Fix: dsl import/export (#13992)

### What problem does this PR solve?

Fix: dsl import/export
### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)



<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **New Features**
* Enhanced JSON import functionality for agents to automatically
populate components from imported graph structures.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Zhichang Yu <yuzhichang@gmail.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

test/testcases/test_web_api/test_chunk_feedback/__init__.py

@@ -12,4 +12,7 @@
 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
-#
+
+from rag.flow.chunker.token_chunker import TokenChunker, TokenChunkerParam
+
+__all__ = ["TokenChunker", "TokenChunkerParam"]

web/src/pages/agents/use-import-json.ts

@@ -8,6 +8,7 @@ import { Node } from '@xyflow/react';
 import isEmpty from 'lodash/isEmpty';
 import { useCallback } from 'react';
 import { useTranslation } from 'react-i18next';
+import { buildDslComponentsByGraph } from '../agent/utils';
 import { DataflowEmptyDsl } from './hooks/use-create-agent';
 import { FormSchemaType } from './upload-agent-dialog/upload-agent-form';
 
@@ -65,6 +66,14 @@ export const useHandleImportJsonFile = () => {
               dsl.variables = graphOrDsl.variables;
             }
 
+            if (Array.isArray(graph?.nodes) && Array.isArray(graph?.edges)) {
+              dsl.components = buildDslComponentsByGraph(
+                graph.nodes as any,
+                graph.edges as any,
+                graphOrDsl.components ?? dsl.components,
+              );
+            }
+
             setAgent({
               title: name,
               dsl,