diff --git a/internal/service/taskcenter/event.go b/internal/service/taskcenter/event.go
index e2a9ff9..c734fb3 100644
--- a/internal/service/taskcenter/event.go
+++ b/internal/service/taskcenter/event.go
@@ -50,7 +50,7 @@ func (s *Service) ReceiveEvent(ctx context.Context, req EventRequest) (*EventRes
 		return nil, NewAppError(http.StatusBadRequest, "invalid_event_type", "eventType is required")
 	}
 	if !isAllowedConditionType(eventType) {
-		return &EventResponse{Processed: false, Updated: 0}, nil
+		return &EventResponse{Processed: false, Updated: 0, Reason: "unsupported_condition_type"}, nil
 	}
 	userID := req.UserID.Int64()
 	if userID <= 0 {
@@ -67,7 +67,7 @@ func (s *Service) ReceiveEvent(ctx context.Context, req EventRequest) (*EventRes
 		return nil, err
 	}
 	if existingCount > 0 {
-		return &EventResponse{Processed: false, Updated: 0}, nil
+		return &EventResponse{Processed: false, Updated: 0, Reason: "duplicate_event"}, nil
 	}
 
 	bundle, err := s.loadEnabledBundle(ctx, sysOrigin)
@@ -75,7 +75,7 @@ func (s *Service) ReceiveEvent(ctx context.Context, req EventRequest) (*EventRes
 		return nil, err
 	}
 	if bundle == nil {
-		return &EventResponse{Processed: false, Updated: 0}, nil
+		return &EventResponse{Processed: false, Updated: 0, Reason: "task_center_disabled"}, nil
 	}
 
 	matchedTasks := make([]model.TaskCenterTaskConfig, 0)
@@ -85,7 +85,7 @@ func (s *Service) ReceiveEvent(ctx context.Context, req EventRequest) (*EventRes
 		}
 	}
 	if len(matchedTasks) == 0 {
-		return &EventResponse{Processed: false, Updated: 0}, nil
+		return &EventResponse{Processed: false, Updated: 0, Reason: "no_matched_task"}, nil
 	}
 
 	occurredAt := parseOccurredAt(req.OccurredAt, time.Now())
@@ -160,7 +160,11 @@ func (s *Service) ReceiveEvent(ctx context.Context, req EventRequest) (*EventRes
 		return nil, err
 	}
 
-	return &EventResponse{Processed: updated > 0, Updated: updated}, nil
+	reason := ""
+	if updated == 0 {
+		reason = "no_updated_task"
+	}
+	return &EventResponse{Processed: updated > 0, Updated: updated, Reason: reason}, nil
 }
 
 func (s *Service) loadOrCreateProgressTx(tx *gorm.DB, sysOrigin string, userID int64, task model.TaskCenterTaskConfig, cycleKey string) (model.TaskCenterUserProgress, error) {
diff --git a/internal/service/taskcenter/types.go b/internal/service/taskcenter/types.go
index 32ebd9d..5ef9f8b 100644
--- a/internal/service/taskcenter/types.go
+++ b/internal/service/taskcenter/types.go
@@ -193,8 +193,9 @@ type EventRequest struct {
 }
 
 type EventResponse struct {
-	Processed bool `json:"processed"`
-	Updated   int  `json:"updated"`
+	Processed bool   `json:"processed"`
+	Updated   int    `json:"updated"`
+	Reason    string `json:"reason,omitempty"`
 }
 
 type PageResponse[T any] struct {