diff --git a/TrackingToolWebAU/api.py b/TrackingToolWebAU/api.py
index 893ebe0..c4e0b4c 100644
--- a/TrackingToolWebAU/api.py
+++ b/TrackingToolWebAU/api.py
@@ -30,6 +30,7 @@ def sync_checkin(email: str, timestamp_ms: int, image_data: bytes, student_name:
             "image": image_b64,
         
     }
+    print("[sync_checkin] payload:", {k: v for k, v in payload.items() if k != "image"})
     try:
         response = requests.post(HOST + "/api/log-time/check-in-out", json=payload)
         response.raise_for_status()
diff --git a/TrackingToolWebAU/main.py b/TrackingToolWebAU/main.py
index 0ba4738..cac3b61 100644
--- a/TrackingToolWebAU/main.py
+++ b/TrackingToolWebAU/main.py
@@ -259,7 +259,7 @@ async def register_student(
 
 
 @app.post("/checkin")
-async def checkin(background_tasks: BackgroundTasks, file: UploadFile = File(...), camera_id: str = Form("cam1"), db: Session = Depends(get_db)):
+async def checkin(file: UploadFile = File(...), camera_id: str = Form("cam1"), db: Session = Depends(get_db)):
     image_data = await file.read()
 
     # Phương án 3: resize ảnh trước khi detect — bỏ disk I/O
@@ -341,7 +341,28 @@ async def checkin(background_tasks: BackgroundTasks, file: UploadFile = File(...
         ).fetchone()
         status = "check out" if last_log and last_log.status == "check in" else "check in"
 
-        insert_result = db.execute(
+        try:
+            res = sync_checkin(
+                enc_emails.get(best_student, ""),
+                int(now.timestamp() * 1000),
+                image_data,
+                enc_names.get(best_student, ""),
+                status,
+            )
+        except Exception as e:
+            logging.error(f"MS sync error: {e}")
+            return {"message": "Server sync failed, checkin not recorded.", "status": False}
+
+        if res.get("Status") == "ERROR":
+            msg = f"[MS Server] {res.get('Msg', 'Unknown error')}"
+            logging.warning(f"MS rejected checkin: {msg}")
+            return {"message": msg, "status": False}
+
+        # Ghi log sau khi server xác nhận thành công
+        check_in_flag = (res.get("data") or {}).get("checkIn")
+        final_status = ("check in" if check_in_flag else "check out") if check_in_flag is not None else status
+
+        db.execute(
             text("""
                 INSERT INTO checkin_logs (student_id, time, camera_id, status)
                 VALUES (:student_id, :time, :camera_id, :status)
@@ -350,43 +371,11 @@ async def checkin(background_tasks: BackgroundTasks, file: UploadFile = File(...
                 "student_id": best_student,
                 "time": now,
                 "camera_id": camera_id,
-                "status": status
+                "status": final_status
             }
         )
-        log_id = insert_result.lastrowid
         db.commit()
 
-        def _sync_to_ms(email: str, timestamp_ms: int, img_data: bytes, name: str, local_status: str, checkin_log_id: int):
-            try:
-                res = sync_checkin(email, timestamp_ms, img_data, name, local_status)
-                check_in_flag = res.get("data", {}).get("checkIn")
-                if check_in_flag is None:
-                    return
-                ms_status = "check in" if check_in_flag else "check out"
-                if ms_status != local_status:
-                    fix_db = SessionLocal()
-                    try:
-                        fix_db.execute(
-                            text("UPDATE checkin_logs SET status = :status WHERE id = :id"),
-                            {"status": ms_status, "id": checkin_log_id}
-                        )
-                        fix_db.commit()
-                        logging.info(f"Corrected log #{checkin_log_id}: {local_status} → {ms_status}")
-                    finally:
-                        fix_db.close()
-            except Exception as e:
-                logging.error(f"MS sync error: {e}")
-
-        background_tasks.add_task(
-            _sync_to_ms,
-            enc_emails.get(best_student, ""),
-            int(now.timestamp() * 1000),
-            image_data,
-            enc_names.get(best_student, ""),
-            status,
-            log_id,
-        )
-
         student = db.execute(
             text("""
                 SELECT id, name, email
@@ -402,7 +391,7 @@ async def checkin(background_tasks: BackgroundTasks, file: UploadFile = File(...
             "email": student.email,
         } if student else None
 
-        return {"message": f"{status} successful for {enc_names.get(best_student)} (dist={best_distance:.4f})", "status": True, "status_type": status, "data": user_data}
+        return {"message": f"{final_status} successful for {enc_names.get(best_student)} (dist={best_distance:.4f})", "status": True, "status_type": final_status, "data": user_data}
 
     # Nếu không thỏa threshold/rule thì trả no match (và log lý do)
     reasons = []
@@ -490,7 +479,7 @@ def delete_user(user_id: int, db: Session = Depends(get_db)):
         {"id": user_id}
     ).fetchone()
     if not student:
-        raise HTTPException(status_code=404, detail="User not found")
+        raise HTTPException(status_code=404, detail="User not found in local database")
 
     db.execute(text("DELETE FROM student_encodings WHERE student_id = :id"), {"id": user_id})
     db.execute(text("DELETE FROM checkin_logs WHERE student_id = :id"), {"id": user_id})