diff --git a/backend/internal/httpapi/task_api.go b/backend/internal/httpapi/task_api.go
index e31658d..f813d56 100644
--- a/backend/internal/httpapi/task_api.go
+++ b/backend/internal/httpapi/task_api.go
@@ -20,6 +20,10 @@ func (s *Server) issueDomainAsTask(c *gin.Context) {
 		s.writeError(c, http.StatusNotImplemented, "证书申请接口尚未配置", errors.New("证书申请工作流未配置"))
 		return
 	}
+	if s.repository == nil || s.tasks == nil {
+		s.writeError(c, http.StatusNotImplemented, "证书任务接口尚未配置", errors.New("域名仓储或任务仓储未配置"))
+		return
+	}
 	domainID := strings.TrimSpace(c.Param("id"))
 	if _, err := s.repository.GetByID(c.Request.Context(), domainID); err != nil {
 		if repository.IsNotFound(err) {
diff --git a/backend/internal/httpapi/task_api_test.go b/backend/internal/httpapi/task_api_test.go
index 9a65038..31e7528 100644
--- a/backend/internal/httpapi/task_api_test.go
+++ b/backend/internal/httpapi/task_api_test.go
@@ -224,3 +224,19 @@ func TestTaskAPIReplaysIdempotentIssue(t *testing.T) {
 		t.Fatalf("幂等键没有正确保存：%+v %v", items, err)
 	}
 }
+
+func TestTaskAPIReturnsNotImplementedWhenTaskDependenciesAreMissing(t *testing.T) {
+	cfg := readyTestConfig(t.TempDir())
+	server := New(Dependencies{
+		Config: cfg,
+		Tasks:  (*repository.SQLTaskRepository)(nil),
+		IssueCertificate: func(context.Context, string) (certificate.IssueResult, deployment.Report, error) {
+			return certificate.IssueResult{}, deployment.Report{}, nil
+		},
+	})
+	response := httptest.NewRecorder()
+	serveAdminHTTP(server, response, httptest.NewRequest(http.MethodPost, "/api/v1/domains/domain-1/issue", nil))
+	if response.Code != http.StatusNotImplemented || !strings.Contains(response.Body.String(), "证书任务接口尚未配置") {
+		t.Fatalf("任务依赖缺失时应返回 501：%d %s", response.Code, response.Body.String())
+	}
+}