fix(agent): 图片审批 - 修改生成参数时不再因容量检查自锁

审批落库时已经持有存储锁，干跑创建任务又申请同一把锁。互斥锁不能重入，修改图片参数会一直停住，后端测试也会在 20 分钟后超时。

backend/internal/app/cloud_agent_media_approval.go

@@ -49,8 +49,10 @@ func (s *Service) updateCloudAgentMediaApproval(repo *repository.Repository, run
 	}
 	// Dry admission uses the same model, ownership and option checks as task
 	// submission, without reserving credits or creating a generation task.
+	// DecideCloudAgentApproval already holds storageMu for this mutation.
 	preparation := &creationTaskPreparation{}
 	req.creationPrepare = preparation
+	req.callerHoldsStorageMu = true
 	task, err := s.CreateTask(run.UserID, req)
 	if err != nil {
 		return err

backend/internal/app/service.go

@@ -101,16 +101,19 @@ const taskLogPayloadLimit = 4000
 type CreateTaskRequest struct {
 	creationPrepare *creationTaskPreparation
 	admission       *taskAdmission
-	ProjectID       string         `json:"projectId"`
-	Type            string         `json:"type"`
-	Operation       string         `json:"operation"`
-	Prompt          string         `json:"prompt"`
-	Provider        string         `json:"provider"`
-	Model           string         `json:"model"`
-	LogicalModelID  string         `json:"logicalModelId"`
-	Input           map[string]any `json:"input"`
-	TraceID         string         `json:"-"`
-	RequestID       string         `json:"-"`
+	// callerHoldsStorageMu 只给已经持有 Service.storageMu 的内部调用设置。
+	// 文件容量检查不能再锁一次，否则审批改参数会自锁。
+	callerHoldsStorageMu bool
+	ProjectID            string         `json:"projectId"`
+	Type                 string         `json:"type"`
+	Operation            string         `json:"operation"`
+	Prompt               string         `json:"prompt"`
+	Provider             string         `json:"provider"`
+	Model                string         `json:"model"`
+	LogicalModelID       string         `json:"logicalModelId"`
+	Input                map[string]any `json:"input"`
+	TraceID              string         `json:"-"`
+	RequestID            string         `json:"-"`
 }
 
 type TaskListOptions struct {

backend/internal/app/task_creation.go

@@ -119,8 +119,15 @@ func (s *Service) CreateTask(userID string, req CreateTaskRequest) (*model.Task,
 		return nil, BadAuthRequest(fmt.Sprintf("同时排队或运行的任务最多 %d 个，请等待已有任务完成", policy.Task.ActiveTaskLimit))
 	}
 	// 媒体任务在扣费和调用上游前确认账号文件容量，避免容量已满仍然计费却无法回存产物。
-	if err := s.requireStoredFileCapacityForTask(userID, taskType, policy); err != nil {
-		return nil, err
+	// 调用方已持锁时走不加锁的版本；这里不能再抢同一把 storageMu。
+	var capacityErr error
+	if req.callerHoldsStorageMu {
+		capacityErr = s.requireStoredFileCapacityWhileLocked(userID, taskType, policy)
+	} else {
+		capacityErr = s.requireStoredFileCapacityForTask(userID, taskType, policy)
+	}
+	if capacityErr != nil {
+		return nil, capacityErr
 	}
 	task := model.Task{ID: newID(), UserID: userID, TraceID: req.TraceID, RequestID: req.RequestID, ProjectID: req.ProjectID, Type: taskType, Status: model.TaskStatusQueued, Stage: "等待队列调度", Progress: 5, Prompt: prompt, Operation: req.Operation, Provider: req.Provider, Model: req.Model}
 	if req.admission != nil {

backend/internal/app/task_storage_admission.go

@@ -20,6 +20,15 @@ func taskTypeProducesStoredFile(taskType string) bool {
 // 账号文件容量此前只在产物回存时校验，上游调用已经发出并扣费，失败只能表现为
 // 媒体无法入库。生成任务必须在扣费前确认账号还有可用容量，容量已满时直接拒绝。
 func (s *Service) requireStoredFileCapacityForTask(userID string, taskType string, policy RuntimePolicySetting) error {
+	s.storageMu.Lock()
+	defer s.storageMu.Unlock()
+	return s.requireStoredFileCapacityWhileLocked(userID, taskType, policy)
+}
+
+// requireStoredFileCapacityWhileLocked 与上面相同，但调用方必须已经持有 storageMu。
+// sync.Mutex 不可重入；审批改参数的干跑 admission 发生在 DecideCloudAgentApproval
+// 的临界区内，再次加锁会把测试和线上审批一起卡死。
+func (s *Service) requireStoredFileCapacityWhileLocked(userID string, taskType string, policy RuntimePolicySetting) error {
 	if !taskTypeProducesStoredFile(taskType) {
 		return nil
 	}
@@ -27,8 +36,6 @@ func (s *Service) requireStoredFileCapacityForTask(userID string, taskType strin
 	if storedLimit <= 0 {
 		return nil
 	}
-	s.storageMu.Lock()
-	defer s.storageMu.Unlock()
 	storedBytes, err := s.repo.UserStoredFileBytes(userID)
 	if err != nil {
 		return err