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+```mermaid
+sequenceDiagram
+    participant Controller
+    participant Service
+    participant Database
+
+    Controller->>Service: 결제 처리 요청
+    activate Service
+    Service->>Database: DB 작업 수행
+    activate Database
+    Database-->>Service: 결과
+    deactivate Database
+    Service-->>Controller: 결제 결과 반환
+    deactivate Service
+
+    Note over Controller: 외부 실패 및 DB 실패 처리
+    alt 외부 실패
+        Controller->>Service: 외부 결제 서비스 실패
+    else DB 실패
+        Service->>Database: DB 처리 실패
+    end
+
+    Note over Controller: 최종 커밋/롤백 경계
+    activate Database
+    opt Commit
+        Database-->>Service: 커밋 성공
+    else Rollback
+        Database-->>Service: 롤백 수행
+    end
+```
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