feat(tasks): implement atomic claims and leases

backend-api/internal/transport/webui/handler.go

@@ -299,9 +299,9 @@ func (h *Handler) CancelTask(ctx *gin.Context) {
 		)
 		return
 	}
-	_, err := h.service.CancelPending(
+	task, err := h.service.CancelTask(
 		ctx.Request.Context(),
-		CancelPendingInput{
+		CancelTaskInput{
 			TaskID:         taskID,
 			IdempotencyKey: cancelKey,
 		},
@@ -317,9 +317,13 @@ func (h *Handler) CancelTask(ctx *gin.Context) {
 		h.renderServiceError(ctx, err, "取消失败，请稍后重试。")
 		return
 	}
+	notice := "cancel-requested"
+	if task.Status == "CANCELED" {
+		notice = "canceled"
+	}
 	ctx.Redirect(
 		http.StatusSeeOther,
-		"/tasks/"+pathEscape(taskID)+"?notice=canceled",
+		"/tasks/"+pathEscape(taskID)+"?notice="+notice,
 	)
 }
 
@@ -644,6 +648,8 @@ func detailNotice(value string) string {
 	switch value {
 	case "canceled":
 		return "任务已取消，不会自动恢复。"
+	case "cancel-requested":
+		return "已请求设备安全停止；设备确认前任务仍保持当前执行状态。"
 	case "cancel-conflict":
 		return "任务状态已变化，当前不能取消。"
 	default:
@@ -736,19 +742,20 @@ type newTaskPageView struct {
 }
 
 type taskDetailView struct {
-	ID               string
-	Title            string
-	SKU              string
-	Description      string
-	Quantity         int64
-	MaxBudget        string
-	Status           string
-	StatusLabel      string
-	StatusClass      string
-	ReferenceAssetID string
-	CreatedAt        time.Time
-	UpdatedAt        time.Time
-	CanCancel        bool
+	ID                string
+	Title             string
+	SKU               string
+	Description       string
+	Quantity          int64
+	MaxBudget         string
+	Status            string
+	StatusLabel       string
+	StatusClass       string
+	ReferenceAssetID  string
+	CreatedAt         time.Time
+	UpdatedAt         time.Time
+	CanCancel         bool
+	CancelRequiresAck bool
 }
 
 type taskDetailPage struct {
@@ -779,7 +786,18 @@ func taskDetailViewFrom(task Task) taskDetailView {
 		ReferenceAssetID: task.ReferenceAssetID,
 		CreatedAt:        task.CreatedAt,
 		UpdatedAt:        task.UpdatedAt,
-		CanCancel:        task.Status == "PENDING",
+		CanCancel:        canCancelTaskStatus(task.Status),
+		CancelRequiresAck: task.Status == "RUNNING" ||
+			task.Status == "WAITING_CONFIRMATION",
+	}
+}
+
+func canCancelTaskStatus(status string) bool {
+	switch status {
+	case "PENDING", "CLAIMED", "RUNNING", "WAITING_CONFIRMATION":
+		return true
+	default:
+		return false
 	}
 }