feat(结算): 实现血战麻将查叫与退税功能

新增局终处理逻辑，当牌墙耗尽且有多家未胡时：
1. 退税：未听牌玩家需退还此前杠分收入
2. 查叫：未听牌玩家向听牌玩家赔付最大理论点炮值
新增 SettlementType.TUI_SHUI 和 SettlementType.CHA_JIAO 结算类型
新增 ReadyHandOption 记录最优听牌选项

支持一炮多响裁决，新增 ResponseActionResolutionBatch 承载多赢家结果
在 GameSession 中新增 settlementHistory 保留结算记录供复用
更新开发文档要求加强关键区域的中文注释

.serena/memories/blood_battle_scoring_v1.md

@@ -29,12 +29,30 @@
   - `明杠/点杠`：放杠者单独支付 2 分
   - `补杠`：所有未胡玩家各支付 1 分
   - `暗杠`：所有未胡玩家各支付 2 分
-- `GameSession` 已新增 `PostGangContext`，只记录“杠后补摸到下一次自摸/弃牌裁决”这段窗口，用于判断 `杠上花/杠上炮`。
+- `GameSession` 已新增：
+  - `PostGangContext`：只记录“杠后补摸到下一次自摸/弃牌裁决”这段窗口，用于判断 `杠上花/杠上炮`
+  - `settlementHistory`：记录已应用结算结果，供局终 `退税/查叫` 直接复用
 - 海底相关不新增额外状态对象，直接复用“胡牌时牌墙已空”这一现有事实，保持 `KISS`。
+- 查叫/退税已接入局终处理：
+  - 触发时机：牌墙耗尽且仍有多家未胡时
+  - 处理顺序：先 `退税`，再 `查叫`
+  - `退税`：未听牌玩家若此前有杠分收入，需要按原支付关系逐笔退还
+  - `查叫`：未听牌玩家向仍在场且已听牌玩家，按对方理论最大可胡牌型的点炮赔分支付
+  - 已新增 `SettlementType.TUI_SHUI` 与 `SettlementType.CHA_JIAO`
+  - 已新增 `ReadyHandOption`，用于查叫时记录最优听牌目标牌与对应结算明细
+- 一炮多响已接入响应裁决：
+  - `HU` 现在支持多赢家同窗裁决，只要响应窗口内有多个 `HU` 声明，就会一起结算
+  - `PENG/GANG` 仍保持单赢家，顺位规则不变
+  - 抢杠胡窗口也会复用这套多赢家 `HU` 裁决路径
+  - 已新增 `ResponseActionResolutionBatch` 承载多赢家响应结果
 - `HuEvaluator` 已补 `七对` 胡牌判定，并暴露 `isSevenPairs` / `isPengPengHu` 给计分层复用。
 - 当前仍未实现：
   - 自摸加番/加底地方变体
   - 天胡、地胡
-  - 查叫、退税、过水不胡、一炮多响
-- 文档约定已补到 `docs/DEVELOPMENT_PLAN.md`：后续前端、后端、数据库表结构与 SQL 脚本都需要补充必要中文注释，重点说明复杂规则、关键字段、状态切换、约束原因和索引用途。
-- 最小验证：`cd backend && mvn clean test`，当前 48 个测试通过。
+  - 过水不胡
+- 文档约定已加强到 `docs/DEVELOPMENT_PLAN.md`：
+  - 后端复杂规则、状态切换、结算口径和跨阶段流程，必须补适量中文注释
+  - 前端复杂交互、实时消息消费、动作面板联动和视图状态切换，必须补适量中文注释
+  - 数据库表结构、迁移脚本、初始化 SQL、索引和存储过程，必须补中文注释说明业务含义、约束原因、字段口径和回滚要点
+  - 麻将规则判断、结算分摊、响应裁决、实时消息边界、局终处理、数据迁移与回滚脚本，默认视为中文注释必需区域
+- 最小验证：`cd backend && mvn clean test`，当前 51 个测试通过。

backend/src/main/java/com/xuezhanmaster/game/domain/GameSession.java

@@ -16,6 +16,8 @@ public class GameSession {
     private final Instant createdAt;
     private final GameTable table;
     private final List<GameEvent> events;
+    // 保留已应用结算结果，供局终退税与查叫直接复用，避免从事件载荷反推。
+    private final List<SettlementResult> settlementHistory;
     private ResponseActionWindow pendingResponseActionWindow;
     // 记录最近一次杠后补摸窗口，用于判断杠上花与杠上炮。
     private PostGangContext postGangContext;
@@ -27,6 +29,7 @@ public class GameSession {
         this.createdAt = Instant.now();
         this.table = table;
         this.events = new ArrayList<>();
+        this.settlementHistory = new ArrayList<>();
         this.responseActionSelections = new LinkedHashMap<>();
     }
 
@@ -50,6 +53,10 @@ public class GameSession {
         return events;
     }
 
+    public List<SettlementResult> getSettlementHistory() {
+        return settlementHistory;
+    }
+
     public ResponseActionWindow getPendingResponseActionWindow() {
         return pendingResponseActionWindow;
     }

backend/src/main/java/com/xuezhanmaster/game/domain/ReadyHandOption.java

@@ -0,0 +1,7 @@
+package com.xuezhanmaster.game.domain;
+
+public record ReadyHandOption(
+        String triggerTile,
+        SettlementDetail settlementDetail
+) {
+}

backend/src/main/java/com/xuezhanmaster/game/domain/ResponseActionResolutionBatch.java

@@ -0,0 +1,9 @@
+package com.xuezhanmaster.game.domain;
+
+import java.util.List;
+
+public record ResponseActionResolutionBatch(
+        ActionType actionType,
+        List<ResponseActionResolution> resolutions
+) {
+}

backend/src/main/java/com/xuezhanmaster/game/domain/SettlementType.java

@@ -6,5 +6,7 @@ public enum SettlementType {
     ZI_MO_HU,
     BU_GANG,
     MING_GANG,
-    AN_GANG
+    AN_GANG,
+    TUI_SHUI,
+    CHA_JIAO
 }

backend/src/main/java/com/xuezhanmaster/game/service/BloodBattleScoringService.java

@@ -3,6 +3,7 @@ package com.xuezhanmaster.game.service;
 import com.xuezhanmaster.game.domain.GameSeat;
 import com.xuezhanmaster.game.domain.MeldGroup;
 import com.xuezhanmaster.game.domain.MeldType;
+import com.xuezhanmaster.game.domain.ReadyHandOption;
 import com.xuezhanmaster.game.domain.SettlementDetail;
 import com.xuezhanmaster.game.domain.SettlementFan;
 import com.xuezhanmaster.game.domain.Tile;
@@ -13,6 +14,7 @@ import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
 @Component
 public class BloodBattleScoringService {
@@ -61,6 +63,22 @@ public class BloodBattleScoringService {
         return new SettlementDetail(BASE_SCORE, 0, CONCEALED_GANG_SCORE, List.of());
     }
 
+    public Optional<ReadyHandOption> findBestReadyHandOption(GameSeat seat) {
+        ReadyHandOption bestOption = null;
+        for (Tile candidateTile : buildAllTileCandidates()) {
+            if (!huEvaluator.canHuWithClaimedTile(seat.getHandTiles(), candidateTile)) {
+                continue;
+            }
+            GameSeat virtualSeat = copySeatWithClaimedTile(seat, candidateTile);
+            SettlementDetail settlementDetail = buildDiscardHuDetail(virtualSeat, false, false);
+            ReadyHandOption candidateOption = new ReadyHandOption(candidateTile.getDisplayName(), settlementDetail);
+            if (bestOption == null || isBetterReadyHandOption(candidateOption, bestOption)) {
+                bestOption = candidateOption;
+            }
+        }
+        return Optional.ofNullable(bestOption);
+    }
+
     private SettlementDetail buildHuDetail(
             GameSeat winnerSeat,
             boolean robbingGang,
@@ -164,4 +182,35 @@ public class BloodBattleScoringService {
             case MING_GANG, BU_GANG, AN_GANG -> 4;
         };
     }
+
+    private List<Tile> buildAllTileCandidates() {
+        List<Tile> candidates = new ArrayList<>();
+        for (TileSuit tileSuit : TileSuit.values()) {
+            for (int rank = 1; rank <= 9; rank++) {
+                candidates.add(new Tile(tileSuit, rank));
+            }
+        }
+        return candidates;
+    }
+
+    private GameSeat copySeatWithClaimedTile(GameSeat seat, Tile claimedTile) {
+        GameSeat virtualSeat = new GameSeat(seat.getSeatNo(), seat.isAi(), seat.getPlayerId(), seat.getNickname());
+        virtualSeat.setLackSuit(seat.getLackSuit());
+        virtualSeat.setWon(seat.isWon());
+        virtualSeat.addScore(seat.getScore());
+        virtualSeat.getHandTiles().addAll(seat.getHandTiles());
+        virtualSeat.getMeldGroups().addAll(seat.getMeldGroups());
+        virtualSeat.receiveTile(claimedTile);
+        return virtualSeat;
+    }
+
+    private boolean isBetterReadyHandOption(ReadyHandOption candidate, ReadyHandOption currentBest) {
+        if (candidate.settlementDetail().paymentScore() != currentBest.settlementDetail().paymentScore()) {
+            return candidate.settlementDetail().paymentScore() > currentBest.settlementDetail().paymentScore();
+        }
+        if (candidate.settlementDetail().totalFan() != currentBest.settlementDetail().totalFan()) {
+            return candidate.settlementDetail().totalFan() > currentBest.settlementDetail().totalFan();
+        }
+        return candidate.triggerTile().compareTo(currentBest.triggerTile()) < 0;
+    }
 }

backend/src/main/java/com/xuezhanmaster/game/service/GameSessionService.java

@@ -7,11 +7,15 @@ import com.xuezhanmaster.game.domain.GameSeat;
 import com.xuezhanmaster.game.domain.GameSession;
 import com.xuezhanmaster.game.domain.GameTable;
 import com.xuezhanmaster.game.domain.PostGangContext;
+import com.xuezhanmaster.game.domain.ReadyHandOption;
 import com.xuezhanmaster.game.domain.ResponseActionResolution;
+import com.xuezhanmaster.game.domain.ResponseActionResolutionBatch;
 import com.xuezhanmaster.game.domain.ResponseActionSeatCandidate;
 import com.xuezhanmaster.game.domain.ResponseActionWindow;
 import com.xuezhanmaster.game.domain.ScoreChange;
+import com.xuezhanmaster.game.domain.SettlementDetail;
 import com.xuezhanmaster.game.domain.SettlementResult;
+import com.xuezhanmaster.game.domain.SettlementType;
 import com.xuezhanmaster.game.domain.Tile;
 import com.xuezhanmaster.game.domain.TileSuit;
 import com.xuezhanmaster.game.dto.GameActionRequest;
@@ -35,9 +39,11 @@ import com.xuezhanmaster.ws.dto.PrivateActionCandidate;
 import org.springframework.stereotype.Service;
 
 import java.util.List;
+import java.util.LinkedHashMap;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
 @Service
@@ -49,6 +55,7 @@ public class GameSessionService {
     private final ResponseActionWindowBuilder responseActionWindowBuilder;
     private final ResponseActionResolver responseActionResolver;
     private final SettlementService settlementService;
+    private final BloodBattleScoringService scoringService;
     private final HuEvaluator huEvaluator;
     private final StrategyService strategyService;
     private final PlayerVisibilityService playerVisibilityService;
@@ -63,6 +70,7 @@ public class GameSessionService {
             ResponseActionWindowBuilder responseActionWindowBuilder,
             ResponseActionResolver responseActionResolver,
             SettlementService settlementService,
+            BloodBattleScoringService scoringService,
             HuEvaluator huEvaluator,
             StrategyService strategyService,
             PlayerVisibilityService playerVisibilityService,
@@ -75,6 +83,7 @@ public class GameSessionService {
         this.responseActionWindowBuilder = responseActionWindowBuilder;
         this.responseActionResolver = responseActionResolver;
         this.settlementService = settlementService;
+        this.scoringService = scoringService;
         this.huEvaluator = huEvaluator;
         this.strategyService = strategyService;
         this.playerVisibilityService = playerVisibilityService;
@@ -155,17 +164,16 @@ public class GameSessionService {
         );
     }
 
-    private void moveToNextSeat(GameTable table, String gameId) {
-        if (shouldFinishTable(table)) {
-            table.setPhase(GamePhase.FINISHED);
-            gameMessagePublisher.publishPublicEvent(GameEvent.phaseChanged(gameId, table.getPhase().name()));
+    private void moveToNextSeat(GameSession session) {
+        GameTable table = session.getTable();
+        if (finishTableIfNeeded(session)) {
             return;
         }
 
         Optional<GameSeat> nextSeatOptional = findNextActiveSeat(table, table.getCurrentSeatNo());
         if (nextSeatOptional.isEmpty()) {
             table.setPhase(GamePhase.FINISHED);
-            gameMessagePublisher.publishPublicEvent(GameEvent.phaseChanged(gameId, table.getPhase().name()));
+            appendAndPublish(session, GameEvent.phaseChanged(session.getGameId(), table.getPhase().name()));
             return;
         }
 
@@ -173,8 +181,8 @@ public class GameSessionService {
         Tile drawnTile = table.getWallTiles().remove(0);
         nextSeat.receiveTile(drawnTile);
         table.setCurrentSeatNo(nextSeat.getSeatNo());
-        gameMessagePublisher.publishPublicEvent(GameEvent.tileDrawn(gameId, nextSeat.getSeatNo(), table.getWallTiles().size()));
-        gameMessagePublisher.publishPublicEvent(GameEvent.turnSwitched(gameId, nextSeat.getSeatNo()));
+        gameMessagePublisher.publishPublicEvent(GameEvent.tileDrawn(session.getGameId(), nextSeat.getSeatNo(), table.getWallTiles().size()));
+        gameMessagePublisher.publishPublicEvent(GameEvent.turnSwitched(session.getGameId(), nextSeat.getSeatNo()));
     }
 
     private void autoPlayBots(GameSession session) {
@@ -182,7 +190,7 @@ public class GameSessionService {
         while (table.getPhase() == GamePhase.PLAYING) {
             GameSeat currentSeat = table.getSeats().get(table.getCurrentSeatNo());
             if (currentSeat.isWon()) {
-                moveToNextSeat(table, session.getGameId());
+                moveToNextSeat(session);
                 continue;
             }
             if (!currentSeat.isAi()) {
@@ -248,7 +256,7 @@ public class GameSessionService {
                     )
             );
             appendAndPublish(session, events);
-            moveToNextSeat(table, session.getGameId());
+            moveToNextSeat(session);
             if (table.getPhase() == GamePhase.FINISHED) {
                 return;
             }
@@ -434,14 +442,14 @@ public class GameSessionService {
             return;
         }
 
-        Optional<ResponseActionResolution> resolution = responseActionResolver.resolve(
+        Optional<ResponseActionResolutionBatch> resolutionBatch = responseActionResolver.resolve(
                 responseActionWindow,
                 session.getResponseActionSelections(),
                 session.getTable().getSeats().size()
         );
 
-        if (resolution.isPresent()) {
-            executeResolvedResponseAction(session, responseActionWindow, resolution.get());
+        if (resolutionBatch.isPresent()) {
+            executeResolvedResponseAction(session, responseActionWindow, resolutionBatch.get());
             return;
         }
 
@@ -497,7 +505,7 @@ public class GameSessionService {
 
     private void continueAfterDiscardWithoutResponse(GameSession session) {
         session.clearPostGangContext();
-        moveToNextSeat(session.getTable(), session.getGameId());
+        moveToNextSeat(session);
         autoPlayBots(session);
         notifyActionIfHumanTurn(session);
     }
@@ -505,13 +513,13 @@ public class GameSessionService {
     private void executeResolvedResponseAction(
             GameSession session,
             ResponseActionWindow responseActionWindow,
-            ResponseActionResolution resolution
+            ResponseActionResolutionBatch resolutionBatch
     ) {
-        closeResponseWindowWithResolution(session, responseActionWindow, resolution.actionType());
-        switch (resolution.actionType()) {
-            case PENG -> executePeng(session, resolution);
-            case GANG -> executeGang(session, resolution);
-            case HU -> executeHu(session, responseActionWindow, resolution);
+        closeResponseWindowWithResolution(session, responseActionWindow, resolutionBatch.actionType());
+        switch (resolutionBatch.actionType()) {
+            case PENG -> executePeng(session, resolutionBatch.resolutions().get(0));
+            case GANG -> executeGang(session, resolutionBatch.resolutions().get(0));
+            case HU -> executeHu(session, responseActionWindow, resolutionBatch.resolutions());
             default -> throw new BusinessException("GAME_ACTION_INVALID", "未知的响应裁决结果");
         }
     }
@@ -576,9 +584,7 @@ public class GameSessionService {
                 claimedTile.getDisplayName()
         ));
 
-        if (table.getWallTiles().isEmpty()) {
-            table.setPhase(GamePhase.FINISHED);
-            appendAndPublish(session, GameEvent.phaseChanged(session.getGameId(), table.getPhase().name()));
+        if (finishTableIfNeeded(session)) {
             return;
         }
 
@@ -602,19 +608,22 @@ public class GameSessionService {
     private void executeHu(
             GameSession session,
             ResponseActionWindow responseActionWindow,
-            ResponseActionResolution resolution
+            List<ResponseActionResolution> resolutions
     ) {
-        Tile claimedTile = parseTile(resolution.triggerTile());
+        ResponseActionResolution primaryResolution = resolutions.get(0);
+        Tile claimedTile = parseTile(primaryResolution.triggerTile());
         GameTable table = session.getTable();
-        GameSeat winnerSeat = table.getSeats().get(resolution.winnerSeatNo());
-        GameSeat sourceSeat = table.getSeats().get(resolution.sourceSeatNo());
+        GameSeat sourceSeat = table.getSeats().get(primaryResolution.sourceSeatNo());
 
-        winnerSeat.receiveTile(claimedTile);
         if (isSupplementalGangWindow(responseActionWindow)) {
             sourceSeat.removeMatchingHandTiles(claimedTile, 1);
         } else {
             sourceSeat.removeMatchingDiscardTile(claimedTile);
         }
+        // 一炮多响时多个赢家共用同一张弃牌或补杠牌，牌源只移除一次，赢家逐个补牌并独立结算。
+        for (ResponseActionResolution resolution : resolutions) {
+            GameSeat winnerSeat = table.getSeats().get(resolution.winnerSeatNo());
+            winnerSeat.receiveTile(claimedTile);
             winnerSeat.declareHu();
 
             appendAndPublish(session, GameEvent.responseActionDeclared(
@@ -636,7 +645,8 @@ public class GameSessionService {
                         sourceSeat.getSeatNo(),
                         claimedTile.getDisplayName()
                 ));
-        } else {
+                continue;
+            }
             appendSettlementEvents(session, settlementService.settleDiscardHu(
                     table,
                     winnerSeat.getSeatNo(),
@@ -648,9 +658,7 @@ public class GameSessionService {
         }
         session.clearPostGangContext();
 
-        if (shouldFinishTable(table)) {
-            table.setPhase(GamePhase.FINISHED);
-            appendAndPublish(session, GameEvent.phaseChanged(session.getGameId(), table.getPhase().name()));
+        if (finishTableIfNeeded(session)) {
             return;
         }
 
@@ -681,13 +689,11 @@ public class GameSessionService {
         ));
         session.clearPostGangContext();
 
-        if (shouldFinishTable(table)) {
-            table.setPhase(GamePhase.FINISHED);
-            appendAndPublish(session, GameEvent.phaseChanged(session.getGameId(), table.getPhase().name()));
+        if (finishTableIfNeeded(session)) {
             return;
         }
 
-        moveToNextSeat(table, session.getGameId());
+        moveToNextSeat(session);
         autoPlayBots(session);
         notifyActionIfHumanTurn(session);
     }
@@ -714,9 +720,7 @@ public class GameSessionService {
                 gangTile.getDisplayName()
         ));
 
-        if (table.getWallTiles().isEmpty()) {
-            table.setPhase(GamePhase.FINISHED);
-            appendAndPublish(session, GameEvent.phaseChanged(session.getGameId(), table.getPhase().name()));
+        if (finishTableIfNeeded(session)) {
             return;
         }
 
@@ -776,9 +780,7 @@ public class GameSessionService {
                 gangTile.getDisplayName()
         ));
 
-        if (table.getWallTiles().isEmpty()) {
-            table.setPhase(GamePhase.FINISHED);
-            appendAndPublish(session, GameEvent.phaseChanged(session.getGameId(), table.getPhase().name()));
+        if (finishTableIfNeeded(session)) {
             return;
         }
 
@@ -816,6 +818,7 @@ public class GameSessionService {
     }
 
     private void appendSettlementEvents(GameSession session, SettlementResult settlementResult) {
+        session.getSettlementHistory().add(settlementResult);
         appendAndPublish(session, GameEvent.settlementApplied(session.getGameId(), settlementResult));
         for (ScoreChange scoreChange : settlementResult.scoreChanges()) {
             appendAndPublish(session, GameEvent.scoreChanged(
@@ -828,6 +831,99 @@ public class GameSessionService {
         }
     }
 
+    private boolean finishTableIfNeeded(GameSession session) {
+        GameTable table = session.getTable();
+        if (!shouldFinishTable(table)) {
+            return false;
+        }
+        // 血战流局场景下，牌墙耗尽但仍有多人未胡，需要先做退税和查叫，再真正结束牌局。
+        if (table.getWallTiles().isEmpty() && countActiveSeats(table) > 1) {
+            applyDrawEndSettlements(session);
+        }
+        session.clearPostGangContext();
+        table.setPhase(GamePhase.FINISHED);
+        appendAndPublish(session, GameEvent.phaseChanged(session.getGameId(), table.getPhase().name()));
+        return true;
+    }
+
+    private void applyDrawEndSettlements(GameSession session) {
+        Map<Integer, ReadyHandOption> readyHandOptions = buildReadyHandOptions(session.getTable());
+        Set<Integer> notReadySeatNos = session.getTable().getSeats().stream()
+                .filter(seat -> !seat.isWon())
+                .map(GameSeat::getSeatNo)
+                .filter(seatNo -> !readyHandOptions.containsKey(seatNo))
+                .collect(java.util.stream.Collectors.toSet());
+
+        applyTaxRefunds(session, notReadySeatNos);
+        applyChaJiao(session, readyHandOptions, notReadySeatNos);
+    }
+
+    private Map<Integer, ReadyHandOption> buildReadyHandOptions(GameTable table) {
+        Map<Integer, ReadyHandOption> readyHandOptions = new LinkedHashMap<>();
+        for (GameSeat seat : table.getSeats()) {
+            if (seat.isWon()) {
+                continue;
+            }
+            scoringService.findBestReadyHandOption(seat)
+                    .ifPresent(option -> readyHandOptions.put(seat.getSeatNo(), option));
+        }
+        return readyHandOptions;
+    }
+
+    private void applyTaxRefunds(GameSession session, Set<Integer> notReadySeatNos) {
+        if (notReadySeatNos.isEmpty()) {
+            return;
+        }
+        // 退税只针对未听牌玩家此前“已经拿到手”的杠分收入，按原支付关系逐笔退回。
+        for (SettlementResult settlementResult : List.copyOf(session.getSettlementHistory())) {
+            if (!isGangSettlement(settlementResult) || !notReadySeatNos.contains(settlementResult.actorSeatNo())) {
+                continue;
+            }
+            for (ScoreChange scoreChange : settlementResult.scoreChanges()) {
+                if (scoreChange.delta() >= 0) {
+                    continue;
+                }
+                appendSettlementEvents(session, settlementService.settleTaxRefund(
+                        session.getTable(),
+                        scoreChange.seatNo(),
+                        settlementResult.actorSeatNo(),
+                        -scoreChange.delta(),
+                        settlementResult.triggerTile()
+                ));
+            }
+        }
+    }
+
+    private void applyChaJiao(
+            GameSession session,
+            Map<Integer, ReadyHandOption> readyHandOptions,
+            Set<Integer> notReadySeatNos
+    ) {
+        if (notReadySeatNos.isEmpty()) {
+            return;
+        }
+        // 查叫按“未听牌向所有听牌玩家分别赔付其最大理论点炮值”处理，先不做花猪等额外分支。
+        for (Integer notReadySeatNo : notReadySeatNos) {
+            for (Map.Entry<Integer, ReadyHandOption> entry : readyHandOptions.entrySet()) {
+                ReadyHandOption readyHandOption = entry.getValue();
+                SettlementDetail settlementDetail = readyHandOption.settlementDetail();
+                appendSettlementEvents(session, settlementService.settleChaJiao(
+                        session.getTable(),
+                        entry.getKey(),
+                        notReadySeatNo,
+                        readyHandOption.triggerTile(),
+                        settlementDetail
+                ));
+            }
+        }
+    }
+
+    private boolean isGangSettlement(SettlementResult settlementResult) {
+        return settlementResult.settlementType() == SettlementType.MING_GANG
+                || settlementResult.settlementType() == SettlementType.BU_GANG
+                || settlementResult.settlementType() == SettlementType.AN_GANG;
+    }
+
     private boolean shouldFinishTable(GameTable table) {
         return table.getWallTiles().isEmpty() || countActiveSeats(table) <= 1;
     }

backend/src/main/java/com/xuezhanmaster/game/service/ResponseActionResolver.java

@@ -2,27 +2,52 @@ package com.xuezhanmaster.game.service;
 
 import com.xuezhanmaster.game.domain.ActionType;
 import com.xuezhanmaster.game.domain.ResponseActionResolution;
+import com.xuezhanmaster.game.domain.ResponseActionResolutionBatch;
 import com.xuezhanmaster.game.domain.ResponseActionWindow;
 import org.springframework.stereotype.Component;
 
 import java.util.Comparator;
+import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 
 @Component
 public class ResponseActionResolver {
 
-    public Optional<ResponseActionResolution> resolve(ResponseActionWindow window, Map<Integer, ActionType> selections, int seatCount) {
-        return selections.entrySet().stream()
-                .filter(entry -> entry.getValue() != ActionType.PASS)
-                .min(Comparator
-                        .comparingInt((Map.Entry<Integer, ActionType> entry) -> priority(entry.getValue()))
-                        .thenComparingInt(entry -> seatDistance(window.sourceSeatNo(), entry.getKey(), seatCount)))
+    public Optional<ResponseActionResolutionBatch> resolve(
+            ResponseActionWindow window,
+            Map<Integer, ActionType> selections,
+            int seatCount
+    ) {
+        // 只要有胡牌声明，就按一炮多响返回全部胡牌赢家，其它动作全部失效。
+        List<ResponseActionResolution> huResolutions = selections.entrySet().stream()
+                .filter(entry -> entry.getValue() == ActionType.HU)
+                .sorted(Comparator.comparingInt(entry -> seatDistance(window.sourceSeatNo(), entry.getKey(), seatCount)))
                 .map(entry -> new ResponseActionResolution(
                         entry.getValue(),
                         entry.getKey(),
                         window.sourceSeatNo(),
                         window.triggerTile()
+                ))
+                .toList();
+        if (!huResolutions.isEmpty()) {
+            // 一炮多响时保留所有胡牌赢家，后续由执行层逐个结算。
+            return Optional.of(new ResponseActionResolutionBatch(ActionType.HU, huResolutions));
+        }
+
+        return selections.entrySet().stream()
+                .filter(entry -> entry.getValue() != ActionType.PASS)
+                .min(Comparator
+                        .comparingInt((Map.Entry<Integer, ActionType> entry) -> priority(entry.getValue()))
+                        .thenComparingInt(entry -> seatDistance(window.sourceSeatNo(), entry.getKey(), seatCount)))
+                .map(entry -> new ResponseActionResolutionBatch(
+                        entry.getValue(),
+                        List.of(new ResponseActionResolution(
+                                entry.getValue(),
+                                entry.getKey(),
+                                window.sourceSeatNo(),
+                                window.triggerTile()
+                        ))
                 ));
     }
 

backend/src/main/java/com/xuezhanmaster/game/service/SettlementService.java

@@ -191,6 +191,49 @@ public class SettlementService {
         );
     }
 
+    public SettlementResult settleTaxRefund(
+            GameTable table,
+            int recipientSeatNo,
+            int sourceSeatNo,
+            int refundAmount,
+            String triggerTile
+    ) {
+        return applySettlement(
+                table,
+                SettlementType.TUI_SHUI,
+                ActionType.GANG,
+                recipientSeatNo,
+                sourceSeatNo,
+                triggerTile,
+                buildFlatDetail(refundAmount),
+                orderedDeltas(recipientSeatNo, refundAmount, sourceSeatNo, -refundAmount)
+        );
+    }
+
+    public SettlementResult settleChaJiao(
+            GameTable table,
+            int winnerSeatNo,
+            int sourceSeatNo,
+            String triggerTile,
+            SettlementDetail settlementDetail
+    ) {
+        return applySettlement(
+                table,
+                SettlementType.CHA_JIAO,
+                ActionType.HU,
+                winnerSeatNo,
+                sourceSeatNo,
+                triggerTile,
+                settlementDetail,
+                orderedDeltas(
+                        winnerSeatNo,
+                        settlementDetail.paymentScore(),
+                        sourceSeatNo,
+                        -settlementDetail.paymentScore()
+                )
+        );
+    }
+
     private SettlementResult applySettlement(
             GameTable table,
             SettlementType settlementType,
@@ -228,4 +271,8 @@ public class SettlementService {
         deltas.put(sourceSeatNo, sourceDelta);
         return deltas;
     }
+
+    private SettlementDetail buildFlatDetail(int paymentScore) {
+        return new SettlementDetail(1, 0, paymentScore, List.of());
+    }
 }

backend/src/test/java/com/xuezhanmaster/game/service/GameSessionServiceTest.java

@@ -5,6 +5,7 @@ import com.xuezhanmaster.game.domain.GameSeat;
 import com.xuezhanmaster.game.domain.GameSession;
 import com.xuezhanmaster.game.domain.Tile;
 import com.xuezhanmaster.game.dto.GameActionRequest;
+import com.xuezhanmaster.game.domain.SettlementType;
 import com.xuezhanmaster.game.domain.TileSuit;
 import com.xuezhanmaster.game.dto.GameStateResponse;
 import com.xuezhanmaster.game.service.GameActionProcessor;
@@ -42,6 +43,7 @@ class GameSessionServiceTest {
             new ResponseActionWindowBuilder(huEvaluator),
             new ResponseActionResolver(),
             new SettlementService(bloodBattleScoringService),
+            bloodBattleScoringService,
             huEvaluator,
             new StrategyService(),
             new PlayerVisibilityService(),
@@ -644,6 +646,124 @@ class GameSessionServiceTest {
         assertThat(latestSettlementFanCodes(session)).contains("HAI_DI_PAO");
     }
 
+    @Test
+    void shouldRefundGangScoresForNotReadySeatWhenWallExhausted() {
+        RoomSummaryResponse room = roomService.createRoom(new CreateRoomRequest("host-1", true));
+        roomService.joinRoom(room.roomId(), new com.xuezhanmaster.room.dto.JoinRoomRequest("player-2", "玩家二"));
+        roomService.joinRoom(room.roomId(), new com.xuezhanmaster.room.dto.JoinRoomRequest("player-3", "玩家三"));
+        roomService.joinRoom(room.roomId(), new com.xuezhanmaster.room.dto.JoinRoomRequest("player-4", "玩家四"));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("host-1", true));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("player-2", true));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("player-3", true));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("player-4", true));
+
+        GameStateResponse started = gameSessionService.startGame(room.roomId(), "host-1");
+        gameSessionService.selectLackSuit(started.gameId(), "host-1", TileSuit.WAN.name());
+        gameSessionService.selectLackSuit(started.gameId(), "player-2", TileSuit.TONG.name());
+        gameSessionService.selectLackSuit(started.gameId(), "player-3", TileSuit.TIAO.name());
+        gameSessionService.selectLackSuit(started.gameId(), "player-4", TileSuit.WAN.name());
+
+        GameSession session = getSession(started.gameId());
+        prepareTaxRefundGangHand(session.getTable().getSeats().get(0), "3万");
+        setNextWallTile(session, "9万");
+
+        GameStateResponse afterGang = gameSessionService.performAction(
+                started.gameId(),
+                new GameActionRequest("host-1", "GANG", "3万", null)
+        );
+        session.getTable().getWallTiles().clear();
+        removeMatchingTilesFromOtherSeats(session, "9万", 0);
+
+        GameStateResponse afterDiscard = gameSessionService.discardTile(started.gameId(), "host-1", "9万");
+
+        assertThat(afterGang.selfSeat().score()).isEqualTo(6);
+        assertThat(afterDiscard.phase()).isEqualTo("FINISHED");
+        assertThat(settlementResultsOfType(session, SettlementType.TUI_SHUI)).hasSize(3);
+        assertThat(afterDiscard.seats()).extracting(seat -> seat.score()).contains(0, 0, 0, 0);
+    }
+
+    @Test
+    void shouldApplyChaJiaoFromNotReadySeatToReadySeatWhenWallExhausted() {
+        RoomSummaryResponse room = roomService.createRoom(new CreateRoomRequest("host-1", true));
+        roomService.joinRoom(room.roomId(), new com.xuezhanmaster.room.dto.JoinRoomRequest("player-2", "玩家二"));
+        roomService.joinRoom(room.roomId(), new com.xuezhanmaster.room.dto.JoinRoomRequest("player-3", "玩家三"));
+        roomService.joinRoom(room.roomId(), new com.xuezhanmaster.room.dto.JoinRoomRequest("player-4", "玩家四"));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("host-1", true));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("player-2", true));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("player-3", true));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("player-4", true));
+
+        GameStateResponse started = gameSessionService.startGame(room.roomId(), "host-1");
+        gameSessionService.selectLackSuit(started.gameId(), "host-1", TileSuit.WAN.name());
+        gameSessionService.selectLackSuit(started.gameId(), "player-2", TileSuit.TONG.name());
+        gameSessionService.selectLackSuit(started.gameId(), "player-3", TileSuit.TIAO.name());
+        gameSessionService.selectLackSuit(started.gameId(), "player-4", TileSuit.WAN.name());
+
+        GameSession session = getSession(started.gameId());
+        prepareNotReadyHand(session.getTable().getSeats().get(0));
+        prepareWinningHand(session.getTable().getSeats().get(1));
+        session.getTable().getSeats().get(2).declareHu();
+        session.getTable().getSeats().get(3).declareHu();
+        ensureSeatHasMatchingTiles(session.getTable().getSeats().get(0), "1万", 1);
+        removeMatchingTilesFromOtherSeats(session, "1万", 0);
+        session.getTable().getWallTiles().clear();
+
+        GameStateResponse afterDiscard = gameSessionService.discardTile(started.gameId(), "host-1", "1万");
+
+        assertThat(afterDiscard.phase()).isEqualTo("FINISHED");
+        assertThat(afterDiscard.seats().get(0).score()).isEqualTo(-1);
+        assertThat(afterDiscard.seats().get(1).score()).isEqualTo(1);
+        assertThat(settlementResultsOfType(session, SettlementType.CHA_JIAO)).hasSize(1);
+        assertThat(latestSettlementFanCodes(session)).isEmpty();
+    }
+
+    @Test
+    void shouldAllowMultipleHuWinnersOnSingleDiscard() {
+        RoomSummaryResponse room = roomService.createRoom(new CreateRoomRequest("host-1", true));
+        roomService.joinRoom(room.roomId(), new com.xuezhanmaster.room.dto.JoinRoomRequest("player-2", "玩家二"));
+        roomService.joinRoom(room.roomId(), new com.xuezhanmaster.room.dto.JoinRoomRequest("player-3", "玩家三"));
+        roomService.joinRoom(room.roomId(), new com.xuezhanmaster.room.dto.JoinRoomRequest("player-4", "玩家四"));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("host-1", true));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("player-2", true));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("player-3", true));
+        roomService.toggleReady(room.roomId(), new ToggleReadyRequest("player-4", true));
+
+        GameStateResponse started = gameSessionService.startGame(room.roomId(), "host-1");
+        gameSessionService.selectLackSuit(started.gameId(), "host-1", TileSuit.WAN.name());
+        gameSessionService.selectLackSuit(started.gameId(), "player-2", TileSuit.TONG.name());
+        gameSessionService.selectLackSuit(started.gameId(), "player-3", TileSuit.TIAO.name());
+        gameSessionService.selectLackSuit(started.gameId(), "player-4", TileSuit.WAN.name());
+
+        GameSession session = getSession(started.gameId());
+        prepareWinningHand(session.getTable().getSeats().get(1));
+        prepareWinningHand(session.getTable().getSeats().get(2));
+        ensureSeatHasMatchingTiles(session.getTable().getSeats().get(0), "9筒", 1);
+        removeMatchingTilesFromOtherSeats(session, "9筒", 0, 1, 2);
+
+        gameSessionService.discardTile(started.gameId(), "host-1", "9筒");
+        GameStateResponse afterHu = gameSessionService.performAction(
+                started.gameId(),
+                new GameActionRequest("player-2", "HU", "9筒", 0)
+        );
+        afterHu = gameSessionService.performAction(
+                started.gameId(),
+                new GameActionRequest("player-3", "HU", "9筒", 0)
+        );
+
+        assertThat(session.getPendingResponseActionWindow()).isNull();
+        assertThat(afterHu.phase()).isEqualTo("PLAYING");
+        assertThat(afterHu.currentSeatNo()).isEqualTo(3);
+        assertThat(afterHu.seats().get(0).score()).isEqualTo(-2);
+        assertThat(afterHu.seats().get(1).won()).isTrue();
+        assertThat(afterHu.seats().get(2).won()).isTrue();
+        assertThat(afterHu.seats().get(1).score()).isEqualTo(1);
+        assertThat(afterHu.selfSeat().score()).isEqualTo(1);
+        assertThat(session.getEvents())
+                .extracting(event -> event.eventType())
+                .contains(GameEventType.HU_DECLARED, GameEventType.SETTLEMENT_APPLIED, GameEventType.SCORE_CHANGED);
+        assertThat(settlementResultsOfType(session, SettlementType.DIAN_PAO_HU)).hasSize(2);
+    }
+
     @Test
     void shouldRejectSelfDrawHuWhenHandIsNotWinning() {
         RoomSummaryResponse room = roomService.createRoom(new CreateRoomRequest("host-1", true));
@@ -814,6 +934,41 @@ class GameSessionServiceTest {
         seat.receiveTile(new Tile(TileSuit.TONG, 9));
     }
 
+    private void prepareTaxRefundGangHand(GameSeat seat, String gangTileDisplayName) {
+        seat.getHandTiles().clear();
+        Tile gangTile = parseTile(gangTileDisplayName);
+        for (int i = 0; i < 4; i++) {
+            seat.receiveTile(gangTile);
+        }
+        seat.receiveTile(new Tile(TileSuit.WAN, 1));
+        seat.receiveTile(new Tile(TileSuit.WAN, 4));
+        seat.receiveTile(new Tile(TileSuit.WAN, 7));
+        seat.receiveTile(new Tile(TileSuit.TONG, 2));
+        seat.receiveTile(new Tile(TileSuit.TONG, 5));
+        seat.receiveTile(new Tile(TileSuit.TONG, 8));
+        seat.receiveTile(new Tile(TileSuit.TIAO, 1));
+        seat.receiveTile(new Tile(TileSuit.TIAO, 4));
+        seat.receiveTile(new Tile(TileSuit.TIAO, 7));
+        seat.receiveTile(new Tile(TileSuit.WAN, 8));
+    }
+
+    private void prepareNotReadyHand(GameSeat seat) {
+        seat.getHandTiles().clear();
+        seat.receiveTile(new Tile(TileSuit.WAN, 2));
+        seat.receiveTile(new Tile(TileSuit.WAN, 5));
+        seat.receiveTile(new Tile(TileSuit.WAN, 8));
+        seat.receiveTile(new Tile(TileSuit.TONG, 1));
+        seat.receiveTile(new Tile(TileSuit.TONG, 4));
+        seat.receiveTile(new Tile(TileSuit.TONG, 7));
+        seat.receiveTile(new Tile(TileSuit.TIAO, 2));
+        seat.receiveTile(new Tile(TileSuit.TIAO, 5));
+        seat.receiveTile(new Tile(TileSuit.TIAO, 8));
+        seat.receiveTile(new Tile(TileSuit.WAN, 9));
+        seat.receiveTile(new Tile(TileSuit.TONG, 9));
+        seat.receiveTile(new Tile(TileSuit.TIAO, 9));
+        seat.receiveTile(new Tile(TileSuit.WAN, 3));
+    }
+
     private void prepareSupplementalGangHand(GameSeat seat, String gangTileDisplayName) {
         seat.getHandTiles().clear();
         seat.getMeldGroups().clear();
@@ -836,6 +991,13 @@ class GameSessionServiceTest {
         session.getTable().getWallTiles().set(0, parseTile(tileDisplayName));
     }
 
+    private java.util.List<SettlementType> settlementResultsOfType(GameSession session, SettlementType settlementType) {
+        return session.getSettlementHistory().stream()
+                .map(settlementResult -> settlementResult.settlementType())
+                .filter(type -> type == settlementType)
+                .toList();
+    }
+
     @SuppressWarnings("unchecked")
     private java.util.List<String> latestSettlementFanCodes(GameSession session) {
         return session.getEvents().stream()

docs/DEVELOPMENT_PLAN.md

@@ -234,10 +234,11 @@
 
 ### 5.3 注释与脚本约定
 
-- 后端新增或修改的业务代码，需要为复杂规则、关键字段和跨阶段状态补充简洁中文注释，避免只靠方法名猜语义。
-- 前端新增或修改的页面与状态逻辑，需要为复杂交互、实时消息消费和视图状态切换补充简洁中文注释，避免后续拆页时理解断层。
-- 后续数据库表结构、迁移脚本、初始化 SQL 与存储过程，也需要补充必要中文注释，重点说明业务含义、约束原因与关键索引用途。
-- 注释要求遵守 `KISS`：只解释不直观的意图、约束和边界，不写“变量赋值”这类冗余注释。
+- 后端新增或修改的业务代码，必须为复杂规则、关键字段、状态切换、结算口径和跨阶段流程补充适量中文注释，不能只保留方法名级别语义。
+- 前端新增或修改的页面、组件与状态逻辑，必须为复杂交互、实时消息消费、动作面板联动和视图状态切换补充适量中文注释，避免后续拆页或联调时理解断层。
+- 后续数据库表结构、迁移脚本、初始化 SQL、索引和存储过程，也必须补充必要中文注释，重点说明业务含义、约束原因、字段口径、回填策略和关键索引用途。
+- 注释要求遵守 `KISS`：可以适当多写，但只解释不直观的意图、约束、边界和取舍，不写“变量赋值”这类冗余注释。
+- 对以下高风险区域，中文注释默认视为必需项：麻将规则判断、结算分摊、响应裁决、实时消息边界、局终处理、数据迁移与回滚脚本。
 
 ### 5.2 最关键的系统约束