fix: 防止开始节点重名参数被删除

- 校验开始节点参数名并保留冲突输入

- 在字段归一化前拦截重名并补充回归测试

easyflow-ui-admin/packages/tinyflow-ui/src/utils/workflowNodeFields.test.ts

@@ -13,6 +13,7 @@ import {
   createInitialWorkflowData,
   ensureStartNodeParameters,
   FIELD_BINDING_META_KEY,
+  isStartFormFieldKeyAvailable,
   normalizeStartNodeData,
   normalizeWorkflowStartNodes,
   renameStartFieldReferencesInNodes,
@@ -148,6 +149,47 @@ describe('workflow node fields', () => {
     expect(nextParameter?.id).toBe(previousParameter?.id);
   });
 
+  it('keeps start fields unchanged when renaming to an existing key', () => {
+    const initial = createInitialWorkflowData();
+    const withTopic = appendStartFormField(
+      initial.nodes[0]?.data as Record<string, any>,
+      {
+        key: 'topic',
+        label: '主题',
+        type: 'text',
+      },
+    );
+    const withDetails = appendStartFormField(withTopic, {
+      key: 'details',
+      label: '详情',
+      type: 'textarea',
+    });
+    const previousFields = withDetails.startFormSchema;
+    const previousParameters = withDetails.parameters;
+
+    expect(
+      isStartFormFieldKeyAvailable(withDetails, 'details', 'summary'),
+    ).toBe(true);
+    expect(
+      isStartFormFieldKeyAvailable(withDetails, 'details', 'topic'),
+    ).toBe(false);
+    expect(
+      isStartFormFieldKeyAvailable(withDetails, 'details', 'user_input'),
+    ).toBe(false);
+
+    const duplicatedCustomKey = updateStartFormField(withDetails, 'details', {
+      key: 'topic',
+    });
+    const duplicatedSystemKey = updateStartFormField(withDetails, 'details', {
+      key: 'user_input',
+    });
+
+    expect(duplicatedCustomKey.startFormSchema).toEqual(previousFields);
+    expect(duplicatedCustomKey.parameters).toEqual(previousParameters);
+    expect(duplicatedSystemKey.startFormSchema).toEqual(previousFields);
+    expect(duplicatedSystemKey.parameters).toEqual(previousParameters);
+  });
+
   it('renames downstream token and managed references when start field key changes', () => {
     const initialStartData = appendStartFormField(
       createInitialWorkflowData().nodes[0]?.data as Record<string, any>,