feat: 월별 예산 + 전월/다음달 복사

- budget 테이블에 year/month 추가, (member,category)→(member,category,year,month) 유니크 교체
  기존 상시 예산은 현재 월로 1회 이관
- 예산 조회/생성/현황/기간차트를 월별로(findByMember에 year/month)
- copyMonth: 다른 월 예산을 대상 월로 복사(같은 분류 덮어씀) + POST /budgets/copy
- 백업 복구 시 예산은 현재 월로 등록

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

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

@@ -50,8 +50,22 @@ public class BudgetController {
 
     @GetMapping
     public List<BudgetResponse> list(
+            @RequestParam int year,
+            @RequestParam int month,
             @RequestAttribute(AuthInterceptor.CURRENT_MEMBER) SessionUser current) {
-        return budgetService.list(current.getId());
+        return budgetService.list(current.getId(), year, month);
+    }
+
+    /** 다른 월의 예산을 이 달로 복사(전월 복사 등). 같은 분류는 덮어씀 */
+    @PostMapping("/copy")
+    public List<BudgetResponse> copy(
+            @RequestParam int fromYear,
+            @RequestParam int fromMonth,
+            @RequestParam int toYear,
+            @RequestParam int toMonth,
+            @RequestAttribute(AuthInterceptor.CURRENT_MEMBER) SessionUser current) {
+        budgetService.copy(current.getId(), fromYear, fromMonth, toYear, toMonth);
+        return budgetService.list(current.getId(), toYear, toMonth);
     }
 
     @GetMapping("/status")
@@ -74,9 +88,11 @@ public class BudgetController {
 
     @PostMapping
     public ResponseEntity<BudgetResponse> create(
+            @RequestParam int year,
+            @RequestParam int month,
             @Valid @RequestBody BudgetRequest req,
             @RequestAttribute(AuthInterceptor.CURRENT_MEMBER) SessionUser current) {
-        return ResponseEntity.status(HttpStatus.CREATED).body(budgetService.create(req, current.getId()));
+        return ResponseEntity.status(HttpStatus.CREATED).body(budgetService.create(req, current.getId(), year, month));
     }
 
     @PutMapping("/{id}")

src/main/java/com/sb/web/account/domain/Budget.java

@@ -28,6 +28,8 @@ public class Budget implements Serializable {
     private Long weekly;
     private Long monthly;
     private Long yearly;
+    private Integer year;      // 예산 연도(월별 예산)
+    private Integer month;     // 예산 월(1~12)
     private LocalDateTime createdAt;
     private LocalDateTime updatedAt;
 }

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

@@ -12,13 +12,24 @@ import java.util.List;
 @Mapper
 public interface BudgetMapper {
 
-    List<Budget> findByMember(@Param("memberId") Long memberId);
+    List<Budget> findByMember(@Param("memberId") Long memberId,
+                              @Param("year") Integer year,
+                              @Param("month") Integer month);
 
     Budget findByIdAndMember(@Param("id") Long id, @Param("memberId") Long memberId);
 
     int countByCategory(@Param("memberId") Long memberId,
                         @Param("category") String category,
-                        @Param("excludeId") Long excludeId);
+                        @Param("excludeId") Long excludeId,
+                        @Param("year") Integer year,
+                        @Param("month") Integer month);
+
+    /** fromYear/fromMonth 예산을 toYear/toMonth 로 복사(같은 분류는 덮어씀). 복사된 건수 반환 */
+    int copyMonth(@Param("memberId") Long memberId,
+                  @Param("fromYear") Integer fromYear,
+                  @Param("fromMonth") Integer fromMonth,
+                  @Param("toYear") Integer toYear,
+                  @Param("toMonth") Integer toMonth);
 
     int insert(Budget budget);
 

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

@@ -156,11 +156,12 @@ public class BackupService {
             }
         }
 
-        // 7) 예산
+        // 7) 예산 — 복구 시 현재 월 예산으로 등록(백업엔 월 정보 없음)
         if (req.getBudgets() != null) {
+            java.time.LocalDate today = java.time.LocalDate.now();
             for (BudgetRequest b : req.getBudgets()) {
                 if (b == null || b.getCategory() == null) continue;
-                budgetService.create(b, memberId);
+                budgetService.create(b, memberId, today.getYear(), today.getMonthValue());
             }
         }
 

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

@@ -31,36 +31,46 @@ public class BudgetService {
     private final BudgetMapper budgetMapper;
     private final AccountEntryMapper entryMapper;
 
-    public List<BudgetResponse> list(Long memberId) {
-        return budgetMapper.findByMember(memberId).stream().map(BudgetResponse::from).toList();
+    public List<BudgetResponse> list(Long memberId, int year, int month) {
+        return budgetMapper.findByMember(memberId, year, month).stream().map(BudgetResponse::from).toList();
     }
 
     @Transactional
-    public BudgetResponse create(BudgetRequest req, Long memberId) {
+    public BudgetResponse create(BudgetRequest req, Long memberId, int year, int month) {
         String category = req.getCategory().trim();
-        if (budgetMapper.countByCategory(memberId, category, null) > 0) {
+        if (budgetMapper.countByCategory(memberId, category, null, year, month) > 0) {
             throw new ApiException(HttpStatus.CONFLICT, "이미 예산이 설정된 카테고리입니다.");
         }
         Budget budget = toBudget(req, category);
         budget.setMemberId(memberId);
+        budget.setYear(year);
+        budget.setMonth(month);
         budgetMapper.insert(budget);
         return BudgetResponse.from(budget);
     }
 
     @Transactional
     public BudgetResponse update(Long id, BudgetRequest req, Long memberId) {
-        mustFind(id, memberId);
+        Budget existing = mustFind(id, memberId);
         String category = req.getCategory().trim();
-        if (budgetMapper.countByCategory(memberId, category, id) > 0) {
+        if (budgetMapper.countByCategory(memberId, category, id, existing.getYear(), existing.getMonth()) > 0) {
             throw new ApiException(HttpStatus.CONFLICT, "이미 예산이 설정된 카테고리입니다.");
         }
         Budget budget = toBudget(req, category);
         budget.setId(id);
         budget.setMemberId(memberId);
+        budget.setYear(existing.getYear());
+        budget.setMonth(existing.getMonth());
         budgetMapper.update(budget);
         return BudgetResponse.from(budget);
     }
 
+    /** fromYear/fromMonth 예산을 toYear/toMonth 로 복사(같은 분류 덮어씀). 복사된 건수 반환 */
+    @Transactional
+    public int copy(Long memberId, int fromYear, int fromMonth, int toYear, int toMonth) {
+        return budgetMapper.copyMonth(memberId, fromYear, fromMonth, toYear, toMonth);
+    }
+
     @Transactional
     public void delete(Long id, Long memberId) {
         mustFind(id, memberId);
@@ -79,7 +89,7 @@ public class BudgetService {
         }
 
         List<BudgetStatus> result = new ArrayList<>();
-        for (Budget b : budgetMapper.findByMember(memberId)) {
+        for (Budget b : budgetMapper.findByMember(memberId, year, month)) {
             long monthlyBudget = monthlyBudget(b, daysInMonth);
             long spent = spentByCategory.getOrDefault(b.getCategory(), 0L);
             result.add(BudgetStatus.builder()
@@ -103,7 +113,8 @@ public class BudgetService {
         int y = year != null ? year : Year.now().getValue();
         int m = month != null ? month : 1;
 
-        List<Budget> budgets = budgetMapper.findByMember(memberId);
+        // 기간 차트는 선택 월의 예산을 기준으로 각 버킷에 적용(월별 예산 도입 전 동작과 동일)
+        List<Budget> budgets = budgetMapper.findByMember(memberId, y, m);
         Map<String, Long> expense = new HashMap<>();
         for (Map<String, Object> row : entryMapper.statsByPeriod(memberId, unit, year, month)) {
             expense.put(String.valueOf(((Number) row.get("bucket")).longValue()),

src/main/resources/db/account.sql

@@ -165,6 +165,15 @@ CREATE TABLE IF NOT EXISTS budget (
     UNIQUE KEY uk_budget_member_category (member_id, category)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
+-- 월별 예산: 예산을 연/월별로 분리(전월 복사로 다음 달에 동일 예산 저장 가능).
+ALTER TABLE budget ADD COLUMN IF NOT EXISTS `year`  INT NULL COMMENT '예산 연도';
+ALTER TABLE budget ADD COLUMN IF NOT EXISTS `month` INT NULL COMMENT '예산 월(1~12)';
+-- 기존 상시 예산을 현재 연/월로 1회 이관
+UPDATE budget SET `year` = YEAR(NOW()), `month` = MONTH(NOW()) WHERE `year` IS NULL OR `month` IS NULL;
+-- 분류 유니크를 (member,category) → (member,category,year,month) 로 교체
+ALTER TABLE budget DROP INDEX IF EXISTS uk_budget_member_category;
+ALTER TABLE budget ADD UNIQUE KEY IF NOT EXISTS uk_budget_member_cat_ym (member_id, category, `year`, `month`);
+
 -- 가계부 항목 - 태그 (다대다, tag_id 는 account_tag.id 참조)
 CREATE TABLE IF NOT EXISTS account_entry_tag (
     entry_id BIGINT NOT NULL,

src/main/resources/mapper/BudgetMapper.xml

@@ -14,15 +14,19 @@
         <result property="weekly" column="weekly"/>
         <result property="monthly" column="monthly"/>
         <result property="yearly" column="yearly"/>
+        <result property="year" column="year"/>
+        <result property="month" column="month"/>
         <result property="createdAt" column="created_at"/>
         <result property="updatedAt" column="updated_at"/>
     </resultMap>
 
     <sql id="cols">id, member_id, category, fixed, base_unit, base_amount,
-        daily, weekly, monthly, yearly, created_at, updated_at</sql>
+        daily, weekly, monthly, yearly, `year`, `month`, created_at, updated_at</sql>
 
-    <select id="findByMember" parameterType="long" resultMap="budgetResultMap">
-        SELECT <include refid="cols"/> FROM budget WHERE member_id = #{memberId} ORDER BY category
+    <select id="findByMember" resultMap="budgetResultMap">
+        SELECT <include refid="cols"/> FROM budget
+        WHERE member_id = #{memberId} AND `year` = #{year} AND `month` = #{month}
+        ORDER BY category
     </select>
 
     <select id="findByIdAndMember" resultMap="budgetResultMap">
@@ -32,15 +36,30 @@
     <select id="countByCategory" resultType="int">
         SELECT COUNT(*) FROM budget
         WHERE member_id = #{memberId} AND category = #{category}
+          AND `year` = #{year} AND `month` = #{month}
         <if test="excludeId != null">AND id != #{excludeId}</if>
     </select>
 
     <insert id="insert" parameterType="com.sb.web.account.domain.Budget"
             useGeneratedKeys="true" keyProperty="id">
         INSERT INTO budget (member_id, category, fixed, base_unit, base_amount,
-                            daily, weekly, monthly, yearly, created_at, updated_at)
+                            daily, weekly, monthly, yearly, `year`, `month`, created_at, updated_at)
         VALUES (#{memberId}, #{category}, #{fixed}, #{baseUnit}, #{baseAmount},
-                #{daily}, #{weekly}, #{monthly}, #{yearly}, NOW(), NOW())
+                #{daily}, #{weekly}, #{monthly}, #{yearly}, #{year}, #{month}, NOW(), NOW())
+    </insert>
+
+    <!-- 전월(또는 임의 월) 예산을 다른 월로 복사. 같은 분류는 덮어씀(ON DUPLICATE) -->
+    <insert id="copyMonth">
+        INSERT INTO budget (member_id, category, fixed, base_unit, base_amount,
+                            daily, weekly, monthly, yearly, `year`, `month`, created_at, updated_at)
+        SELECT member_id, category, fixed, base_unit, base_amount,
+               daily, weekly, monthly, yearly, #{toYear}, #{toMonth}, NOW(), NOW()
+        FROM budget
+        WHERE member_id = #{memberId} AND `year` = #{fromYear} AND `month` = #{fromMonth}
+        ON DUPLICATE KEY UPDATE
+            fixed = VALUES(fixed), base_unit = VALUES(base_unit), base_amount = VALUES(base_amount),
+            daily = VALUES(daily), weekly = VALUES(weekly), monthly = VALUES(monthly),
+            yearly = VALUES(yearly), updated_at = NOW()
     </insert>
 
     <update id="update" parameterType="com.sb.web.account.domain.Budget">