fix(editor): transcript note will create useless docs (#14976)

fix #13520


#### PR Dependency Tree


* **PR #14976** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

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## Summary by CodeRabbit

* **Tests**
* Added comprehensive test coverage for markdown insertion functionality
to verify that existing document metadata remains unchanged when
importing markdown content into workspace documents.

* **Chores**
* Optimized internal markdown-to-snapshot conversion process to use a
more direct and efficient conversion approach.

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packages/frontend/core/src/blocksuite/utils/markdown-utils.spec.ts

@@ -0,0 +1,34 @@
+import 'fake-indexeddb/auto';
+
+import { getStoreManager } from '@affine/core/blocksuite/manager/store';
+import { Text } from '@blocksuite/affine/store';
+import { TestWorkspace } from '@blocksuite/affine/store/test';
+import { describe, expect, test } from 'vitest';
+
+import { insertFromMarkdown } from './markdown-utils';
+
+const extensions = getStoreManager().config.init().value.get('store');
+
+describe('markdown-utils', () => {
+  test('insertFromMarkdown does not create docs in the target workspace', async () => {
+    const collection = new TestWorkspace({ id: 'test' });
+    collection.meta.initialize();
+
+    const store = collection.createDoc('page0').getStore({ extensions });
+    store.load();
+    const rootId = store.addBlock('affine:page', {
+      title: new Text(''),
+    });
+    const noteId = store.addBlock('affine:note', {}, rootId);
+
+    await insertFromMarkdown(
+      undefined,
+      ['- Summary item', '## Decisions', '- Ship it'].join('\n'),
+      store,
+      noteId,
+      0
+    );
+
+    expect(collection.meta.docMetas.map(meta => meta.id)).toEqual(['page0']);
+  });
+});

packages/frontend/core/src/blocksuite/utils/markdown-utils.ts

@@ -153,33 +153,12 @@ export const markdownToSnapshot = async (
     pageId: store.id,
   };
 
-  const page = await markdownAdapter.toDoc(payload);
+  const snapshot = await markdownAdapter.toSliceSnapshot(payload);
-
-  if (page) {
-    const pageSnapshot = transformer.docToSnapshot(page);
-    if (pageSnapshot) {
-      const snapshot: SliceSnapshot = {
-        type: 'slice',
-        content: [
-          pageSnapshot.blocks.children.find(
-            b => b.flavour === 'affine:note'
-          ) as BlockSnapshot,
-        ],
-        workspaceId: payload.workspaceId,
-        pageId: payload.pageId,
-      };
 
   return {
     snapshot,
     transformer,
   };
-    }
-  }
-
-  return {
-    snapshot: null,
-    transformer,
-  };
 };
 
 export async function insertFromMarkdown(