feat: 분류 순서변경(reorder) + 월 예상 수입 설정 API

- 분류: sort_order reorder 엔드포인트, 생성 시 맨 뒤 배치
- 예산: account_setting 테이블 + 월 예상 수입 GET/PUT

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/main/java/com/sb/web/account/controller/BudgetController.java

@@ -4,6 +4,8 @@ import com.sb.web.account.dto.BudgetPeriodStat;
 import com.sb.web.account.dto.BudgetRequest;
 import com.sb.web.account.dto.BudgetResponse;
 import com.sb.web.account.dto.BudgetStatus;
+import com.sb.web.account.dto.ExpectedIncomeRequest;
+import com.sb.web.account.service.AccountSettingService;
 import com.sb.web.account.service.BudgetService;
 import com.sb.web.auth.dto.SessionUser;
 import com.sb.web.auth.web.AuthInterceptor;
@@ -24,6 +26,23 @@ import java.util.List;
 public class BudgetController {
 
     private final BudgetService budgetService;
+    private final AccountSettingService settingService;
+
+    /** 월 예상 수입 조회 */
+    @GetMapping("/income")
+    public ExpectedIncomeRequest getIncome(
+            @RequestAttribute(AuthInterceptor.CURRENT_MEMBER) SessionUser current) {
+        return new ExpectedIncomeRequest(settingService.getExpectedIncome(current.getId()));
+    }
+
+    /** 월 예상 수입 설정 */
+    @PutMapping("/income")
+    public ExpectedIncomeRequest setIncome(
+            @Valid @RequestBody ExpectedIncomeRequest req,
+            @RequestAttribute(AuthInterceptor.CURRENT_MEMBER) SessionUser current) {
+        settingService.setExpectedIncome(current.getId(), req.getExpectedIncome());
+        return req;
+    }
 
     @GetMapping
     public List<BudgetResponse> list(

src/main/java/com/sb/web/account/controller/CategoryController.java

@@ -1,5 +1,6 @@
 package com.sb.web.account.controller;
 
+import com.sb.web.account.dto.CategoryReorderRequest;
 import com.sb.web.account.dto.CategoryRequest;
 import com.sb.web.account.dto.CategoryResponse;
 import com.sb.web.account.service.CategoryService;
@@ -52,6 +53,14 @@ public class CategoryController {
         return ResponseEntity.noContent().build();
     }
 
+    /** 드래그앤드랍 순서 변경 */
+    @PutMapping("/reorder")
+    public List<CategoryResponse> reorder(
+            @RequestBody CategoryReorderRequest req,
+            @RequestAttribute(AuthInterceptor.CURRENT_MEMBER) SessionUser current) {
+        return categoryService.reorder(current.getId(), req.getType(), req.getIds());
+    }
+
     /** 기존 내역의 분류를 목록으로 가져오기 */
     @PostMapping("/import")
     public List<CategoryResponse> importFromEntries(

src/main/java/com/sb/web/account/dto/CategoryReorderRequest.java

@@ -0,0 +1,15 @@
+package com.sb.web.account.dto;
+
+import lombok.Data;
+
+import java.util.List;
+
+/**
+ * 분류 순서 변경 요청. ids 순서대로 sort_order 를 재설정한다.
+ */
+@Data
+public class CategoryReorderRequest {
+
+    private String type;       // INCOME / EXPENSE
+    private List<Long> ids;    // 새 순서의 분류 id 목록
+}

src/main/java/com/sb/web/account/dto/ExpectedIncomeRequest.java

@@ -0,0 +1,18 @@
+package com.sb.web.account.dto;
+
+import jakarta.validation.constraints.PositiveOrZero;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+/**
+ * 월 예상 수입 요청/응답.
+ */
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+public class ExpectedIncomeRequest {
+
+    @PositiveOrZero(message = "예상 수입은 0 이상이어야 합니다.")
+    private Long expectedIncome;
+}

src/main/java/com/sb/web/account/mapper/AccountSettingMapper.java

@@ -0,0 +1,17 @@
+package com.sb.web.account.mapper;
+
+import org.apache.ibatis.annotations.Mapper;
+import org.apache.ibatis.annotations.Param;
+
+/**
+ * 사용자별 가계부 설정 매퍼 (account_setting).
+ */
+@Mapper
+public interface AccountSettingMapper {
+
+    /** 월 예상 수입 (없으면 null) */
+    Long findExpectedIncome(@Param("memberId") Long memberId);
+
+    /** 월 예상 수입 upsert */
+    int upsertExpectedIncome(@Param("memberId") Long memberId, @Param("expectedIncome") Long expectedIncome);
+}

src/main/java/com/sb/web/account/mapper/CategoryMapper.java

@@ -28,4 +28,10 @@ public interface CategoryMapper {
     int update(AccountCategory category);
 
     int delete(@Param("id") Long id, @Param("memberId") Long memberId);
+
+    /** 순서(sort_order) 변경 */
+    int updateSortOrder(@Param("id") Long id, @Param("memberId") Long memberId, @Param("sortOrder") int sortOrder);
+
+    /** 해당 타입의 현재 최대 sort_order (신규 분류를 맨 뒤에 배치) */
+    Integer maxSortOrder(@Param("memberId") Long memberId, @Param("type") String type);
 }

src/main/java/com/sb/web/account/service/AccountSettingService.java

@@ -0,0 +1,25 @@
+package com.sb.web.account.service;
+
+import com.sb.web.account.mapper.AccountSettingMapper;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+/**
+ * 사용자별 가계부 설정 서비스 (월 예상 수입 등).
+ */
+@Service
+@RequiredArgsConstructor
+public class AccountSettingService {
+
+    private final AccountSettingMapper settingMapper;
+
+    public Long getExpectedIncome(Long memberId) {
+        return settingMapper.findExpectedIncome(memberId);
+    }
+
+    @Transactional
+    public void setExpectedIncome(Long memberId, Long expectedIncome) {
+        settingMapper.upsertExpectedIncome(memberId, expectedIncome);
+    }
+}

src/main/java/com/sb/web/account/service/CategoryService.java

@@ -35,12 +35,27 @@ public class CategoryService {
         if (categoryMapper.countByName(memberId, req.getType(), name, null) > 0) {
             throw new ApiException(HttpStatus.CONFLICT, "이미 존재하는 분류입니다.");
         }
+        Integer max = categoryMapper.maxSortOrder(memberId, req.getType());
+        int order = (max == null ? 0 : max + 1);
         AccountCategory c = AccountCategory.builder()
-                .memberId(memberId).type(req.getType()).name(name).sortOrder(0).build();
+                .memberId(memberId).type(req.getType()).name(name).sortOrder(order).build();
         categoryMapper.insert(c);
         return CategoryResponse.from(c);
     }
 
+    /** 드래그앤드랍 순서 변경: 전달된 id 순서대로 sort_order 재설정 (본인·동일 타입만) */
+    @Transactional
+    public List<CategoryResponse> reorder(Long memberId, String type, List<Long> ids) {
+        int i = 0;
+        for (Long id : ids) {
+            AccountCategory c = categoryMapper.findByIdAndMember(id, memberId);
+            if (c != null && c.getType().equals(type)) {
+                categoryMapper.updateSortOrder(id, memberId, i++);
+            }
+        }
+        return list(memberId);
+    }
+
     /** 이름만 변경 가능. 변경 시 기존 내역·예산의 분류명도 함께 갱신 */
     @Transactional
     public CategoryResponse update(Long id, CategoryRequest req, Long memberId) {