feat(reports): align outgoing message counts

internal/handler/api/v1/analytics_handler.go

@@ -595,7 +595,7 @@ func (h *AnalyticsHandler) OutgoingMessagesCount(c *gin.Context) {
 	}
 	groupBy := c.Query("group_by")
 	if groupBy != "agent" && groupBy != "team" && groupBy != "inbox" && groupBy != "label" {
-		response.AbortWithStatusError(c, http.StatusUnprocessableEntity, response.ErrBadRequest, "invalid group_by")
+		c.Status(http.StatusUnprocessableEntity)
 		return
 	}
 

internal/handler/api/v1/analytics_handler_test.go

@@ -75,6 +75,7 @@ func (s *AnalyticsHandlerTestSuite) SetupSuite() {
 	accounts.GET("/reports/conversations", s.handler.Conversations)
 	accounts.GET("/reports/conversations_summary", s.handler.ConversationsSummary)
 	accounts.GET("/reports/inbox_label_matrix", s.handler.InboxLabelMatrix)
+	accounts.GET("/reports/outgoing_messages_count", s.handler.OutgoingMessagesCount)
 	s.router = r
 }
 
@@ -504,6 +505,15 @@ func (s *AnalyticsHandlerTestSuite) TestInboxLabelMatrix_ParsesFrontendFilters()
 	s.Require().Len(payload["labels"], 1)
 }
 
+func (s *AnalyticsHandlerTestSuite) TestOutgoingMessagesCount_InvalidGroupByReturnsEmptyUnprocessableEntity() {
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/accounts/1/reports/outgoing_messages_count?since=1735689600&until=1735776000&group_by=bad", nil)
+	s.router.ServeHTTP(w, req)
+
+	s.Equal(http.StatusUnprocessableEntity, w.Code)
+	s.Empty(w.Body.String())
+}
+
 // ========== Nil service guard ==========
 
 func (s *AnalyticsHandlerTestSuite) TestNilService() {