H-386: unify legacy widget message serialization (#69)

Co-authored-by: Rogee <rogee@ipao.vip>

backend/internal/handler/widget/widget_handler.go

@@ -196,14 +196,6 @@ func (h *WidgetHandler) SendMessage(c *gin.Context) {
 		return
 	}
 
-	if c.FullPath() == "/widget/messages" {
-		payload := widgetMessagePayload(resp.Message, resp.ConversationID)
-		if len(resp.Attachments) > 0 {
-			payload["attachments"] = widgetAttachmentPayloads(resp.Attachments)
-		}
-		c.JSON(http.StatusOK, resp)
-		return
-	}
 	conversationID := resp.ConversationID
 	if conversation, lookupErr := h.widgetService.GetConversation(c.Request.Context(), widgetToken, resp.ConversationID); lookupErr == nil {
 		conversationID = widgetConversationID(*conversation)

backend/internal/handler/widget/widget_handler_test.go

@@ -1931,7 +1931,7 @@ func TestWidgetHandler_ChatwootLabelsReturnNotFoundWithoutConversationContext(t
 
 // ========== SendMessage Handler Tests ==========
 
-func TestWidgetHandler_SendMessage_Success(t *testing.T) {
+func TestWidgetHandler_LegacySendMessageUsesWidgetPayload(t *testing.T) {
 	db, router, _ := setupWidgetHandlerTest(t)
 	_, _ = seedWidgetHandlerData(t, db)
 
@@ -1967,9 +1967,23 @@ func TestWidgetHandler_SendMessage_Success(t *testing.T) {
 
 	assert.Equal(t, http.StatusOK, w.Code)
 
+	var conversation model.Conversation
+	require.NoError(t, db.First(&conversation).Error)
+	displayID := uint(42)
+	require.NoError(t, db.Model(&conversation).Update("display_id", displayID).Error)
+
+	w = httptest.NewRecorder()
+	req, _ = http.NewRequest("POST", "/widget/messages", bytes.NewReader(msgJSON))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-Widget-Token", widgetToken)
+	router.ServeHTTP(w, req)
+	require.Equal(t, http.StatusOK, w.Code)
+
 	var msgResp map[string]interface{}
 	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &msgResp))
-	assert.NotEmpty(t, msgResp["message"])
+	assert.Nil(t, msgResp["message"])
+	assert.Equal(t, float64(0), msgResp["message_type"])
+	assert.Equal(t, float64(displayID), msgResp["conversation_id"])
 }
 
 func TestWidgetHandler_SendMessage_NoWidgetToken(t *testing.T) {
@@ -2098,8 +2112,7 @@ func TestWidgetHandler_GetMessages_Success(t *testing.T) {
 
 	var msgResp map[string]interface{}
 	require.NoError(t, json.Unmarshal(wMsg.Body.Bytes(), &msgResp))
-	msgData := msgResp["message"].(map[string]interface{})
-	conversationID := uint(msgData["conversation_id"].(float64))
+	conversationID := uint(msgResp["conversation_id"].(float64))
 
 	// Get messages for that conversation
 	url := "/widget/conversations/" + strconv.FormatUint(uint64(conversationID), 10) + "/messages"
@@ -2256,8 +2269,7 @@ func TestWidgetHandler_ToggleTyping_Success(t *testing.T) {
 
 	var msgResp map[string]interface{}
 	require.NoError(t, json.Unmarshal(wMsg.Body.Bytes(), &msgResp))
-	msgData := msgResp["message"].(map[string]interface{})
-	conversationID := uint(msgData["conversation_id"].(float64))
+	conversationID := uint(msgResp["conversation_id"].(float64))
 
 	// Toggle typing
 	typingBody := map[string]interface{}{