feat: add chess resign and undo actions

LOG.md

@@ -2,6 +2,18 @@
 
 ## 2026-06-19
 
+- Added Maia game resign and undo API wrappers, then wired the play screen with in-progress-only "무르기" and "기권" actions plus a persistent "새 게임" link back to the setup screen.
+- Locked board/actions during move, undo, and resign requests, updated the game cache from backend responses as the single source of truth, and refreshed history/stat queries after successful state changes.
+- Added resigned-loss labeling so play, recent games, and history can show `기권패` for `RESIGNED` losses while still grouping them under losses.
+- Validation: `npm run lint` passed and `npm run build` passed. Authenticated browser verification against the live Maia backend was not run in this session.
+- Recommended next task: test resign and undo with an authenticated real game, including black-player games where Maia's opening white move must remain after undo.
+
+- Reworked the shared chess board UI with a bordered board surface, high-contrast chip-style pieces, stronger selected/legal/last-move highlights, and transform-based piece movement transitions so player and Maia moves read as motion instead of instant jumps.
+- Connected the daily puzzle board to the shared `ChessBoard` component, removing duplicated piece rendering and adding drag/drop support for puzzle moves.
+- Updated Maia play state so optimistic player moves are highlighted locally while pending, then Maia's returned move can animate from the server response; changed the pending overlay into a small status pill so it no longer hides the board.
+- Validation: `npm run lint` passed and `npm run build` passed. A local dev server is running on `http://localhost:3124`; browser verification with a temporary local puzzle API confirmed 64 squares, 32 piece-layer nodes, 0.42s piece transition styling, square selection/legal target markers, and no console errors. The temporary API was stopped after verification.
+- Recommended next task: verify `/chess/play/{gameId}` against the real Maia backend with an authenticated account to tune the exact Maia response timing and capture/promotion edge cases.
+
 - Added the authenticated Maia chess frontend: `/chess` lobby with rating/color/model and advanced settings, `/chess/play/[gameId]` playable board with backend FEN synchronization and PGN copy, and `/chess/history` account game history with outcome filters.
 - Extended the chess API client and shared types for Maia game create/list/stats/detail/PGN/move endpoints while leaving the public `/api/chess-puzzles/**` puzzle request unchanged.
 - Updated the Dock/menu/shell route handling so Chess opens the Maia lobby, with the existing public puzzle page still available at `/play/chess`.

src/api/chess.ts

@@ -71,3 +71,15 @@ export const postChessMove = async (gameId: string, data: ChessMoveRequest) => {
 
   return requireApiData(response.data, '착수를 처리하지 못했습니다.');
 };
+
+export const resignChessGame = async (gameId: string) => {
+  const response = await http.post<ApiResponse<ChessGameResponse>>(`/api/chess/games/${gameId}/resign`);
+
+  return requireApiData(response.data, '기권을 처리하지 못했습니다.');
+};
+
+export const undoChessMove = async (gameId: string) => {
+  const response = await http.post<ApiResponse<ChessGameResponse>>(`/api/chess/games/${gameId}/undo`);
+
+  return requireApiData(response.data, '무르기를 처리하지 못했습니다.');
+};

src/components/chess/ChessBoard.tsx

@@ -1,15 +1,25 @@
 'use client';
 
-import { useMemo } from 'react';
+import { useEffect, useMemo, useRef, useState, type CSSProperties } from 'react';
 import { Chess as ChessGame, type Color, type PieceSymbol, type Square } from 'chess.js';
 import { clsx } from 'clsx';
 import { ChessColor } from '@/types';
 
-type MoveSquares = {
+export type MoveSquares = {
   from: Square;
   to: Square;
 };
 
+type BoardPiece = {
+  square: Square;
+  color: Color;
+  type: PieceSymbol;
+};
+
+type VisualPiece = BoardPiece & {
+  id: string;
+};
+
 interface ChessBoardProps {
   fen: string;
   orientation?: ChessColor;
@@ -26,6 +36,10 @@ const FILES = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] as const;
 const WHITE_RANKS = [8, 7, 6, 5, 4, 3, 2, 1] as const;
 const BLACK_RANKS = [1, 2, 3, 4, 5, 6, 7, 8] as const;
 
+export const BOARD_SQUARES = WHITE_RANKS.flatMap((rank) =>
+  FILES.map((file) => `${file}${rank}` as Square),
+);
+
 const PIECE_SYMBOLS: Record<Color, Record<PieceSymbol, string>> = {
   w: {
     k: '♔',
@@ -71,6 +85,15 @@ const getBoardSquares = (orientation: ChessColor) => {
   return ranks.flatMap((rank) => files.map((file) => `${file}${rank}` as Square));
 };
 
+const getPieces = (game: ChessGame): BoardPiece[] =>
+  BOARD_SQUARES.flatMap((square) => {
+    const piece = game.get(square);
+
+    if (!piece) return [];
+
+    return [{ square, color: piece.color, type: piece.type }];
+  });
+
 const getSquareLabel = (square: Square, piece?: { color: Color; type: PieceSymbol }) => {
   if (!piece) return `${square} 빈 칸`;
 
@@ -84,6 +107,73 @@ const isLightSquare = (square: Square) => {
   return (fileIndex + rank) % 2 === 0;
 };
 
+const getSquarePosition = (square: Square, orientation: ChessColor): CSSProperties => {
+  const fileIndex = FILES.indexOf(square[0] as (typeof FILES)[number]);
+  const rank = Number(square[1]);
+  const x = orientation === 'black' ? 7 - fileIndex : fileIndex;
+  const y = orientation === 'black' ? rank - 1 : 8 - rank;
+
+  return {
+    transform: `translate(${x * 100}%, ${y * 100}%)`,
+  };
+};
+
+const samePiece = (a: BoardPiece, b: BoardPiece) => a.color === b.color && a.type === b.type;
+
+const canRepresentMove = (fromPiece: VisualPiece, toPiece: BoardPiece) =>
+  fromPiece.color === toPiece.color && (fromPiece.type === toPiece.type || fromPiece.type === 'p');
+
+const createPieceId = (piece: BoardPiece, index: number) =>
+  `${piece.color}-${piece.type}-${piece.square}-${index}`;
+
+const createVisualPieces = (pieces: BoardPiece[]) => pieces.map((piece, index) => ({ ...piece, id: createPieceId(piece, index) }));
+
+const reconcileVisualPieces = (
+  previousPieces: VisualPiece[],
+  nextPieces: BoardPiece[],
+  lastMoveSquares?: MoveSquares | null,
+) => {
+  if (!lastMoveSquares) return createVisualPieces(nextPieces);
+
+  const nextBySquare = new Map(nextPieces.map((piece) => [piece.square, piece]));
+  const movedPieceTarget = nextBySquare.get(lastMoveSquares.to);
+
+  if (!movedPieceTarget) return createVisualPieces(nextPieces);
+
+  const usedVisualIds = new Set<string>();
+  const usedSquares = new Set<Square>();
+  const reconciled: VisualPiece[] = [];
+  const movingPiece =
+    previousPieces.find(
+      (piece) => piece.square === lastMoveSquares.from && canRepresentMove(piece, movedPieceTarget),
+    ) ?? previousPieces.find((piece) => piece.square === lastMoveSquares.from);
+
+  if (movingPiece) {
+    reconciled.push({ ...movingPiece, ...movedPieceTarget });
+    usedVisualIds.add(movingPiece.id);
+    usedSquares.add(movedPieceTarget.square);
+  }
+
+  previousPieces.forEach((visualPiece) => {
+    if (usedVisualIds.has(visualPiece.id)) return;
+
+    const nextPiece = nextBySquare.get(visualPiece.square);
+    if (!nextPiece || usedSquares.has(nextPiece.square) || !samePiece(visualPiece, nextPiece)) return;
+
+    reconciled.push({ ...visualPiece, ...nextPiece });
+    usedVisualIds.add(visualPiece.id);
+    usedSquares.add(nextPiece.square);
+  });
+
+  nextPieces.forEach((nextPiece, index) => {
+    if (usedSquares.has(nextPiece.square)) return;
+
+    reconciled.push({ ...nextPiece, id: createPieceId(nextPiece, previousPieces.length + index) });
+  });
+
+  return reconciled;
+};
+
 export const getMoveSquares = (move?: string | null): MoveSquares | null => {
   if (!move || move.length < 4) return null;
 
@@ -112,104 +202,146 @@ export default function ChessBoard({
   const boardSquares = useMemo(() => getBoardSquares(orientation), [orientation]);
   const firstFile = orientation === 'black' ? 'h' : 'a';
   const lastRank = orientation === 'black' ? '8' : '1';
+  const [visualPieces, setVisualPieces] = useState(() => createVisualPieces(getPieces(game)));
+  const previousFenRef = useRef(fen);
+
+  useEffect(() => {
+    const nextPieces = getPieces(game);
+
+    setVisualPieces((previousPieces) => {
+      if (previousFenRef.current === fen) return previousPieces;
+
+      previousFenRef.current = fen;
+      return reconcileVisualPieces(previousPieces, nextPieces, lastMoveSquares);
+    });
+  }, [fen, game, lastMoveSquares]);
 
   return (
-    <div className="grid aspect-square w-full grid-cols-8 overflow-hidden rounded-lg border border-[var(--color-line)] shadow-[var(--shadow-control)]">
-      {boardSquares.map((square) => {
-        const piece = game.get(square);
-        const isLight = isLightSquare(square);
-        const isSelected = selectedSquare === square;
-        const isTarget = legalTargets?.has(square) ?? false;
-        const isLastMoveSquare = lastMoveSquares?.from === square || lastMoveSquares?.to === square;
-        const canDrag = !disabled && Boolean(piece) && (isDraggableSquare?.(square) ?? true);
-        const file = square[0];
-        const rank = square[1];
+    <div className="relative aspect-square w-full rounded-xl border border-[#3f2d1f]/25 bg-[#4b3828] p-1.5 shadow-[0_20px_42px_rgb(49_35_24_/_0.22),0_1px_0_rgb(255_255_255_/_0.25)_inset] sm:p-2 dark:border-white/10 dark:bg-[#2a241f]">
+      <div className="relative h-full w-full overflow-hidden rounded-lg border border-black/25 bg-[#1f2a24] shadow-[0_1px_0_rgb(255_255_255_/_0.18)_inset]">
+        <div className="grid h-full w-full grid-cols-[repeat(8,minmax(0,1fr))] grid-rows-[repeat(8,minmax(0,1fr))]">
+          {boardSquares.map((square) => {
+            const piece = game.get(square);
+            const isLight = isLightSquare(square);
+            const isSelected = selectedSquare === square;
+            const isTarget = legalTargets?.has(square) ?? false;
+            const isLastMoveSquare = lastMoveSquares?.from === square || lastMoveSquares?.to === square;
+            const canDrag = !disabled && Boolean(piece) && (isDraggableSquare?.(square) ?? true);
+            const file = square[0];
+            const rank = square[1];
 
-        return (
-          <button
-            key={square}
-            type="button"
-            onClick={() => onSquareClick?.(square)}
-            draggable={canDrag}
-            onDragStart={(event) => {
-              if (!canDrag) {
-                event.preventDefault();
-                return;
-              }
+            return (
+              <button
+                key={square}
+                type="button"
+                onClick={() => onSquareClick?.(square)}
+                draggable={canDrag}
+                onDragStart={(event) => {
+                  if (!canDrag) {
+                    event.preventDefault();
+                    return;
+                  }
 
-              event.dataTransfer.effectAllowed = 'move';
-              event.dataTransfer.setData('text/plain', square);
-            }}
-            onDragOver={(event) => {
-              if (!disabled && onSquareDrop) {
-                event.preventDefault();
-                event.dataTransfer.dropEffect = 'move';
-              }
-            }}
-            onDrop={(event) => {
-              if (disabled || !onSquareDrop) return;
+                  event.dataTransfer.effectAllowed = 'move';
+                  event.dataTransfer.setData('text/plain', square);
+                }}
+                onDragOver={(event) => {
+                  if (!disabled && onSquareDrop) {
+                    event.preventDefault();
+                    event.dataTransfer.dropEffect = 'move';
+                  }
+                }}
+                onDrop={(event) => {
+                  if (disabled || !onSquareDrop) return;
 
-              event.preventDefault();
-              const from = event.dataTransfer.getData('text/plain') as Square;
-              if (!from || from === square) return;
+                  event.preventDefault();
+                  const from = event.dataTransfer.getData('text/plain') as Square;
+                  if (!from || from === square) return;
 
-              onSquareDrop(from, square);
-            }}
-            className={clsx(
-              'relative flex aspect-square items-center justify-center overflow-hidden text-[2rem] leading-none transition sm:text-[2.5rem] md:text-[3.5rem]',
-              isLight ? 'bg-[#eef0e6]' : 'bg-[#5f8d68]',
-              isSelected && 'z-10 ring-4 ring-[var(--color-accent)] ring-inset',
-              isLastMoveSquare && 'bg-[var(--color-accent-soft)]',
-              !disabled && 'hover:brightness-105 focus-visible:z-20',
-              disabled && 'cursor-not-allowed',
-            )}
-            aria-label={getSquareLabel(square, piece)}
-            aria-pressed={isSelected}
-          >
-            {file === firstFile && (
-              <span
+                  onSquareDrop(from, square);
+                }}
                 className={clsx(
-                  'absolute left-1.5 top-1 text-[10px] font-bold leading-none',
-                  isLight ? 'text-[#5f8d68]' : 'text-[#eef0e6]',
-                )}
-              >
-                {rank}
-              </span>
-            )}
-            {rank === lastRank && (
-              <span
-                className={clsx(
-                  'absolute bottom-1 right-1.5 text-[10px] font-bold leading-none',
-                  isLight ? 'text-[#5f8d68]' : 'text-[#eef0e6]',
-                )}
-              >
-                {file}
-              </span>
-            )}
-            {isTarget && (
-              <span
-                className={clsx(
-                  'absolute h-4 w-4 rounded-full',
-                  piece ? 'h-full w-full rounded-none ring-4 ring-black/20 ring-inset' : 'bg-black/20',
-                )}
-              />
-            )}
-            {piece && (
-              <span
-                className={clsx(
-                  'relative z-10 select-none',
+                  'relative min-h-0 min-w-0 overflow-hidden transition-[filter,box-shadow] duration-150',
+                  isLight ? 'bg-[#f0dfc1]' : 'bg-[#6f8f72]',
                   canDrag && 'cursor-grab active:cursor-grabbing',
-                  piece.color === 'w'
-                    ? 'text-[#fbfbfb] [text-shadow:0_1px_2px_rgb(0_0_0_/_0.55)]'
-                    : 'text-[#202124] [text-shadow:0_1px_1px_rgb(255_255_255_/_0.22)]',
+                  !disabled && 'hover:brightness-110 focus-visible:z-20',
+                  disabled && 'cursor-not-allowed',
                 )}
+                aria-label={getSquareLabel(square, piece)}
+                aria-pressed={isSelected}
               >
-                {PIECE_SYMBOLS[piece.color][piece.type]}
+                {isLastMoveSquare && (
+                  <span className="absolute inset-1 rounded-md bg-amber-300/35 shadow-[0_0_0_1px_rgb(255_244_184_/_0.42)_inset,0_0_18px_rgb(245_158_11_/_0.28)]" />
+                )}
+                {isSelected && (
+                  <span className="absolute inset-1 rounded-md border-2 border-sky-300 bg-sky-300/20 shadow-[0_0_18px_rgb(56_189_248_/_0.42)]" />
+                )}
+                {file === firstFile && (
+                  <span
+                    className={clsx(
+                      'absolute left-1.5 top-1 text-[10px] font-bold leading-none',
+                      isLight ? 'text-[#6f8f72]' : 'text-[#f0dfc1]',
+                    )}
+                  >
+                    {rank}
+                  </span>
+                )}
+                {rank === lastRank && (
+                  <span
+                    className={clsx(
+                      'absolute bottom-1 right-1.5 text-[10px] font-bold leading-none',
+                      isLight ? 'text-[#6f8f72]' : 'text-[#f0dfc1]',
+                    )}
+                  >
+                    {file}
+                  </span>
+                )}
+                {isTarget && (
+                  <span
+                    className={clsx(
+                      'absolute z-10 rounded-full transition',
+                      piece
+                        ? 'inset-[12%] border-[3px] border-rose-500/55 shadow-[0_0_0_1px_rgb(255_255_255_/_0.26)_inset]'
+                        : 'left-1/2 top-1/2 h-[24%] w-[24%] -translate-x-1/2 -translate-y-1/2 bg-slate-950/35 shadow-[0_1px_3px_rgb(0_0_0_/_0.24)]',
+                    )}
+                  />
+                )}
+              </button>
+            );
+          })}
+        </div>
+
+        <div className="pointer-events-none absolute inset-0">
+          {visualPieces.map((piece) => {
+            const canDrag = !disabled && (isDraggableSquare?.(piece.square) ?? true);
+            const isSelected = selectedSquare === piece.square;
+            const isLastMovePiece = lastMoveSquares?.to === piece.square;
+
+            return (
+              <span
+                key={piece.id}
+                className="absolute left-0 top-0 flex h-[12.5%] w-[12.5%] items-center justify-center transition-transform duration-[420ms] ease-[cubic-bezier(0.22,1,0.36,1)] motion-reduce:transition-none"
+                style={getSquarePosition(piece.square, orientation)}
+                aria-hidden="true"
+              >
+                <span
+                  className={clsx(
+                    'flex h-[82%] w-[82%] select-none items-center justify-center rounded-full font-serif text-[2rem] font-bold leading-none transition-[transform,filter] duration-200 sm:text-[2.45rem] md:text-[3.35rem]',
+                    canDrag && 'cursor-grab active:cursor-grabbing',
+                    isSelected && 'scale-110 -translate-y-0.5 brightness-110',
+                    isLastMovePiece && 'scale-105',
+                    piece.color === 'w'
+                      ? 'border border-[#6a4f31]/45 bg-[radial-gradient(circle_at_35%_28%,#fffdf7_0%,#f5ead7_62%,#dbc8a5_100%)] text-[#2f271f] shadow-[0_5px_10px_rgb(53_39_25_/_0.30),0_1px_0_rgb(255_255_255_/_0.75)_inset] [text-shadow:0_1px_0_rgb(255_255_255_/_0.65)]'
+                      : 'border border-black/45 bg-[radial-gradient(circle_at_35%_28%,#53565d_0%,#1f2329_64%,#090b0f_100%)] text-[#fff1d1] shadow-[0_7px_12px_rgb(0_0_0_/_0.42),0_1px_0_rgb(255_255_255_/_0.22)_inset] [text-shadow:0_1px_2px_rgb(0_0_0_/_0.8)]',
+                  )}
+                >
+                  {PIECE_SYMBOLS[piece.color][piece.type]}
+                </span>
               </span>
-            )}
-          </button>
-        );
-      })}
+            );
+          })}
+        </div>
+      </div>
     </div>
   );
 }

src/components/chess/ChessGamePlayClient.tsx

@@ -9,20 +9,23 @@ import {
   AlertCircle,
   ChevronLeft,
   Clipboard,
+  Flag,
   History,
   Home,
   Loader2,
+  PlusCircle,
   RotateCcw,
   Swords,
+  Undo2,
 } from 'lucide-react';
 import toast from 'react-hot-toast';
-import { getChessGame, postChessMove } from '@/api/chess';
-import ChessBoard, { getMoveSquares, getTurnLabel, toChessJsColor } from '@/components/chess/ChessBoard';
-import { getChessErrorMessage, isAuthError, outcomeBadgeTones, outcomeLabels } from '@/components/chess/chessUi';
+import { getChessGame, postChessMove, resignChessGame, undoChessMove } from '@/api/chess';
+import ChessBoard, { getMoveSquares, getTurnLabel, toChessJsColor, type MoveSquares } from '@/components/chess/ChessBoard';
+import { getChessErrorMessage, getChessOutcomeLabel, isAuthError, outcomeBadgeTones } from '@/components/chess/chessUi';
 import StatusBadge from '@/components/ui/StatusBadge';
 import WindowSurface from '@/components/ui/WindowSurface';
 import { useAuthStore } from '@/store/authStore';
-import { ChessGameResponse } from '@/types';
+import { ChessColor, ChessGameResponse } from '@/types';
 
 interface ChessGamePlayClientProps {
   gameId: string;
@@ -46,6 +49,14 @@ const getPreferredMove = (moves: Move[], to: Square) => {
 
 const toUciMove = (move: Move) => `${move.from}${move.to}${move.promotion ?? ''}`;
 
+const hasPlayerMoved = (moves: string[], playerColor: ChessColor) => {
+  return moves.some((_, index) => {
+    const side = index % 2 === 0 ? 'white' : 'black';
+
+    return side === playerColor;
+  });
+};
+
 function ChessPageFrame({ children }: { children: ReactNode }) {
   return (
     <main className="mx-auto flex w-full min-w-0 max-w-[1180px] flex-col gap-5 px-0 py-3 md:py-6">
@@ -109,19 +120,27 @@ function GameInfoPanel({
   game,
   isPlayerTurn,
   pending,
+  canUndo,
+  canResign,
   onCopyPgn,
+  onUndo,
+  onResign,
 }: {
   game: ChessGameResponse;
   isPlayerTurn: boolean;
   pending: boolean;
+  canUndo: boolean;
+  canResign: boolean;
   onCopyPgn: () => void;
+  onUndo: () => void;
+  onResign: () => void;
 }) {
   const gameEnded = game.status !== 'IN_PROGRESS';
 
   return (
     <WindowSurface title="Game Info" showTrafficLights={false} as="aside" bodyClassName="p-4 md:p-5">
       <div className="mb-4 flex min-w-0 flex-wrap items-center gap-2">
-        <StatusBadge tone={outcomeBadgeTones[game.outcome]}>{outcomeLabels[game.outcome]}</StatusBadge>
+        <StatusBadge tone={outcomeBadgeTones[game.outcome]}>{getChessOutcomeLabel(game.outcome, game.status)}</StatusBadge>
         {game.result && <StatusBadge tone="neutral">{game.result}</StatusBadge>}
       </div>
 
@@ -153,11 +172,43 @@ function GameInfoPanel({
         )}
       >
         {gameEnded && '종료된 대국입니다.'}
-        {!gameEnded && pending && 'Maia 응답을 기다리는 중입니다.'}
+        {!gameEnded && pending && '요청을 처리하는 중입니다.'}
         {!gameEnded && !pending && isPlayerTurn && '내 차례입니다. 말을 움직이세요.'}
         {!gameEnded && !pending && !isPlayerTurn && 'Maia 차례입니다.'}
       </div>
 
+      <div className="mt-4 grid grid-cols-1 gap-2 sm:grid-cols-3 xl:grid-cols-1">
+        {game.status === 'IN_PROGRESS' && (
+          <>
+            <button
+              type="button"
+              onClick={onUndo}
+              disabled={!canUndo}
+              className="inline-flex h-10 min-w-0 items-center justify-center gap-2 rounded-lg border border-[var(--control-border)] bg-[var(--color-control)] px-3 text-sm font-semibold text-[var(--color-text-muted)] shadow-[var(--shadow-control)] transition hover:bg-[var(--card-bg-strong)] hover:text-[var(--color-text)] disabled:cursor-not-allowed disabled:opacity-50"
+            >
+              <Undo2 size={16} />
+              무르기
+            </button>
+            <button
+              type="button"
+              onClick={onResign}
+              disabled={!canResign}
+              className="inline-flex h-10 min-w-0 items-center justify-center gap-2 rounded-lg border border-red-500/20 bg-red-500/10 px-3 text-sm font-semibold text-red-700 shadow-[var(--shadow-control)] transition hover:bg-red-500/15 disabled:cursor-not-allowed disabled:opacity-50 dark:text-red-300"
+            >
+              <Flag size={16} />
+              기권
+            </button>
+          </>
+        )}
+        <Link
+          href="/chess"
+          className="inline-flex h-10 min-w-0 items-center justify-center gap-2 rounded-lg bg-[var(--color-accent)] px-3 text-sm font-semibold text-white shadow-[var(--shadow-control)] transition hover:bg-[var(--color-accent-hover)]"
+        >
+          <PlusCircle size={16} />
+          새 게임
+        </Link>
+      </div>
+
       <div className="mt-4 rounded-lg border border-[var(--color-line)] bg-black/[0.025] px-3 py-3 dark:bg-white/[0.06]">
         <p className="text-xs font-semibold text-[var(--color-text-subtle)]">마지막 Maia 수</p>
         <p className="mt-1 break-words font-mono text-sm font-semibold text-[var(--color-text)]">
@@ -190,6 +241,7 @@ export default function ChessGamePlayClient({ gameId }: ChessGamePlayClientProps
   const { isLoggedIn, _hasHydrated } = useAuthStore();
   const [selectedSquare, setSelectedSquare] = useState<Square | null>(null);
   const [optimisticFen, setOptimisticFen] = useState<string | null>(null);
+  const [optimisticMoveSquares, setOptimisticMoveSquares] = useState<MoveSquares | null>(null);
   const gameQueryKey = useMemo(() => ['chess-game', gameId] as const, [gameId]);
 
   const gameQuery = useQuery({
@@ -199,26 +251,63 @@ export default function ChessGamePlayClient({ gameId }: ChessGamePlayClientProps
     retry: 0,
   });
 
+  const syncUpdatedGame = async (updatedGame: ChessGameResponse) => {
+    queryClient.setQueryData(gameQueryKey, updatedGame);
+    setOptimisticFen(null);
+    setOptimisticMoveSquares(null);
+    setSelectedSquare(null);
+    await Promise.all([
+      queryClient.invalidateQueries({ queryKey: ['chess-games'] }),
+      queryClient.invalidateQueries({ queryKey: ['chess-game-stats'] }),
+    ]);
+  };
+
   const moveMutation = useMutation({
     mutationFn: (move: string) => postChessMove(gameId, { move }),
     onSuccess: async (updatedGame) => {
-      queryClient.setQueryData(gameQueryKey, updatedGame);
-      setOptimisticFen(null);
-      setSelectedSquare(null);
-      await Promise.all([
-        queryClient.invalidateQueries({ queryKey: ['chess-games'] }),
-        queryClient.invalidateQueries({ queryKey: ['chess-game-stats'] }),
-      ]);
+      await syncUpdatedGame(updatedGame);
     },
     onError: (error) => {
       setOptimisticFen(null);
+      setOptimisticMoveSquares(null);
       setSelectedSquare(null);
       toast.error(getChessErrorMessage(error, '봇 응답을 가져오지 못했습니다. 잠시 후 다시 시도해주세요.'));
       void gameQuery.refetch();
     },
   });
 
+  const undoMutation = useMutation({
+    mutationFn: () => undoChessMove(gameId),
+    onSuccess: async (updatedGame) => {
+      await syncUpdatedGame(updatedGame);
+      toast.success('무르기를 적용했습니다.');
+    },
+    onError: (error) => {
+      setOptimisticFen(null);
+      setOptimisticMoveSquares(null);
+      setSelectedSquare(null);
+      toast.error(getChessErrorMessage(error, '무르기를 처리하지 못했습니다.'));
+      void gameQuery.refetch();
+    },
+  });
+
+  const resignMutation = useMutation({
+    mutationFn: () => resignChessGame(gameId),
+    onSuccess: async (updatedGame) => {
+      await syncUpdatedGame(updatedGame);
+      toast.success('기권 처리되었습니다.');
+    },
+    onError: (error) => {
+      setOptimisticFen(null);
+      setOptimisticMoveSquares(null);
+      setSelectedSquare(null);
+      toast.error(getChessErrorMessage(error, '기권을 처리하지 못했습니다.'));
+      void gameQuery.refetch();
+    },
+  });
+
   const game = gameQuery.data;
+  const isPending = moveMutation.isPending || undoMutation.isPending || resignMutation.isPending;
   const currentFen = optimisticFen ?? game?.fen ?? INITIAL_FEN;
   const localGame = useMemo(() => createGame(currentFen), [currentFen]);
   const playerColor = game ? toChessJsColor(game.playerColor) : null;
@@ -226,7 +315,7 @@ export default function ChessGamePlayClient({ gameId }: ChessGamePlayClientProps
     Boolean(game && localGame && playerColor) &&
     game?.status === 'IN_PROGRESS' &&
     game.turn === game.playerColor &&
-    !moveMutation.isPending;
+    !isPending;
 
   const legalMoves = useMemo<Move[]>(() => {
     if (!localGame || !selectedSquare || !canInteract) return [];
@@ -235,7 +324,8 @@ export default function ChessGamePlayClient({ gameId }: ChessGamePlayClientProps
   }, [canInteract, localGame, selectedSquare]);
 
   const legalTargets = useMemo(() => new Set(legalMoves.map((move) => move.to)), [legalMoves]);
-  const lastMoveSquares = useMemo(() => getMoveSquares(game?.maiaMove ?? game?.moves.at(-1)), [game?.maiaMove, game?.moves]);
+  const serverLastMoveSquares = useMemo(() => getMoveSquares(game?.maiaMove ?? game?.moves.at(-1)), [game?.maiaMove, game?.moves]);
+  const lastMoveSquares = optimisticMoveSquares ?? serverLastMoveSquares;
 
   const isOwnTurnPiece = (square: Square) => {
     if (!localGame || !playerColor || !canInteract) return false;
@@ -266,9 +356,11 @@ export default function ChessGamePlayClient({ gameId }: ChessGamePlayClientProps
       });
 
       setOptimisticFen(nextGame.fen());
+      setOptimisticMoveSquares({ from, to });
       setSelectedSquare(null);
       moveMutation.mutate(toUciMove(candidate));
     } catch {
+      setOptimisticMoveSquares(null);
       toast.error('합법적인 수가 아닙니다.');
     }
   };
@@ -313,6 +405,29 @@ export default function ChessGamePlayClient({ gameId }: ChessGamePlayClientProps
       .catch(() => toast.error('PGN 복사에 실패했습니다.'));
   };
 
+  const canResign = Boolean(game && game.status === 'IN_PROGRESS' && !isPending);
+  const canUndo = Boolean(game && game.status === 'IN_PROGRESS' && !isPending && hasPlayerMoved(game.moves, game.playerColor));
+  const pendingLabel = resignMutation.isPending
+    ? '기권 처리 중'
+    : undoMutation.isPending
+      ? '무르기 처리 중'
+      : moveMutation.isPending
+        ? 'Maia 생각 중'
+        : '';
+
+  const handleUndo = () => {
+    if (!canUndo) return;
+
+    undoMutation.mutate();
+  };
+
+  const handleResign = () => {
+    if (!canResign) return;
+    if (!window.confirm('정말 기권하시겠습니까? 이 대국은 패배로 종료됩니다.')) return;
+
+    resignMutation.mutate();
+  };
+
   if (!_hasHydrated) return <LoadingState message="로그인 상태를 확인하는 중입니다." />;
   if (!isLoggedIn) return <LoginRequired />;
   if (gameQuery.isLoading) return <LoadingState />;
@@ -377,11 +492,11 @@ export default function ChessGamePlayClient({ gameId }: ChessGamePlayClientProps
       <section className="grid min-w-0 items-start gap-5 xl:grid-cols-[minmax(0,1fr)_22rem]">
         <WindowSurface
           title="Board"
-          subtitle={moveMutation.isPending ? 'Maia thinking' : isPlayerTurn ? 'Your move' : 'Synced'}
+          subtitle={isPending ? 'Updating' : isPlayerTurn ? 'Your move' : 'Synced'}
           showTrafficLights={false}
           bodyClassName="p-3 md:p-5"
         >
-          <div className="relative mx-auto max-w-full" style={{ width: 'min(100%, clamp(18rem, calc(100svh - 15rem), 42rem))' }}>
+          <div className="relative mx-auto max-w-full" style={{ width: 'min(100%, clamp(18rem, calc(100svh - 23rem), 40rem))' }}>
             <ChessBoard
               fen={currentFen}
               orientation={game.playerColor}
@@ -393,11 +508,11 @@ export default function ChessGamePlayClient({ gameId }: ChessGamePlayClientProps
               onSquareClick={handleSquareClick}
               onSquareDrop={attemptMove}
             />
-            {moveMutation.isPending && (
-              <div className="absolute inset-0 flex items-center justify-center rounded-lg bg-black/20 backdrop-blur-[2px]">
-                <div className="flex items-center gap-2 rounded-full border border-white/20 bg-black/55 px-4 py-2 text-sm font-semibold text-white shadow-[var(--shadow-control)]">
-                  <Loader2 className="animate-spin" size={17} />
-                  Maia 응답 대기
+            {isPending && (
+              <div className="pointer-events-none absolute bottom-3 left-1/2 z-30 -translate-x-1/2">
+                <div className="flex items-center gap-2 rounded-full border border-white/25 bg-black/62 px-4 py-2 text-sm font-semibold text-white shadow-[0_12px_28px_rgb(0_0_0_/_0.28)] backdrop-blur-md">
+                  <Loader2 className="animate-spin" size={16} />
+                  {pendingLabel || '처리 중'}
                 </div>
               </div>
             )}
@@ -407,8 +522,12 @@ export default function ChessGamePlayClient({ gameId }: ChessGamePlayClientProps
         <GameInfoPanel
           game={game}
           isPlayerTurn={isPlayerTurn}
-          pending={moveMutation.isPending}
+          pending={isPending}
+          canUndo={canUndo}
+          canResign={canResign}
           onCopyPgn={copyPgn}
+          onUndo={handleUndo}
+          onResign={handleResign}
         />
       </section>
     </ChessPageFrame>

src/components/chess/ChessHistoryClient.tsx

@@ -9,9 +9,9 @@ import { getTurnLabel } from '@/components/chess/ChessBoard';
 import {
   formatChessDateTime,
   getChessErrorMessage,
+  getChessOutcomeLabel,
   isAuthError,
   outcomeBadgeTones,
-  outcomeLabels,
   type OutcomeFilter,
 } from '@/components/chess/chessUi';
 import SegmentedControl, { SegmentedControlOption } from '@/components/ui/SegmentedControl';
@@ -95,7 +95,7 @@ function HistoryRow({ game }: { game: ChessGameSummaryResponse }) {
     >
       <div className="min-w-0">
         <div className="mb-1.5 flex min-w-0 flex-wrap items-center gap-2">
-          <StatusBadge tone={outcomeBadgeTones[game.outcome]}>{outcomeLabels[game.outcome]}</StatusBadge>
+          <StatusBadge tone={outcomeBadgeTones[game.outcome]}>{getChessOutcomeLabel(game.outcome, game.status)}</StatusBadge>
           {game.result && <StatusBadge tone="neutral">{game.result}</StatusBadge>}
         </div>
         <p className="truncate text-sm font-bold text-[var(--color-text)]">

src/components/chess/ChessHomeClient.tsx

@@ -18,7 +18,7 @@ import {
 import toast from 'react-hot-toast';
 import { createChessGame, getChessGames, getChessGameStats } from '@/api/chess';
 import { getTurnLabel } from '@/components/chess/ChessBoard';
-import { formatChessDateTime, getChessErrorMessage, outcomeBadgeTones, outcomeLabels } from '@/components/chess/chessUi';
+import { formatChessDateTime, getChessErrorMessage, getChessOutcomeLabel, outcomeBadgeTones, outcomeLabels } from '@/components/chess/chessUi';
 import MetricCard from '@/components/ui/MetricCard';
 import SegmentedControl, { SegmentedControlOption } from '@/components/ui/SegmentedControl';
 import StatusBadge from '@/components/ui/StatusBadge';
@@ -112,6 +112,7 @@ function GameSummaryRow({
     playerColor: ChessColor;
     model: string;
     outcome: keyof typeof outcomeLabels;
+    status: string;
     movesCount: number;
     updatedAt: string;
   };
@@ -123,7 +124,7 @@ function GameSummaryRow({
     >
       <div className="min-w-0">
         <div className="mb-1.5 flex min-w-0 flex-wrap items-center gap-2">
-          <StatusBadge tone={outcomeBadgeTones[game.outcome]}>{outcomeLabels[game.outcome]}</StatusBadge>
+          <StatusBadge tone={outcomeBadgeTones[game.outcome]}>{getChessOutcomeLabel(game.outcome, game.status)}</StatusBadge>
           <span className="text-xs font-semibold text-[var(--color-text-subtle)]">
             Maia {game.model} · {game.rating}
           </span>

src/components/chess/ChessPuzzleClient.tsx

@@ -3,7 +3,7 @@
 import type { CSSProperties, ReactNode } from 'react';
 import { useMemo, useState } from 'react';
 import { useQuery } from '@tanstack/react-query';
-import { Chess as ChessGame, type Color, type Move, type PieceSymbol, type Square } from 'chess.js';
+import { Chess as ChessGame, type Color, type Move, type Square } from 'chess.js';
 import { clsx } from 'clsx';
 import {
   AlertCircle,
@@ -15,45 +15,15 @@ import {
   Target,
 } from 'lucide-react';
 import { getTodayChessPuzzle } from '@/api/chess';
+import ChessBoard, { BOARD_SQUARES, type MoveSquares } from '@/components/chess/ChessBoard';
 import WindowSurface from '@/components/ui/WindowSurface';
 import { type ChessPuzzle } from '@/types';
 
 type FeedbackTone = 'neutral' | 'success' | 'error';
 
 const TIMEZONE = 'Asia/Seoul';
-const FILES = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] as const;
-const RANKS = [8, 7, 6, 5, 4, 3, 2, 1] as const;
-const BOARD_SQUARES = RANKS.flatMap((rank) => FILES.map((file) => `${file}${rank}` as Square));
 const BOARD_SIZE_STYLE: CSSProperties = {
-  width: 'min(100%, clamp(18rem, calc(100svh - 15rem), 42rem))',
-};
-
-const PIECE_SYMBOLS: Record<Color, Record<PieceSymbol, string>> = {
-  w: {
-    k: '♔',
-    q: '♕',
-    r: '♖',
-    b: '♗',
-    n: '♘',
-    p: '♙',
-  },
-  b: {
-    k: '♚',
-    q: '♛',
-    r: '♜',
-    b: '♝',
-    n: '♞',
-    p: '♟',
-  },
-};
-
-const PIECE_NAMES: Record<PieceSymbol, string> = {
-  k: '킹',
-  q: '퀸',
-  r: '룩',
-  b: '비숍',
-  n: '나이트',
-  p: '폰',
+  width: 'min(100%, clamp(18rem, calc(100svh - 23rem), 40rem))',
 };
 
 const turnLabel = (color: Color) => (color === 'w' ? '백' : '흑');
@@ -67,10 +37,10 @@ const getReadyFeedback = (puzzle: ChessPuzzle): { tone: FeedbackTone; message: s
   };
 };
 
-const getSquareLabel = (square: Square, piece?: { color: Color; type: PieceSymbol }) => {
-  if (!piece) return `${square} 빈 칸`;
+const getPreferredMove = (moves: Move[], to: Square) => {
+  const candidates = moves.filter((move) => move.to === to);
 
-  return `${square} ${turnLabel(piece.color)} ${PIECE_NAMES[piece.type]}`;
+  return candidates.find((move) => move.promotion === 'q') ?? candidates[0] ?? null;
 };
 
 const formatDate = (value: string) => {
@@ -176,7 +146,7 @@ function ChessPuzzleBoard({ puzzle }: { puzzle: ChessPuzzle }) {
   const [currentFen, setCurrentFen] = useState(puzzle.fen);
   const [selectedSquare, setSelectedSquare] = useState<Square | null>(null);
   const [solved, setSolved] = useState(false);
-  const [lastMoveSquares, setLastMoveSquares] = useState<{ from: Square; to: Square } | null>(null);
+  const [lastMoveSquares, setLastMoveSquares] = useState<MoveSquares | null>(null);
   const [feedback, setFeedback] = useState(getReadyFeedback(puzzle));
 
   const game = useMemo(() => new ChessGame(currentFen), [currentFen]);
@@ -206,8 +176,19 @@ function ChessPuzzleBoard({ puzzle }: { puzzle: ChessPuzzle }) {
     });
   };
 
+  const isDraggablePuzzleSquare = (square: Square) => {
+    if (solved) return false;
+
+    const piece = game.get(square);
+
+    return piece?.color === game.turn();
+  };
+
   const tryMove = (from: Square, to: Square) => {
-    const candidate = legalMoves.find((move) => move.to === to);
+    if (solved || !isDraggablePuzzleSquare(from)) return;
+
+    const movesFromSquare = game.moves({ square: from, verbose: true });
+    const candidate = getPreferredMove(movesFromSquare, to);
 
     if (!candidate) {
       setFeedback({
@@ -290,77 +271,16 @@ function ChessPuzzleBoard({ puzzle }: { puzzle: ChessPuzzle }) {
 
       <section className="grid min-w-0 items-start gap-5 lg:grid-cols-[minmax(0,1fr)_20rem]">
         <BoardWindow>
-          <div className="grid aspect-square w-full grid-cols-8 overflow-hidden rounded-lg border border-[var(--color-line)] shadow-[var(--shadow-control)]">
-            {BOARD_SQUARES.map((square, index) => {
-              const piece = game.get(square);
-              const file = square[0];
-              const rank = square[1];
-              const fileIndex = index % 8;
-              const rankIndex = Math.floor(index / 8);
-              const isLight = (fileIndex + rankIndex) % 2 === 0;
-              const isSelected = selectedSquare === square;
-              const isTarget = legalTargets.has(square);
-              const isLastMoveSquare = lastMoveSquares?.from === square || lastMoveSquares?.to === square;
-
-              return (
-                <button
-                  key={square}
-                  type="button"
-                  onClick={() => handleSquareClick(square)}
-                  className={clsx(
-                    'relative flex aspect-square items-center justify-center overflow-hidden text-[2rem] leading-none transition sm:text-[2.5rem] md:text-[3.75rem]',
-                    isLight ? 'bg-[#eef0e6]' : 'bg-[#5f8d68]',
-                    isSelected && 'z-10 ring-4 ring-[var(--color-accent)] ring-inset',
-                    isLastMoveSquare && 'bg-[var(--color-accent-soft)]',
-                    !solved && 'hover:brightness-105 focus-visible:z-20',
-                  )}
-                  aria-label={getSquareLabel(square, piece)}
-                  aria-pressed={isSelected}
-                >
-                  {file === 'a' && (
-                    <span
-                      className={clsx(
-                        'absolute left-1.5 top-1 text-[10px] font-bold leading-none',
-                        isLight ? 'text-[#5f8d68]' : 'text-[#eef0e6]',
-                      )}
-                    >
-                      {rank}
-                    </span>
-                  )}
-                  {rank === '1' && (
-                    <span
-                      className={clsx(
-                        'absolute bottom-1 right-1.5 text-[10px] font-bold leading-none',
-                        isLight ? 'text-[#5f8d68]' : 'text-[#eef0e6]',
-                      )}
-                    >
-                      {file}
-                    </span>
-                  )}
-                  {isTarget && (
-                    <span
-                      className={clsx(
-                        'absolute h-4 w-4 rounded-full',
-                        piece ? 'h-full w-full rounded-none ring-4 ring-black/20 ring-inset' : 'bg-black/20',
-                      )}
-                    />
-                  )}
-                  {piece && (
-                    <span
-                      className={clsx(
-                        'relative z-10 select-none',
-                        piece.color === 'w'
-                          ? 'text-[#fbfbfb] [text-shadow:0_1px_2px_rgb(0_0_0_/_0.55)]'
-                          : 'text-[#202124] [text-shadow:0_1px_1px_rgb(255_255_255_/_0.22)]',
-                      )}
-                    >
-                      {PIECE_SYMBOLS[piece.color][piece.type]}
-                    </span>
-                  )}
-                </button>
-              );
-            })}
-          </div>
+          <ChessBoard
+            fen={currentFen}
+            selectedSquare={selectedSquare}
+            legalTargets={legalTargets}
+            lastMoveSquares={lastMoveSquares}
+            disabled={solved}
+            isDraggableSquare={isDraggablePuzzleSquare}
+            onSquareClick={handleSquareClick}
+            onSquareDrop={tryMove}
+          />
         </BoardWindow>
 
         <WindowSurface title="Puzzle" showTrafficLights={false} as="aside" bodyClassName="p-4 md:p-5">

src/components/chess/chessUi.ts

@@ -19,6 +19,12 @@ export const outcomeBadgeTones: Record<ChessOutcome, 'neutral' | 'info' | 'succe
   UNKNOWN: 'neutral',
 };
 
+export const getChessOutcomeLabel = (outcome: ChessOutcome, status?: string) => {
+  if (status === 'RESIGNED' && outcome === 'LOSS') return '기권패';
+
+  return outcomeLabels[outcome];
+};
+
 export const formatChessDateTime = (value?: string) => {
   if (!value) return '';