refactor(task): extract billing and polling logic from controller to service layer

Restructure the task relay system for better separation of concerns:
- Extract task billing into service/task_billing.go with unified settlement flow
- Move task polling loop from controller to service/task_polling.go (supports Suno + video platforms)
- Split RelayTask into fetch/submit paths with dedicated retry logic (taskSubmitWithRetry)
- Add TaskDto, TaskResponse generics, and FetchReq to dto/task.go
- Add taskcommon/helpers.go for shared task adaptor utilities
- Remove controller/task_video.go (logic consolidated into service layer)
- Update all task adaptors (ali, doubao, gemini, hailuo, jimeng, kling, sora, suno, vertex, vidu)
- Simplify frontend task logs to use new TaskDto response format

controller/video_proxy.go

@@ -16,59 +16,44 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
+// videoProxyError returns a standardized OpenAI-style error response.
+func videoProxyError(c *gin.Context, status int, errType, message string) {
+	c.JSON(status, gin.H{
+		"error": gin.H{
+			"message": message,
+			"type":    errType,
+		},
+	})
+}
+
 func VideoProxy(c *gin.Context) {
 	taskID := c.Param("task_id")
 	if taskID == "" {
-		c.JSON(http.StatusBadRequest, gin.H{
-			"error": gin.H{
-				"message": "task_id is required",
-				"type":    "invalid_request_error",
-			},
-		})
+		videoProxyError(c, http.StatusBadRequest, "invalid_request_error", "task_id is required")
 		return
 	}
 
 	task, exists, err := model.GetByOnlyTaskId(taskID)
 	if err != nil {
 		logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to query task %s: %s", taskID, err.Error()))
-		c.JSON(http.StatusInternalServerError, gin.H{
-			"error": gin.H{
-				"message": "Failed to query task",
-				"type":    "server_error",
-			},
-		})
+		videoProxyError(c, http.StatusInternalServerError, "server_error", "Failed to query task")
 		return
 	}
 	if !exists || task == nil {
-		logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to get task %s: %v", taskID, err))
-		c.JSON(http.StatusNotFound, gin.H{
-			"error": gin.H{
-				"message": "Task not found",
-				"type":    "invalid_request_error",
-			},
-		})
+		videoProxyError(c, http.StatusNotFound, "invalid_request_error", "Task not found")
 		return
 	}
 
 	if task.Status != model.TaskStatusSuccess {
-		c.JSON(http.StatusBadRequest, gin.H{
-			"error": gin.H{
-				"message": fmt.Sprintf("Task is not completed yet, current status: %s", task.Status),
-				"type":    "invalid_request_error",
-			},
-		})
+		videoProxyError(c, http.StatusBadRequest, "invalid_request_error",
+			fmt.Sprintf("Task is not completed yet, current status: %s", task.Status))
 		return
 	}
 
 	channel, err := model.CacheGetChannel(task.ChannelId)
 	if err != nil {
-		logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to get task %s: not found", taskID))
-		c.JSON(http.StatusInternalServerError, gin.H{
-			"error": gin.H{
-				"message": "Failed to retrieve channel information",
-				"type":    "server_error",
-			},
-		})
+		logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to get channel for task %s: %s", taskID, err.Error()))
+		videoProxyError(c, http.StatusInternalServerError, "server_error", "Failed to retrieve channel information")
 		return
 	}
 	baseURL := channel.GetBaseURL()
@@ -81,12 +66,7 @@ func VideoProxy(c *gin.Context) {
 	client, err := service.GetHttpClientWithProxy(proxy)
 	if err != nil {
 		logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to create proxy client for task %s: %s", taskID, err.Error()))
-		c.JSON(http.StatusInternalServerError, gin.H{
-			"error": gin.H{
-				"message": "Failed to create proxy client",
-				"type":    "server_error",
-			},
-		})
+		videoProxyError(c, http.StatusInternalServerError, "server_error", "Failed to create proxy client")
 		return
 	}
 
@@ -95,12 +75,7 @@ func VideoProxy(c *gin.Context) {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, "", nil)
 	if err != nil {
 		logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to create request: %s", err.Error()))
-		c.JSON(http.StatusInternalServerError, gin.H{
-			"error": gin.H{
-				"message": "Failed to create proxy request",
-				"type":    "server_error",
-			},
-		})
+		videoProxyError(c, http.StatusInternalServerError, "server_error", "Failed to create proxy request")
 		return
 	}
 
@@ -109,68 +84,43 @@ func VideoProxy(c *gin.Context) {
 		apiKey := task.PrivateData.Key
 		if apiKey == "" {
 			logger.LogError(c.Request.Context(), fmt.Sprintf("Missing stored API key for Gemini task %s", taskID))
-			c.JSON(http.StatusInternalServerError, gin.H{
-				"error": gin.H{
-					"message": "API key not stored for task",
-					"type":    "server_error",
-				},
-			})
+			videoProxyError(c, http.StatusInternalServerError, "server_error", "API key not stored for task")
 			return
 		}
-
 		videoURL, err = getGeminiVideoURL(channel, task, apiKey)
 		if err != nil {
 			logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to resolve Gemini video URL for task %s: %s", taskID, err.Error()))
-			c.JSON(http.StatusBadGateway, gin.H{
-				"error": gin.H{
-					"message": "Failed to resolve Gemini video URL",
-					"type":    "server_error",
-				},
-			})
+			videoProxyError(c, http.StatusBadGateway, "server_error", "Failed to resolve Gemini video URL")
 			return
 		}
 		req.Header.Set("x-goog-api-key", apiKey)
 	case constant.ChannelTypeOpenAI, constant.ChannelTypeSora:
-		videoURL = fmt.Sprintf("%s/v1/videos/%s/content", baseURL, task.TaskID)
+		videoURL = fmt.Sprintf("%s/v1/videos/%s/content", baseURL, task.GetUpstreamTaskID())
 		req.Header.Set("Authorization", "Bearer "+channel.Key)
 	default:
-		// Video URL is directly in task.FailReason
-		videoURL = task.FailReason
+		// Video URL is stored in PrivateData.ResultURL (fallback to FailReason for old data)
+		videoURL = task.GetResultURL()
 	}
 
 	req.URL, err = url.Parse(videoURL)
 	if err != nil {
 		logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to parse URL %s: %s", videoURL, err.Error()))
-		c.JSON(http.StatusInternalServerError, gin.H{
-			"error": gin.H{
-				"message": "Failed to create proxy request",
-				"type":    "server_error",
-			},
-		})
+		videoProxyError(c, http.StatusInternalServerError, "server_error", "Failed to create proxy request")
 		return
 	}
 
 	resp, err := client.Do(req)
 	if err != nil {
 		logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to fetch video from %s: %s", videoURL, err.Error()))
-		c.JSON(http.StatusBadGateway, gin.H{
-			"error": gin.H{
-				"message": "Failed to fetch video content",
-				"type":    "server_error",
-			},
-		})
+		videoProxyError(c, http.StatusBadGateway, "server_error", "Failed to fetch video content")
 		return
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
 		logger.LogError(c.Request.Context(), fmt.Sprintf("Upstream returned status %d for %s", resp.StatusCode, videoURL))
-		c.JSON(http.StatusBadGateway, gin.H{
-			"error": gin.H{
-				"message": fmt.Sprintf("Upstream service returned status %d", resp.StatusCode),
-				"type":    "server_error",
-			},
-		})
+		videoProxyError(c, http.StatusBadGateway, "server_error",
+			fmt.Sprintf("Upstream service returned status %d", resp.StatusCode))
 		return
 	}
 
@@ -180,10 +130,9 @@ func VideoProxy(c *gin.Context) {
 		}
 	}
 
-	c.Writer.Header().Set("Cache-Control", "public, max-age=86400") // Cache for 24 hours
+	c.Writer.Header().Set("Cache-Control", "public, max-age=86400")
 	c.Writer.WriteHeader(resp.StatusCode)
-	_, err = io.Copy(c.Writer, resp.Body)
-	if err != nil {
+	if _, err = io.Copy(c.Writer, resp.Body); err != nil {
 		logger.LogError(c.Request.Context(), fmt.Sprintf("Failed to stream video content: %s", err.Error()))
 	}
 }