-------------|---------|
-| `api` | `:modules:api` | Shared domain model: Board, Piece, Move, GameState, ApiResponse |
-| `core` | `:modules:core` | TUI chess app: game logic, move validation, rendering |
-
-`core` depends on `api` via `implementation(project(":modules:api"))`.
-
-## VERSIONS (root `build.gradle.kts`)
-
-| Key | Value |
-|-----|-------|
-| `QUARKUS_SCALA3` | 1.0.0 |
-| `SCALA3` | 3.5.1 |
-| `SCALA_LIBRARY` | 2.13.18 |
-| `SCALATEST` | 3.2.19 |
-| `SCALATEST_JUNIT` | 0.1.11 |
-| `SCOVERAGE` | 2.1.1 |
-
-## Navigation rules
- **Always skip** `build/`, `.gradle/`, `.idea/` when exploring — they are generated artifacts
- Tests use `AnyFunSuite with Matchers` (ScalaTest), not JUnit `@Test`
- No Quarkus in current modules — Quarkus is planned for future services
- Agent workflow: architect → scala-implementer → test-writer → gradle-builder → code-reviewer
@@ -12,7 +12,6 @@
            <option value="$PROJECT_DIR$/modules" />
            <option value="$PROJECT_DIR$/modules/api" />
            <option value="$PROJECT_DIR$/modules/core" />
-            <option value="$PROJECT_DIR$/modules/ui" />
          </set>
        </option>
      </GradleProjectSettings>
@@ -5,7 +5,7 @@
      <option name="deprecationWarnings" value="true" />
      <option name="uncheckedWarnings" value="true" />
    </profile>
-    <profile name="Gradle 2" modules="NowChessSystems.modules.core.main,NowChessSystems.modules.core.scoverage,NowChessSystems.modules.core.test,NowChessSystems.modules.ui.main,NowChessSystems.modules.ui.scoverage,NowChessSystems.modules.ui.test">
+    <profile name="Gradle 2" modules="NowChessSystems.modules.core.main,NowChessSystems.modules.core.scoverage,NowChessSystems.modules.core.test">
      <option name="deprecationWarnings" value="true" />
      <option name="uncheckedWarnings" value="true" />
      <parameters>
@@ -3,10 +3,6 @@
 ## Stack
 Scala 3.5.x · Quarkus + quarkus-scala3 · Hibernate/Jakarta · Lanterna TUI · K8s + ArgoCD + Kargo · Frontend TBD (Vite/React/Angular/Vue)

-### Memory
-
-Your memory is saved under .claude/memory/MEMORY.md.
-
 ## Structure
 ```
 build.gradle.kts / settings.gradle.kts   # root; include(":modules:<svc>") per service
@@ -36,7 +32,7 @@ Versions in root `extra["VERSIONS"]`; modules read via `rootProject.extra["VERSI
 - Integration tests: `@QuarkusTest` + JUnit 5 — `@Test` methods need explicit `: Unit`

 ## Coverage
-Line = 100% · Branch = 100% · Method = 100% · Regression tests · document exceptions
+Line ≥ 95% · Branch ≥ 90% · Method ≥ 90% (document exceptions)
 Check: `jacoco-reporter/scoverage_coverage_gaps.py modules/{svc}/build/reports/scoverageTest/scoverage.xml`
 ⚠️ Use `scoverageTest/`, NOT `scoverage/`.

@@ -1,4 +0,0 @@
-##  (2026-03-27)
-##  (2026-03-28)
-##  (2026-03-28)
-##  (2026-03-29)
@@ -8,12 +8,10 @@ object Board:

  extension (b: Board)
    def pieceAt(sq: Square): Option[Piece] = b.get(sq)
-    def updated(sq: Square, piece: Piece): Board = b.updated(sq, piece)
-    def removed(sq: Square): Board = b.removed(sq)
    def withMove(from: Square, to: Square): (Board, Option[Piece]) =
      val captured = b.get(to)
-      val updatedBoard = b.removed(from).updated(to, b(from))
-      (updatedBoard, captured)
+      val updated  = b.removed(from).updated(to, b(from))
+      (updated, captured)
    def pieces: Map[Square, Piece] = b

  val initial: Board =
@@ -100,23 +100,3 @@ class BoardTest extends AnyFunSuite with Matchers:
    do
      Board.initial.pieceAt(Square(file, rank)) shouldBe None
  }
-
-  test("updated adds or replaces piece at square") {
-    val b = Board(Map(e2 -> Piece.WhitePawn))
-    val updated = b.updated(e4, Piece.WhiteKnight)
-    updated.pieceAt(e2) shouldBe Some(Piece.WhitePawn)
-    updated.pieceAt(e4) shouldBe Some(Piece.WhiteKnight)
-  }
-
-  test("updated replaces existing piece") {
-    val b = Board(Map(e2 -> Piece.WhitePawn))
-    val updated = b.updated(e2, Piece.WhiteKnight)
-    updated.pieceAt(e2) shouldBe Some(Piece.WhiteKnight)
-  }
-
-  test("removed deletes piece from board") {
-    val b = Board(Map(e2 -> Piece.WhitePawn, e4 -> Piece.WhiteKnight))
-    val removed = b.removed(e2)
-    removed.pieceAt(e2) shouldBe None
-    removed.pieceAt(e4) shouldBe Some(Piece.WhiteKnight)
-  }
@@ -1,3 +0,0 @@
-MAJOR=0
-MINOR=0
-PATCH=4
@@ -1,63 +0,0 @@
-##  (2026-03-27)
-
-### Features
-
-* add GameRules stub with PositionStatus enum ([76d4168](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/76d4168038de23e5d6083d4e8f0504fbf31d15a3))
-* add MovedInCheck/Checkmate/Stalemate MoveResult variants (stub dispatch) ([8b7ec57](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/8b7ec57e5ea6ee1615a1883848a426dc07d26364))
-* implement GameRules with isInCheck, legalMoves, gameStatus ([94a02ff](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/94a02ff6849436d9496c70a0f16c21666dae8e4e))
-* implement legal castling ([#1](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/1)) ([00d326c](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/00d326c1ba67711fbe180f04e1100c3f01dd0254))
-* wire check/checkmate/stalemate into processMove and gameLoop ([5264a22](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/5264a225418b885c5e6ea6411b96f85e38837f6c))
-
-### Bug Fixes
-
-* add missing kings to gameLoop capture test board ([aedd787](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/aedd787b77203c2af934751dba7b784eaf165032))
-* correct test board positions and captureOutput/withInput interaction ([f0481e2](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/f0481e2561b779df00925b46ee281dc36a795150))
-* update main class path in build configuration and adjust VCS directory mapping ([7b1f8b1](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/7b1f8b117623d327232a1a92a8a44d18582e0189))
-##  (2026-03-28)
-
-### Features
-
-* add GameRules stub with PositionStatus enum ([76d4168](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/76d4168038de23e5d6083d4e8f0504fbf31d15a3))
-* add MovedInCheck/Checkmate/Stalemate MoveResult variants (stub dispatch) ([8b7ec57](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/8b7ec57e5ea6ee1615a1883848a426dc07d26364))
-* implement GameRules with isInCheck, legalMoves, gameStatus ([94a02ff](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/94a02ff6849436d9496c70a0f16c21666dae8e4e))
-* implement legal castling ([#1](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/1)) ([00d326c](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/00d326c1ba67711fbe180f04e1100c3f01dd0254))
-* wire check/checkmate/stalemate into processMove and gameLoop ([5264a22](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/5264a225418b885c5e6ea6411b96f85e38837f6c))
-
-### Bug Fixes
-
-* add missing kings to gameLoop capture test board ([aedd787](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/aedd787b77203c2af934751dba7b784eaf165032))
-* correct test board positions and captureOutput/withInput interaction ([f0481e2](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/f0481e2561b779df00925b46ee281dc36a795150))
-* update main class path in build configuration and adjust VCS directory mapping ([7b1f8b1](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/7b1f8b117623d327232a1a92a8a44d18582e0189))
-##  (2026-03-29)
-
-### Features
-
-* add GameRules stub with PositionStatus enum ([76d4168](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/76d4168038de23e5d6083d4e8f0504fbf31d15a3))
-* add MovedInCheck/Checkmate/Stalemate MoveResult variants (stub dispatch) ([8b7ec57](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/8b7ec57e5ea6ee1615a1883848a426dc07d26364))
-* implement GameRules with isInCheck, legalMoves, gameStatus ([94a02ff](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/94a02ff6849436d9496c70a0f16c21666dae8e4e))
-* implement legal castling ([#1](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/1)) ([00d326c](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/00d326c1ba67711fbe180f04e1100c3f01dd0254))
-* NCS-6 Implementing FEN & PGN ([#7](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/7)) ([f28e69d](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/f28e69dc181416aa2f221fdc4b45c2cda5efbf07))
-* wire check/checkmate/stalemate into processMove and gameLoop ([5264a22](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/5264a225418b885c5e6ea6411b96f85e38837f6c))
-
-### Bug Fixes
-
-* add missing kings to gameLoop capture test board ([aedd787](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/aedd787b77203c2af934751dba7b784eaf165032))
-* correct test board positions and captureOutput/withInput interaction ([f0481e2](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/f0481e2561b779df00925b46ee281dc36a795150))
-* update main class path in build configuration and adjust VCS directory mapping ([7b1f8b1](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/7b1f8b117623d327232a1a92a8a44d18582e0189))
-##  (2026-03-29)
-
-### Features
-
-* add GameRules stub with PositionStatus enum ([76d4168](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/76d4168038de23e5d6083d4e8f0504fbf31d15a3))
-* add MovedInCheck/Checkmate/Stalemate MoveResult variants (stub dispatch) ([8b7ec57](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/8b7ec57e5ea6ee1615a1883848a426dc07d26364))
-* implement GameRules with isInCheck, legalMoves, gameStatus ([94a02ff](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/94a02ff6849436d9496c70a0f16c21666dae8e4e))
-* implement legal castling ([#1](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/1)) ([00d326c](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/00d326c1ba67711fbe180f04e1100c3f01dd0254))
-* NCS-6 Implementing FEN & PGN ([#7](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/7)) ([f28e69d](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/f28e69dc181416aa2f221fdc4b45c2cda5efbf07))
-* NCS-9 En passant implementation ([#8](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/8)) ([919beb3](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/919beb3b4bfa8caf2f90976a415fe9b19b7e9747))
-* wire check/checkmate/stalemate into processMove and gameLoop ([5264a22](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/5264a225418b885c5e6ea6411b96f85e38837f6c))
-
-### Bug Fixes
-
-* add missing kings to gameLoop capture test board ([aedd787](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/aedd787b77203c2af934751dba7b784eaf165032))
-* correct test board positions and captureOutput/withInput interaction ([f0481e2](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/f0481e2561b779df00925b46ee281dc36a795150))
-* update main class path in build configuration and adjust VCS directory mapping ([7b1f8b1](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/7b1f8b117623d327232a1a92a8a44d18582e0189))
@@ -0,0 +1,11 @@
+package de.nowchess.chess
+
+import de.nowchess.api.board.Color
+import de.nowchess.chess.controller.GameController
+import de.nowchess.chess.logic.GameContext
+
+object Main {
+  def main(args: Array[String]): Unit =
+    println("NowChess TUI — type moves in coordinate notation (e.g. e2e4). Type 'quit' to exit.")
+    GameController.gameLoop(GameContext.initial, Color.White)
+}
@@ -1,64 +0,0 @@
-package de.nowchess.chess.command
-
-import de.nowchess.api.board.{Square, Board, Color, Piece}
-import de.nowchess.chess.logic.GameHistory
-
-/** Marker trait for all commands that can be executed and undone.
- *  Commands encapsulate user actions and game state transitions.
- */
-trait Command:
-  /** Execute the command and return true if successful, false otherwise. */
-  def execute(): Boolean
-
-  /** Undo the command and return true if successful, false otherwise. */
-  def undo(): Boolean
-
-  /** A human-readable description of this command. */
-  def description: String
-
-/** Command to move a piece from one square to another.
- *  Stores the move result so undo can restore previous state.
- */
-case class MoveCommand(
-  from: Square,
-  to: Square,
-  moveResult: Option[MoveResult] = None,
-  previousBoard: Option[Board] = None,
-  previousHistory: Option[GameHistory] = None,
-  previousTurn: Option[Color] = None
-) extends Command:
-
-  override def execute(): Boolean =
-    moveResult.isDefined
-
-  override def undo(): Boolean =
-    previousBoard.isDefined && previousHistory.isDefined && previousTurn.isDefined
-
-  override def description: String = s"Move from $from to $to"
-
-// Sealed hierarchy of move outcomes (for tracking state changes)
-sealed trait MoveResult
-object MoveResult:
-  case class Successful(newBoard: Board, newHistory: GameHistory, newTurn: Color, captured: Option[Piece]) extends MoveResult
-  case object InvalidFormat extends MoveResult
-  case object InvalidMove extends MoveResult
-
-/** Command to quit the game. */
-case class QuitCommand() extends Command:
-  override def execute(): Boolean = true
-  override def undo(): Boolean = false
-  override def description: String = "Quit game"
-
-/** Command to reset the board to initial position. */
-case class ResetCommand(
-  previousBoard: Option[Board] = None,
-  previousHistory: Option[GameHistory] = None,
-  previousTurn: Option[Color] = None
-) extends Command:
-
-  override def execute(): Boolean = true
-
-  override def undo(): Boolean =
-    previousBoard.isDefined && previousHistory.isDefined && previousTurn.isDefined
-
-  override def description: String = "Reset board"
@@ -1,73 +0,0 @@
-package de.nowchess.chess.command
-
-/** Manages command execution and history for undo/redo support. */
-class CommandInvoker:
-  private val executedCommands = scala.collection.mutable.ListBuffer[Command]()
-  private var currentIndex = -1
-
-  /** Execute a command and add it to history.
-   *  Discards any redo history if not at the end of the stack.
-   */
-  def execute(command: Command): Boolean = synchronized {
-    if command.execute() then
-      // Remove any commands after current index (redo stack is discarded)
-      while currentIndex < executedCommands.size - 1 do
-        executedCommands.remove(executedCommands.size - 1)
-      executedCommands += command
-      currentIndex += 1
-      true
-    else
-      false
-  }
-
-  /** Undo the last executed command if possible. */
-  def undo(): Boolean = synchronized {
-    if currentIndex >= 0 && currentIndex < executedCommands.size then
-      val command = executedCommands(currentIndex)
-      if command.undo() then
-        currentIndex -= 1
-        true
-      else
-        false
-    else
-      false
-  }
-
-  /** Redo the next command in history if available. */
-  def redo(): Boolean = synchronized {
-    if currentIndex + 1 < executedCommands.size then
-      val command = executedCommands(currentIndex + 1)
-      if command.execute() then
-        currentIndex += 1
-        true
-      else
-        false
-    else
-      false
-  }
-
-  /** Get the history of all executed commands. */
-  def history: List[Command] = synchronized {
-    executedCommands.toList
-  }
-
-  /** Get the current position in command history. */
-  def getCurrentIndex: Int = synchronized {
-    currentIndex
-  }
-
-  /** Clear all command history. */
-  def clear(): Unit = synchronized {
-    executedCommands.clear()
-    currentIndex = -1
-  }
-
-  /** Check if undo is available. */
-  def canUndo: Boolean = synchronized {
-    currentIndex >= 0
-  }
-
-  /** Check if redo is available. */
-  def canRedo: Boolean = synchronized {
-    currentIndex + 1 < executedCommands.size
-  }
@@ -1,7 +1,10 @@
 package de.nowchess.chess.controller

+import scala.io.StdIn
 import de.nowchess.api.board.{Board, Color, File, Piece, Rank, Square}
-import de.nowchess.chess.logic.*
+import de.nowchess.api.game.CastlingRights
+import de.nowchess.chess.logic.{GameContext, MoveValidator, GameRules, PositionStatus, CastleSide, withCastle}
+import de.nowchess.chess.view.Renderer

 // ---------------------------------------------------------------------------
 // Result ADT returned by the pure processMove function
@@ -14,8 +17,8 @@ object MoveResult:
  case object NoPiece                                                                   extends MoveResult
  case object WrongColor                                                                extends MoveResult
  case object IllegalMove                                                               extends MoveResult
-  case class  Moved(newBoard: Board, newHistory: GameHistory, captured: Option[Piece], newTurn: Color)      extends MoveResult
-  case class  MovedInCheck(newBoard: Board, newHistory: GameHistory, captured: Option[Piece], newTurn: Color) extends MoveResult
+  case class  Moved(newCtx: GameContext, captured: Option[Piece], newTurn: Color)      extends MoveResult
+  case class  MovedInCheck(newCtx: GameContext, captured: Option[Piece], newTurn: Color) extends MoveResult
  case class  Checkmate(winner: Color)                                                  extends MoveResult
  case object Stalemate                                                                 extends MoveResult

@@ -28,7 +31,7 @@ object GameController:
  /** Pure function: interprets one raw input line against the current game context.
   *  Has no I/O side effects — all output must be handled by the caller.
   */
-  def processMove(board: Board, history: GameHistory, turn: Color, raw: String): MoveResult =
+  def processMove(ctx: GameContext, turn: Color, raw: String): MoveResult =
    raw.trim match
      case "quit" | "q" =>
        MoveResult.Quit
@@ -37,30 +40,97 @@ object GameController:
          case None =>
            MoveResult.InvalidFormat(trimmed)
          case Some((from, to)) =>
-            board.pieceAt(from) match
+            ctx.board.pieceAt(from) match
              case None =>
                MoveResult.NoPiece
              case Some(piece) if piece.color != turn =>
                MoveResult.WrongColor
              case Some(_) =>
-                if !MoveValidator.isLegal(board, history, from, to) then
+                if !MoveValidator.isLegal(ctx, from, to) then
                  MoveResult.IllegalMove
                else
-                  val castleOpt = if MoveValidator.isCastle(board, from, to)
+                  val castleOpt = if MoveValidator.isCastle(ctx.board, from, to)
                                  then Some(MoveValidator.castleSide(from, to))
                                  else None
-                  val isEP = EnPassantCalculator.isEnPassant(board, history, from, to)
                  val (newBoard, captured) = castleOpt match
-                    case Some(side) => (board.withCastle(turn, side), None)
-                    case None =>
-                      val (b, cap) = board.withMove(from, to)
-                      if isEP then
-                        val capturedSq = EnPassantCalculator.capturedPawnSquare(to, turn)
-                        (b.removed(capturedSq), board.pieceAt(capturedSq))
-                      else (b, cap)
-                  val newHistory = history.addMove(from, to, castleOpt)
-                  GameRules.gameStatus(newBoard, newHistory, turn.opposite) match
-                    case PositionStatus.Normal  => MoveResult.Moved(newBoard, newHistory, captured, turn.opposite)
-                    case PositionStatus.InCheck => MoveResult.MovedInCheck(newBoard, newHistory, captured, turn.opposite)
+                    case Some(side) => (ctx.board.withCastle(turn, side), None)
+                    case None       => ctx.board.withMove(from, to)
+                  val newCtx = applyRightsRevocation(
+                    ctx.copy(board = newBoard), turn, from, to, castleOpt
+                  )
+                  GameRules.gameStatus(newCtx, turn.opposite) match
+                    case PositionStatus.Normal  => MoveResult.Moved(newCtx, captured, turn.opposite)
+                    case PositionStatus.InCheck => MoveResult.MovedInCheck(newCtx, captured, turn.opposite)
                    case PositionStatus.Mated   => MoveResult.Checkmate(turn)
                    case PositionStatus.Drawn   => MoveResult.Stalemate
+
+  private def applyRightsRevocation(
+    ctx: GameContext,
+    turn: Color,
+    from: Square,
+    to: Square,
+    castle: Option[CastleSide]
+  ): GameContext =
+    // Step 1: Revoke all rights for a castling move (idempotent with step 2)
+    val ctx0 = castle.fold(ctx)(_ => ctx.withUpdatedRights(turn, CastlingRights.None))
+
+    // Step 2: Source-square revocation
+    val ctx1 = from match
+      case Square(File.E, Rank.R1) => ctx0.withUpdatedRights(Color.White, CastlingRights.None)
+      case Square(File.E, Rank.R8) => ctx0.withUpdatedRights(Color.Black, CastlingRights.None)
+      case Square(File.A, Rank.R1) => ctx0.withUpdatedRights(Color.White, ctx0.whiteCastling.copy(queenSide = false))
+      case Square(File.H, Rank.R1) => ctx0.withUpdatedRights(Color.White, ctx0.whiteCastling.copy(kingSide  = false))
+      case Square(File.A, Rank.R8) => ctx0.withUpdatedRights(Color.Black, ctx0.blackCastling.copy(queenSide = false))
+      case Square(File.H, Rank.R8) => ctx0.withUpdatedRights(Color.Black, ctx0.blackCastling.copy(kingSide  = false))
+      case _                       => ctx0
+
+    // Step 3: Destination-square revocation (enemy captures a rook on its home square)
+    to match
+      case Square(File.A, Rank.R1) => ctx1.withUpdatedRights(Color.White, ctx1.whiteCastling.copy(queenSide = false))
+      case Square(File.H, Rank.R1) => ctx1.withUpdatedRights(Color.White, ctx1.whiteCastling.copy(kingSide  = false))
+      case Square(File.A, Rank.R8) => ctx1.withUpdatedRights(Color.Black, ctx1.blackCastling.copy(queenSide = false))
+      case Square(File.H, Rank.R8) => ctx1.withUpdatedRights(Color.Black, ctx1.blackCastling.copy(kingSide  = false))
+      case _                       => ctx1
+
+  /** Thin I/O shell: renders the board, reads a line, delegates to processMove,
+   *  prints the outcome, and recurses until the game ends.
+   */
+  def gameLoop(ctx: GameContext, turn: Color): Unit =
+    println()
+    print(Renderer.render(ctx.board))
+    println(s"${turn.label}'s turn. Enter move: ")
+    val input = Option(StdIn.readLine()).getOrElse("quit").trim
+    processMove(ctx, turn, input) match
+      case MoveResult.Quit =>
+        println("Game over. Goodbye!")
+      case MoveResult.InvalidFormat(raw) =>
+        println(s"Invalid move format '$raw'. Use coordinate notation, e.g. e2e4.")
+        gameLoop(ctx, turn)
+      case MoveResult.NoPiece =>
+        println(s"No piece on ${Parser.parseMove(input).map(_._1).fold("?")(_.toString)}.")
+        gameLoop(ctx, turn)
+      case MoveResult.WrongColor =>
+        println(s"That is not your piece.")
+        gameLoop(ctx, turn)
+      case MoveResult.IllegalMove =>
+        println(s"Illegal move.")
+        gameLoop(ctx, turn)
+      case MoveResult.Moved(newCtx, captured, newTurn) =>
+        val prevTurn = newTurn.opposite
+        captured.foreach: cap =>
+          val toSq = Parser.parseMove(input).map(_._2).fold("?")(_.toString)
+          println(s"${prevTurn.label} captures ${cap.color.label} ${cap.pieceType.label} on $toSq")
+        gameLoop(newCtx, newTurn)
+      case MoveResult.MovedInCheck(newCtx, captured, newTurn) =>
+        val prevTurn = newTurn.opposite
+        captured.foreach: cap =>
+          val toSq = Parser.parseMove(input).map(_._2).fold("?")(_.toString)
+          println(s"${prevTurn.label} captures ${cap.color.label} ${cap.pieceType.label} on $toSq")
+        println(s"${newTurn.label} is in check!")
+        gameLoop(newCtx, newTurn)
+      case MoveResult.Checkmate(winner) =>
+        println(s"Checkmate! ${winner.label} wins.")
+        gameLoop(GameContext.initial, Color.White)
+      case MoveResult.Stalemate =>
+        println("Stalemate! The game is a draw.")
+        gameLoop(GameContext.initial, Color.White)
@@ -1,209 +0,0 @@
-package de.nowchess.chess.engine
-
-import de.nowchess.api.board.{Board, Color, Piece, Square}
-import de.nowchess.chess.logic.{GameHistory, GameRules, PositionStatus}
-import de.nowchess.chess.controller.{GameController, Parser, MoveResult}
-import de.nowchess.chess.observer.*
-import de.nowchess.chess.command.{CommandInvoker, MoveCommand}
-
-/** Pure game engine that manages game state and notifies observers of state changes.
- *  This class is the single source of truth for the game state.
- *  All user interactions must go through this engine via Commands, and all state changes
- *  are communicated to observers via GameEvent notifications.
- */
-class GameEngine extends Observable:
-  private var currentBoard: Board = Board.initial
-  private var currentHistory: GameHistory = GameHistory.empty
-  private var currentTurn: Color = Color.White
-  private val invoker = new CommandInvoker()
-
-  // Synchronized accessors for current state
-  def board: Board = synchronized { currentBoard }
-  def history: GameHistory = synchronized { currentHistory }
-  def turn: Color = synchronized { currentTurn }
-
-  /** Check if undo is available. */
-  def canUndo: Boolean = synchronized { invoker.canUndo }
-
-  /** Check if redo is available. */
-  def canRedo: Boolean = synchronized { invoker.canRedo }
-
-  /** Get the command history for inspection (testing/debugging). */
-  def commandHistory: List[de.nowchess.chess.command.Command] = synchronized { invoker.history }
-
-  /** Process a raw move input string and update game state if valid.
-   *  Notifies all observers of the outcome via GameEvent.
-   */
-  def processUserInput(rawInput: String): Unit = synchronized {
-    val trimmed = rawInput.trim.toLowerCase
-    trimmed match
-      case "quit" | "q" =>
-        // Client should handle quit logic; we just return
-        ()
-
-      case "undo" =>
-        performUndo()
-
-      case "redo" =>
-        performRedo()
-
-      case "" =>
-        val event = InvalidMoveEvent(
-          currentBoard,
-          currentHistory,
-          currentTurn,
-          "Please enter a valid move or command."
-        )
-        notifyObservers(event)
-
-      case moveInput =>
-        // Try to parse as a move
-        Parser.parseMove(moveInput) match
-          case None =>
-            val event = InvalidMoveEvent(
-              currentBoard,
-              currentHistory,
-              currentTurn,
-              s"Invalid move format '$moveInput'. Use coordinate notation, e.g. e2e4."
-            )
-            notifyObservers(event)
-
-          case Some((from, to)) =>
-            // Create a move command with current state snapshot
-            val cmd = MoveCommand(
-              from = from,
-              to = to,
-              previousBoard = Some(currentBoard),
-              previousHistory = Some(currentHistory),
-              previousTurn = Some(currentTurn)
-            )
-
-            // Execute the move through GameController
-            GameController.processMove(currentBoard, currentHistory, currentTurn, moveInput) match
-              case MoveResult.InvalidFormat(_) | MoveResult.NoPiece | MoveResult.WrongColor | MoveResult.IllegalMove | MoveResult.Quit =>
-                handleFailedMove(moveInput)
-
-              case MoveResult.Moved(newBoard, newHistory, captured, newTurn) =>
-                // Move succeeded - store result and execute through invoker
-                val updatedCmd = cmd.copy(moveResult = Some(de.nowchess.chess.command.MoveResult.Successful(newBoard, newHistory, newTurn, captured)))
-                invoker.execute(updatedCmd)
-                updateGameState(newBoard, newHistory, newTurn)
-                emitMoveEvent(from.toString, to.toString, captured, newTurn)
-
-              case MoveResult.MovedInCheck(newBoard, newHistory, captured, newTurn) =>
-                // Move succeeded with check
-                val updatedCmd = cmd.copy(moveResult = Some(de.nowchess.chess.command.MoveResult.Successful(newBoard, newHistory, newTurn, captured)))
-                invoker.execute(updatedCmd)
-                updateGameState(newBoard, newHistory, newTurn)
-                emitMoveEvent(from.toString, to.toString, captured, newTurn)
-                notifyObservers(CheckDetectedEvent(currentBoard, currentHistory, currentTurn))
-
-              case MoveResult.Checkmate(winner) =>
-                // Move resulted in checkmate
-                val updatedCmd = cmd.copy(moveResult = Some(de.nowchess.chess.command.MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None)))
-                invoker.execute(updatedCmd)
-                currentBoard = Board.initial
-                currentHistory = GameHistory.empty
-                currentTurn = Color.White
-                notifyObservers(CheckmateEvent(currentBoard, currentHistory, currentTurn, winner))
-
-              case MoveResult.Stalemate =>
-                // Move resulted in stalemate
-                val updatedCmd = cmd.copy(moveResult = Some(de.nowchess.chess.command.MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None)))
-                invoker.execute(updatedCmd)
-                currentBoard = Board.initial
-                currentHistory = GameHistory.empty
-                currentTurn = Color.White
-                notifyObservers(StalemateEvent(currentBoard, currentHistory, currentTurn))
-  }
-
-  /** Undo the last move. */
-  def undo(): Unit = synchronized {
-    performUndo()
-  }
-
-  /** Redo the last undone move. */
-  def redo(): Unit = synchronized {
-    performRedo()
-  }
-
-  /** Reset the board to initial position. */
-  def reset(): Unit = synchronized {
-    currentBoard = Board.initial
-    currentHistory = GameHistory.empty
-    currentTurn = Color.White
-    invoker.clear()
-    notifyObservers(BoardResetEvent(
-      currentBoard,
-      currentHistory,
-      currentTurn
-    ))
-  }
-
-  // ──── Private Helpers ────
-
-  private def performUndo(): Unit =
-    if invoker.canUndo then
-      val cmd = invoker.history(invoker.getCurrentIndex)
-      (cmd: @unchecked) match
-        case moveCmd: MoveCommand =>
-          moveCmd.previousBoard.foreach(currentBoard = _)
-          moveCmd.previousHistory.foreach(currentHistory = _)
-          moveCmd.previousTurn.foreach(currentTurn = _)
-          invoker.undo()
-          notifyObservers(BoardResetEvent(currentBoard, currentHistory, currentTurn))
-    else
-      notifyObservers(InvalidMoveEvent(currentBoard, currentHistory, currentTurn, "Nothing to undo."))
-
-  private def performRedo(): Unit =
-    if invoker.canRedo then
-      val cmd = invoker.history(invoker.getCurrentIndex + 1)
-      (cmd: @unchecked) match
-        case moveCmd: MoveCommand =>
-          for case de.nowchess.chess.command.MoveResult.Successful(nb, nh, nt, cap) <- moveCmd.moveResult do
-            updateGameState(nb, nh, nt)
-            invoker.redo()
-            emitMoveEvent(moveCmd.from.toString, moveCmd.to.toString, cap, nt)
-    else
-      notifyObservers(InvalidMoveEvent(currentBoard, currentHistory, currentTurn, "Nothing to redo."))
-
-  private def updateGameState(newBoard: Board, newHistory: GameHistory, newTurn: Color): Unit =
-    currentBoard = newBoard
-    currentHistory = newHistory
-    currentTurn = newTurn
-
-  private def emitMoveEvent(fromSq: String, toSq: String, captured: Option[Piece], newTurn: Color): Unit =
-    val capturedDesc = captured.map(c => s"${c.color.label} ${c.pieceType.label}")
-    notifyObservers(MoveExecutedEvent(
-      currentBoard,
-      currentHistory,
-      newTurn,
-      fromSq,
-      toSq,
-      capturedDesc
-    ))
-
-  private def handleFailedMove(moveInput: String): Unit =
-    (GameController.processMove(currentBoard, currentHistory, currentTurn, moveInput): @unchecked) match
-      case MoveResult.NoPiece =>
-        notifyObservers(InvalidMoveEvent(
-          currentBoard,
-          currentHistory,
-          currentTurn,
-          "No piece on that square."
-        ))
-      case MoveResult.WrongColor =>
-        notifyObservers(InvalidMoveEvent(
-          currentBoard,
-          currentHistory,
-          currentTurn,
-          "That is not your piece."
-        ))
-      case MoveResult.IllegalMove =>
-        notifyObservers(InvalidMoveEvent(
-          currentBoard,
-          currentHistory,
-          currentTurn,
-          "Illegal move."
-        ))
-
@@ -1,23 +0,0 @@
-package de.nowchess.chess.logic
-
-import de.nowchess.api.board.*
-
-enum CastleSide:
-  case Kingside, Queenside
-
-extension (b: Board)
-  def withCastle(color: Color, side: CastleSide): Board =
-    val rank = if color == Color.White then Rank.R1 else Rank.R8
-    val kingFrom = Square(File.E, rank)
-    val (kingTo, rookFrom, rookTo) = side match
-      case CastleSide.Kingside =>
-        (Square(File.G, rank), Square(File.H, rank), Square(File.F, rank))
-      case CastleSide.Queenside =>
-        (Square(File.C, rank), Square(File.A, rank), Square(File.D, rank))
-
-    val king = b.pieceAt(kingFrom).get
-    val rook = b.pieceAt(rookFrom).get
-
-    b.removed(kingFrom).removed(rookFrom)
-      .updated(kingTo, king)
-      .updated(rookTo, rook)
@@ -1,31 +0,0 @@
-package de.nowchess.chess.logic
-
-import de.nowchess.api.board.{Color, File, Rank, Square}
-import de.nowchess.api.game.CastlingRights
-
-/** Derives castling rights from move history. */
-object CastlingRightsCalculator:
-
-  def deriveCastlingRights(history: GameHistory, color: Color): CastlingRights =
-    val (kingRow, kingsideRookFile, queensideRookFile) = color match
-      case Color.White => (Rank.R1, File.H, File.A)
-      case Color.Black => (Rank.R8, File.H, File.A)
-
-    // Check if king has moved
-    val kingHasMoved = history.moves.exists: move =>
-      move.from == Square(File.E, kingRow) || move.castleSide.isDefined
-
-    if kingHasMoved then
-      CastlingRights.None
-    else
-      // Check if kingside rook has moved or was captured
-      val kingsideLost = history.moves.exists: move =>
-        move.from == Square(kingsideRookFile, kingRow) ||
-        move.to == Square(kingsideRookFile, kingRow)
-
-      // Check if queenside rook has moved or was captured
-      val queensideLost = history.moves.exists: move =>
-        move.from == Square(queensideRookFile, kingRow) ||
-        move.to == Square(queensideRookFile, kingRow)
-
-      CastlingRights(kingSide = !kingsideLost, queenSide = !queensideLost)
@@ -1,32 +0,0 @@
-package de.nowchess.chess.logic
-
-import de.nowchess.api.board.*
-
-object EnPassantCalculator:
-
-  /** Returns the en passant target square if the last move was a double pawn push.
-   *  The target is the square the pawn passed through (e.g. e2→e4 yields e3).
-   */
-  def enPassantTarget(board: Board, history: GameHistory): Option[Square] =
-    history.moves.lastOption.flatMap: move =>
-      val rankDiff = move.to.rank.ordinal - move.from.rank.ordinal
-      val isDoublePush = math.abs(rankDiff) == 2
-      val isPawn = board.pieceAt(move.to).exists(_.pieceType == PieceType.Pawn)
-      if isDoublePush && isPawn then
-        val midRankIdx = move.from.rank.ordinal + rankDiff / 2
-        Some(Square(move.to.file, Rank.values(midRankIdx)))
-      else None
-
-  /** True if moving from→to is an en passant capture. */
-  def isEnPassant(board: Board, history: GameHistory, from: Square, to: Square): Boolean =
-    board.pieceAt(from).exists(_.pieceType == PieceType.Pawn) &&
-    enPassantTarget(board, history).contains(to) &&
-    math.abs(to.file.ordinal - from.file.ordinal) == 1
-
-  /** Returns the square of the pawn to remove when an en passant capture lands on `to`.
-   *  White captures upward → captured pawn is one rank below `to`.
-   *  Black captures downward → captured pawn is one rank above `to`.
-   */
-  def capturedPawnSquare(to: Square, color: Color): Square =
-    val capturedRankIdx = to.rank.ordinal + (if color == Color.White then -1 else 1)
-    Square(to.file, Rank.values(capturedRankIdx))
@@ -0,0 +1,47 @@
+package de.nowchess.chess.logic
+
+import de.nowchess.api.board.{Board, Color, File, Piece, PieceType, Rank, Square}
+import de.nowchess.api.game.CastlingRights
+
+enum CastleSide:
+  case Kingside, Queenside
+
+case class GameContext(
+  board: Board,
+  whiteCastling: CastlingRights,
+  blackCastling: CastlingRights
+):
+  def castlingFor(color: Color): CastlingRights =
+    if color == Color.White then whiteCastling else blackCastling
+
+  def withUpdatedRights(color: Color, rights: CastlingRights): GameContext =
+    if color == Color.White then copy(whiteCastling = rights)
+    else copy(blackCastling = rights)
+
+object GameContext:
+  /** Convenience constructor for test boards: no castling rights on either side. */
+  def apply(board: Board): GameContext =
+    GameContext(board, CastlingRights.None, CastlingRights.None)
+
+  val initial: GameContext =
+    GameContext(Board.initial, CastlingRights.Both, CastlingRights.Both)
+
+extension (b: Board)
+  def withCastle(color: Color, side: CastleSide): Board =
+    val (kingFrom, kingTo, rookFrom, rookTo) = (color, side) match
+      case (Color.White, CastleSide.Kingside)  =>
+        (Square(File.E, Rank.R1), Square(File.G, Rank.R1),
+         Square(File.H, Rank.R1), Square(File.F, Rank.R1))
+      case (Color.White, CastleSide.Queenside) =>
+        (Square(File.E, Rank.R1), Square(File.C, Rank.R1),
+         Square(File.A, Rank.R1), Square(File.D, Rank.R1))
+      case (Color.Black, CastleSide.Kingside)  =>
+        (Square(File.E, Rank.R8), Square(File.G, Rank.R8),
+         Square(File.H, Rank.R8), Square(File.F, Rank.R8))
+      case (Color.Black, CastleSide.Queenside) =>
+        (Square(File.E, Rank.R8), Square(File.C, Rank.R8),
+         Square(File.A, Rank.R8), Square(File.D, Rank.R8))
+    val king = Piece(color, PieceType.King)
+    val rook = Piece(color, PieceType.Rook)
+    Board(b.pieces.removed(kingFrom).removed(rookFrom)
+                  .updated(kingTo, king).updated(rookTo, rook))
@@ -1,24 +0,0 @@
-package de.nowchess.chess.logic
-
-import de.nowchess.api.board.Square
-
-/** A single move recorded in the game history. Distinct from api.move.Move which represents user intent. */
-case class HistoryMove(
-  from: Square,
-  to: Square,
-  castleSide: Option[CastleSide]
-)
-
-/** Complete game history: ordered list of moves. */
-case class GameHistory(moves: List[HistoryMove] = List.empty):
-  def addMove(move: HistoryMove): GameHistory =
-    GameHistory(moves :+ move)
-
-  def addMove(from: Square, to: Square): GameHistory =
-    addMove(HistoryMove(from, to, None))
-
-  def addMove(from: Square, to: Square, castleSide: Option[CastleSide]): GameHistory =
-    addMove(HistoryMove(from, to, castleSide))
-
-object GameHistory:
-  val empty: GameHistory = GameHistory()
@@ -1,7 +1,7 @@
 package de.nowchess.chess.logic

 import de.nowchess.api.board.*
-import de.nowchess.chess.logic.GameHistory
+import de.nowchess.chess.logic.GameContext

 enum PositionStatus:
  case Normal, InCheck, Mated, Drawn
@@ -20,17 +20,17 @@ object GameRules:
      }

  /** All (from, to) moves for `color` that do not leave their own king in check. */
-  def legalMoves(board: Board, history: GameHistory, color: Color): Set[(Square, Square)] =
-    board.pieces
+  def legalMoves(ctx: GameContext, color: Color): Set[(Square, Square)] =
+    ctx.board.pieces
      .collect { case (from, piece) if piece.color == color => from }
      .flatMap { from =>
-        MoveValidator.legalTargets(board, history, from)           // context-aware: includes castling
+        MoveValidator.legalTargets(ctx, from)           // context-aware: includes castling
          .filter { to =>
            val newBoard =
-              if MoveValidator.isCastle(board, from, to) then
-                board.withCastle(color, MoveValidator.castleSide(from, to))
+              if MoveValidator.isCastle(ctx.board, from, to) then
+                ctx.board.withCastle(color, MoveValidator.castleSide(from, to))
              else
-                board.withMove(from, to)._1
+                ctx.board.withMove(from, to)._1
            !isInCheck(newBoard, color)
          }
          .map(to => from -> to)
@@ -38,9 +38,9 @@ object GameRules:
      .toSet

  /** Position status for the side whose turn it is (`color`). */
-  def gameStatus(board: Board, history: GameHistory, color: Color): PositionStatus =
-    val moves   = legalMoves(board, history, color)
-    val inCheck = isInCheck(board, color)
+  def gameStatus(ctx: GameContext, color: Color): PositionStatus =
+    val moves   = legalMoves(ctx, color)
+    val inCheck = isInCheck(ctx.board, color)
    if moves.isEmpty && inCheck then PositionStatus.Mated
    else if moves.isEmpty       then PositionStatus.Drawn
    else if inCheck             then PositionStatus.InCheck
@@ -1,7 +1,7 @@
 package de.nowchess.chess.logic

 import de.nowchess.api.board.*
-import de.nowchess.chess.logic.{CastleSide, GameHistory}
+import de.nowchess.chess.logic.{GameContext, CastleSide}

 object MoveValidator:

@@ -126,50 +126,37 @@ object MoveValidator:
  def castleSide(from: Square, to: Square): CastleSide =
    if to.file.ordinal > from.file.ordinal then CastleSide.Kingside else CastleSide.Queenside

-  def castlingTargets(board: Board, history: GameHistory, color: Color): Set[Square] =
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, color)
+  def castlingTargets(ctx: GameContext, color: Color): Set[Square] =
+    val rights = ctx.castlingFor(color)
    val rank   = if color == Color.White then Rank.R1 else Rank.R8
    val kingSq = Square(File.E, rank)
    val enemy  = color.opposite

-    if !board.pieceAt(kingSq).contains(Piece(color, PieceType.King)) ||
-       GameRules.isInCheck(board, color) then Set.empty
+    if !ctx.board.pieceAt(kingSq).contains(Piece(color, PieceType.King)) ||
+       GameRules.isInCheck(ctx.board, color) then Set.empty
    else
      val kingsideSq = Option.when(
        rights.kingSide &&
-        board.pieceAt(Square(File.H, rank)).contains(Piece(color, PieceType.Rook)) &&
-        List(Square(File.F, rank), Square(File.G, rank)).forall(s => board.pieceAt(s).isEmpty) &&
-        !List(Square(File.F, rank), Square(File.G, rank)).exists(s => isAttackedBy(board, s, enemy))
+        ctx.board.pieceAt(Square(File.H, rank)).contains(Piece(color, PieceType.Rook)) &&
+        List(Square(File.F, rank), Square(File.G, rank)).forall(s => ctx.board.pieceAt(s).isEmpty) &&
+        !List(Square(File.F, rank), Square(File.G, rank)).exists(s => isAttackedBy(ctx.board, s, enemy))
      )(Square(File.G, rank))

      val queensideSq = Option.when(
        rights.queenSide &&
-        board.pieceAt(Square(File.A, rank)).contains(Piece(color, PieceType.Rook)) &&
-        List(Square(File.B, rank), Square(File.C, rank), Square(File.D, rank)).forall(s => board.pieceAt(s).isEmpty) &&
-        !List(Square(File.D, rank), Square(File.C, rank)).exists(s => isAttackedBy(board, s, enemy))
+        ctx.board.pieceAt(Square(File.A, rank)).contains(Piece(color, PieceType.Rook)) &&
+        List(Square(File.B, rank), Square(File.C, rank), Square(File.D, rank)).forall(s => ctx.board.pieceAt(s).isEmpty) &&
+        !List(Square(File.D, rank), Square(File.C, rank)).exists(s => isAttackedBy(ctx.board, s, enemy))
      )(Square(File.C, rank))

      kingsideSq.toSet ++ queensideSq.toSet

-  def legalTargets(board: Board, history: GameHistory, from: Square): Set[Square] =
-    board.pieceAt(from) match
+  def legalTargets(ctx: GameContext, from: Square): Set[Square] =
+    ctx.board.pieceAt(from) match
      case Some(piece) if piece.pieceType == PieceType.King =>
-        legalTargets(board, from) ++ castlingTargets(board, history, piece.color)
-      case Some(piece) if piece.pieceType == PieceType.Pawn =>
-        pawnTargets(board, history, from, piece.color)
+        legalTargets(ctx.board, from) ++ castlingTargets(ctx, piece.color)
      case _ =>
-        legalTargets(board, from)
+        legalTargets(ctx.board, from)

-  private def pawnTargets(board: Board, history: GameHistory, from: Square, color: Color): Set[Square] =
-    val existing = pawnTargets(board, from, color)
-    val fi  = from.file.ordinal
-    val ri  = from.rank.ordinal
-    val dir = if color == Color.White then 1 else -1
-    val epCapture: Set[Square] =
-      EnPassantCalculator.enPassantTarget(board, history).filter: target =>
-        squareAt(fi - 1, ri + dir).contains(target) || squareAt(fi + 1, ri + dir).contains(target)
-      .toSet
-    existing ++ epCapture
-
-  def isLegal(board: Board, history: GameHistory, from: Square, to: Square): Boolean =
-    legalTargets(board, history, from).contains(to)
+  def isLegal(ctx: GameContext, from: Square, to: Square): Boolean =
+    legalTargets(ctx, from).contains(to)
@@ -1,60 +0,0 @@
-package de.nowchess.chess.notation
-
-import de.nowchess.api.board.*
-import de.nowchess.api.game.{CastlingRights, GameState}
-import de.nowchess.api.board.Color
-
-object FenExporter:
-
-  /** Convert a Board to FEN piece-placement string (rank 8 to rank 1, separated by '/'). */
-  def boardToFen(board: Board): String =
-    Rank.values.reverse
-      .map(rank => buildRankString(board, rank))
-      .mkString("/")
-
-  /** 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 += pieceToPgnChar(piece)
-        case None =>
-          emptyCount += 1
-
-    if emptyCount > 0 then rankChars += emptyCount.toString.charAt(0)
-    rankChars.mkString
-
-  /** Convert a GameState to a complete FEN string. */
-  def gameStateToFen(state: GameState): String =
-    val piecePlacement = state.piecePlacement
-    val activeColor = if state.activeColor == Color.White then "w" else "b"
-    val castling = castlingString(state.castlingWhite, state.castlingBlack)
-    val enPassant = state.enPassantTarget.map(_.toString).getOrElse("-")
-    s"$piecePlacement $activeColor $castling $enPassant ${state.halfMoveClock} ${state.fullMoveNumber}"
-
-  /** Convert castling rights to FEN notation. */
-  private def castlingString(white: CastlingRights, black: CastlingRights): String =
-    val wk = if white.kingSide then "K" else ""
-    val wq = if white.queenSide then "Q" else ""
-    val bk = if black.kingSide then "k" else ""
-    val bq = if black.queenSide then "q" else ""
-    val result = s"$wk$wq$bk$bq"
-    if result.isEmpty then "-" else result
-
-  /** Convert a Piece to its FEN character (uppercase = White, lowercase = Black). */
-  private def pieceToPgnChar(piece: Piece): Char =
-    val base = piece.pieceType match
-      case PieceType.Pawn   => 'p'
-      case PieceType.Knight => 'n'
-      case PieceType.Bishop => 'b'
-      case PieceType.Rook   => 'r'
-      case PieceType.Queen  => 'q'
-      case PieceType.King   => 'k'
-    if piece.color == Color.White then base.toUpper else base
@@ -1,103 +0,0 @@
-package de.nowchess.chess.notation
-
-import de.nowchess.api.board.*
-import de.nowchess.api.game.{CastlingRights, GameState, GameStatus}
-
-object FenParser:
-
-  /** Parse a complete FEN string into a GameState.
-   *  Returns None if the format is invalid. */
-  def parseFen(fen: String): Option[GameState] =
-    val parts = fen.trim.split("\\s+")
-    Option.when(parts.length == 6)(parts).flatMap: parts =>
-      for
-        _ <- parseBoard(parts(0))
-        activeColor <- parseColor(parts(1))
-        castlingRights <- parseCastling(parts(2))
-        enPassant <- parseEnPassant(parts(3))
-        halfMoveClock <- parts(4).toIntOption
-        fullMoveNumber <- parts(5).toIntOption
-        if halfMoveClock >= 0 && fullMoveNumber >= 1
-      yield GameState(
-        piecePlacement = parts(0),
-        activeColor = activeColor,
-        castlingWhite = castlingRights._1,
-        castlingBlack = castlingRights._2,
-        enPassantTarget = enPassant,
-        halfMoveClock = halfMoveClock,
-        fullMoveNumber = fullMoveNumber,
-        status = GameStatus.InProgress
-      )
-
-  /** Parse active color ("w" or "b"). */
-  private def parseColor(s: String): Option[Color] =
-    if s == "w" then Some(Color.White)
-    else if s == "b" then Some(Color.Black)
-    else None
-
-  /** Parse castling rights string (e.g. "KQkq", "K", "-") into rights for White and Black. */
-  private def parseCastling(s: String): Option[(CastlingRights, CastlingRights)] =
-    if s == "-" then
-      Some((CastlingRights.None, CastlingRights.None))
-    else if s.length <= 4 && s.forall(c => "KQkq".contains(c)) then
-      val white = CastlingRights(kingSide = s.contains('K'), queenSide = s.contains('Q'))
-      val black = CastlingRights(kingSide = s.contains('k'), queenSide = s.contains('q'))
-      Some((white, black))
-    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. */
-  def parseBoard(fen: String): Option[Board] =
-    val rankStrings = fen.split("/", -1)
-    if rankStrings.length != 8 then None
-    else
-      // Parse each rank, collecting all (Square, Piece) pairs or failing on the first error
-      val parsedRanks: Option[List[List[(Square, Piece)]]] =
-        rankStrings.zipWithIndex.foldLeft(Option(List.empty[List[(Square, Piece)]])):
-          case (None, _) => None
-          case (Some(acc), (rankStr, rankIdx)) =>
-            val rank = Rank.values(7 - rankIdx) // ranks go 8→1, so reverse
-            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. */
-  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
-
-    if failed || fileIdx != 8 then None
-    else Some(squares.toList)
-
-  /** Convert a FEN piece character to a Piece. Uppercase = White, lowercase = Black. */
-  private def charToPiece(c: Char): Option[Piece] =
-    val color = if Character.isUpperCase(c) then Color.White else Color.Black
-    val pieceTypeOpt = c.toLower match
-      case 'p' => Some(PieceType.Pawn)
-      case 'n' => Some(PieceType.Knight)
-      case 'b' => Some(PieceType.Bishop)
-      case 'r' => Some(PieceType.Rook)
-      case 'q' => Some(PieceType.Queen)
-      case 'k' => Some(PieceType.King)
-      case _   => None
-    pieceTypeOpt.map(pt => Piece(color, pt))
@@ -1,35 +0,0 @@
-package de.nowchess.chess.notation
-
-import de.nowchess.api.board.*
-import de.nowchess.chess.logic.{CastleSide, GameHistory, HistoryMove}
-
-object PgnExporter:
-
-  /** Export a game with headers and history to PGN format. */
-  def exportGame(headers: Map[String, String], history: GameHistory): String =
-    val headerLines = headers.map { case (key, value) =>
-      s"""[$key "$value"]"""
-    }.mkString("\n")
-
-    val moveText = if history.moves.isEmpty then ""
-    else
-      val groupedMoves = history.moves.zipWithIndex.groupBy(_._2 / 2)
-      val moveLines = for (moveNumber, movePairs) <- groupedMoves.toList.sortBy(_._1) yield
-        val moveNum = moveNumber + 1
-        val whiteMoveStr = movePairs.find(_._2 % 2 == 0).map(p => moveToAlgebraic(p._1)).getOrElse("")
-        val blackMoveStr = movePairs.find(_._2 % 2 == 1).map(p => moveToAlgebraic(p._1)).getOrElse("")
-        if blackMoveStr.isEmpty then s"$moveNum. $whiteMoveStr"
-        else s"$moveNum. $whiteMoveStr $blackMoveStr"
-
-      moveLines.mkString(" ") + " *"
-
-    if headerLines.isEmpty then moveText
-    else if moveText.isEmpty then headerLines
-    else s"$headerLines\n\n$moveText"
-
-  /** Convert a HistoryMove to algebraic notation. */
-  private def moveToAlgebraic(move: HistoryMove): String =
-    move.castleSide match
-      case Some(CastleSide.Kingside)  => "O-O"
-      case Some(CastleSide.Queenside) => "O-O-O"
-      case None => s"${move.from}${move.to}"
@@ -1,150 +0,0 @@
-package de.nowchess.chess.notation
-
-import de.nowchess.api.board.*
-import de.nowchess.chess.logic.{CastleSide, GameHistory, HistoryMove, GameRules, MoveValidator, withCastle}
-
-/** A parsed PGN game containing headers and the resolved move list. */
-case class PgnGame(
-  headers: Map[String, String],
-  moves: List[HistoryMove]
-)
-
-object PgnParser:
-
-  /** 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 (headerLines, rest) = lines.span(_.startsWith("["))
-
-    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"]. */
-  private def parseHeaders(lines: Array[String]): Map[String, String] =
-    val pattern = """^\[(\w+)\s+"([^"]*)"\s*\]$""".r
-    lines.flatMap(line => pattern.findFirstMatchIn(line).map(m => m.group(1) -> m.group(2))).toMap
-
-  /** Parse the move-text section (e.g. "1. e4 e5 2. Nf3") into resolved HistoryMoves. */
-  private def parseMovesText(moveText: String): List[HistoryMove] =
-    val tokens = moveText.split("\\s+").filter(_.nonEmpty)
-
-    // Fold over tokens, threading (board, history, currentColor, accumulator)
-    val (_, _, _, moves) = tokens.foldLeft(
-      (Board.initial, GameHistory.empty, Color.White, List.empty[HistoryMove])
-    ):
-      case (state @ (board, history, color, acc), token) =>
-        // Skip move-number markers (e.g. "1.", "2.") and result tokens
-        if isMoveNumberOrResult(token) then state
-        else
-          parseAlgebraicMove(token, board, history, color) match
-            case None => state  // unrecognised token — skip silently
-            case Some(move) =>
-              val newBoard = move.castleSide match
-                case Some(side) => board.withCastle(color, side)
-                case None       => board.withMove(move.from, move.to)._1
-              val newHistory = history.addMove(move)
-              (newBoard, newHistory, 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"
-
-  /** Parse a single algebraic notation token into a HistoryMove, given the current board state. */
-  def parseAlgebraicMove(notation: String, board: Board, history: GameHistory, color: Color): Option[HistoryMove] =
-    notation match
-      case "O-O" | "O-O+" | "O-O#" =>
-        val rank = if color == Color.White then Rank.R1 else Rank.R8
-        Some(HistoryMove(Square(File.E, rank), Square(File.G, rank), Some(CastleSide.Kingside)))
-
-      case "O-O-O" | "O-O-O+" | "O-O-O#" =>
-        val rank = if color == Color.White then Rank.R1 else Rank.R8
-        Some(HistoryMove(Square(File.E, rank), Square(File.C, rank), Some(CastleSide.Queenside)))
-
-      case _ =>
-        parseRegularMove(notation, board, history, color)
-
-  /** Parse regular algebraic notation (pawn moves, piece moves, captures, disambiguation). */
-  private def parseRegularMove(notation: String, board: Board, history: GameHistory, color: Color): Option[HistoryMove] =
-    // Strip check/mate/capture indicators and promotion suffix (e.g. =Q)
-    val clean = notation
-      .replace("+", "")
-      .replace("#", "")
-      .replace("x", "")
-      .replaceAll("=[NBRQ]$", "")
-
-    // The destination square is always the last two characters
-    if clean.length < 2 then None
-    else
-      val destStr = clean.takeRight(2)
-      Square.fromAlgebraic(destStr).flatMap: toSquare =>
-        val disambig = clean.dropRight(2) // "" | "N"|"B"|"R"|"Q"|"K" | file | rank | file+rank
-
-        // Determine required piece type: upper-case first char = piece letter; else 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)
-
-        // Collect the disambiguation hint that remains after stripping the piece letter
-        val hint =
-          if disambig.nonEmpty && disambig.head.isUpper then disambig.tail
-          else disambig  // hint is file/rank info or empty
-
-        // Candidate source squares: pieces of `color` that can geometrically reach `toSquare`.
-        // We prefer pieces that can actually reach the target; if none can (positionally illegal
-        // PGN input), fall back to any piece of the matching type belonging to `color`.
-        val reachable: Set[Square] =
-          board.pieces.collect {
-            case (from, piece) if piece.color == color &&
-              MoveValidator.legalTargets(board, from).contains(toSquare) => from
-          }.toSet
-
-        val candidates: Set[Square] =
-          if reachable.nonEmpty then reachable
-          else
-            // Fallback for positionally-illegal but syntactically valid PGN notation:
-            // find any piece of `color` with the correct piece type on the board.
-            board.pieces.collect {
-              case (from, piece) if piece.color == color => from
-            }.toSet
-
-        // Filter by required piece type
-        val byPiece = candidates.filter(from =>
-          requiredPieceType.forall(pt => board.pieceAt(from).exists(_.pieceType == pt))
-        )
-
-        // Apply disambiguation hint (file letter or rank digit)
-        val disambiguated =
-          if hint.isEmpty then byPiece
-          else byPiece.filter(from => matchesHint(from, hint))
-
-        disambiguated.headOption.map(from => HistoryMove(from, toSquare, None))
-
-  /** True if `sq` matches a disambiguation hint (file letter, rank digit, or both). */
-  private def matchesHint(sq: Square, hint: String): Boolean =
-    hint.foldLeft(true): (ok, c) =>
-      ok && (
-        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
-      )
-
-  /** Convert a piece-letter character to a PieceType. */
-  private def charToPieceType(c: Char): Option[PieceType] =
-    c match
-      case 'N' => Some(PieceType.Knight)
-      case 'B' => Some(PieceType.Bishop)
-      case 'R' => Some(PieceType.Rook)
-      case 'Q' => Some(PieceType.Queen)
-      case 'K' => Some(PieceType.King)
-      case _   => None
@@ -1,87 +0,0 @@
-package de.nowchess.chess.observer
-
-import de.nowchess.api.board.{Board, Color}
-import de.nowchess.chess.logic.GameHistory
-
-/** Base trait for all game state events.
- *  Events are immutable snapshots of game state changes.
- */
-sealed trait GameEvent:
-  def board: Board
-  def history: GameHistory
-  def turn: Color
-
-/** Fired when a move is successfully executed. */
-case class MoveExecutedEvent(
-  board: Board,
-  history: GameHistory,
-  turn: Color,
-  fromSquare: String,
-  toSquare: String,
-  capturedPiece: Option[String]
-) extends GameEvent
-
-/** Fired when the current player is in check. */
-case class CheckDetectedEvent(
-  board: Board,
-  history: GameHistory,
-  turn: Color
-) extends GameEvent
-
-/** Fired when the game reaches checkmate. */
-case class CheckmateEvent(
-  board: Board,
-  history: GameHistory,
-  turn: Color,
-  winner: Color
-) extends GameEvent
-
-/** Fired when the game reaches stalemate. */
-case class StalemateEvent(
-  board: Board,
-  history: GameHistory,
-  turn: Color
-) extends GameEvent
-
-/** Fired when a move is invalid. */
-case class InvalidMoveEvent(
-  board: Board,
-  history: GameHistory,
-  turn: Color,
-  reason: String
-) extends GameEvent
-
-/** Fired when the board is reset. */
-case class BoardResetEvent(
-  board: Board,
-  history: GameHistory,
-  turn: Color
-) extends GameEvent
-
-/** Observer trait: implement to receive game state updates. */
-trait Observer:
-  def onGameEvent(event: GameEvent): Unit
-
-/** Observable trait: manages observers and notifies them of events. */
-trait Observable:
-  private val observers = scala.collection.mutable.Set[Observer]()
-
-  /** Register an observer to receive game events. */
-  def subscribe(observer: Observer): Unit = synchronized {
-    observers += observer
-  }
-
-  /** Unregister an observer. */
-  def unsubscribe(observer: Observer): Unit = synchronized {
-    observers -= observer
-  }
-
-  /** Notify all observers of a game event. */
-  protected def notifyObservers(event: GameEvent): Unit = synchronized {
-    observers.foreach(_.onGameEvent(event))
-  }
-
-  /** Return current list of observers (for testing). */
-  def observerCount: Int = synchronized {
-    observers.size
-  }
@@ -1,216 +0,0 @@
-package de.nowchess.chess.command
-
-import de.nowchess.api.board.{Square, File, Rank, Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class CommandInvokerBranchTest extends AnyFunSuite with Matchers:
-  
-  private def sq(f: File, r: Rank): Square = Square(f, r)
-
-  // ──── Helper: Command that always fails ────
-  private case class FailingCommand() extends Command:
-    override def execute(): Boolean = false
-    override def undo(): Boolean = false
-    override def description: String = "Failing command"
-
-  // ──── Helper: Command that conditionally fails on undo or execute ────
-  private case class ConditionalFailCommand(var shouldFailOnUndo: Boolean = false, var shouldFailOnExecute: Boolean = false) extends Command:
-    override def execute(): Boolean = !shouldFailOnExecute
-    override def undo(): Boolean = !shouldFailOnUndo
-    override def description: String = "Conditional fail"
-
-  private def createMoveCommand(from: Square, to: Square, executeSucceeds: Boolean = true): MoveCommand =
-    val cmd = MoveCommand(
-      from = from,
-      to = to,
-      moveResult = if executeSucceeds then Some(MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None)) else None,
-      previousBoard = Some(Board.initial),
-      previousHistory = Some(GameHistory.empty),
-      previousTurn = Some(Color.White)
-    )
-    cmd
-
-  // ──── BRANCH: execute() returns false ────
-  test("CommandInvoker.execute() with failing command returns false"):
-    val invoker = new CommandInvoker()
-    val cmd = FailingCommand()
-    invoker.execute(cmd) shouldBe false
-    invoker.history.size shouldBe 0
-    invoker.getCurrentIndex shouldBe -1
-
-  test("CommandInvoker.execute() does not add failed command to history"):
-    val invoker = new CommandInvoker()
-    val failingCmd = FailingCommand()
-    val successCmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    
-    invoker.execute(failingCmd) shouldBe false
-    invoker.history.size shouldBe 0
-    
-    invoker.execute(successCmd) shouldBe true
-    invoker.history.size shouldBe 1
-    invoker.history(0) shouldBe successCmd
-
-  // ──── BRANCH: undo() with invalid index (currentIndex < 0) ────
-  test("CommandInvoker.undo() returns false when currentIndex < 0"):
-    val invoker = new CommandInvoker()
-    // currentIndex starts at -1
-    invoker.undo() shouldBe false
-
-  test("CommandInvoker.undo() returns false when empty history"):
-    val invoker = new CommandInvoker()
-    invoker.canUndo shouldBe false
-    invoker.undo() shouldBe false
-
-  // ──── BRANCH: undo() with invalid index (currentIndex >= size) ────
-  test("CommandInvoker.undo() returns false when currentIndex >= history size"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    // currentIndex now = 1, history.size = 2
-    
-    invoker.undo()  // currentIndex becomes 0
-    invoker.undo()  // currentIndex becomes -1
-    invoker.undo()  // currentIndex still -1, should fail
-
-  // ──── BRANCH: undo() command returns false ────
-  test("CommandInvoker.undo() returns false when command.undo() fails"):
-    val invoker = new CommandInvoker()
-    val failingCmd = ConditionalFailCommand(shouldFailOnUndo = true)
-    
-    invoker.execute(failingCmd) shouldBe true
-    invoker.canUndo shouldBe true
-    
-    invoker.undo() shouldBe false
-    // Index should not change when undo fails
-    invoker.getCurrentIndex shouldBe 0
-
-  test("CommandInvoker.undo() returns true when command.undo() succeeds"):
-    val invoker = new CommandInvoker()
-    val successCmd = ConditionalFailCommand(shouldFailOnUndo = false)
-    
-    invoker.execute(successCmd) shouldBe true
-    invoker.undo() shouldBe true
-    invoker.getCurrentIndex shouldBe -1
-
-  // ──── BRANCH: redo() with invalid index (currentIndex + 1 >= size) ────
-  test("CommandInvoker.redo() returns false when nothing to redo"):
-    val invoker = new CommandInvoker()
-    invoker.redo() shouldBe false
-
-  test("CommandInvoker.redo() returns false when at end of history"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    
-    invoker.execute(cmd)
-    // currentIndex = 0, history.size = 1
-    invoker.canRedo shouldBe false
-    invoker.redo() shouldBe false
-
-  test("CommandInvoker.redo() returns false when currentIndex + 1 >= size"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    // currentIndex = 1, size = 2, currentIndex + 1 = 2, so 2 < 2 is false
-    invoker.canRedo shouldBe false
-    invoker.redo() shouldBe false
-
-  // ──── BRANCH: redo() command returns false ────
-  test("CommandInvoker.redo() returns false when command.execute() fails"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val redoFailCmd = ConditionalFailCommand(shouldFailOnExecute = false)  // Succeeds on first execute
-    
-    invoker.execute(cmd1)
-    invoker.execute(redoFailCmd)  // Succeeds and added to history
-    
-    invoker.undo()
-    // currentIndex = 0, redoFailCmd is at index 1
-    invoker.canRedo shouldBe true
-    
-    // Now modify to fail on next execute (redo)
-    redoFailCmd.shouldFailOnExecute = true
-    invoker.redo() shouldBe false
-    // currentIndex should not change
-    invoker.getCurrentIndex shouldBe 0
-
-  test("CommandInvoker.redo() returns true when command.execute() succeeds"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    
-    invoker.execute(cmd) shouldBe true
-    invoker.undo() shouldBe true
-    invoker.redo() shouldBe true
-    invoker.getCurrentIndex shouldBe 0
-
-  // ──── BRANCH: execute() with redo history discarding (while loop) ────
-  test("CommandInvoker.execute() discards redo history via while loop"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    val cmd3 = createMoveCommand(sq(File.D, Rank.R2), sq(File.D, Rank.R4))
-    
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    // currentIndex = 1, size = 2
-    
-    invoker.undo()
-    // currentIndex = 0, size = 2
-    // Redo history exists: cmd2 is at index 1
-    invoker.canRedo shouldBe true
-    
-    invoker.execute(cmd3)
-    // while loop should discard cmd2
-    invoker.canRedo shouldBe false
-    invoker.history.size shouldBe 2
-    invoker.history(1) shouldBe cmd3
-
-  test("CommandInvoker.execute() discards multiple redo commands"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    val cmd3 = createMoveCommand(sq(File.G, Rank.R1), sq(File.F, Rank.R3))
-    val cmd4 = createMoveCommand(sq(File.D, Rank.R2), sq(File.D, Rank.R4))
-    
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    invoker.execute(cmd3)
-    invoker.execute(cmd4)
-    // currentIndex = 3, size = 4
-    
-    invoker.undo()
-    invoker.undo()
-    // currentIndex = 1, size = 4
-    // Redo history: cmd3 (idx 2), cmd4 (idx 3)
-    invoker.canRedo shouldBe true
-    
-    val newCmd = createMoveCommand(sq(File.B, Rank.R2), sq(File.B, Rank.R4))
-    invoker.execute(newCmd)
-    // While loop should discard indices 2 and 3 (cmd3 and cmd4)
-    invoker.history.size shouldBe 3
-    invoker.canRedo shouldBe false
-
-  // ──── BRANCH: execute() with no redo history to discard ────
-  test("CommandInvoker.execute() with no redo history (while condition false)"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    // currentIndex = 1, size = 2
-    // currentIndex < size - 1 is 1 < 1 which is false, so while loop doesn't run
-    
-    invoker.canRedo shouldBe false
-    
-    val cmd3 = createMoveCommand(sq(File.D, Rank.R2), sq(File.D, Rank.R4))
-    invoker.execute(cmd3)  // While loop condition should be false, no iterations
-    invoker.history.size shouldBe 3
-
@@ -1,123 +0,0 @@
-package de.nowchess.chess.command
-
-import de.nowchess.api.board.{Square, File, Rank, Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class CommandInvokerTest extends AnyFunSuite with Matchers:
-
-  private def sq(f: File, r: Rank): Square = Square(f, r)
-  
-  private def createMoveCommand(from: Square, to: Square): MoveCommand =
-    MoveCommand(
-      from = from,
-      to = to,
-      moveResult = Some(MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None)),
-      previousBoard = Some(Board.initial),
-      previousHistory = Some(GameHistory.empty),
-      previousTurn = Some(Color.White)
-    )
-
-  test("CommandInvoker executes a command and adds it to history"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd) shouldBe true
-    invoker.history.size shouldBe 1
-    invoker.getCurrentIndex shouldBe 0
-
-  test("CommandInvoker executes multiple commands in sequence"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    invoker.execute(cmd1) shouldBe true
-    invoker.execute(cmd2) shouldBe true
-    invoker.history.size shouldBe 2
-    invoker.getCurrentIndex shouldBe 1
-
-  test("CommandInvoker.canUndo returns false when empty"):
-    val invoker = new CommandInvoker()
-    invoker.canUndo shouldBe false
-
-  test("CommandInvoker.canUndo returns true after execution"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.canUndo shouldBe true
-
-  test("CommandInvoker.undo decrements current index"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.getCurrentIndex shouldBe 0
-    invoker.undo() shouldBe true
-    invoker.getCurrentIndex shouldBe -1
-
-  test("CommandInvoker.canRedo returns true after undo"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.undo()
-    invoker.canRedo shouldBe true
-
-  test("CommandInvoker.redo re-executes a command"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.undo() shouldBe true
-    invoker.redo() shouldBe true
-    invoker.getCurrentIndex shouldBe 0
-
-  test("CommandInvoker.canUndo returns false when at beginning"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.undo()
-    invoker.canUndo shouldBe false
-
-  test("CommandInvoker clear removes all history"):
-    val invoker = new CommandInvoker()
-    val cmd = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    invoker.execute(cmd)
-    invoker.clear()
-    invoker.history.size shouldBe 0
-    invoker.getCurrentIndex shouldBe -1
-
-  test("CommandInvoker discards all history when executing after undoing all"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    val cmd3 = createMoveCommand(sq(File.D, Rank.R2), sq(File.D, Rank.R4))
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    invoker.undo()
-    invoker.undo()
-    // After undoing twice, we're at the beginning (before any commands)
-    invoker.getCurrentIndex shouldBe -1
-    invoker.canRedo shouldBe true
-    // Executing a new command from the beginning discards all redo history
-    invoker.execute(cmd3)
-    invoker.canRedo shouldBe false
-    invoker.history.size shouldBe 1
-    invoker.history(0) shouldBe cmd3
-    invoker.getCurrentIndex shouldBe 0
-
-  test("CommandInvoker discards redo history when executing mid-history"):
-    val invoker = new CommandInvoker()
-    val cmd1 = createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val cmd2 = createMoveCommand(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    val cmd3 = createMoveCommand(sq(File.D, Rank.R2), sq(File.D, Rank.R4))
-    invoker.execute(cmd1)
-    invoker.execute(cmd2)
-    invoker.undo()
-    // After one undo, we're at the end of cmd1
-    invoker.getCurrentIndex shouldBe 0
-    invoker.canRedo shouldBe true
-    // Executing a new command discards cmd2 (the redo history)
-    invoker.execute(cmd3)
-    invoker.canRedo shouldBe false
-    invoker.history.size shouldBe 2
-    invoker.history(0) shouldBe cmd1
-    invoker.history(1) shouldBe cmd3
-    invoker.getCurrentIndex shouldBe 1
-
@@ -1,131 +0,0 @@
-package de.nowchess.chess.command
-
-import de.nowchess.api.board.{Square, File, Rank, Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-import scala.collection.mutable
-
-class CommandInvokerThreadSafetyTest extends AnyFunSuite with Matchers:
-
-  private def sq(f: File, r: Rank): Square = Square(f, r)
-
-  private def createMoveCommand(from: Square, to: Square): MoveCommand =
-    MoveCommand(
-      from = from,
-      to = to,
-      moveResult = Some(MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None)),
-      previousBoard = Some(Board.initial),
-      previousHistory = Some(GameHistory.empty),
-      previousTurn = Some(Color.White)
-    )
-
-  test("CommandInvoker is thread-safe for concurrent execute and history reads"):
-    val invoker = new CommandInvoker()
-    @volatile var raceDetected = false
-    val exceptions = mutable.ListBuffer[Exception]()
-
-    // Thread 1: executes commands
-    val executorThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for i <- 1 to 1000 do
-            val cmd = createMoveCommand(
-              sq(File.E, Rank.R2),
-              sq(File.E, Rank.R4)
-            )
-            invoker.execute(cmd)
-        } catch {
-          case e: Exception =>
-            exceptions += e
-            raceDetected = true
-        }
-      }
-    })
-
-    // Thread 2: reads history during execution
-    val readerThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 1000 do
-            val _ = invoker.history
-            val _ = invoker.getCurrentIndex
-            Thread.sleep(0) // Yield to increase contention
-        } catch {
-          case e: Exception =>
-            exceptions += e
-            raceDetected = true
-        }
-      }
-    })
-
-    executorThread.start()
-    readerThread.start()
-    executorThread.join()
-    readerThread.join()
-
-    exceptions.isEmpty shouldBe true
-    raceDetected shouldBe false
-
-  test("CommandInvoker is thread-safe for concurrent execute, undo, and redo"):
-    val invoker = new CommandInvoker()
-    @volatile var raceDetected = false
-    val exceptions = mutable.ListBuffer[Exception]()
-
-    // Pre-populate with some commands
-    for _ <- 1 to 5 do
-      invoker.execute(createMoveCommand(sq(File.E, Rank.R2), sq(File.E, Rank.R4)))
-
-    // Thread 1: executes new commands
-    val executorThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 500 do
-            invoker.execute(createMoveCommand(sq(File.D, Rank.R2), sq(File.D, Rank.R4)))
-        } catch {
-          case e: Exception =>
-            exceptions += e
-            raceDetected = true
-        }
-      }
-    })
-
-    // Thread 2: undoes commands
-    val undoThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 500 do
-            if invoker.canUndo then
-              invoker.undo()
-        } catch {
-          case e: Exception =>
-            exceptions += e
-            raceDetected = true
-        }
-      }
-    })
-
-    // Thread 3: redoes commands
-    val redoThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 500 do
-            if invoker.canRedo then
-              invoker.redo()
-        } catch {
-          case e: Exception =>
-            exceptions += e
-            raceDetected = true
-        }
-      }
-    })
-
-    executorThread.start()
-    undoThread.start()
-    redoThread.start()
-    executorThread.join()
-    undoThread.join()
-    redoThread.join()
-
-    exceptions.isEmpty shouldBe true
-    raceDetected shouldBe false
@@ -1,52 +0,0 @@
-package de.nowchess.chess.command
-
-import de.nowchess.api.board.{Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class CommandTest extends AnyFunSuite with Matchers:
-
-  test("QuitCommand can be created"):
-    val cmd = QuitCommand()
-    cmd shouldNot be(null)
-
-  test("QuitCommand execute returns true"):
-    val cmd = QuitCommand()
-    cmd.execute() shouldBe true
-
-  test("QuitCommand undo returns false (cannot undo quit)"):
-    val cmd = QuitCommand()
-    cmd.undo() shouldBe false
-
-  test("QuitCommand description"):
-    val cmd = QuitCommand()
-    cmd.description shouldBe "Quit game"
-
-  test("ResetCommand with no prior state"):
-    val cmd = ResetCommand()
-    cmd.execute() shouldBe true
-    cmd.undo() shouldBe false
-
-  test("ResetCommand with prior state can undo"):
-    val cmd = ResetCommand(
-      previousBoard = Some(Board.initial),
-      previousHistory = Some(GameHistory.empty),
-      previousTurn = Some(Color.White)
-    )
-    cmd.execute() shouldBe true
-    cmd.undo() shouldBe true
-
-  test("ResetCommand with partial state cannot undo"):
-    val cmd = ResetCommand(
-      previousBoard = Some(Board.initial),
-      previousHistory = None,  // missing
-      previousTurn = Some(Color.White)
-    )
-    cmd.execute() shouldBe true
-    cmd.undo() shouldBe false
-
-  test("ResetCommand description"):
-    val cmd = ResetCommand()
-    cmd.description shouldBe "Reset board"
-
@@ -1,65 +0,0 @@
-package de.nowchess.chess.command
-
-import de.nowchess.api.board.{Square, File, Rank, Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class MoveCommandImmutabilityTest extends AnyFunSuite with Matchers:
-
-  private def sq(f: File, r: Rank): Square = Square(f, r)
-
-  test("MoveCommand should be immutable - fields cannot be mutated after creation"):
-    val cmd1 = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4)
-    )
-
-    // Create second command with filled state
-    val result = MoveResult.Successful(Board.initial, GameHistory.empty, Color.Black, None)
-    val cmd2 = cmd1.copy(
-      moveResult = Some(result),
-      previousBoard = Some(Board.initial),
-      previousHistory = Some(GameHistory.empty),
-      previousTurn = Some(Color.White)
-    )
-
-    // Original should be unchanged
-    cmd1.moveResult shouldBe None
-    cmd1.previousBoard shouldBe None
-    cmd1.previousHistory shouldBe None
-    cmd1.previousTurn shouldBe None
-
-    // New should have values
-    cmd2.moveResult shouldBe Some(result)
-    cmd2.previousBoard shouldBe Some(Board.initial)
-    cmd2.previousHistory shouldBe Some(GameHistory.empty)
-    cmd2.previousTurn shouldBe Some(Color.White)
-
-  test("MoveCommand equals and hashCode respect immutability"):
-    val cmd1 = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4),
-      moveResult = None,
-      previousBoard = None,
-      previousHistory = None,
-      previousTurn = None
-    )
-
-    val cmd2 = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4),
-      moveResult = None,
-      previousBoard = None,
-      previousHistory = None,
-      previousTurn = None
-    )
-
-    // Same values should be equal
-    cmd1 shouldBe cmd2
-    cmd1.hashCode shouldBe cmd2.hashCode
-
-    // Hash should be consistent (required for use as map keys)
-    val hash1 = cmd1.hashCode
-    val hash2 = cmd1.hashCode
-    hash1 shouldBe hash2
@@ -2,294 +2,406 @@ package de.nowchess.chess.controller

 import de.nowchess.api.board.*
 import de.nowchess.api.game.CastlingRights
-import de.nowchess.chess.logic.{CastleSide, GameHistory}
+import de.nowchess.chess.logic.{GameContext, CastleSide}
 import org.scalatest.funsuite.AnyFunSuite
 import org.scalatest.matchers.should.Matchers

+import java.io.ByteArrayInputStream
+
 class GameControllerTest extends AnyFunSuite with Matchers:

  private def sq(f: File, r: Rank): Square = Square(f, r)
-  private def processMove(board: Board, history: GameHistory, turn: Color, raw: String): MoveResult =
-    GameController.processMove(board, history, turn, raw)
-
-  private def castlingRights(history: GameHistory, color: Color): CastlingRights =
-    de.nowchess.chess.logic.CastlingRightsCalculator.deriveCastlingRights(history, color)
+  private val initial = GameContext.initial

  // ──── processMove ────────────────────────────────────────────────────

  test("processMove: 'quit' input returns Quit"):
-    processMove(Board.initial, GameHistory.empty, Color.White, "quit") shouldBe MoveResult.Quit
+    GameController.processMove(initial, Color.White, "quit") shouldBe MoveResult.Quit

  test("processMove: 'q' input returns Quit"):
-    processMove(Board.initial, GameHistory.empty, Color.White, "q") shouldBe MoveResult.Quit
+    GameController.processMove(initial, Color.White, "q") shouldBe MoveResult.Quit

  test("processMove: quit with surrounding whitespace returns Quit"):
-    processMove(Board.initial, GameHistory.empty, Color.White, "  quit  ") shouldBe MoveResult.Quit
+    GameController.processMove(initial, Color.White, "  quit  ") shouldBe MoveResult.Quit

  test("processMove: unparseable input returns InvalidFormat"):
-    processMove(Board.initial, GameHistory.empty, Color.White, "xyz") shouldBe MoveResult.InvalidFormat("xyz")
+    GameController.processMove(initial, Color.White, "xyz") shouldBe MoveResult.InvalidFormat("xyz")

  test("processMove: valid format but empty square returns NoPiece"):
    // E3 is empty in the initial position
-    processMove(Board.initial, GameHistory.empty, Color.White, "e3e4") shouldBe MoveResult.NoPiece
+    GameController.processMove(initial, Color.White, "e3e4") shouldBe MoveResult.NoPiece

  test("processMove: piece of wrong color returns WrongColor"):
    // E7 has a Black pawn; it is White's turn
-    processMove(Board.initial, GameHistory.empty, Color.White, "e7e6") shouldBe MoveResult.WrongColor
+    GameController.processMove(initial, Color.White, "e7e6") shouldBe MoveResult.WrongColor

  test("processMove: geometrically illegal move returns IllegalMove"):
    // White pawn at E2 cannot jump three squares to E5
-    processMove(Board.initial, GameHistory.empty, Color.White, "e2e5") shouldBe MoveResult.IllegalMove
+    GameController.processMove(initial, Color.White, "e2e5") shouldBe MoveResult.IllegalMove

  test("processMove: legal pawn move returns Moved with updated board and flipped turn"):
-    processMove(Board.initial, GameHistory.empty, Color.White, "e2e4") match
-      case MoveResult.Moved(newBoard, newHistory, captured, newTurn) =>
-        newBoard.pieceAt(sq(File.E, Rank.R4)) shouldBe Some(Piece.WhitePawn)
-        newBoard.pieceAt(sq(File.E, Rank.R2)) shouldBe None
+    GameController.processMove(initial, Color.White, "e2e4") match
+      case MoveResult.Moved(newCtx, captured, newTurn) =>
+        newCtx.board.pieceAt(sq(File.E, Rank.R4)) shouldBe Some(Piece.WhitePawn)
+        newCtx.board.pieceAt(sq(File.E, Rank.R2)) shouldBe None
        captured shouldBe None
        newTurn shouldBe Color.Black
      case other => fail(s"Expected Moved, got $other")

  test("processMove: legal capture returns Moved with the captured piece"):
-    val board = Board(Map(
+    val captureCtx = GameContext(Board(Map(
+      sq(File.E, Rank.R5) -> Piece.WhitePawn,
+      sq(File.D, Rank.R6) -> Piece.BlackPawn,
+      sq(File.H, Rank.R1) -> Piece.BlackKing,
+      sq(File.H, Rank.R8) -> Piece.WhiteKing
+    )))
+    GameController.processMove(captureCtx, Color.White, "e5d6") match
+      case MoveResult.Moved(newCtx, captured, newTurn) =>
+        captured shouldBe Some(Piece.BlackPawn)
+        newCtx.board.pieceAt(sq(File.D, Rank.R6)) shouldBe Some(Piece.WhitePawn)
+        newTurn shouldBe Color.Black
+      case other => fail(s"Expected Moved, got $other")
+
+  // ──── gameLoop ───────────────────────────────────────────────────────
+
+  private def withInput(input: String)(block: => Unit): Unit =
+    val stream = ByteArrayInputStream(input.getBytes("UTF-8"))
+    scala.Console.withIn(stream)(block)
+
+  test("gameLoop: 'quit' exits cleanly without exception"):
+    withInput("quit\n"):
+      GameController.gameLoop(GameContext.initial, Color.White)
+
+  test("gameLoop: EOF (null readLine) exits via quit fallback"):
+    withInput(""):
+      GameController.gameLoop(GameContext.initial, Color.White)
+
+  test("gameLoop: invalid format prints message and recurses until quit"):
+    withInput("badmove\nquit\n"):
+      GameController.gameLoop(GameContext.initial, Color.White)
+
+  test("gameLoop: NoPiece prints message and recurses until quit"):
+    // E3 is empty in the initial position
+    withInput("e3e4\nquit\n"):
+      GameController.gameLoop(GameContext.initial, Color.White)
+
+  test("gameLoop: WrongColor prints message and recurses until quit"):
+    // E7 has a Black pawn; it is White's turn
+    withInput("e7e6\nquit\n"):
+      GameController.gameLoop(GameContext.initial, Color.White)
+
+  test("gameLoop: IllegalMove prints message and recurses until quit"):
+    withInput("e2e5\nquit\n"):
+      GameController.gameLoop(GameContext.initial, Color.White)
+
+  test("gameLoop: legal non-capture move recurses with new board then quits"):
+    withInput("e2e4\nquit\n"):
+      GameController.gameLoop(GameContext.initial, Color.White)
+
+  test("gameLoop: capture move prints capture message then recurses and quits"):
+    val captureBoard = Board(Map(
      sq(File.E, Rank.R5) -> Piece.WhitePawn,
      sq(File.D, Rank.R6) -> Piece.BlackPawn,
      sq(File.H, Rank.R1) -> Piece.BlackKing,
      sq(File.H, Rank.R8) -> Piece.WhiteKing
    ))
-    processMove(board, GameHistory.empty, Color.White, "e5d6") match
-      case MoveResult.Moved(newBoard, newHistory, captured, newTurn) =>
-        captured shouldBe Some(Piece.BlackPawn)
-        newBoard.pieceAt(sq(File.D, Rank.R6)) shouldBe Some(Piece.WhitePawn)
-        newTurn shouldBe Color.Black
-      case other => fail(s"Expected Moved, got $other")
+    withInput("e5d6\nquit\n"):
+      GameController.gameLoop(GameContext(captureBoard), Color.White)
+
+  // ──── helpers ────────────────────────────────────────────────────────
+
+  private def captureOutput(block: => Unit): String =
+    val out = java.io.ByteArrayOutputStream()
+    scala.Console.withOut(out)(block)
+    out.toString("UTF-8")

  // ──── processMove: check / checkmate / stalemate ─────────────────────

  test("processMove: legal move that delivers check returns MovedInCheck"):
    // White Ra1, Ka3; Black Kh8 — White plays Ra1-Ra8, Ra8 attacks rank 8 putting Kh8 in check
    // Kh8 can escape to g7/g8/h7 so this is InCheck, not Mated
-    val b = Board(Map(
+    val ctx = GameContext(Board(Map(
      sq(File.A, Rank.R1) -> Piece.WhiteRook,
      sq(File.C, Rank.R3) -> Piece.WhiteKing,
      sq(File.H, Rank.R8) -> Piece.BlackKing
-    ))
-    processMove(b, GameHistory.empty, Color.White, "a1a8") match
-      case MoveResult.MovedInCheck(_, _, _, newTurn) => newTurn shouldBe Color.Black
+    )))
+    GameController.processMove(ctx, Color.White, "a1a8") match
+      case MoveResult.MovedInCheck(_, _, newTurn) => newTurn shouldBe Color.Black
      case other => fail(s"Expected MovedInCheck, got $other")

  test("processMove: legal move that results in checkmate returns Checkmate"):
    // White Qa1, Ka6; Black Ka8 — White plays Qa1-Qh8 (diagonal a1→h8)
    // After Qh8: White Qh8 + Ka6 vs Black Ka8 = checkmate (spec-verified position)
    // Qa1 does NOT currently attack Ka8 — path along file A is blocked by Ka6
-    val b = Board(Map(
+    val ctx = GameContext(Board(Map(
      sq(File.A, Rank.R1) -> Piece.WhiteQueen,
      sq(File.A, Rank.R6) -> Piece.WhiteKing,
      sq(File.A, Rank.R8) -> Piece.BlackKing
-    ))
-    processMove(b, GameHistory.empty, Color.White, "a1h8") match
+    )))
+    GameController.processMove(ctx, Color.White, "a1h8") match
      case MoveResult.Checkmate(winner) => winner shouldBe Color.White
      case other => fail(s"Expected Checkmate(White), got $other")

  test("processMove: legal move that results in stalemate returns Stalemate"):
    // White Qb1, Kc6; Black Ka8 — White plays Qb1-Qb6
    // After Qb6: White Qb6 + Kc6 vs Black Ka8 = stalemate (spec-verified position)
+    val ctx = GameContext(Board(Map(
+      sq(File.B, Rank.R1) -> Piece.WhiteQueen,
+      sq(File.C, Rank.R6) -> Piece.WhiteKing,
+      sq(File.A, Rank.R8) -> Piece.BlackKing
+    )))
+    GameController.processMove(ctx, Color.White, "b1b6") match
+      case MoveResult.Stalemate => succeed
+      case other => fail(s"Expected Stalemate, got $other")
+
+  // ──── gameLoop: check / checkmate / stalemate ─────────────────────────
+
+  test("gameLoop: checkmate prints winner message and resets to new game"):
+    // After Qa1-Qh8, position is checkmate; second "quit" exits the new game
+    val b = Board(Map(
+      sq(File.A, Rank.R1) -> Piece.WhiteQueen,
+      sq(File.A, Rank.R6) -> Piece.WhiteKing,
+      sq(File.A, Rank.R8) -> Piece.BlackKing
+    ))
+    val output = captureOutput:
+      withInput("a1h8\nquit\n"):
+        GameController.gameLoop(GameContext(b), Color.White)
+    output should include("Checkmate! White wins.")
+
+  test("gameLoop: stalemate prints draw message and resets to new game"):
    val b = Board(Map(
      sq(File.B, Rank.R1) -> Piece.WhiteQueen,
      sq(File.C, Rank.R6) -> Piece.WhiteKing,
      sq(File.A, Rank.R8) -> Piece.BlackKing
    ))
-    processMove(b, GameHistory.empty, Color.White, "b1b6") match
-      case MoveResult.Stalemate => succeed
-      case other => fail(s"Expected Stalemate, got $other")
+    val output = captureOutput:
+      withInput("b1b6\nquit\n"):
+        GameController.gameLoop(GameContext(b), Color.White)
+    output should include("Stalemate! The game is a draw.")
+
+  test("gameLoop: MovedInCheck without capture prints check message"):
+    val b = Board(Map(
+      sq(File.A, Rank.R1) -> Piece.WhiteRook,
+      sq(File.C, Rank.R3) -> Piece.WhiteKing,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    ))
+    val output = captureOutput:
+      withInput("a1a8\nquit\n"):
+        GameController.gameLoop(GameContext(b), Color.White)
+    output should include("Black is in check!")
+
+  test("gameLoop: MovedInCheck with capture prints both capture and check message"):
+    // White Rook A1 captures Black Pawn on A8, Ra8 then attacks rank 8 putting Kh8 in check
+    val b = Board(Map(
+      sq(File.A, Rank.R1) -> Piece.WhiteRook,
+      sq(File.C, Rank.R3) -> Piece.WhiteKing,
+      sq(File.A, Rank.R8) -> Piece.BlackPawn,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    ))
+    val output = captureOutput:
+      withInput("a1a8\nquit\n"):
+        GameController.gameLoop(GameContext(b), Color.White)
+    output should include("captures")
+    output should include("Black is in check!")

  // ──── castling execution ─────────────────────────────────────────────

  test("processMove: e1g1 returns Moved with king on g1 and rook on f1"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.H, Rank.R1) -> Piece.WhiteRook,
        sq(File.H, Rank.R8) -> Piece.BlackKing
-      ))
-    processMove(b, GameHistory.empty, Color.White, "e1g1") match
-      case MoveResult.Moved(newBoard, newHistory, captured, newTurn) =>
-        newBoard.pieceAt(sq(File.G, Rank.R1)) shouldBe Some(Piece.WhiteKing)
-        newBoard.pieceAt(sq(File.F, Rank.R1)) shouldBe Some(Piece.WhiteRook)
-        newBoard.pieceAt(sq(File.E, Rank.R1)) shouldBe None
-        newBoard.pieceAt(sq(File.H, Rank.R1)) shouldBe None
+      )),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameController.processMove(ctx, Color.White, "e1g1") match
+      case MoveResult.Moved(newCtx, captured, newTurn) =>
+        newCtx.board.pieceAt(sq(File.G, Rank.R1)) shouldBe Some(Piece.WhiteKing)
+        newCtx.board.pieceAt(sq(File.F, Rank.R1)) shouldBe Some(Piece.WhiteRook)
+        newCtx.board.pieceAt(sq(File.E, Rank.R1)) shouldBe None
+        newCtx.board.pieceAt(sq(File.H, Rank.R1)) shouldBe None
        captured shouldBe None
        newTurn shouldBe Color.Black
      case other => fail(s"Expected Moved, got $other")

  test("processMove: e1c1 returns Moved with king on c1 and rook on d1"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.A, Rank.R1) -> Piece.WhiteRook,
        sq(File.H, Rank.R8) -> Piece.BlackKing
-      ))
-    processMove(b, GameHistory.empty, Color.White, "e1c1") match
-      case MoveResult.Moved(newBoard, _, _, _) =>
-        newBoard.pieceAt(sq(File.C, Rank.R1)) shouldBe Some(Piece.WhiteKing)
-        newBoard.pieceAt(sq(File.D, Rank.R1)) shouldBe Some(Piece.WhiteRook)
+      )),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameController.processMove(ctx, Color.White, "e1c1") match
+      case MoveResult.Moved(newCtx, _, _) =>
+        newCtx.board.pieceAt(sq(File.C, Rank.R1)) shouldBe Some(Piece.WhiteKing)
+        newCtx.board.pieceAt(sq(File.D, Rank.R1)) shouldBe Some(Piece.WhiteRook)
      case other => fail(s"Expected Moved, got $other")

  // ──── rights revocation ──────────────────────────────────────────────

  test("processMove: e1g1 revokes both white castling rights"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.H, Rank.R1) -> Piece.WhiteRook,
        sq(File.H, Rank.R8) -> Piece.BlackKing
-      ))
-    processMove(b, GameHistory.empty, Color.White, "e1g1") match
-      case MoveResult.Moved(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.White) shouldBe CastlingRights.None
+      )),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameController.processMove(ctx, Color.White, "e1g1") match
+      case MoveResult.Moved(newCtx, _, _) =>
+        newCtx.whiteCastling shouldBe CastlingRights.None
      case other => fail(s"Expected Moved, got $other")

  test("processMove: moving rook from h1 revokes white kingside right"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.H, Rank.R1) -> Piece.WhiteRook,
        sq(File.H, Rank.R8) -> Piece.BlackKing
-      ))
-    processMove(b, GameHistory.empty, Color.White, "h1h4") match
-      case MoveResult.Moved(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.White).kingSide  shouldBe false
-        castlingRights(newHistory, Color.White).queenSide shouldBe true
-      case MoveResult.MovedInCheck(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.White).kingSide  shouldBe false
-        castlingRights(newHistory, Color.White).queenSide shouldBe true
+      )),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameController.processMove(ctx, Color.White, "h1h4") match
+      case MoveResult.Moved(newCtx, _, _) =>
+        newCtx.whiteCastling.kingSide  shouldBe false
+        newCtx.whiteCastling.queenSide shouldBe true
+      case MoveResult.MovedInCheck(newCtx, _, _) =>
+        newCtx.whiteCastling.kingSide  shouldBe false
+        newCtx.whiteCastling.queenSide shouldBe true
      case other => fail(s"Expected Moved or MovedInCheck, got $other")

  test("processMove: moving king from e1 revokes both white rights"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.H, Rank.R8) -> Piece.BlackKing
-      ))
-    processMove(b, GameHistory.empty, Color.White, "e1e2") match
-      case MoveResult.Moved(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.White) shouldBe CastlingRights.None
+      )),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameController.processMove(ctx, Color.White, "e1e2") match
+      case MoveResult.Moved(newCtx, _, _) =>
+        newCtx.whiteCastling shouldBe CastlingRights.None
      case other => fail(s"Expected Moved, got $other")

  test("processMove: enemy capture on h1 revokes white kingside right"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.H, Rank.R1) -> Piece.WhiteRook,
        sq(File.H, Rank.R2) -> Piece.BlackRook,
        sq(File.A, Rank.R8) -> Piece.BlackKing
-      ))
-    processMove(b, GameHistory.empty, Color.Black, "h2h1") match
-      case MoveResult.Moved(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.White).kingSide shouldBe false
-      case MoveResult.MovedInCheck(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.White).kingSide shouldBe false
+      )),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameController.processMove(ctx, Color.Black, "h2h1") match
+      case MoveResult.Moved(newCtx, _, _) =>
+        newCtx.whiteCastling.kingSide shouldBe false
+      case MoveResult.MovedInCheck(newCtx, _, _) =>
+        newCtx.whiteCastling.kingSide shouldBe false
      case other => fail(s"Expected Moved or MovedInCheck, got $other")

  test("processMove: castle attempt when rights revoked returns IllegalMove"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.H, Rank.R1) -> Piece.WhiteRook,
        sq(File.H, Rank.R8) -> Piece.BlackKing
-      ))
-    val history = GameHistory.empty.addMove(sq(File.E, Rank.R1), sq(File.E, Rank.R2)).addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R1))
-    processMove(b, history, Color.White, "e1g1") shouldBe MoveResult.IllegalMove
+      )),
+      whiteCastling = CastlingRights.None,
+      blackCastling = CastlingRights.None
+    )
+    GameController.processMove(ctx, Color.White, "e1g1") shouldBe MoveResult.IllegalMove

  test("processMove: castle attempt when rook not on home square returns IllegalMove"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.G, Rank.R1) -> Piece.WhiteRook,
        sq(File.H, Rank.R8) -> Piece.BlackKing
-      ))
-    processMove(b, GameHistory.empty, Color.White, "e1g1") shouldBe MoveResult.IllegalMove
+      )),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameController.processMove(ctx, Color.White, "e1g1") shouldBe MoveResult.IllegalMove

  test("processMove: moving king from e8 revokes both black rights"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R8) -> Piece.BlackKing,
        sq(File.H, Rank.R1) -> Piece.WhiteKing
-      ))
-    processMove(b, GameHistory.empty, Color.Black, "e8e7") match
-      case MoveResult.Moved(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.Black) shouldBe CastlingRights.None
-      case MoveResult.MovedInCheck(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.Black) shouldBe CastlingRights.None
+      )),
+      whiteCastling = CastlingRights.None,
+      blackCastling = CastlingRights.Both
+    )
+    GameController.processMove(ctx, Color.Black, "e8e7") match
+      case MoveResult.Moved(newCtx, _, _) =>
+        newCtx.blackCastling shouldBe CastlingRights.None
+      case MoveResult.MovedInCheck(newCtx, _, _) =>
+        newCtx.blackCastling shouldBe CastlingRights.None
      case other => fail(s"Expected Moved or MovedInCheck, got $other")

  test("processMove: moving rook from a8 revokes black queenside right"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R8) -> Piece.BlackKing,
        sq(File.A, Rank.R8) -> Piece.BlackRook,
        sq(File.H, Rank.R1) -> Piece.WhiteKing
-      ))
-    processMove(b, GameHistory.empty, Color.Black, "a8a1") match
-      case MoveResult.Moved(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.Black).queenSide shouldBe false
-        castlingRights(newHistory, Color.Black).kingSide  shouldBe true
-      case MoveResult.MovedInCheck(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.Black).queenSide shouldBe false
-        castlingRights(newHistory, Color.Black).kingSide  shouldBe true
+      )),
+      whiteCastling = CastlingRights.None,
+      blackCastling = CastlingRights.Both
+    )
+    GameController.processMove(ctx, Color.Black, "a8a7") match
+      case MoveResult.Moved(newCtx, _, _) =>
+        newCtx.blackCastling.queenSide shouldBe false
+        newCtx.blackCastling.kingSide  shouldBe true
+      case MoveResult.MovedInCheck(newCtx, _, _) =>
+        newCtx.blackCastling.queenSide shouldBe false
+        newCtx.blackCastling.kingSide  shouldBe true
      case other => fail(s"Expected Moved or MovedInCheck, got $other")

  test("processMove: moving rook from h8 revokes black kingside right"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R8) -> Piece.BlackKing,
        sq(File.H, Rank.R8) -> Piece.BlackRook,
-        sq(File.A, Rank.R1) -> Piece.WhiteKing
-      ))
-    processMove(b, GameHistory.empty, Color.Black, "h8h4") match
-      case MoveResult.Moved(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.Black).kingSide  shouldBe false
-        castlingRights(newHistory, Color.Black).queenSide shouldBe true
-      case MoveResult.MovedInCheck(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.Black).kingSide  shouldBe false
-        castlingRights(newHistory, Color.Black).queenSide shouldBe true
+        sq(File.H, Rank.R1) -> Piece.WhiteKing
+      )),
+      whiteCastling = CastlingRights.None,
+      blackCastling = CastlingRights.Both
+    )
+    GameController.processMove(ctx, Color.Black, "h8h7") match
+      case MoveResult.Moved(newCtx, _, _) =>
+        newCtx.blackCastling.kingSide  shouldBe false
+        newCtx.blackCastling.queenSide shouldBe true
+      case MoveResult.MovedInCheck(newCtx, _, _) =>
+        newCtx.blackCastling.kingSide  shouldBe false
+        newCtx.blackCastling.queenSide shouldBe true
      case other => fail(s"Expected Moved or MovedInCheck, got $other")

  test("processMove: enemy capture on a1 revokes white queenside right"):
-    val b = Board(Map(
+    val ctx = GameContext(
+      board = Board(Map(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.A, Rank.R1) -> Piece.WhiteRook,
        sq(File.A, Rank.R2) -> Piece.BlackRook,
        sq(File.H, Rank.R8) -> Piece.BlackKing
-      ))
-    processMove(b, GameHistory.empty, Color.Black, "a2a1") match
-      case MoveResult.Moved(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.White).queenSide shouldBe false
-      case MoveResult.MovedInCheck(_, newHistory, _, _) =>
-        castlingRights(newHistory, Color.White).queenSide shouldBe false
+      )),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameController.processMove(ctx, Color.Black, "a2a1") match
+      case MoveResult.Moved(newCtx, _, _) =>
+        newCtx.whiteCastling.queenSide shouldBe false
+      case MoveResult.MovedInCheck(newCtx, _, _) =>
+        newCtx.whiteCastling.queenSide shouldBe false
      case other => fail(s"Expected Moved or MovedInCheck, got $other")
-
-  // ──── en passant ────────────────────────────────────────────────────────
-
-  test("en passant capture removes the captured pawn from the board"):
-    // Setup: white pawn e5, black pawn just double-pushed to d5 (ep target = d6)
-    val b = Board(Map(
-      Square(File.E, Rank.R5) -> Piece.WhitePawn,
-      Square(File.D, Rank.R5) -> Piece.BlackPawn,
-      Square(File.E, Rank.R1) -> Piece.WhiteKing,
-      Square(File.E, Rank.R8) -> Piece.BlackKing
-    ))
-    val h = GameHistory.empty.addMove(Square(File.D, Rank.R7), Square(File.D, Rank.R5))
-    val result = GameController.processMove(b, h, Color.White, "e5d6")
-    result match
-      case MoveResult.Moved(newBoard, _, captured, _) =>
-        newBoard.pieceAt(Square(File.D, Rank.R5)) shouldBe None  // captured pawn removed
-        newBoard.pieceAt(Square(File.D, Rank.R6)) shouldBe Some(Piece.WhitePawn)  // capturing pawn placed
-        captured shouldBe Some(Piece.BlackPawn)
-      case other => fail(s"Expected Moved but got $other")
-
-  test("en passant capture by black removes the captured white pawn"):
-    // Setup: black pawn d4, white pawn just double-pushed to e4 (ep target = e3)
-    val b = Board(Map(
-      Square(File.D, Rank.R4) -> Piece.BlackPawn,
-      Square(File.E, Rank.R4) -> Piece.WhitePawn,
-      Square(File.E, Rank.R8) -> Piece.BlackKing,
-      Square(File.E, Rank.R1) -> Piece.WhiteKing
-    ))
-    val h = GameHistory.empty.addMove(Square(File.E, Rank.R2), Square(File.E, Rank.R4))
-    val result = GameController.processMove(b, h, Color.Black, "d4e3")
-    result match
-      case MoveResult.Moved(newBoard, _, captured, _) =>
-        newBoard.pieceAt(Square(File.E, Rank.R4)) shouldBe None  // captured pawn removed
-        newBoard.pieceAt(Square(File.E, Rank.R3)) shouldBe Some(Piece.BlackPawn)  // capturing pawn placed
-        captured shouldBe Some(Piece.WhitePawn)
-      case other => fail(s"Expected Moved but got $other")
@@ -1,214 +0,0 @@
-package de.nowchess.chess.engine
-
-import scala.collection.mutable
-import de.nowchess.api.board.{Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import de.nowchess.chess.observer.{Observer, GameEvent, MoveExecutedEvent, CheckDetectedEvent, BoardResetEvent, InvalidMoveEvent}
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-/** Tests for GameEngine edge cases and uncovered paths */
-class GameEngineEdgeCasesTest extends AnyFunSuite with Matchers:
-
-  test("GameEngine handles empty input"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("")
-    
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("Please enter a valid move or command")
-
-  test("GameEngine processes quit command"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("quit")
-    // Quit just returns, no events
-    observer.events.isEmpty shouldBe true
-
-  test("GameEngine processes q command (short form)"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("q")
-    observer.events.isEmpty shouldBe true
-
-  test("GameEngine handles uppercase quit"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("QUIT")
-    observer.events.isEmpty shouldBe true
-
-  test("GameEngine handles undo on empty history"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.canUndo shouldBe false
-    engine.processUserInput("undo")
-    
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("Nothing to undo")
-
-  test("GameEngine handles redo on empty redo history"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.canRedo shouldBe false
-    engine.processUserInput("redo")
-    
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("Nothing to redo")
-
-  test("GameEngine parses invalid move format"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("invalid_move_format")
-    
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("Invalid move format")
-
-  test("GameEngine handles lowercase input normalization"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("  UNDO  ")  // With spaces and uppercase
-    
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]  // No moves to undo yet
-
-  test("GameEngine preserves board state on invalid move"):
-    val engine = new GameEngine()
-    val initialBoard = engine.board
-    
-    engine.processUserInput("invalid")
-    
-    engine.board shouldBe initialBoard
-
-  test("GameEngine preserves turn on invalid move"):
-    val engine = new GameEngine()
-    val initialTurn = engine.turn
-    
-    engine.processUserInput("invalid")
-    
-    engine.turn shouldBe initialTurn
-
-  test("GameEngine undo with no commands available"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    // Make a valid move
-    engine.processUserInput("e2e4")
-    observer.events.clear()
-    
-    // Undo it
-    engine.processUserInput("undo")
-    
-    // Board should be reset
-    engine.board shouldBe Board.initial
-    engine.turn shouldBe Color.White
-
-  test("GameEngine redo after undo"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("e2e4")
-    val boardAfterMove = engine.board
-    val turnAfterMove = engine.turn
-    observer.events.clear()
-    
-    engine.processUserInput("undo")
-    engine.processUserInput("redo")
-    
-    engine.board shouldBe boardAfterMove
-    engine.turn shouldBe turnAfterMove
-
-  test("GameEngine canUndo flag tracks state correctly"):
-    val engine = new GameEngine()
-    
-    engine.canUndo shouldBe false
-    engine.processUserInput("e2e4")
-    engine.canUndo shouldBe true
-    engine.processUserInput("undo")
-    engine.canUndo shouldBe false
-
-  test("GameEngine canRedo flag tracks state correctly"):
-    val engine = new GameEngine()
-    
-    engine.canRedo shouldBe false
-    engine.processUserInput("e2e4")
-    engine.canRedo shouldBe false
-    engine.processUserInput("undo")
-    engine.canRedo shouldBe true
-
-  test("GameEngine command history is accessible"):
-    val engine = new GameEngine()
-    
-    engine.commandHistory.isEmpty shouldBe true
-    engine.processUserInput("e2e4")
-    engine.commandHistory.size shouldBe 1
-
-  test("GameEngine processes multiple moves in sequence"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    observer.events.clear()
-    
-    engine.processUserInput("e2e4")
-    engine.processUserInput("e7e5")
-    
-    observer.events.size shouldBe 2
-    engine.commandHistory.size shouldBe 2
-
-  test("GameEngine can undo multiple moves"):
-    val engine = new GameEngine()
-    
-    engine.processUserInput("e2e4")
-    engine.processUserInput("e7e5")
-    
-    engine.processUserInput("undo")
-    engine.turn shouldBe Color.Black
-    
-    engine.processUserInput("undo")
-    engine.turn shouldBe Color.White
-
-  test("GameEngine thread-safe operations"):
-    val engine = new GameEngine()
-    
-    // Access from synchronized methods
-    val board = engine.board
-    val history = engine.history
-    val turn = engine.turn
-    val canUndo = engine.canUndo
-    val canRedo = engine.canRedo
-    
-    board shouldBe Board.initial
-    canUndo shouldBe false
-    canRedo shouldBe false
-
-
-private class MockObserver extends Observer:
-  val events = mutable.ListBuffer[GameEvent]()
-  
-  override def onGameEvent(event: GameEvent): Unit =
-    events += event
@@ -1,93 +0,0 @@
-package de.nowchess.chess.engine
-
-import scala.collection.mutable
-import de.nowchess.api.board.{Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import de.nowchess.chess.observer.{Observer, GameEvent, CheckDetectedEvent, CheckmateEvent, StalemateEvent}
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-/** Tests for GameEngine check/checkmate/stalemate paths */
-class GameEngineGameEndingTest extends AnyFunSuite with Matchers:
-
-  test("GameEngine handles Checkmate (Fool's Mate)"):
-    val engine = new GameEngine()
-    val observer = new EndingMockObserver()
-    engine.subscribe(observer)
-    
-    // Play Fool's mate
-    engine.processUserInput("f2f3")
-    engine.processUserInput("e7e5")
-    engine.processUserInput("g2g4")
-    
-    observer.events.clear()
-    engine.processUserInput("d8h4")
-    
-    // Verify CheckmateEvent
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe a[CheckmateEvent]
-    
-    val event = observer.events.head.asInstanceOf[CheckmateEvent]
-    event.winner shouldBe Color.Black
-    
-    // Board should be reset after checkmate
-    engine.board shouldBe Board.initial
-    engine.turn shouldBe Color.White
-
-  test("GameEngine handles check detection"):
-    val engine = new GameEngine()
-    val observer = new EndingMockObserver()
-    engine.subscribe(observer)
-    
-    // Play a simple check
-    engine.processUserInput("e2e4")
-    engine.processUserInput("e7e5")
-    engine.processUserInput("f1c4")
-    engine.processUserInput("g8f6")
-    
-    observer.events.clear()
-    engine.processUserInput("c4f7") // Check!
-    
-    val checkEvents = observer.events.collect { case e: CheckDetectedEvent => e }
-    checkEvents.size shouldBe 1
-    checkEvents.head.turn shouldBe Color.Black // Black is now in check
-    
-  // Shortest known stalemate is 19 moves. Here is a faster one:
-  // e3 a5 Qh5 Ra6 Qxa5 h5 h4 Rah6 Qxc7 f6 Qxd7+ Kf7 Qxb7 Qd3 Qxb8 Qh7 Qxc8 Kg6 Qe6
-  // Wait, let's just use Sam Loyd's 10-move stalemate:
-  // 1. e3 a5 2. Qh5 Ra6 3. Qxa5 h5 4. h4 Rah6 5. Qxc7 f6 6. Qxd7+ Kf7 7. Qxb7 Qd3 8. Qxb8 Qh7 9. Qxc8 Kg6 10. Qe6
-  test("GameEngine handles Stalemate via 10-move known sequence"):
-    val engine = new GameEngine()
-    val observer = new EndingMockObserver()
-    engine.subscribe(observer)
-    
-    val moves = List(
-      "e2e3", "a7a5",
-      "d1h5", "a8a6",
-      "h5a5", "h7h5",
-      "h2h4", "a6h6",
-      "a5c7", "f7f6",
-      "c7d7", "e8f7",
-      "d7b7", "d8d3",
-      "b7b8", "d3h7",
-      "b8c8", "f7g6",
-      "c8e6"
-    )
-    
-    moves.dropRight(1).foreach(engine.processUserInput)
-    
-    observer.events.clear()
-    engine.processUserInput(moves.last)
-    
-    val stalemateEvents = observer.events.collect { case e: StalemateEvent => e }
-    stalemateEvents.size shouldBe 1
-    
-    // Board should be reset after stalemate
-    engine.board shouldBe Board.initial
-    engine.turn shouldBe Color.White
-
-private class EndingMockObserver extends Observer:
-  val events = mutable.ListBuffer[GameEvent]()
-  
-  override def onGameEvent(event: GameEvent): Unit =
-    events += event
@@ -1,110 +0,0 @@
-package de.nowchess.chess.engine
-
-import scala.collection.mutable
-import de.nowchess.api.board.{Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import de.nowchess.chess.observer.{Observer, GameEvent, InvalidMoveEvent}
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-/** Tests to maximize handleFailedMove coverage */
-class GameEngineHandleFailedMoveTest extends AnyFunSuite with Matchers:
-
-  test("GameEngine handles InvalidFormat error type"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("not_a_valid_move_format")
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val msg1 = observer.events.head.asInstanceOf[InvalidMoveEvent].reason
-    msg1 should include("Invalid move format")
-
-  test("GameEngine handles NoPiece error type"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("h3h4")
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val msg2 = observer.events.head.asInstanceOf[InvalidMoveEvent].reason
-    msg2 should include("No piece on that square")
-
-  test("GameEngine handles WrongColor error type"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("e2e4")  // White move
-    observer.events.clear()
-    
-    engine.processUserInput("a1b2")  // Try to move black's rook position with white's move (wrong color)
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val msg3 = observer.events.head.asInstanceOf[InvalidMoveEvent].reason
-    msg3 should include("That is not your piece")
-
-  test("GameEngine handles IllegalMove error type"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("e2e1")  // Try pawn backward
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val msg4 = observer.events.head.asInstanceOf[InvalidMoveEvent].reason
-    msg4 should include("Illegal move")
-
-  test("GameEngine invalid move message for InvalidFormat"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("xyz123")
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("coordinate notation")
-
-  test("GameEngine invalid move message for NoPiece"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("a3a4")  // a3 is empty
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("No piece")
-
-  test("GameEngine invalid move message for WrongColor"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("e2e4")
-    observer.events.clear()
-    
-    engine.processUserInput("e4e5")  // e4 has white pawn, it's black's turn
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("not your piece")
-
-  test("GameEngine invalid move message for IllegalMove"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    engine.processUserInput("e2e1")  // Pawn can't move backward
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("Illegal move")
-
-  test("GameEngine board unchanged after each type of invalid move"):
-    val engine = new GameEngine()
-    val initial = engine.board
-    
-    engine.processUserInput("invalid")
-    engine.board shouldBe initial
-    
-    engine.processUserInput("h3h4")
-    engine.board shouldBe initial
-    
-    engine.processUserInput("e2e1")
-    engine.board shouldBe initial
@@ -1,114 +0,0 @@
-package de.nowchess.chess.engine
-
-import scala.collection.mutable
-import de.nowchess.api.board.{Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import de.nowchess.chess.observer.{Observer, GameEvent, InvalidMoveEvent, MoveExecutedEvent}
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-/** Tests for GameEngine invalid move handling via handleFailedMove */
-class GameEngineInvalidMovesTest extends AnyFunSuite with Matchers:
-
-  test("GameEngine handles no piece at source square"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    // Try to move from h1 which may be empty or not have our piece
-    // We'll try from a clearly empty square
-    engine.processUserInput("h1h2")
-    
-    // Should get an InvalidMoveEvent about NoPiece
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-
-  test("GameEngine handles moving wrong color piece"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    // White moves first
-    engine.processUserInput("e2e4")
-    observer.events.clear()
-    
-    // White tries to move again (should fail - it's black's turn)
-    // But we need to try a move that looks legal but has wrong color
-    // This is hard to test because we'd need to be black and move white's piece
-    // Let's skip this for now and focus on testable cases
-    
-    // Actually, let's try moving a square that definitely has the wrong piece
-    // Move a white pawn as black by reaching that position
-    engine.processUserInput("e7e5")
-    observer.events.clear()
-    
-    // Now try to move white's e4 pawn as black (it's black's turn but e4 is white)
-    engine.processUserInput("e4e5")
-    
-    observer.events.size shouldBe 1
-    val event = observer.events.head
-    event shouldBe an[InvalidMoveEvent]
-
-  test("GameEngine handles illegal move"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    // A pawn can't move backward
-    engine.processUserInput("e2e1")
-    
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("Illegal move")
-
-  test("GameEngine handles pawn trying to move 3 squares"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    // Pawn can only move 1 or 2 squares on first move, not 3
-    engine.processUserInput("e2e5")
-    
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-
-  test("GameEngine handles moving from empty square"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    // h3 is empty in starting position
-    engine.processUserInput("h3h4")
-    
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[InvalidMoveEvent]
-    val event = observer.events.head.asInstanceOf[InvalidMoveEvent]
-    event.reason should include("No piece on that square")
-
-  test("GameEngine processes valid move after invalid attempt"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    
-    // Try invalid move
-    engine.processUserInput("h3h4")
-    observer.events.clear()
-    
-    // Make valid move
-    engine.processUserInput("e2e4")
-    
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe an[MoveExecutedEvent]
-
-  test("GameEngine maintains state after failed move attempt"):
-    val engine = new GameEngine()
-    val initialTurn = engine.turn
-    val initialBoard = engine.board
-    
-    // Try invalid move
-    engine.processUserInput("h3h4")
-    
-    // State should not change
-    engine.turn shouldBe initialTurn
-    engine.board shouldBe initialBoard
@@ -1,310 +0,0 @@
-package de.nowchess.chess.engine
-
-import scala.collection.mutable
-import de.nowchess.api.board.{Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import de.nowchess.chess.observer.{Observer, GameEvent, MoveExecutedEvent, CheckDetectedEvent, BoardResetEvent, InvalidMoveEvent}
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class GameEngineTest extends AnyFunSuite with Matchers:
-
-  test("GameEngine starts with initial board state"):
-    val engine = new GameEngine()
-    engine.board shouldBe Board.initial
-    engine.history shouldBe GameHistory.empty
-    engine.turn shouldBe Color.White
-
-  test("GameEngine accepts Observer subscription"):
-    val engine = new GameEngine()
-    val mockObserver = new MockObserver()
-    engine.subscribe(mockObserver)
-    engine.observerCount shouldBe 1
-
-  test("GameEngine notifies observers on valid move"):
-    val engine = new GameEngine()
-    val mockObserver = new MockObserver()
-    engine.subscribe(mockObserver)
-    engine.processUserInput("e2e4")
-    mockObserver.events.size shouldBe 1
-    mockObserver.events.head shouldBe a[MoveExecutedEvent]
-
-  test("GameEngine updates state after valid move"):
-    val engine = new GameEngine()
-    val initialTurn = engine.turn
-    engine.processUserInput("e2e4")
-    engine.turn shouldNot be(initialTurn)
-    engine.turn shouldBe Color.Black
-
-  test("GameEngine notifies observers on invalid move"):
-    val engine = new GameEngine()
-    val mockObserver = new MockObserver()
-    engine.subscribe(mockObserver)
-    engine.processUserInput("invalid_move")
-    mockObserver.events.size shouldBe 1
-
-  test("GameEngine notifies multiple observers"):
-    val engine = new GameEngine()
-    val observer1 = new MockObserver()
-    val observer2 = new MockObserver()
-    engine.subscribe(observer1)
-    engine.subscribe(observer2)
-    engine.processUserInput("e2e4")
-    observer1.events.size shouldBe 1
-    observer2.events.size shouldBe 1
-
-  test("GameEngine allows observer unsubscription"):
-    val engine = new GameEngine()
-    val mockObserver = new MockObserver()
-    engine.subscribe(mockObserver)
-    engine.unsubscribe(mockObserver)
-    engine.observerCount shouldBe 0
-
-  test("GameEngine unsubscribed observer receives no events"):
-    val engine = new GameEngine()
-    val mockObserver = new MockObserver()
-    engine.subscribe(mockObserver)
-    engine.unsubscribe(mockObserver)
-    engine.processUserInput("e2e4")
-    mockObserver.events.size shouldBe 0
-
-  test("GameEngine reset notifies observers and resets state"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    engine.reset()
-    engine.board shouldBe Board.initial
-    engine.turn shouldBe Color.White
-    observer.events.size shouldBe 1
-
-  test("GameEngine processes sequence of moves"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    engine.processUserInput("e2e4")
-    engine.processUserInput("e7e5")
-    observer.events.size shouldBe 2
-    engine.turn shouldBe Color.White
-
-  test("GameEngine is thread-safe for synchronized operations"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    val t = new Thread(() => engine.processUserInput("e2e4"))
-    t.start()
-    t.join()
-    observer.events.size shouldBe 1
-
-  test("GameEngine canUndo returns false initially"):
-    val engine = new GameEngine()
-    engine.canUndo shouldBe false
-
-  test("GameEngine canUndo returns true after move"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    engine.canUndo shouldBe true
-
-  test("GameEngine canRedo returns false initially"):
-    val engine = new GameEngine()
-    engine.canRedo shouldBe false
-
-  test("GameEngine undo restores previous state"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    val boardAfterMove = engine.board
-    engine.undo()
-    engine.board shouldBe Board.initial
-    engine.turn shouldBe Color.White
-
-  test("GameEngine undo notifies observers"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    observer.events.clear()
-    engine.undo()
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe a[BoardResetEvent]
-
-  test("GameEngine redo replays undone move"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    val boardAfterMove = engine.board
-    engine.undo()
-    engine.redo()
-    engine.board shouldBe boardAfterMove
-    engine.turn shouldBe Color.Black
-
-  test("GameEngine canUndo false when nothing to undo"):
-    val engine = new GameEngine()
-    engine.canUndo shouldBe false
-    engine.processUserInput("e2e4")
-    engine.undo()
-    engine.canUndo shouldBe false
-
-  test("GameEngine canRedo true after undo"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    engine.undo()
-    engine.canRedo shouldBe true
-
-  test("GameEngine canRedo false after redo"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    engine.undo()
-    engine.redo()
-    engine.canRedo shouldBe false
-
-  test("GameEngine undo on empty history sends invalid event"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    engine.undo()
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe a[InvalidMoveEvent]
-
-  test("GameEngine redo on empty redo sends invalid event"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    engine.redo()
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe a[InvalidMoveEvent]
-
-  test("GameEngine undo via processUserInput"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    val boardAfterMove = engine.board
-    engine.processUserInput("undo")
-    engine.board shouldBe Board.initial
-
-  test("GameEngine redo via processUserInput"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    val boardAfterMove = engine.board
-    engine.processUserInput("undo")
-    engine.processUserInput("redo")
-    engine.board shouldBe boardAfterMove
-
-  test("GameEngine handles empty input"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    engine.processUserInput("")
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe a[InvalidMoveEvent]
-
-  test("GameEngine multiple undo/redo sequence"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    engine.processUserInput("e7e5")
-    engine.processUserInput("g1f3")
-    
-    engine.turn shouldBe Color.Black
-    
-    engine.undo()
-    engine.turn shouldBe Color.White
-    
-    engine.undo()
-    engine.turn shouldBe Color.Black
-    
-    engine.undo()
-    engine.turn shouldBe Color.White
-    engine.board shouldBe Board.initial
-
-  test("GameEngine redo after multiple undos"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    engine.processUserInput("e7e5")
-    engine.processUserInput("g1f3")
-    
-    engine.undo()
-    engine.undo()
-    engine.undo()
-    
-    engine.redo()
-    engine.turn shouldBe Color.Black
-    
-    engine.redo()
-    engine.turn shouldBe Color.White
-    
-    engine.redo()
-    engine.turn shouldBe Color.Black
-
-  test("GameEngine new move after undo clears redo history"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    engine.processUserInput("e7e5")
-    engine.undo()
-    engine.canRedo shouldBe true
-    
-    engine.processUserInput("e7e6")  // Different move
-    engine.canRedo shouldBe false
-
-  test("GameEngine command history tracking"):
-    val engine = new GameEngine()
-    engine.commandHistory.size shouldBe 0
-    
-    engine.processUserInput("e2e4")
-    engine.commandHistory.size shouldBe 1
-    
-    engine.processUserInput("e7e5")
-    engine.commandHistory.size shouldBe 2
-
-  test("GameEngine quit input"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    val initialEvents = observer.events.size
-    engine.processUserInput("quit")
-    // quit should not produce an event
-    observer.events.size shouldBe initialEvents
-
-  test("GameEngine quit via q"):
-    val engine = new GameEngine()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    val initialEvents = observer.events.size
-    engine.processUserInput("q")
-    observer.events.size shouldBe initialEvents
-  
-  test("GameEngine undo notifies with BoardResetEvent after successful undo"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    engine.processUserInput("e7e5")
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    observer.events.clear()
-
-    engine.undo()
-
-    // Should have received a BoardResetEvent on undo
-    observer.events.size should be > 0
-    observer.events.exists(_.isInstanceOf[BoardResetEvent]) shouldBe true
-
-  test("GameEngine redo notifies with MoveExecutedEvent after successful redo"):
-    val engine = new GameEngine()
-    engine.processUserInput("e2e4")
-    engine.processUserInput("e7e5")
-    val boardAfterSecondMove = engine.board
-
-    engine.undo()
-    val observer = new MockObserver()
-    engine.subscribe(observer)
-    observer.events.clear()
-
-    engine.redo()
-
-    // Should have received a MoveExecutedEvent for the redo
-    observer.events.size shouldBe 1
-    observer.events.head shouldBe a[MoveExecutedEvent]
-    engine.board shouldBe boardAfterSecondMove
-    engine.turn shouldBe Color.White
-
-  // Mock Observer for testing
-  private class MockObserver extends Observer:
-    val events = mutable.ListBuffer[GameEvent]()
-    override def onGameEvent(event: GameEvent): Unit =
-      events += event
-
@@ -1,110 +0,0 @@
-package de.nowchess.chess.command
-
-import de.nowchess.api.board.{Square, File, Rank, Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class MoveCommandDefaultsTest extends AnyFunSuite with Matchers:
-  
-  private def sq(f: File, r: Rank): Square = Square(f, r)
-
-  // Tests for MoveCommand with default parameter values
-  test("MoveCommand with no moveResult defaults to None"):
-    val cmd = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4)
-    )
-    cmd.moveResult shouldBe None
-    cmd.execute() shouldBe false
-
-  test("MoveCommand with no previousBoard defaults to None"):
-    val cmd = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4)
-    )
-    cmd.previousBoard shouldBe None
-    cmd.undo() shouldBe false
-
-  test("MoveCommand with no previousHistory defaults to None"):
-    val cmd = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4)
-    )
-    cmd.previousHistory shouldBe None
-    cmd.undo() shouldBe false
-
-  test("MoveCommand with no previousTurn defaults to None"):
-    val cmd = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4)
-    )
-    cmd.previousTurn shouldBe None
-    cmd.undo() shouldBe false
-
-  test("MoveCommand description is always returned"):
-    val cmd = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4)
-    )
-    cmd.description shouldBe "Move from e2 to e4"
-
-  test("MoveCommand execute returns false when moveResult is None"):
-    val cmd = MoveCommand(
-      from = sq(File.A, Rank.R1),
-      to = sq(File.B, Rank.R3)
-    )
-    cmd.execute() shouldBe false
-
-  test("MoveCommand undo returns false when any previous state is None"):
-    // Missing previousBoard
-    val cmd1 = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4),
-      moveResult = Some(MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None)),
-      previousBoard = None,
-      previousHistory = Some(GameHistory.empty),
-      previousTurn = Some(Color.White)
-    )
-    cmd1.undo() shouldBe false
-
-    // Missing previousHistory
-    val cmd2 = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4),
-      moveResult = Some(MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None)),
-      previousBoard = Some(Board.initial),
-      previousHistory = None,
-      previousTurn = Some(Color.White)
-    )
-    cmd2.undo() shouldBe false
-
-    // Missing previousTurn
-    val cmd3 = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4),
-      moveResult = Some(MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None)),
-      previousBoard = Some(Board.initial),
-      previousHistory = Some(GameHistory.empty),
-      previousTurn = None
-    )
-    cmd3.undo() shouldBe false
-
-  test("MoveCommand execute returns true when moveResult is defined"):
-    val cmd = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4),
-      moveResult = Some(MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None))
-    )
-    cmd.execute() shouldBe true
-
-  test("MoveCommand undo returns true when all previous states are defined"):
-    val cmd = MoveCommand(
-      from = sq(File.E, Rank.R2),
-      to = sq(File.E, Rank.R4),
-      moveResult = Some(MoveResult.Successful(Board.initial, GameHistory.empty, Color.White, None)),
-      previousBoard = Some(Board.initial),
-      previousHistory = Some(GameHistory.empty),
-      previousTurn = Some(Color.White)
-    )
-    cmd.undo() shouldBe true
@@ -1,70 +0,0 @@
-package de.nowchess.chess.logic
-
-import de.nowchess.api.board.*
-import de.nowchess.api.game.CastlingRights
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class CastlingRightsCalculatorTest extends AnyFunSuite with Matchers:
-
-  private def sq(f: File, r: Rank): Square = Square(f, r)
-
-  test("Empty history gives full castling rights"):
-    val rights = CastlingRightsCalculator.deriveCastlingRights(GameHistory.empty, Color.White)
-    rights shouldBe CastlingRights.Both
-
-  test("White loses kingside rights after h1 rook moves"):
-    val history = GameHistory.empty.addMove(sq(File.H, Rank.R1), sq(File.H, Rank.R2))
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, Color.White)
-    rights.kingSide shouldBe false
-    rights.queenSide shouldBe true
-
-  test("White loses queenside rights after a1 rook moves"):
-    val history = GameHistory.empty.addMove(sq(File.A, Rank.R1), sq(File.A, Rank.R2))
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, Color.White)
-    rights.queenSide shouldBe false
-    rights.kingSide shouldBe true
-
-  test("White loses all rights after king moves"):
-    val history = GameHistory.empty.addMove(sq(File.E, Rank.R1), sq(File.E, Rank.R2))
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, Color.White)
-    rights shouldBe CastlingRights.None
-
-  test("Black loses kingside rights after h8 rook moves"):
-    val history = GameHistory.empty.addMove(sq(File.H, Rank.R8), sq(File.H, Rank.R7))
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, Color.Black)
-    rights.kingSide shouldBe false
-    rights.queenSide shouldBe true
-
-  test("Black loses queenside rights after a8 rook moves"):
-    val history = GameHistory.empty.addMove(sq(File.A, Rank.R8), sq(File.A, Rank.R7))
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, Color.Black)
-    rights.queenSide shouldBe false
-    rights.kingSide shouldBe true
-
-  test("Black loses all rights after king moves"):
-    val history = GameHistory.empty.addMove(sq(File.E, Rank.R8), sq(File.E, Rank.R7))
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, Color.Black)
-    rights shouldBe CastlingRights.None
-
-  test("Castle move revokes all castling rights"):
-    val history = GameHistory.empty.addMove(
-      sq(File.E, Rank.R1),
-      sq(File.G, Rank.R1),
-      Some(CastleSide.Kingside)
-    )
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, Color.White)
-    rights shouldBe CastlingRights.None
-
-  test("Other pieces moving does not revoke castling rights"):
-    val history = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, Color.White)
-    rights shouldBe CastlingRights.Both
-
-  test("Multiple moves preserve white kingside but lose queenside"):
-    val history = GameHistory.empty
-      .addMove(sq(File.A, Rank.R1), sq(File.A, Rank.R2))  // White queenside rook moves
-      .addMove(sq(File.E, Rank.R7), sq(File.E, Rank.R5))  // Black pawn moves
-    val rights = CastlingRightsCalculator.deriveCastlingRights(history, Color.White)
-    rights.kingSide shouldBe true
-    rights.queenSide shouldBe false
@@ -1,101 +0,0 @@
-package de.nowchess.chess.logic
-
-import de.nowchess.api.board.*
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class EnPassantCalculatorTest extends AnyFunSuite with Matchers:
-
-  private def sq(f: File, r: Rank): Square = Square(f, r)
-  private def board(entries: (Square, Piece)*): Board = Board(entries.toMap)
-
-  // ──── enPassantTarget ────────────────────────────────────────────────
-
-  test("enPassantTarget returns None for empty history"):
-    val b = board(sq(File.E, Rank.R4) -> Piece.WhitePawn)
-    EnPassantCalculator.enPassantTarget(b, GameHistory.empty) shouldBe None
-
-  test("enPassantTarget returns None when last move was a single pawn push"):
-    val b = board(sq(File.E, Rank.R3) -> Piece.WhitePawn)
-    val h = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R3))
-    EnPassantCalculator.enPassantTarget(b, h) shouldBe None
-
-  test("enPassantTarget returns None when last move was not a pawn"):
-    val b = board(sq(File.E, Rank.R4) -> Piece.WhiteRook)
-    val h = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    EnPassantCalculator.enPassantTarget(b, h) shouldBe None
-
-  test("enPassantTarget returns e3 after white pawn double push e2-e4"):
-    val b = board(sq(File.E, Rank.R4) -> Piece.WhitePawn)
-    val h = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    EnPassantCalculator.enPassantTarget(b, h) shouldBe Some(sq(File.E, Rank.R3))
-
-  test("enPassantTarget returns e6 after black pawn double push e7-e5"):
-    val b = board(sq(File.E, Rank.R5) -> Piece.BlackPawn)
-    val h = GameHistory.empty.addMove(sq(File.E, Rank.R7), sq(File.E, Rank.R5))
-    EnPassantCalculator.enPassantTarget(b, h) shouldBe Some(sq(File.E, Rank.R6))
-
-  test("enPassantTarget returns d3 after white pawn double push d2-d4"):
-    val b = board(sq(File.D, Rank.R4) -> Piece.WhitePawn)
-    val h = GameHistory.empty.addMove(sq(File.D, Rank.R2), sq(File.D, Rank.R4))
-    EnPassantCalculator.enPassantTarget(b, h) shouldBe Some(sq(File.D, Rank.R3))
-
-  // ──── capturedPawnSquare ─────────────────────────────────────────────
-
-  test("capturedPawnSquare for white capturing on e6 returns e5"):
-    EnPassantCalculator.capturedPawnSquare(sq(File.E, Rank.R6), Color.White) shouldBe sq(File.E, Rank.R5)
-
-  test("capturedPawnSquare for black capturing on e3 returns e4"):
-    EnPassantCalculator.capturedPawnSquare(sq(File.E, Rank.R3), Color.Black) shouldBe sq(File.E, Rank.R4)
-
-  test("capturedPawnSquare for white capturing on d6 returns d5"):
-    EnPassantCalculator.capturedPawnSquare(sq(File.D, Rank.R6), Color.White) shouldBe sq(File.D, Rank.R5)
-
-  // ──── isEnPassant ────────────────────────────────────────────────────
-
-  test("isEnPassant returns true for valid white en passant capture"):
-    // White pawn on e5, black pawn just double-pushed to d5 (ep target = d6)
-    val b = board(
-      sq(File.E, Rank.R5) -> Piece.WhitePawn,
-      sq(File.D, Rank.R5) -> Piece.BlackPawn
-    )
-    val h = GameHistory.empty.addMove(sq(File.D, Rank.R7), sq(File.D, Rank.R5))
-    EnPassantCalculator.isEnPassant(b, h, sq(File.E, Rank.R5), sq(File.D, Rank.R6)) shouldBe true
-
-  test("isEnPassant returns true for valid black en passant capture"):
-    // Black pawn on d4, white pawn just double-pushed to e4 (ep target = e3)
-    val b = board(
-      sq(File.D, Rank.R4) -> Piece.BlackPawn,
-      sq(File.E, Rank.R4) -> Piece.WhitePawn
-    )
-    val h = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    EnPassantCalculator.isEnPassant(b, h, sq(File.D, Rank.R4), sq(File.E, Rank.R3)) shouldBe true
-
-  test("isEnPassant returns false when no en passant target in history"):
-    val b = board(
-      sq(File.E, Rank.R5) -> Piece.WhitePawn,
-      sq(File.D, Rank.R5) -> Piece.BlackPawn
-    )
-    val h = GameHistory.empty.addMove(sq(File.D, Rank.R6), sq(File.D, Rank.R5))  // single push
-    EnPassantCalculator.isEnPassant(b, h, sq(File.E, Rank.R5), sq(File.D, Rank.R6)) shouldBe false
-
-  test("isEnPassant returns false when piece at from is not a pawn"):
-    val b = board(
-      sq(File.E, Rank.R5) -> Piece.WhiteRook,
-      sq(File.D, Rank.R5) -> Piece.BlackPawn
-    )
-    val h = GameHistory.empty.addMove(sq(File.D, Rank.R7), sq(File.D, Rank.R5))
-    EnPassantCalculator.isEnPassant(b, h, sq(File.E, Rank.R5), sq(File.D, Rank.R6)) shouldBe false
-
-  test("isEnPassant returns false when to does not match ep target"):
-    val b = board(
-      sq(File.E, Rank.R5) -> Piece.WhitePawn,
-      sq(File.D, Rank.R5) -> Piece.BlackPawn
-    )
-    val h = GameHistory.empty.addMove(sq(File.D, Rank.R7), sq(File.D, Rank.R5))
-    EnPassantCalculator.isEnPassant(b, h, sq(File.E, Rank.R5), sq(File.E, Rank.R6)) shouldBe false
-
-  test("isEnPassant returns false when from square is empty"):
-    val b = board(sq(File.D, Rank.R5) -> Piece.BlackPawn)
-    val h = GameHistory.empty.addMove(sq(File.D, Rank.R7), sq(File.D, Rank.R5))
-    EnPassantCalculator.isEnPassant(b, h, sq(File.E, Rank.R5), sq(File.D, Rank.R6)) shouldBe false
@@ -0,0 +1,81 @@
+package de.nowchess.chess.logic
+
+import de.nowchess.api.board.*
+import de.nowchess.api.game.CastlingRights
+import org.scalatest.funsuite.AnyFunSuite
+import org.scalatest.matchers.should.Matchers
+
+class GameContextTest extends AnyFunSuite with Matchers:
+
+  private def sq(f: File, r: Rank): Square = Square(f, r)
+  private def board(entries: (Square, Piece)*): Board = Board(entries.toMap)
+
+  test("GameContext.initial has Board.initial and CastlingRights.Both for both sides"):
+    GameContext.initial.board         shouldBe Board.initial
+    GameContext.initial.whiteCastling shouldBe CastlingRights.Both
+    GameContext.initial.blackCastling shouldBe CastlingRights.Both
+
+  test("castlingFor returns white rights for Color.White"):
+    GameContext.initial.castlingFor(Color.White) shouldBe CastlingRights.Both
+
+  test("castlingFor returns black rights for Color.Black"):
+    GameContext.initial.castlingFor(Color.Black) shouldBe CastlingRights.Both
+
+  test("withUpdatedRights updates white castling without touching black"):
+    val ctx = GameContext.initial.withUpdatedRights(Color.White, CastlingRights.None)
+    ctx.whiteCastling shouldBe CastlingRights.None
+    ctx.blackCastling shouldBe CastlingRights.Both
+
+  test("withUpdatedRights updates black castling without touching white"):
+    val ctx = GameContext.initial.withUpdatedRights(Color.Black, CastlingRights.None)
+    ctx.blackCastling shouldBe CastlingRights.None
+    ctx.whiteCastling shouldBe CastlingRights.Both
+
+  test("withCastle: white kingside — king e1→g1, rook h1→f1"):
+    val b = board(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook
+    )
+    val after = b.withCastle(Color.White, CastleSide.Kingside)
+    after.pieceAt(sq(File.G, Rank.R1)) shouldBe Some(Piece.WhiteKing)
+    after.pieceAt(sq(File.F, Rank.R1)) shouldBe Some(Piece.WhiteRook)
+    after.pieceAt(sq(File.E, Rank.R1)) shouldBe None
+    after.pieceAt(sq(File.H, Rank.R1)) shouldBe None
+
+  test("withCastle: white queenside — king e1→c1, rook a1→d1"):
+    val b = board(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.A, Rank.R1) -> Piece.WhiteRook
+    )
+    val after = b.withCastle(Color.White, CastleSide.Queenside)
+    after.pieceAt(sq(File.C, Rank.R1)) shouldBe Some(Piece.WhiteKing)
+    after.pieceAt(sq(File.D, Rank.R1)) shouldBe Some(Piece.WhiteRook)
+    after.pieceAt(sq(File.E, Rank.R1)) shouldBe None
+    after.pieceAt(sq(File.A, Rank.R1)) shouldBe None
+
+  test("withCastle: black kingside — king e8→g8, rook h8→f8"):
+    val b = board(
+      sq(File.E, Rank.R8) -> Piece.BlackKing,
+      sq(File.H, Rank.R8) -> Piece.BlackRook
+    )
+    val after = b.withCastle(Color.Black, CastleSide.Kingside)
+    after.pieceAt(sq(File.G, Rank.R8)) shouldBe Some(Piece.BlackKing)
+    after.pieceAt(sq(File.F, Rank.R8)) shouldBe Some(Piece.BlackRook)
+    after.pieceAt(sq(File.E, Rank.R8)) shouldBe None
+    after.pieceAt(sq(File.H, Rank.R8)) shouldBe None
+
+  test("withCastle: black queenside — king e8→c8, rook a8→d8"):
+    val b = board(
+      sq(File.E, Rank.R8) -> Piece.BlackKing,
+      sq(File.A, Rank.R8) -> Piece.BlackRook
+    )
+    val after = b.withCastle(Color.Black, CastleSide.Queenside)
+    after.pieceAt(sq(File.C, Rank.R8)) shouldBe Some(Piece.BlackKing)
+    after.pieceAt(sq(File.D, Rank.R8)) shouldBe Some(Piece.BlackRook)
+    after.pieceAt(sq(File.E, Rank.R8)) shouldBe None
+    after.pieceAt(sq(File.A, Rank.R8)) shouldBe None
+
+  test("GameContext single-arg apply defaults to CastlingRights.None for both sides"):
+    val ctx = GameContext(Board.initial)
+    ctx.whiteCastling shouldBe CastlingRights.None
+    ctx.blackCastling shouldBe CastlingRights.None
@@ -1,41 +0,0 @@
-package de.nowchess.chess.logic
-
-import de.nowchess.api.board.*
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class GameHistoryTest extends AnyFunSuite with Matchers:
-
-  private def sq(f: File, r: Rank): Square = Square(f, r)
-
-  test("GameHistory starts empty"):
-    val history = GameHistory.empty
-    history.moves shouldBe empty
-
-  test("GameHistory can add a move"):
-    val history = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    history.moves should have length 1
-    history.moves.head.from shouldBe sq(File.E, Rank.R2)
-    history.moves.head.to shouldBe sq(File.E, Rank.R4)
-    history.moves.head.castleSide shouldBe None
-
-  test("GameHistory can add multiple moves in order"):
-    val h1 = GameHistory.empty
-    val h2 = h1.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    val h3 = h2.addMove(sq(File.C, Rank.R7), sq(File.C, Rank.R5))
-    h3.moves should have length 2
-    h3.moves(0).from shouldBe sq(File.E, Rank.R2)
-    h3.moves(1).from shouldBe sq(File.C, Rank.R7)
-
-  test("GameHistory can add a castle move"):
-    val history = GameHistory.empty.addMove(
-      sq(File.E, Rank.R1),
-      sq(File.G, Rank.R1),
-      Some(CastleSide.Kingside)
-    )
-    history.moves.head.castleSide shouldBe Some(CastleSide.Kingside)
-
-  test("GameHistory.addMove with two arguments uses None for castleSide default"):
-    val history = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    history.moves should have length 1
-    history.moves.head.castleSide shouldBe None
@@ -2,7 +2,7 @@ package de.nowchess.chess.logic

 import de.nowchess.api.board.*
 import de.nowchess.api.game.CastlingRights
-import de.nowchess.chess.logic.GameHistory
+import de.nowchess.chess.logic.GameContext
 import org.scalatest.funsuite.AnyFunSuite
 import org.scalatest.matchers.should.Matchers

@@ -12,11 +12,7 @@ class GameRulesTest extends AnyFunSuite with Matchers:
  private def board(entries: (Square, Piece)*): Board = Board(entries.toMap)

  /** Wrap a board in a GameContext with no castling rights — for non-castling tests. */
-  private def testLegalMoves(entries: (Square, Piece)*)(color: Color): Set[(Square, Square)] =
-    GameRules.legalMoves(Board(entries.toMap), GameHistory.empty, color)
-
-  private def testGameStatus(entries: (Square, Piece)*)(color: Color): PositionStatus =
-    GameRules.gameStatus(Board(entries.toMap), GameHistory.empty, color)
+  private def ctx(entries: (Square, Piece)*): GameContext = GameContext(Board(entries.toMap))

  // ──── isInCheck ──────────────────────────────────────────────────────

@@ -45,20 +41,20 @@ class GameRulesTest extends AnyFunSuite with Matchers:
  test("legalMoves: move that exposes own king to rook is excluded"):
    // White King E1, White Rook E4 (pinned on E-file), Black Rook E8
    // Moving the White Rook off the E-file would expose the king
-    val moves = testLegalMoves(
+    val moves = GameRules.legalMoves(ctx(
      sq(File.E, Rank.R1) -> Piece.WhiteKing,
      sq(File.E, Rank.R4) -> Piece.WhiteRook,
      sq(File.E, Rank.R8) -> Piece.BlackRook
-    )(Color.White)
+    ), Color.White)
    moves should not contain (sq(File.E, Rank.R4) -> sq(File.D, Rank.R4))

  test("legalMoves: move that blocks check is included"):
    // White King E1 in check from Black Rook E8; White Rook A5 can interpose on E5
-    val moves = testLegalMoves(
+    val moves = GameRules.legalMoves(ctx(
      sq(File.E, Rank.R1) -> Piece.WhiteKing,
      sq(File.A, Rank.R5) -> Piece.WhiteRook,
      sq(File.E, Rank.R8) -> Piece.BlackRook
-    )(Color.White)
+    ), Color.White)
    moves should contain(sq(File.A, Rank.R5) -> sq(File.E, Rank.R5))

  // ──── gameStatus ──────────────────────────────────────────────────────
@@ -66,96 +62,70 @@ class GameRulesTest extends AnyFunSuite with Matchers:
  test("gameStatus: checkmate returns Mated"):
    // White Qh8, Ka6; Black Ka8
    // Qh8 attacks Ka8 along rank 8; all escape squares covered (spec-verified position)
-    testGameStatus(
+    GameRules.gameStatus(ctx(
      sq(File.H, Rank.R8) -> Piece.WhiteQueen,
      sq(File.A, Rank.R6) -> Piece.WhiteKing,
      sq(File.A, Rank.R8) -> Piece.BlackKing
-    )(Color.Black) shouldBe PositionStatus.Mated
+    ), Color.Black) shouldBe PositionStatus.Mated

  test("gameStatus: stalemate returns Drawn"):
    // White Qb6, Kc6; Black Ka8
    // Black king has no legal moves and is not in check (spec-verified position)
-    testGameStatus(
+    GameRules.gameStatus(ctx(
      sq(File.B, Rank.R6) -> Piece.WhiteQueen,
      sq(File.C, Rank.R6) -> Piece.WhiteKing,
      sq(File.A, Rank.R8) -> Piece.BlackKing
-    )(Color.Black) shouldBe PositionStatus.Drawn
+    ), Color.Black) shouldBe PositionStatus.Drawn

  test("gameStatus: king in check with legal escape returns InCheck"):
    // White Ra8 attacks Black Ke8 along rank 8; king can escape to d7, e7, f7
-    testGameStatus(
+    GameRules.gameStatus(ctx(
      sq(File.A, Rank.R8) -> Piece.WhiteRook,
      sq(File.E, Rank.R8) -> Piece.BlackKing
-    )(Color.Black) shouldBe PositionStatus.InCheck
+    ), Color.Black) shouldBe PositionStatus.InCheck

  test("gameStatus: normal starting position returns Normal"):
-    GameRules.gameStatus(Board.initial, GameHistory.empty, Color.White) shouldBe PositionStatus.Normal
+    GameRules.gameStatus(GameContext(Board.initial), Color.White) shouldBe PositionStatus.Normal

  test("legalMoves: includes castling destination when available"):
-    val b = board(
+    val c = GameContext(
+      board = board(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.H, Rank.R1) -> Piece.WhiteRook,
        sq(File.H, Rank.R8) -> Piece.BlackKing
-      )
-    GameRules.legalMoves(b, GameHistory.empty, Color.White) should contain(sq(File.E, Rank.R1) -> sq(File.G, Rank.R1))
+      ),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameRules.legalMoves(c, Color.White) should contain(sq(File.E, Rank.R1) -> sq(File.G, Rank.R1))

  test("legalMoves: excludes castling when king is in check"):
-    val b = board(
+    val c = GameContext(
+      board = board(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.H, Rank.R1) -> Piece.WhiteRook,
        sq(File.E, Rank.R8) -> Piece.BlackRook,
        sq(File.A, Rank.R8) -> Piece.BlackKing
-      )
-    GameRules.legalMoves(b, GameHistory.empty, Color.White) should not contain (sq(File.E, Rank.R1) -> sq(File.G, Rank.R1))
+      ),
+      whiteCastling = CastlingRights.Both,
+      blackCastling = CastlingRights.None
+    )
+    GameRules.legalMoves(c, Color.White) should not contain (sq(File.E, Rank.R1) -> sq(File.G, Rank.R1))

  test("gameStatus: returns Normal (not Drawn) when castling is the only legal move"):
    // White King e1, Rook h1 (kingside castling available).
    // Black Rooks d2 and f2 box the king: d1 attacked by d2, e2 attacked by both,
    // f1 attacked by f2. King cannot move to any adjacent square without entering
    // an attacked square or an enemy piece. Only legal move: castle to g1.
-    val b = board(
+    val c = GameContext(
+      board = board(
        sq(File.E, Rank.R1) -> Piece.WhiteKing,
        sq(File.H, Rank.R1) -> Piece.WhiteRook,
        sq(File.D, Rank.R2) -> Piece.BlackRook,
        sq(File.F, Rank.R2) -> Piece.BlackRook,
        sq(File.A, Rank.R8) -> Piece.BlackKing
-      )
-    // No history means castling rights are intact
-    GameRules.gameStatus(b, GameHistory.empty, Color.White) shouldBe PositionStatus.Normal
-
-  test("CastleSide.withCastle correctly positions pieces for Queenside castling"):
-    // Directly test the withCastle extension for Queenside (coverage gap on line 10)
-    val b = board(
-      sq(File.E, Rank.R1) -> Piece.WhiteKing,
-      sq(File.A, Rank.R1) -> Piece.WhiteRook,
-      sq(File.H, Rank.R8) -> Piece.BlackKing
+      ),
+      whiteCastling = CastlingRights(kingSide = true, queenSide = false),
+      blackCastling = CastlingRights.None
    )
-    val result = b.withCastle(Color.White, CastleSide.Queenside)
-    result.pieceAt(sq(File.C, Rank.R1)) shouldBe Some(Piece.WhiteKing)
-    result.pieceAt(sq(File.D, Rank.R1)) shouldBe Some(Piece.WhiteRook)
-    result.pieceAt(sq(File.E, Rank.R1)) shouldBe None
-    result.pieceAt(sq(File.A, Rank.R1)) shouldBe None
-
-  test("CastleSide.withCastle correctly positions pieces for Black Kingside castling"):
-    val b = board(
-      sq(File.E, Rank.R8) -> Piece.BlackKing,
-      sq(File.H, Rank.R8) -> Piece.BlackRook,
-      sq(File.A, Rank.R1) -> Piece.WhiteKing
-    )
-    val result = b.withCastle(Color.Black, CastleSide.Kingside)
-    result.pieceAt(sq(File.G, Rank.R8)) shouldBe Some(Piece.BlackKing)
-    result.pieceAt(sq(File.F, Rank.R8)) shouldBe Some(Piece.BlackRook)
-    result.pieceAt(sq(File.E, Rank.R8)) shouldBe None
-    result.pieceAt(sq(File.H, Rank.R8)) shouldBe None
-
-  test("CastleSide.withCastle correctly positions pieces for Black Queenside castling"):
-    val b = board(
-      sq(File.E, Rank.R8) -> Piece.BlackKing,
-      sq(File.A, Rank.R8) -> Piece.BlackRook,
-      sq(File.A, Rank.R1) -> Piece.WhiteKing
-    )
-    val result = b.withCastle(Color.Black, CastleSide.Queenside)
-    result.pieceAt(sq(File.C, Rank.R8)) shouldBe Some(Piece.BlackKing)
-    result.pieceAt(sq(File.D, Rank.R8)) shouldBe Some(Piece.BlackRook)
-    result.pieceAt(sq(File.E, Rank.R8)) shouldBe None
-    result.pieceAt(sq(File.A, Rank.R8)) shouldBe None
+    GameRules.gameStatus(c, Color.White) shouldBe PositionStatus.Normal
@@ -2,7 +2,7 @@ package de.nowchess.chess.logic

 import de.nowchess.api.board.{Board, Color, File, Piece, Rank, Square}
 import de.nowchess.api.game.CastlingRights
-import de.nowchess.chess.logic.{CastleSide, GameHistory}
+import de.nowchess.chess.logic.{GameContext, CastleSide}
 import org.scalatest.funsuite.AnyFunSuite
 import org.scalatest.matchers.should.Matchers

@@ -212,46 +212,167 @@ class MoveValidatorTest extends AnyFunSuite with Matchers:
    )
    MoveValidator.legalTargets(b, sq(File.D, Rank.R4)) should contain(sq(File.E, Rank.R4))

-  // ──── Pawn – en passant targets ──────────────────────────────────────
+  // ──── castlingTargets ────────────────────────────────────────────────

-  test("white pawn includes ep target in legal moves after black double push"):
-    // Black pawn just double-pushed to d5 (ep target = d6); white pawn on e5
-    val b = board(
-      sq(File.E, Rank.R5) -> Piece.WhitePawn,
-      sq(File.D, Rank.R5) -> Piece.BlackPawn
-    )
-    val h = GameHistory.empty.addMove(sq(File.D, Rank.R7), sq(File.D, Rank.R5))
-    MoveValidator.legalTargets(b, h, sq(File.E, Rank.R5)) should contain(sq(File.D, Rank.R6))
+  private def ctxWithRights(
+    entries: (Square, Piece)*
+  )(white: CastlingRights = CastlingRights.Both,
+    black: CastlingRights = CastlingRights.Both
+  ): GameContext =
+    GameContext(Board(entries.toMap), white, black)

-  test("white pawn does not include ep target without a preceding double push"):
-    val b = board(
-      sq(File.E, Rank.R5) -> Piece.WhitePawn,
-      sq(File.D, Rank.R5) -> Piece.BlackPawn
-    )
-    val h = GameHistory.empty.addMove(sq(File.D, Rank.R6), sq(File.D, Rank.R5))  // single push
-    MoveValidator.legalTargets(b, h, sq(File.E, Rank.R5)) should not contain sq(File.D, Rank.R6)
+  test("castlingTargets: white kingside available when all conditions met"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.White) should contain(sq(File.G, Rank.R1))

-  test("black pawn includes ep target in legal moves after white double push"):
-    // White pawn just double-pushed to e4 (ep target = e3); black pawn on d4
-    val b = board(
-      sq(File.D, Rank.R4) -> Piece.BlackPawn,
-      sq(File.E, Rank.R4) -> Piece.WhitePawn
-    )
-    val h = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    MoveValidator.legalTargets(b, h, sq(File.D, Rank.R4)) should contain(sq(File.E, Rank.R3))
+  test("castlingTargets: white queenside available when all conditions met"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.A, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.White) should contain(sq(File.C, Rank.R1))

-  test("pawn on wrong file does not get ep target from adjacent double push"):
-    // White pawn on a5, black pawn double-pushed to d5 — a5 is not adjacent to d5
-    val b = board(
-      sq(File.A, Rank.R5) -> Piece.WhitePawn,
-      sq(File.D, Rank.R5) -> Piece.BlackPawn
-    )
-    val h = GameHistory.empty.addMove(sq(File.D, Rank.R7), sq(File.D, Rank.R5))
-    MoveValidator.legalTargets(b, h, sq(File.A, Rank.R5)) should not contain sq(File.D, Rank.R6)
+  test("castlingTargets: black kingside available when all conditions met"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R8) -> Piece.BlackKing,
+      sq(File.H, Rank.R8) -> Piece.BlackRook,
+      sq(File.H, Rank.R1) -> Piece.WhiteKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.Black) should contain(sq(File.G, Rank.R8))

-  // ──── History-aware legalTargets fallback for non-pawn non-king pieces ─────
+  test("castlingTargets: black queenside available when all conditions met"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R8) -> Piece.BlackKing,
+      sq(File.A, Rank.R8) -> Piece.BlackRook,
+      sq(File.H, Rank.R1) -> Piece.WhiteKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.Black) should contain(sq(File.C, Rank.R8))

-  test("legalTargets with history delegates to geometry-only for non-pawn non-king pieces"):
-    val b = board(sq(File.D, Rank.R4) -> Piece.WhiteRook)
-    val h = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
-    MoveValidator.legalTargets(b, h, sq(File.D, Rank.R4)) shouldBe MoveValidator.legalTargets(b, sq(File.D, Rank.R4))
+  test("castlingTargets: blocked when transit square is occupied"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.F, Rank.R1) -> Piece.WhiteBishop,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.White) should not contain sq(File.G, Rank.R1)
+
+  test("castlingTargets: blocked when king is in check"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.E, Rank.R8) -> Piece.BlackRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.White) shouldBe empty
+
+  test("castlingTargets: blocked when transit square f1 is attacked"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.F, Rank.R8) -> Piece.BlackRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.White) should not contain sq(File.G, Rank.R1)
+
+  test("castlingTargets: blocked when landing square g1 is attacked"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.G, Rank.R8) -> Piece.BlackRook,
+      sq(File.A, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.White) should not contain sq(File.G, Rank.R1)
+
+  test("castlingTargets: blocked when kingSide right is false"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )(white = CastlingRights(kingSide = false, queenSide = true))
+    MoveValidator.castlingTargets(ctx, Color.White) should not contain sq(File.G, Rank.R1)
+
+  test("castlingTargets: blocked when queenSide right is false"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.A, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )(white = CastlingRights(kingSide = true, queenSide = false))
+    MoveValidator.castlingTargets(ctx, Color.White) should not contain sq(File.C, Rank.R1)
+
+  test("castlingTargets: blocked when relevant rook is not on home square"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.G, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.White) should not contain sq(File.G, Rank.R1)
+
+  // ──── context-aware legalTargets includes castling ────────────────────
+
+  test("legalTargets(ctx, from): king on e1 includes g1 when castling available"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.legalTargets(ctx, sq(File.E, Rank.R1)) should contain(sq(File.G, Rank.R1))
+
+  test("legalTargets(ctx, from): non-king pieces unchanged by context"):
+    val ctx = ctxWithRights(
+      sq(File.D, Rank.R4) -> Piece.WhiteBishop,
+      sq(File.H, Rank.R8) -> Piece.BlackKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteKing
+    )()
+    MoveValidator.legalTargets(ctx, sq(File.D, Rank.R4)) shouldBe
+      MoveValidator.legalTargets(ctx.board, sq(File.D, Rank.R4))
+
+  // ──── isCastle / castleSide / isLegal(ctx) ───────────────────────────
+
+  test("isCastle: returns true when king moves two files"):
+    val board = Board(Map(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook
+    ))
+    MoveValidator.isCastle(board, sq(File.E, Rank.R1), sq(File.G, Rank.R1)) shouldBe true
+
+  test("isCastle: returns false when king moves one file"):
+    val board = Board(Map(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing
+    ))
+    MoveValidator.isCastle(board, sq(File.E, Rank.R1), sq(File.F, Rank.R1)) shouldBe false
+
+  test("castleSide: returns Kingside when moving to higher file"):
+    MoveValidator.castleSide(sq(File.E, Rank.R1), sq(File.G, Rank.R1)) shouldBe CastleSide.Kingside
+
+  test("castleSide: returns Queenside when moving to lower file"):
+    MoveValidator.castleSide(sq(File.E, Rank.R1), sq(File.C, Rank.R1)) shouldBe CastleSide.Queenside
+
+  test("isLegal(ctx): returns true for legal castling move"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.isLegal(ctx, sq(File.E, Rank.R1), sq(File.G, Rank.R1)) shouldBe true
+
+  test("isLegal(ctx): returns false for illegal castling move when rights revoked"):
+    val ctx = ctxWithRights(
+      sq(File.E, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )(white = CastlingRights.None)
+    MoveValidator.isLegal(ctx, sq(File.E, Rank.R1), sq(File.G, Rank.R1)) shouldBe false
+
+  test("castlingTargets: returns empty when king not on home square"):
+    val ctx = ctxWithRights(
+      sq(File.D, Rank.R1) -> Piece.WhiteKing,
+      sq(File.H, Rank.R1) -> Piece.WhiteRook,
+      sq(File.H, Rank.R8) -> Piece.BlackKing
+    )()
+    MoveValidator.castlingTargets(ctx, Color.White) shouldBe empty
@@ -0,0 +1,12 @@
+package de.nowchess.chess.main
+
+import de.nowchess.chess.Main
+import java.io.ByteArrayInputStream
+import org.scalatest.funsuite.AnyFunSuite
+import org.scalatest.matchers.should.Matchers
+
+class MainTest extends AnyFunSuite with Matchers:
+
+  test("main exits cleanly when 'quit' is entered"):
+    scala.Console.withIn(ByteArrayInputStream("quit\n".getBytes("UTF-8"))):
+      Main.main(Array.empty)
@@ -1,69 +0,0 @@
-package de.nowchess.chess.notation
-
-import de.nowchess.api.board.*
-import de.nowchess.api.game.*
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class FenExporterTest extends AnyFunSuite with Matchers:
-
-  test("export initial position to FEN"):
-    val gameState = GameState.initial
-    val fen = FenExporter.gameStateToFen(gameState)
-    fen shouldBe "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
-
-  test("export position after e4"):
-    val gameState = GameState(
-      piecePlacement = "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR",
-      activeColor = Color.Black,
-      castlingWhite = CastlingRights.Both,
-      castlingBlack = CastlingRights.Both,
-      enPassantTarget = Some(Square(File.E, Rank.R3)),
-      halfMoveClock = 0,
-      fullMoveNumber = 1,
-      status = GameStatus.InProgress
-    )
-    val fen = FenExporter.gameStateToFen(gameState)
-    fen shouldBe "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1"
-
-  test("export position with no castling"):
-    val gameState = GameState(
-      piecePlacement = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR",
-      activeColor = Color.White,
-      castlingWhite = CastlingRights.None,
-      castlingBlack = CastlingRights.None,
-      enPassantTarget = None,
-      halfMoveClock = 0,
-      fullMoveNumber = 1,
-      status = GameStatus.InProgress
-    )
-    val fen = FenExporter.gameStateToFen(gameState)
-    fen shouldBe "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1"
-
-  test("export position with partial castling"):
-    val gameState = GameState(
-      piecePlacement = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR",
-      activeColor = Color.White,
-      castlingWhite = CastlingRights(kingSide = true, queenSide = false),
-      castlingBlack = CastlingRights(kingSide = false, queenSide = true),
-      enPassantTarget = None,
-      halfMoveClock = 5,
-      fullMoveNumber = 3,
-      status = GameStatus.InProgress
-    )
-    val fen = FenExporter.gameStateToFen(gameState)
-    fen shouldBe "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w Kq - 5 3"
-
-  test("export position with en passant and move counts"):
-    val gameState = GameState(
-      piecePlacement = "rnbqkbnr/pp1ppppp/8/2pP4/8/8/PPPP1PPP/RNBQKBNR",
-      activeColor = Color.White,
-      castlingWhite = CastlingRights.Both,
-      castlingBlack = CastlingRights.Both,
-      enPassantTarget = Some(Square(File.C, Rank.R6)),
-      halfMoveClock = 2,
-      fullMoveNumber = 3,
-      status = GameStatus.InProgress
-    )
-    val fen = FenExporter.gameStateToFen(gameState)
-    fen shouldBe "rnbqkbnr/pp1ppppp/8/2pP4/8/8/PPPP1PPP/RNBQKBNR w KQkq c6 2 3"
@@ -1,134 +0,0 @@
-package de.nowchess.chess.notation
-
-import de.nowchess.api.board.*
-import de.nowchess.api.game.*
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class FenParserTest extends AnyFunSuite with Matchers:
-
-  test("parseBoard: initial position places pieces on correct squares"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"
-    val board = FenParser.parseBoard(fen)
-
-    board.map(_.pieceAt(Square(File.E, Rank.R2))) shouldBe Some(Some(Piece.WhitePawn))
-    board.map(_.pieceAt(Square(File.E, Rank.R7))) shouldBe Some(Some(Piece.BlackPawn))
-    board.map(_.pieceAt(Square(File.E, Rank.R1))) shouldBe Some(Some(Piece.WhiteKing))
-    board.map(_.pieceAt(Square(File.E, Rank.R8))) shouldBe Some(Some(Piece.BlackKing))
-
-  test("parseBoard: empty board has no pieces"):
-    val fen = "8/8/8/8/8/8/8/8"
-    val board = FenParser.parseBoard(fen)
-
-    board shouldBe defined
-    board.get.pieces.size shouldBe 0
-
-  test("parseBoard: returns None for missing rank (only 7 ranks)"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP"
-    val board = FenParser.parseBoard(fen)
-
-    board shouldBe empty
-
-  test("parseBoard: returns None for invalid piece character"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNX"
-    val board = FenParser.parseBoard(fen)
-
-    board shouldBe empty
-
-  test("parseBoard: partial position with two kings placed correctly"):
-    val fen = "8/8/4k3/8/4K3/8/8/8"
-    val board = FenParser.parseBoard(fen)
-
-    board.map(_.pieceAt(Square(File.E, Rank.R6))) shouldBe Some(Some(Piece.BlackKing))
-    board.map(_.pieceAt(Square(File.E, Rank.R4))) shouldBe Some(Some(Piece.WhiteKing))
-
-  test("testRoundTripInitialPosition"):
-    val originalFen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"
-    val board = FenParser.parseBoard(originalFen)
-    val exportedFen = board.map(FenExporter.boardToFen)
-
-    exportedFen shouldBe Some(originalFen)
-
-  test("testRoundTripEmptyBoard"):
-    val originalFen = "8/8/8/8/8/8/8/8"
-    val board = FenParser.parseBoard(originalFen)
-    val exportedFen = board.map(FenExporter.boardToFen)
-
-    exportedFen shouldBe Some(originalFen)
-
-  test("testRoundTripPartialPosition"):
-    val originalFen = "8/8/4k3/8/4K3/8/8/8"
-    val board = FenParser.parseBoard(originalFen)
-    val exportedFen = board.map(FenExporter.boardToFen)
-
-    exportedFen shouldBe Some(originalFen)
-
-  test("parse full FEN - initial position"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
-    val gameState = FenParser.parseFen(fen)
-
-    gameState.isDefined shouldBe true
-    gameState.get.activeColor shouldBe Color.White
-    gameState.get.castlingWhite.kingSide shouldBe true
-    gameState.get.castlingWhite.queenSide shouldBe true
-    gameState.get.castlingBlack.kingSide shouldBe true
-    gameState.get.castlingBlack.queenSide shouldBe true
-    gameState.get.enPassantTarget shouldBe None
-    gameState.get.halfMoveClock shouldBe 0
-    gameState.get.fullMoveNumber shouldBe 1
-
-  test("parse full FEN - after e4"):
-    val fen = "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1"
-    val gameState = FenParser.parseFen(fen)
-
-    gameState.get.activeColor shouldBe Color.Black
-    gameState.get.enPassantTarget shouldBe Some(Square(File.E, Rank.R3))
-
-  test("parse full FEN - invalid parts count"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq"
-    val gameState = FenParser.parseFen(fen)
-
-    gameState.isDefined shouldBe false
-
-  test("parse full FEN - invalid color"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR x KQkq - 0 1"
-    val gameState = FenParser.parseFen(fen)
-
-    gameState.isDefined shouldBe false
-
-  test("parse full FEN - invalid castling"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w XYZ - 0 1"
-    val gameState = FenParser.parseFen(fen)
-
-    gameState.isDefined shouldBe false
-
-  test("parseFen: castling '-' produces CastlingRights.None for both sides"):
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1"
-    val gameState = FenParser.parseFen(fen)
-
-    gameState.isDefined shouldBe true
-    gameState.get.castlingWhite.kingSide shouldBe false
-    gameState.get.castlingWhite.queenSide shouldBe false
-    gameState.get.castlingBlack.kingSide shouldBe false
-    gameState.get.castlingBlack.queenSide shouldBe false
-
-  test("parseBoard: returns None when a rank has too many files (overflow beyond 8)"):
-    // "9" alone would advance fileIdx to 9, exceeding 8 → None
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBN9"
-    val board = FenParser.parseBoard(fen)
-
-    board shouldBe empty
-
-  test("parseBoard: returns None when a rank fails to parse (invalid middle rank)"):
-    // Invalid character 'X' in rank 4 should cause failure
-    val fen = "rnbqkbnr/pppppppp/8/8/XXXXXXXX/8/PPPPPPPP/RNBQKBNR"
-    val board = FenParser.parseBoard(fen)
-
-    board shouldBe empty
-
-  test("parseBoard: returns None when a rank has 9 piece characters (fileIdx > 7)"):
-    // 9 pawns in one rank triggers fileIdx > 7 guard (line 78)
-    val fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/PPPPPPPPP"
-    val board = FenParser.parseBoard(fen)
-
-    board shouldBe empty
@@ -1,65 +0,0 @@
-package de.nowchess.chess.notation
-
-import de.nowchess.api.board.*
-import de.nowchess.chess.logic.{GameHistory, HistoryMove, CastleSide}
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class PgnExporterTest extends AnyFunSuite with Matchers:
-
-  test("export empty game") {
-    val headers = Map("Event" -> "Test", "White" -> "A", "Black" -> "B")
-    val history = GameHistory.empty
-    val pgn = PgnExporter.exportGame(headers, history)
-
-    pgn.contains("[Event \"Test\"]") shouldBe true
-    pgn.contains("[White \"A\"]") shouldBe true
-    pgn.contains("[Black \"B\"]") shouldBe true
-  }
-
-  test("export single move") {
-    val headers = Map("Event" -> "Test", "White" -> "A", "Black" -> "B")
-    val history = GameHistory()
-      .addMove(HistoryMove(Square(File.E, Rank.R2), Square(File.E, Rank.R4), None))
-    val pgn = PgnExporter.exportGame(headers, history)
-
-    pgn.contains("1. e2e4") shouldBe true
-  }
-
-  test("export castling") {
-    val headers = Map("Event" -> "Test")
-    val history = GameHistory()
-      .addMove(HistoryMove(Square(File.E, Rank.R1), Square(File.G, Rank.R1), Some(CastleSide.Kingside)))
-    val pgn = PgnExporter.exportGame(headers, history)
-
-    pgn.contains("O-O") shouldBe true
-  }
-
-  test("export game sequence") {
-    val headers = Map("Event" -> "Test", "White" -> "A", "Black" -> "B", "Result" -> "1-0")
-    val history = GameHistory()
-      .addMove(HistoryMove(Square(File.E, Rank.R2), Square(File.E, Rank.R4), None))
-      .addMove(HistoryMove(Square(File.C, Rank.R7), Square(File.C, Rank.R5), None))
-      .addMove(HistoryMove(Square(File.G, Rank.R1), Square(File.F, Rank.R3), None))
-    val pgn = PgnExporter.exportGame(headers, history)
-
-    pgn.contains("1. e2e4 c7c5") shouldBe true
-    pgn.contains("2. g1f3") shouldBe true
-  }
-
-  test("export game with no headers returns only move text") {
-    val history = GameHistory()
-      .addMove(HistoryMove(Square(File.E, Rank.R2), Square(File.E, Rank.R4), None))
-    val pgn = PgnExporter.exportGame(Map.empty, history)
-
-    pgn shouldBe "1. e2e4 *"
-  }
-
-  test("export queenside castling") {
-    val headers = Map("Event" -> "Test")
-    val history = GameHistory()
-      .addMove(HistoryMove(Square(File.E, Rank.R1), Square(File.C, Rank.R1), Some(CastleSide.Queenside)))
-    val pgn = PgnExporter.exportGame(headers, history)
-
-    pgn.contains("O-O-O") shouldBe true
-  }
@@ -1,334 +0,0 @@
-package de.nowchess.chess.notation
-
-import de.nowchess.api.board.*
-import de.nowchess.chess.logic.{GameHistory, HistoryMove, CastleSide}
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-
-class PgnParserTest extends AnyFunSuite with Matchers:
-
-  test("parse PGN headers only") {
-    val pgn = """[Event "Test Game"]
-[Site "Earth"]
-[Date "2026.03.28"]
-[White "Alice"]
-[Black "Bob"]
-[Result "1-0"]"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    game.get.headers("Event") shouldBe "Test Game"
-    game.get.headers("White") shouldBe "Alice"
-    game.get.headers("Result") shouldBe "1-0"
-    game.get.moves shouldBe List()
-  }
-
-  test("parse PGN simple game") {
-    val pgn = """[Event "Test"]
-[Site "?"]
-[Date "2026.03.28"]
-[White "A"]
-[Black "B"]
-[Result "*"]
-
-1. e4 e5 2. Nf3 Nc6 3. Bb5 a6
-"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    game.get.moves.length shouldBe 6
-    // e4: e2-e4
-    game.get.moves(0).from shouldBe Square(File.E, Rank.R2)
-    game.get.moves(0).to shouldBe Square(File.E, Rank.R4)
-  }
-
-  test("parse PGN move with capture") {
-    val pgn = """[Event "Test"]
-[White "A"]
-[Black "B"]
-
-1. e4 e5 2. Nxe5
-"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    game.get.moves.length shouldBe 3
-    // Nxe5: knight captures on e5
-    game.get.moves(2).to shouldBe Square(File.E, Rank.R5)
-  }
-
-  test("parse PGN castling") {
-    val pgn = """[Event "Test"]
-[White "A"]
-[Black "B"]
-
-1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. O-O
-"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    // O-O is kingside castling: king e1-g1
-    val lastMove = game.get.moves.last
-    lastMove.from shouldBe Square(File.E, Rank.R1)
-    lastMove.to shouldBe Square(File.G, Rank.R1)
-    lastMove.castleSide.isDefined shouldBe true
-  }
-
-  test("parse PGN empty moves") {
-    val pgn = """[Event "Test"]
-[White "A"]
-[Black "B"]
-[Result "1-0"]
-"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    game.get.moves.length shouldBe 0
-  }
-
-  test("parse PGN black kingside castling O-O") {
-    // After e4 e5 Nf3 Nc6 Bc4 Bc5, black can castle kingside
-    val pgn = """[Event "Test"]
-
-1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. O-O O-O
-"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    val blackCastle = game.get.moves.last
-    blackCastle.castleSide shouldBe Some(CastleSide.Kingside)
-    blackCastle.from shouldBe Square(File.E, Rank.R8)
-    blackCastle.to shouldBe Square(File.G, Rank.R8)
-  }
-
-  test("parse PGN result tokens are skipped") {
-    // Result tokens like 1-0, 0-1, 1/2-1/2, * should be silently skipped
-    val pgn = """[Event "Test"]
-
-1. e4 e5 1-0
-"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    game.get.moves.length shouldBe 2
-  }
-
-  test("parseAlgebraicMove: unrecognised token returns None and is skipped") {
-    val board = Board.initial
-    val history = GameHistory.empty
-    // "zzz" is not valid algebraic notation
-    val result = PgnParser.parseAlgebraicMove("zzz", board, history, Color.White)
-    result shouldBe None
-  }
-
-  test("parseAlgebraicMove: piece moves use charToPieceType for N B R Q K") {
-    // Test that piece type characters are recognised
-    val board = Board.initial
-    val history = GameHistory.empty
-
-    // Nf3 - knight move
-    val nMove = PgnParser.parseAlgebraicMove("Nf3", board, history, Color.White)
-    nMove.isDefined shouldBe true
-    nMove.get.to shouldBe Square(File.F, Rank.R3)
-  }
-
-  test("parseAlgebraicMove: single char that is too short returns None") {
-    val board = Board.initial
-    val history = GameHistory.empty
-    // Single char that is not castling and cleaned length < 2
-    val result = PgnParser.parseAlgebraicMove("e", board, history, Color.White)
-    result shouldBe None
-  }
-
-  test("parse PGN with file disambiguation hint") {
-    // Use a position where two rooks can reach the same square to test file hint
-    // Rooks on a1 and h1, destination d1 - "Rad1" uses file 'a' to disambiguate
-    import de.nowchess.api.board.{Board, Square, File, Rank, Piece, Color, PieceType}
-    val pieces: 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)
-    )
-    val board = Board(pieces)
-    val history = GameHistory.empty
-
-    val result = PgnParser.parseAlgebraicMove("Rad1", board, history, Color.White)
-    result.isDefined shouldBe true
-    result.get.from shouldBe Square(File.A, Rank.R1)
-    result.get.to shouldBe Square(File.D, Rank.R1)
-  }
-
-  test("parse PGN with rank disambiguation hint") {
-    // Two rooks on a1 and a4 can reach a3 - "R1a3" uses rank '1' to disambiguate
-    import de.nowchess.api.board.{Board, Square, File, Rank, Piece, Color, PieceType}
-    val pieces: 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)
-    )
-    val board = Board(pieces)
-    val history = GameHistory.empty
-
-    val result = PgnParser.parseAlgebraicMove("R1a3", board, history, Color.White)
-    result.isDefined shouldBe true
-    result.get.from shouldBe Square(File.A, Rank.R1)
-    result.get.to shouldBe Square(File.A, Rank.R3)
-  }
-
-  test("parseAlgebraicMove: charToPieceType covers all piece letters including B R Q K") {
-    import de.nowchess.api.board.{Board, Square, File, Rank, Piece, Color, PieceType}
-    // Bishop move
-    val piecesForBishop: Map[Square, Piece] = Map(
-      Square(File.C, Rank.R1) -> Piece(Color.White, PieceType.Bishop),
-      Square(File.E, Rank.R1) -> Piece(Color.White, PieceType.King),
-      Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King)
-    )
-    val boardBishop = Board(piecesForBishop)
-    val bResult = PgnParser.parseAlgebraicMove("Bd2", boardBishop, GameHistory.empty, Color.White)
-    bResult.isDefined shouldBe true
-
-    // Rook move
-    val piecesForRook: Map[Square, Piece] = Map(
-      Square(File.A, 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)
-    )
-    val boardRook = Board(piecesForRook)
-    val rResult = PgnParser.parseAlgebraicMove("Ra4", boardRook, GameHistory.empty, Color.White)
-    rResult.isDefined shouldBe true
-
-    // Queen move
-    val piecesForQueen: Map[Square, Piece] = Map(
-      Square(File.D, Rank.R1) -> Piece(Color.White, PieceType.Queen),
-      Square(File.E, Rank.R1) -> Piece(Color.White, PieceType.King),
-      Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King)
-    )
-    val boardQueen = Board(piecesForQueen)
-    val qResult = PgnParser.parseAlgebraicMove("Qd4", boardQueen, GameHistory.empty, Color.White)
-    qResult.isDefined shouldBe true
-
-    // King move
-    val piecesForKing: Map[Square, Piece] = Map(
-      Square(File.E, Rank.R1) -> Piece(Color.White, PieceType.King),
-      Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King)
-    )
-    val boardKing = Board(piecesForKing)
-    val kResult = PgnParser.parseAlgebraicMove("Ke2", boardKing, GameHistory.empty, Color.White)
-    kResult.isDefined shouldBe true
-  }
-
-  test("parse PGN queenside castling O-O-O") {
-    val pgn = """[Event "Test"]
-
-1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O
-"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    val lastMove = game.get.moves.last
-    lastMove.castleSide shouldBe Some(CastleSide.Queenside)
-    lastMove.from shouldBe Square(File.E, Rank.R1)
-    lastMove.to shouldBe Square(File.C, Rank.R1)
-  }
-
-  test("parse PGN black queenside castling O-O-O") {
-    // After sufficient moves, black castles queenside
-    val pgn = """[Event "Test"]
-
-1. d4 d5 2. Nc3 Nc6 3. Bf4 Bf5 4. Qd2 Qd7 5. O-O-O O-O-O
-"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    val lastMove = game.get.moves.last
-    lastMove.castleSide shouldBe Some(CastleSide.Queenside)
-    lastMove.from shouldBe Square(File.E, Rank.R8)
-    lastMove.to shouldBe Square(File.C, Rank.R8)
-  }
-
-  test("parse PGN with unrecognised token in move text is silently skipped") {
-    // "INVALID" is not valid PGN; it should be skipped and remaining moves parsed
-    val pgn = """[Event "Test"]
-
-1. e4 INVALID e5
-"""
-    val game = PgnParser.parsePgn(pgn)
-
-    game.isDefined shouldBe true
-    // e4 parsed, INVALID skipped, e5 parsed
-    game.get.moves.length shouldBe 2
-  }
-
-  test("parseAlgebraicMove: file+rank disambiguation with piece letter") {
-    // "Rae1" notation: piece R, disambig "a" -> hint is "a", piece letter is uppercase first char of disambig
-    // But since disambig="a" which is not uppercase, the piece letter comes from clean.head
-    // Test "Rae1" style: R is clean.head uppercase, disambig "a" is the hint
-    import de.nowchess.api.board.{Board, Square, File, Rank, Piece, Color, PieceType}
-    val pieces: Map[Square, Piece] = Map(
-      Square(File.A, Rank.R4) -> Piece(Color.White, PieceType.Rook),
-      Square(File.H, 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)
-    )
-    val board = Board(pieces)
-    val history = GameHistory.empty
-
-    // "Rae4" - Rook from a-file to e4; disambig = "a", clean.head = 'R' uppercase
-    val result = PgnParser.parseAlgebraicMove("Rae4", board, history, Color.White)
-    result.isDefined shouldBe true
-    result.get.from shouldBe Square(File.A, Rank.R4)
-    result.get.to shouldBe Square(File.E, Rank.R4)
-  }
-
-  test("parseAlgebraicMove: charToPieceType returns None for unknown character") {
-    // 'Z' is not a valid piece letter - the regex clean should return None
-    import de.nowchess.api.board.{Board, Square, File, Rank, Piece, Color, PieceType}
-    val board = Board.initial
-    val history = GameHistory.empty
-
-    // "Ze4" - Z is not a valid piece, charToPieceType('Z') returns None
-    // The result will be None because requiredPieceType is None and filtering by None.forall = true
-    // so it finds any piece that can reach e4, but since clean="Ze4" -> destStr="e4", disambig="Z"
-    // disambig.head.isUpper so charToPieceType('Z') is called
-    val result = PgnParser.parseAlgebraicMove("Ze4", board, history, Color.White)
-    // With None piece type, forall(pt => ...) is vacuously true so any piece reaching e4 is candidate
-    // But there's no piece named Z so requiredPieceType=None, meaning any piece can match
-    // This tests that charToPieceType('Z') returns None without crashing
-    result shouldBe defined  // will find a pawn or whatever reaches e4
-  }
-
-  test("parseAlgebraicMove: uppercase dest-only notation hits clean.head.isUpper and charToPieceType unknown char") {
-    // "E4" - clean = "E4", disambig = "", clean.head = 'E' is upper, charToPieceType('E') returns None
-    // This exercises line 97 (else if clean.head.isUpper) and line 152 (case _ => None)
-    import de.nowchess.api.board.{Board, Square, File, Rank, Piece, Color, PieceType}
-    val board = Board.initial
-    val history = GameHistory.empty
-    // 'E' is not a valid piece type but we still get a result since requiredPieceType is None
-    val result = PgnParser.parseAlgebraicMove("E4", board, history, Color.White)
-    // Result may be defined (pawn that can reach e4) or None; main goal is no crash and line coverage
-    result should not be null  // just verifies code path executes without exception
-  }
-
-  test("parseAlgebraicMove: rank disambiguation with digit outside 1-8 hits matchesHint else-true branch") {
-    // Build a board with a Rook that can be targeted with a disambiguation hint containing '9'
-    // hint = "9" → c = '9', not in a-h, not in 1-8, triggers else true
-    import de.nowchess.api.board.{Board, Square, File, Rank, Piece, Color, PieceType}
-    val pieces: 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)
-    )
-    val board = Board(pieces)
-    val history = GameHistory.empty
-
-    // "R9d1" - clean = "R9d1", destStr = "d1", disambig = "R9"
-    // disambig.head = 'R' is upper -> charToPieceType('R') = Rook, hint = "9"
-    // matchesHint called with hint "9" -> '9' not in a-h, not in 1-8 -> else true
-    val result = PgnParser.parseAlgebraicMove("R9d1", board, history, Color.White)
-    // Should find a rook (hint "9" matches everything)
-    result.isDefined shouldBe true
-    result.get.to shouldBe Square(File.D, Rank.R1)
-  }
@@ -1,168 +0,0 @@
-package de.nowchess.chess.observer
-
-import de.nowchess.api.board.{Board, Color}
-import de.nowchess.chess.logic.GameHistory
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-import scala.collection.mutable
-
-class ObservableThreadSafetyTest extends AnyFunSuite with Matchers:
-
-  private class TestObservable extends Observable:
-    def testNotifyObservers(event: GameEvent): Unit =
-      notifyObservers(event)
-
-  private class CountingObserver extends Observer:
-    @volatile private var eventCount = 0
-    @volatile private var lastEvent: Option[GameEvent] = None
-
-    def onGameEvent(event: GameEvent): Unit =
-      eventCount += 1
-      lastEvent = Some(event)
-
-  private def createTestEvent(): GameEvent =
-    BoardResetEvent(
-      board = Board.initial,
-      history = GameHistory.empty,
-      turn = Color.White
-    )
-
-  test("Observable is thread-safe for concurrent subscribe and notify"):
-    val observable = new TestObservable()
-    val testEvent = createTestEvent()
-    @volatile var raceConditionCaught = false
-
-    // Thread 1: repeatedly notifies observers with long iteration
-    val notifierThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 500000 do
-            observable.testNotifyObservers(testEvent)
-        } catch {
-          case _: java.util.ConcurrentModificationException =>
-            raceConditionCaught = true
-        }
-      }
-    })
-
-    // Thread 2: rapidly subscribes/unsubscribes observers during notify
-    val subscriberThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 500000 do
-            val obs = new CountingObserver()
-            observable.subscribe(obs)
-            observable.unsubscribe(obs)
-        } catch {
-          case _: java.util.ConcurrentModificationException =>
-            raceConditionCaught = true
-        }
-      }
-    })
-
-    notifierThread.start()
-    subscriberThread.start()
-    notifierThread.join()
-    subscriberThread.join()
-
-    raceConditionCaught shouldBe false
-
-  test("Observable is thread-safe for concurrent subscribe, unsubscribe, and notify"):
-    val observable = new TestObservable()
-    val testEvent = createTestEvent()
-    val exceptions = mutable.ListBuffer[Exception]()
-    val observers = mutable.ListBuffer[CountingObserver]()
-
-    // Pre-subscribe some observers
-    for _ <- 1 to 10 do
-      val obs = new CountingObserver()
-      observers += obs
-      observable.subscribe(obs)
-
-    // Thread 1: notifies observers
-    val notifierThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 5000 do
-            observable.testNotifyObservers(testEvent)
-        } catch {
-          case e: Exception => exceptions += e
-        }
-      }
-    })
-
-    // Thread 2: subscribes new observers
-    val subscriberThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 5000 do
-            val obs = new CountingObserver()
-            observable.subscribe(obs)
-        } catch {
-          case e: Exception => exceptions += e
-        }
-      }
-    })
-
-    // Thread 3: unsubscribes observers
-    val unsubscriberThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for i <- 1 to 5000 do
-            if observers.nonEmpty then
-              val obs = observers(i % observers.size)
-              observable.unsubscribe(obs)
-        } catch {
-          case e: Exception => exceptions += e
-        }
-      }
-    })
-
-    notifierThread.start()
-    subscriberThread.start()
-    unsubscriberThread.start()
-    notifierThread.join()
-    subscriberThread.join()
-    unsubscriberThread.join()
-
-    exceptions.isEmpty shouldBe true
-
-  test("Observable.observerCount is thread-safe during concurrent modifications"):
-    val observable = new TestObservable()
-    val exceptions = mutable.ListBuffer[Exception]()
-    val countResults = mutable.ListBuffer[Int]()
-
-    // Thread 1: subscribes observers
-    val subscriberThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 500 do
-            observable.subscribe(new CountingObserver())
-        } catch {
-          case e: Exception => exceptions += e
-        }
-      }
-    })
-
-    // Thread 2: reads observer count
-    val readerThread = new Thread(new Runnable {
-      def run(): Unit = {
-        try {
-          for _ <- 1 to 500 do
-            val count = observable.observerCount
-            countResults += count
-        } catch {
-          case e: Exception => exceptions += e
-        }
-      }
-    })
-
-    subscriberThread.start()
-    readerThread.start()
-    subscriberThread.join()
-    readerThread.join()
-
-    exceptions.isEmpty shouldBe true
-    // Count should never go backwards
-    for i <- 1 until countResults.size do
-      countResults(i) >= countResults(i - 1) shouldBe true
@@ -1,3 +0,0 @@
-MAJOR=0
-MINOR=4
-PATCH=0
@@ -1,73 +0,0 @@
-plugins {
-    id("scala")
-    id("org.scoverage") version "8.1"
-    application
-}
-
-group = "de.nowchess"
-version = "1.0-SNAPSHOT"
-
-@Suppress("UNCHECKED_CAST")
-val versions = rootProject.extra["VERSIONS"] as Map<String, String>
-
-repositories {
-    mavenCentral()
-}
-
-scala {
-    scalaVersion = versions["SCALA3"]!!
-}
-
-scoverage {
-    scoverageVersion.set(versions["SCOVERAGE"]!!)
-}
-
-application {
-    mainClass.set("de.nowchess.ui.Main")
-}
-
-tasks.withType<ScalaCompile> {
-    scalaCompileOptions.additionalParameters = listOf("-encoding", "UTF-8")
-}
-
-tasks.named<JavaExec>("run") {
-    jvmArgs("-Dfile.encoding=UTF-8", "-Dstdout.encoding=UTF-8", "-Dstderr.encoding=UTF-8")
-    standardInput = System.`in`
-}
-
-dependencies {
-
-    implementation("org.scala-lang:scala3-compiler_3") {
-        version {
-            strictly(versions["SCALA3"]!!)
-        }
-    }
-    implementation("org.scala-lang:scala3-library_3") {
-        version {
-            strictly(versions["SCALA3"]!!)
-        }
-    }
-
-    implementation(project(":modules:core"))
-    implementation(project(":modules:api"))
-
-    testImplementation(platform("org.junit:junit-bom:5.13.4"))
-    testImplementation("org.junit.jupiter:junit-jupiter")
-    testImplementation("org.scalatest:scalatest_3:${versions["SCALATEST"]!!}")
-    testImplementation("co.helmethair:scalatest-junit-runner:${versions["SCALATEST_JUNIT"]!!}")
-
-    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
-}
-
-tasks.test {
-    useJUnitPlatform {
-        includeEngines("scalatest")
-        testLogging {
-            events("passed", "skipped", "failed")
-        }
-    }
-    finalizedBy(tasks.reportScoverage)
-}
-tasks.reportScoverage {
-    dependsOn(tasks.test)
-}
@@ -1,15 +0,0 @@
-package de.nowchess.ui
-
-import de.nowchess.chess.engine.GameEngine
-import de.nowchess.ui.terminal.TerminalUI
-
-/** Application entry point - starts the Terminal UI for the chess game. */
-object Main:
-  def main(args: Array[String]): Unit =
-    // Create the core game engine (single source of truth)
-    val engine = new GameEngine()
-
-    // Create and start the terminal UI
-    val tui = new TerminalUI(engine)
-    tui.start()
-
@@ -1,76 +0,0 @@
-package de.nowchess.ui.terminal
-
-import scala.io.StdIn
-import de.nowchess.chess.engine.GameEngine
-import de.nowchess.chess.observer.{Observer, GameEvent, *}
-import de.nowchess.chess.view.Renderer
-
-/** Terminal UI that implements Observer pattern.
- *  Subscribes to GameEngine and receives state change events.
- *  Handles all I/O and user interaction in the terminal.
- */
-class TerminalUI(engine: GameEngine) extends Observer:
-  private var running = true
-
-  /** Called by GameEngine whenever a game event occurs. */
-  override def onGameEvent(event: GameEvent): Unit =
-    event match
-      case e: MoveExecutedEvent =>
-        println()
-        print(Renderer.render(e.board))
-        e.capturedPiece.foreach: cap =>
-          println(s"Captured: $cap on ${e.toSquare}")
-        printPrompt(e.turn)
-
-      case e: CheckDetectedEvent =>
-        println(s"${e.turn.label} is in check!")
-
-      case e: CheckmateEvent =>
-        println(s"Checkmate! ${e.winner.label} wins.")
-        println()
-        print(Renderer.render(e.board))
-
-      case e: StalemateEvent =>
-        println("Stalemate! The game is a draw.")
-        println()
-        print(Renderer.render(e.board))
-
-      case e: InvalidMoveEvent =>
-        println(s"⚠️  ${e.reason}")
-
-      case e: BoardResetEvent =>
-        println("Board has been reset to initial position.")
-        println()
-        print(Renderer.render(e.board))
-        printPrompt(e.turn)
-
-  /** Start the terminal UI game loop. */
-  def start(): Unit =
-    // Register as observer
-    engine.subscribe(this)
-
-    // Show initial board
-    println()
-    print(Renderer.render(engine.board))
-    printPrompt(engine.turn)
-
-    // Game loop
-    while running do
-      val input = Option(StdIn.readLine()).getOrElse("quit").trim
-      input.toLowerCase match
-        case "quit" | "q" =>
-          running = false
-          println("Game over. Goodbye!")
-        case "" =>
-          printPrompt(engine.turn)
-        case _ =>
-          engine.processUserInput(input)
-
-    // Unsubscribe when done
-    engine.unsubscribe(this)
-
-  private def printPrompt(turn: de.nowchess.api.board.Color): Unit =
-    val undoHint = if engine.canUndo then " [undo]" else ""
-    val redoHint = if engine.canRedo then " [redo]" else ""
-    print(s"${turn.label}'s turn. Enter move (or 'quit'/'q' to exit)$undoHint$redoHint: ")
-
@@ -1,22 +0,0 @@
-package de.nowchess.ui
-
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-import java.io.{ByteArrayInputStream, ByteArrayOutputStream}
-
-class MainTest extends AnyFunSuite with Matchers {
-
-  test("main should execute and quit immediately when fed 'quit'") {
-    val in = new ByteArrayInputStream("quit\n".getBytes)
-    val out = new ByteArrayOutputStream()
-
-    Console.withIn(in) {
-      Console.withOut(out) {
-        Main.main(Array.empty)
-      }
-    }
-    
-    val output = out.toString
-    output should include ("Game over. Goodbye!")
-  }
-}
@@ -1,189 +0,0 @@
-package de.nowchess.ui.terminal
-
-import org.scalatest.funsuite.AnyFunSuite
-import org.scalatest.matchers.should.Matchers
-import java.io.{ByteArrayInputStream, ByteArrayOutputStream}
-import de.nowchess.chess.engine.GameEngine
-import de.nowchess.chess.observer.*
-import de.nowchess.api.board.{Board, Color}
-import de.nowchess.chess.logic.GameHistory
-
-class TerminalUITest extends AnyFunSuite with Matchers {
-
-  test("TerminalUI should start, print initial state, and correctly respond to 'q'") {
-    val in = new ByteArrayInputStream("q\n".getBytes)
-    val out = new ByteArrayOutputStream()
-
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withIn(in) {
-      Console.withOut(out) {
-        ui.start()
-      }
-    }
-
-    val output = out.toString
-    output should include("White's turn.")
-    output should include("Game over. Goodbye!")
-  }
-
-  test("TerminalUI should ignore empty inputs and re-print prompt") {
-    val in = new ByteArrayInputStream("\nq\n".getBytes)
-    val out = new ByteArrayOutputStream()
-
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withIn(in) {
-      Console.withOut(out) {
-        ui.start()
-      }
-    }
-
-    val output = out.toString
-    // Prompt appears three times: Initial, after empty, on exit.
-    output.split("White's turn.").length should be > 2
-  }
-
-  test("TerminalUI should explicitly handle empty input by re-prompting") {
-    val in = new ByteArrayInputStream("\n\nq\n".getBytes)
-    val out = new ByteArrayOutputStream()
-
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withIn(in) {
-      Console.withOut(out) {
-        ui.start()
-      }
-    }
-
-    val output = out.toString
-    // With two empty inputs, prompt should appear at least 4 times:
-    // 1. Initial board display
-    // 2. After first empty input
-    // 3. After second empty input
-    // 4. Before quit
-    val promptCount = output.split("White's turn.").length
-    promptCount should be >= 4
-    output should include("Game over. Goodbye!")
-  }
-
-  test("TerminalUI printPrompt should include undo and redo hints if engine returns true") {
-    val in = new ByteArrayInputStream("\nq\n".getBytes)
-    val out = new ByteArrayOutputStream()
-
-    val engine = new GameEngine() {
-      // Stub engine to force undo/redo to true
-      override def canUndo: Boolean = true
-      override def canRedo: Boolean = true
-    }
-    
-    val ui = new TerminalUI(engine)
-
-    Console.withIn(in) {
-      Console.withOut(out) {
-        ui.start()
-      }
-    }
-
-    val output = out.toString
-    output should include("[undo]")
-    output should include("[redo]")
-  }
-
-  test("TerminalUI onGameEvent should properly format InvalidMoveEvent") {
-    val out = new ByteArrayOutputStream()
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withOut(out) {
-      ui.onGameEvent(InvalidMoveEvent(Board(Map.empty), GameHistory(), Color.Black, "Invalid move format"))
-    }
-
-    out.toString should include("⚠️")
-    out.toString should include("Invalid move format")
-  }
-
-  test("TerminalUI onGameEvent should properly format CheckDetectedEvent") {
-    val out = new ByteArrayOutputStream()
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withOut(out) {
-      ui.onGameEvent(CheckDetectedEvent(Board(Map.empty), GameHistory(), Color.Black))
-    }
-
-    out.toString should include("Black is in check!")
-  }
-
-  test("TerminalUI onGameEvent should properly format CheckmateEvent") {
-    val out = new ByteArrayOutputStream()
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withOut(out) {
-      ui.onGameEvent(CheckmateEvent(Board(Map.empty), GameHistory(), Color.Black, Color.White))
-    }
-
-    val ostr = out.toString
-    ostr should include("Checkmate! White wins.")
-  }
-
-  test("TerminalUI onGameEvent should properly format StalemateEvent") {
-    val out = new ByteArrayOutputStream()
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withOut(out) {
-      ui.onGameEvent(StalemateEvent(Board(Map.empty), GameHistory(), Color.Black))
-    }
-
-    out.toString should include("Stalemate! The game is a draw.")
-  }
-
-  test("TerminalUI onGameEvent should properly format BoardResetEvent") {
-    val out = new ByteArrayOutputStream()
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withOut(out) {
-      ui.onGameEvent(BoardResetEvent(Board(Map.empty), GameHistory(), Color.White))
-    }
-
-    out.toString should include("Board has been reset to initial position.")
-  }
-
-  test("TerminalUI onGameEvent should properly format MoveExecutedEvent with capturing piece") {
-    val out = new ByteArrayOutputStream()
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withOut(out) {
-      ui.onGameEvent(MoveExecutedEvent(Board(Map.empty), GameHistory(), Color.Black, "A1", "A8", Some("Knight(White)")))
-    }
-
-    out.toString should include("Captured: Knight(White) on A8") // Depending on how piece/coord serialize
-  }
-
-  test("TerminalUI processes valid move input via processUserInput") {
-    val in = new ByteArrayInputStream("e2e4\nq\n".getBytes)
-    val out = new ByteArrayOutputStream()
-
-    val engine = new GameEngine()
-    val ui = new TerminalUI(engine)
-
-    Console.withIn(in) {
-      Console.withOut(out) {
-        ui.start()
-      }
-    }
-
-    val output = out.toString
-    output should include("White's turn.")
-    output should include("Game over. Goodbye!")
-    // The move should have been processed and the board displayed
-    engine.turn shouldBe Color.Black
-  }
-}
@@ -1,2 +1,2 @@
 rootProject.name = "NowChessSystems"
-include("modules:core", "modules:api", "modules:ui")
+include("modules:core", "modules:api")
Author	SHA1	Message	Date
Janis	baed78fea3	refactor: update CLAUDE.md for improved structure and clarity Build & Test (NowChessSystems) TeamCity build finished Details	2026-03-25 08:44:43 +01:00
Janis	c50f678815	refactor: replace StringBuilder/for-loops in render with map/mkString	2026-03-25 08:44:43 +01:00
Janis	6f268966a5	refactor: replace return/var in castlingTargets with functional style	2026-03-25 08:44:43 +01:00
Janis	8b235a25e0	docs: add functional style refactor design spec	2026-03-25 08:44:43 +01:00