diff --git a/blocksuite/affine/shared/package.json b/blocksuite/affine/shared/package.json
index ddbf3305a1..dd8a2cecfe 100644
--- a/blocksuite/affine/shared/package.json
+++ b/blocksuite/affine/shared/package.json
@@ -10,6 +10,8 @@
   "author": "toeverything",
   "license": "MIT",
   "dependencies": {
+    "@blocksuite/affine": "workspace:*",
+    "@blocksuite/affine-ext-loader": "workspace:*",
     "@blocksuite/affine-model": "workspace:*",
     "@blocksuite/global": "workspace:*",
     "@blocksuite/icons": "^2.2.12",
@@ -63,7 +65,8 @@
     "./theme": "./src/theme/index.ts",
     "./styles": "./src/styles/index.ts",
     "./services": "./src/services/index.ts",
-    "./adapters": "./src/adapters/index.ts"
+    "./adapters": "./src/adapters/index.ts",
+    "./test-utils": "./src/test-utils/index.ts"
   },
   "files": [
     "src",
diff --git a/blocksuite/affine/shared/src/__tests__/commands/block-crud/get-first-block.unit.spec.ts b/blocksuite/affine/shared/src/__tests__/commands/block-crud/get-first-block.unit.spec.ts
index 396c43f971..18be608999 100644
--- a/blocksuite/affine/shared/src/__tests__/commands/block-crud/get-first-block.unit.spec.ts
+++ b/blocksuite/affine/shared/src/__tests__/commands/block-crud/get-first-block.unit.spec.ts
@@ -4,7 +4,7 @@
 import { describe, expect, it } from 'vitest';
 
 import { getFirstBlockCommand } from '../../../commands/block-crud/get-first-content-block';
-import { affine } from '../../helpers/affine-template';
+import { affine } from '../../../test-utils';
 
 describe('commands/block-crud', () => {
   describe('getFirstBlockCommand', () => {
diff --git a/blocksuite/affine/shared/src/__tests__/commands/block-crud/get-last-block.unit.spec.ts b/blocksuite/affine/shared/src/__tests__/commands/block-crud/get-last-block.unit.spec.ts
index af8b906fcb..34fdd8deb2 100644
--- a/blocksuite/affine/shared/src/__tests__/commands/block-crud/get-last-block.unit.spec.ts
+++ b/blocksuite/affine/shared/src/__tests__/commands/block-crud/get-last-block.unit.spec.ts
@@ -4,7 +4,7 @@
 import { describe, expect, it } from 'vitest';
 
 import { getLastBlockCommand } from '../../../commands/block-crud/get-last-content-block';
-import { affine } from '../../helpers/affine-template';
+import { affine } from '../../../test-utils';
 
 describe('commands/block-crud', () => {
   describe('getLastBlockCommand', () => {
diff --git a/blocksuite/affine/shared/src/__tests__/commands/model-crud/replace-selected-text-with-blocks.unit.spec.ts b/blocksuite/affine/shared/src/__tests__/commands/model-crud/replace-selected-text-with-blocks.unit.spec.ts
index 8a286d38ca..1ffe119536 100644
--- a/blocksuite/affine/shared/src/__tests__/commands/model-crud/replace-selected-text-with-blocks.unit.spec.ts
+++ b/blocksuite/affine/shared/src/__tests__/commands/model-crud/replace-selected-text-with-blocks.unit.spec.ts
@@ -1,13 +1,13 @@
 /**
  * @vitest-environment happy-dom
  */
-import '../../helpers/affine-test-utils';
+import '../../../test-utils/affine-test-utils';
 
 import type { TextSelection } from '@blocksuite/std';
 import { describe, expect, it } from 'vitest';
 
 import { replaceSelectedTextWithBlocksCommand } from '../../../commands/model-crud/replace-selected-text-with-blocks';
-import { affine, block } from '../../helpers/affine-template';
+import { affine, block } from '../../../test-utils';
 
 describe('commands/model-crud', () => {
   describe('replaceSelectedTextWithBlocksCommand', () => {
diff --git a/blocksuite/affine/shared/src/__tests__/commands/selection/is-nothing-selected.unit.spec.ts b/blocksuite/affine/shared/src/__tests__/commands/selection/is-nothing-selected.unit.spec.ts
index c374a90e5b..610c8a4239 100644
--- a/blocksuite/affine/shared/src/__tests__/commands/selection/is-nothing-selected.unit.spec.ts
+++ b/blocksuite/affine/shared/src/__tests__/commands/selection/is-nothing-selected.unit.spec.ts
@@ -6,7 +6,7 @@ import { describe, expect, it, vi } from 'vitest';
 
 import { isNothingSelectedCommand } from '../../../commands/selection/is-nothing-selected';
 import { ImageSelection } from '../../../selection';
-import { affine } from '../../helpers/affine-template';
+import { affine } from '../../../test-utils';
 
 describe('commands/selection', () => {
   describe('isNothingSelectedCommand', () => {
diff --git a/blocksuite/affine/shared/src/__tests__/helpers/affine-template.unit.spec.ts b/blocksuite/affine/shared/src/__tests__/test-utils/affine-template.unit.spec.ts
similarity index 99%
rename from blocksuite/affine/shared/src/__tests__/helpers/affine-template.unit.spec.ts
rename to blocksuite/affine/shared/src/__tests__/test-utils/affine-template.unit.spec.ts
index 843a07c11a..39fb5a12a7 100644
--- a/blocksuite/affine/shared/src/__tests__/helpers/affine-template.unit.spec.ts
+++ b/blocksuite/affine/shared/src/__tests__/test-utils/affine-template.unit.spec.ts
@@ -1,7 +1,7 @@
 import { TextSelection } from '@blocksuite/std';
 import { describe, expect, it } from 'vitest';
 
-import { affine } from './affine-template';
+import { affine } from '../../test-utils';
 
 describe('helpers/affine-template', () => {
   it('should create a basic document structure from template', () => {
diff --git a/blocksuite/affine/shared/src/__tests__/helpers/README.md b/blocksuite/affine/shared/src/test-utils/README.md
similarity index 100%
rename from blocksuite/affine/shared/src/__tests__/helpers/README.md
rename to blocksuite/affine/shared/src/test-utils/README.md
diff --git a/blocksuite/affine/shared/src/__tests__/helpers/affine-template.ts b/blocksuite/affine/shared/src/test-utils/affine-template.ts
similarity index 88%
rename from blocksuite/affine/shared/src/__tests__/helpers/affine-template.ts
rename to blocksuite/affine/shared/src/test-utils/affine-template.ts
index b3ce806181..393bf0e4e7 100644
--- a/blocksuite/affine/shared/src/__tests__/helpers/affine-template.ts
+++ b/blocksuite/affine/shared/src/test-utils/affine-template.ts
@@ -1,29 +1,32 @@
-import {
-  CodeBlockSchemaExtension,
-  DatabaseBlockSchemaExtension,
-  ImageBlockSchemaExtension,
-  ListBlockSchemaExtension,
-  NoteBlockSchemaExtension,
-  ParagraphBlockSchemaExtension,
-  RootBlockSchemaExtension,
-} from '@blocksuite/affine-model';
+import { getInternalStoreExtensions } from '@blocksuite/affine/extensions/store';
+import { StoreExtensionManager } from '@blocksuite/affine-ext-loader';
+import { Container } from '@blocksuite/global/di';
 import { TextSelection } from '@blocksuite/std';
-import { type Block, type Store } from '@blocksuite/store';
-import { Text } from '@blocksuite/store';
+import { type Block, type Store, Text } from '@blocksuite/store';
 import { TestWorkspace } from '@blocksuite/store/test';
 
 import { createTestHost } from './create-test-host';
 
-// Extensions array
-const extensions = [
-  RootBlockSchemaExtension,
-  NoteBlockSchemaExtension,
-  ParagraphBlockSchemaExtension,
-  ListBlockSchemaExtension,
-  ImageBlockSchemaExtension,
-  DatabaseBlockSchemaExtension,
-  CodeBlockSchemaExtension,
-];
+const manager = new StoreExtensionManager(getInternalStoreExtensions());
+const extensions = manager.get('store');
+
+// // Extensions array
+// const extensions = [
+//   RootBlockSchemaExtension,
+//   NoteBlockSchemaExtension,
+//   ParagraphBlockSchemaExtension,
+//   ListBlockSchemaExtension,
+//   ImageBlockSchemaExtension,
+//   DatabaseBlockSchemaExtension,
+//   CodeBlockSchemaExtension,
+//   RootStoreExtension,
+//   NoteStoreExtension,
+//   ParagraphStoreExtension,
+//   ListStoreExtension,
+//   ImageStoreExtension,
+//   DatabaseStoreExtension,
+//   CodeStoreExtension
+// ];
 
 // Mapping from tag names to flavours
 const tagToFlavour: Record<string, string> = {
@@ -75,8 +78,11 @@ export function affine(strings: TemplateStringsArray, ...values: any[]) {
   const workspace = new TestWorkspace({});
   workspace.meta.initialize();
   const doc = workspace.createDoc('test-doc');
-  const store = doc.getStore({ extensions });
-
+  const container = new Container();
+  extensions.forEach(extension => {
+    extension.setup(container);
+  });
+  const store = doc.getStore({ extensions, provider: container.provider() });
   let selectionInfo: SelectionInfo = {};
 
   // Use DOMParser to parse HTML string
diff --git a/blocksuite/affine/shared/src/__tests__/helpers/affine-test-utils.ts b/blocksuite/affine/shared/src/test-utils/affine-test-utils.ts
similarity index 93%
rename from blocksuite/affine/shared/src/__tests__/helpers/affine-test-utils.ts
rename to blocksuite/affine/shared/src/test-utils/affine-test-utils.ts
index ee27054de6..5ba700a82f 100644
--- a/blocksuite/affine/shared/src/__tests__/helpers/affine-test-utils.ts
+++ b/blocksuite/affine/shared/src/test-utils/affine-test-utils.ts
@@ -63,10 +63,8 @@ function compareBlocks(
   if (JSON.stringify(actualProps) !== JSON.stringify(expectedProps))
     return false;
 
-  // eslint-disable-next-line @typescript-eslint/prefer-for-of
-  for (let i = 0; i < actual.children.length; i++) {
-    if (!compareBlocks(actual.children[i], expected.children[i], compareId))
-      return false;
+  for (const [i, child] of actual.children.entries()) {
+    if (!compareBlocks(child, expected.children[i], compareId)) return false;
   }
 
   return true;
diff --git a/blocksuite/affine/shared/src/__tests__/helpers/create-test-host.ts b/blocksuite/affine/shared/src/test-utils/create-test-host.ts
similarity index 99%
rename from blocksuite/affine/shared/src/__tests__/helpers/create-test-host.ts
rename to blocksuite/affine/shared/src/test-utils/create-test-host.ts
index 4861723dea..d35f754fee 100644
--- a/blocksuite/affine/shared/src/__tests__/helpers/create-test-host.ts
+++ b/blocksuite/affine/shared/src/test-utils/create-test-host.ts
@@ -240,7 +240,7 @@ export function createTestHost(doc: Store): EditorHost {
   std.selection = new MockSelectionStore();
 
   std.command = new CommandManager(std as any);
-  // @ts-expect-error
+  // @ts-expect-error dev-only
   host.command = std.command;
   host.selection = std.selection;
 
diff --git a/blocksuite/affine/shared/src/test-utils/index.ts b/blocksuite/affine/shared/src/test-utils/index.ts
new file mode 100644
index 0000000000..9f5cd5bb48
--- /dev/null
+++ b/blocksuite/affine/shared/src/test-utils/index.ts
@@ -0,0 +1,3 @@
+export * from './affine-template';
+export * from './affine-test-utils';
+export * from './create-test-host';
diff --git a/packages/frontend/core/package.json b/packages/frontend/core/package.json
index 54c200b5a6..efd8b64c1a 100644
--- a/packages/frontend/core/package.json
+++ b/packages/frontend/core/package.json
@@ -19,6 +19,7 @@
     "@affine/templates": "workspace:*",
     "@affine/track": "workspace:*",
     "@blocksuite/affine": "workspace:*",
+    "@blocksuite/affine-shared": "workspace:*",
     "@blocksuite/icons": "^2.2.13",
     "@blocksuite/std": "workspace:*",
     "@dotlottie/player-component": "^2.7.12",
diff --git a/packages/frontend/core/src/__tests__/ai/utils/apply-model/apply-patch-to-doc.spec.ts b/packages/frontend/core/src/__tests__/ai/utils/apply-model/apply-patch-to-doc.spec.ts
new file mode 100644
index 0000000000..e730707839
--- /dev/null
+++ b/packages/frontend/core/src/__tests__/ai/utils/apply-model/apply-patch-to-doc.spec.ts
@@ -0,0 +1,99 @@
+/**
+ * @vitest-environment happy-dom
+ */
+import { affine } from '@blocksuite/affine-shared/test-utils';
+import { describe, expect, it } from 'vitest';
+
+import { applyPatchToDoc } from '../../../../blocksuite/ai/utils/apply-model/apply-patch-to-doc';
+import type { PatchOp } from '../../../../blocksuite/ai/utils/apply-model/markdown-diff';
+
+describe('applyPatchToDoc', () => {
+  it('should delete a block', async () => {
+    const host = affine`
+    <affine-page id="page">
+      <affine-note id="note">
+        <affine-paragraph id="paragraph-1">Hello</affine-paragraph>
+        <affine-paragraph id="paragraph-2">World</affine-paragraph>
+      </affine-note>
+    </affine-page>
+  `;
+
+    const patch: PatchOp[] = [{ op: 'delete', block_id: 'paragraph-1' }];
+    await applyPatchToDoc(host.store, patch);
+
+    const expected = affine`
+      <affine-page id="page">
+        <affine-note id="note">
+          <affine-paragraph id="paragraph-2">World</affine-paragraph>
+        </affine-note>
+      </affine-page>
+    `;
+
+    expect(host.store).toEqualDoc(expected.store);
+  });
+
+  it('should replace a block', async () => {
+    const host = affine`
+    <affine-page id="page">
+      <affine-note id="note">
+        <affine-paragraph id="paragraph-1">Hello</affine-paragraph>
+        <affine-paragraph id="paragraph-2">World</affine-paragraph>
+      </affine-note>
+    </affine-page>
+  `;
+
+    const patch: PatchOp[] = [
+      {
+        op: 'replace',
+        block_id: 'paragraph-1',
+        new_content: 'New content',
+      },
+    ];
+
+    await applyPatchToDoc(host.store, patch);
+
+    const expected = affine`
+      <affine-page id="page">
+        <affine-note id="note">
+          <affine-paragraph id="paragraph-1">New content</affine-paragraph>
+          <affine-paragraph id="paragraph-2">World</affine-paragraph>
+        </affine-note>
+      </affine-page>
+    `;
+
+    expect(host.store).toEqualDoc(expected.store);
+  });
+
+  it('should insert a block at index', async () => {
+    const host = affine`
+    <affine-page id="page">
+      <affine-note id="note">
+        <affine-paragraph id="paragraph-1">Hello</affine-paragraph>
+        <affine-paragraph id="paragraph-2">World</affine-paragraph>
+      </affine-note>
+    </affine-page>
+  `;
+
+    const patch: PatchOp[] = [
+      {
+        op: 'insert_at',
+        index: 2,
+        new_block: { type: 'affine:paragraph', content: 'Inserted' },
+      },
+    ];
+
+    await applyPatchToDoc(host.store, patch);
+
+    const expected = affine`
+      <affine-page id="page">
+        <affine-note id="note">
+          <affine-paragraph id="paragraph-1">Hello</affine-paragraph>
+          <affine-paragraph id="paragraph-2">World</affine-paragraph>
+          <affine-paragraph id="paragraph-3">Inserted</affine-paragraph>
+        </affine-note>
+      </affine-page>
+    `;
+
+    expect(host.store).toEqualDoc(expected.store);
+  });
+});
diff --git a/packages/frontend/core/src/__tests__/ai/utils/apply-model/markdown-diff.spec.ts b/packages/frontend/core/src/__tests__/ai/utils/apply-model/markdown-diff.spec.ts
new file mode 100644
index 0000000000..ec7d40a201
--- /dev/null
+++ b/packages/frontend/core/src/__tests__/ai/utils/apply-model/markdown-diff.spec.ts
@@ -0,0 +1,223 @@
+import { describe, expect, test } from 'vitest';
+
+import { diffMarkdown } from '../../../../blocksuite/ai/utils/apply-model/markdown-diff';
+
+describe('diffMarkdown', () => {
+  test('should diff block insertion', () => {
+    // Only a new block is inserted
+    const oldMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+`;
+    const newMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+
+<!-- block_id=block-002 type=paragraph -->
+This is a new paragraph.
+`;
+    const patch = diffMarkdown(oldMd, newMd);
+    expect(patch).toEqual([
+      {
+        op: 'insert_at',
+        index: 1,
+        new_block: {
+          type: 'paragraph',
+          content: 'This is a new paragraph.',
+        },
+      },
+    ]);
+  });
+
+  test('should diff block deletion', () => {
+    // A block is deleted
+    const oldMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+
+<!-- block_id=block-002 type=paragraph -->
+This paragraph will be deleted.
+`;
+    const newMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+`;
+    const patch = diffMarkdown(oldMd, newMd);
+    expect(patch).toEqual([
+      {
+        op: 'delete',
+        block_id: 'block-002',
+      },
+    ]);
+  });
+
+  test('should diff block replacement', () => {
+    // Only content of a block is changed
+    const oldMd = `
+<!-- block_id=block-001 type=title -->
+# Old Title
+`;
+    const newMd = `
+<!-- block_id=block-001 type=title -->
+# New Title
+`;
+    const patch = diffMarkdown(oldMd, newMd);
+    expect(patch).toEqual([
+      {
+        op: 'replace',
+        block_id: 'block-001',
+        new_content: '# New Title',
+      },
+    ]);
+  });
+
+  test('should diff mixed changes', () => {
+    // Mixed: delete, insert, replace
+    const oldMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+
+<!-- block_id=block-002 type=paragraph -->
+Old paragraph.
+
+<!-- block_id=block-003 type=paragraph -->
+To be deleted.
+`;
+    const newMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+
+<!-- block_id=block-002 type=paragraph -->
+Updated paragraph.
+
+<!-- block_id=block-004 type=paragraph -->
+New paragraph.
+`;
+    const patch = diffMarkdown(oldMd, newMd);
+    expect(patch).toEqual([
+      {
+        op: 'replace',
+        block_id: 'block-002',
+        new_content: 'Updated paragraph.',
+      },
+      {
+        op: 'insert_at',
+        index: 2,
+        new_block: {
+          type: 'paragraph',
+          content: 'New paragraph.',
+        },
+      },
+      {
+        op: 'delete',
+        block_id: 'block-003',
+      },
+    ]);
+  });
+
+  test('should diff consecutive block insertions', () => {
+    // Two new blocks are inserted consecutively
+    const oldMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+`;
+    const newMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+
+<!-- block_id=block-002 type=paragraph -->
+First inserted paragraph.
+
+<!-- block_id=block-003 type=paragraph -->
+Second inserted paragraph.
+`;
+    const patch = diffMarkdown(oldMd, newMd);
+    expect(patch).toEqual([
+      {
+        op: 'insert_at',
+        index: 1,
+        new_block: {
+          type: 'paragraph',
+          content: 'First inserted paragraph.',
+        },
+      },
+      {
+        op: 'insert_at',
+        index: 2,
+        new_block: {
+          type: 'paragraph',
+          content: 'Second inserted paragraph.',
+        },
+      },
+    ]);
+  });
+
+  test('should diff consecutive block deletions', () => {
+    // Two blocks are deleted consecutively
+    const oldMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+
+<!-- block_id=block-002 type=paragraph -->
+First paragraph to be deleted.
+
+<!-- block_id=block-003 type=paragraph -->
+Second paragraph to be deleted.
+`;
+    const newMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+`;
+    const patch = diffMarkdown(oldMd, newMd);
+    expect(patch).toEqual([
+      {
+        op: 'delete',
+        block_id: 'block-002',
+      },
+      {
+        op: 'delete',
+        block_id: 'block-003',
+      },
+    ]);
+  });
+
+  test('should diff deletion followed by insertion at the same position', () => {
+    // A block is deleted and a new block is inserted at the end
+    const oldMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+
+<!-- block_id=block-002 type=paragraph -->
+This paragraph will be deleted
+
+<!-- block_id=block-003 type=paragraph -->
+HelloWorld
+`;
+
+    const newMd = `
+<!-- block_id=block-001 type=title -->
+# Title
+
+<!-- block_id=block-003 type=paragraph -->
+HelloWorld
+
+<!-- block_id=block-004 type=paragraph -->
+This is a new paragraph inserted after deletion.
+`;
+    const patch = diffMarkdown(oldMd, newMd);
+    expect(patch).toEqual([
+      {
+        op: 'insert_at',
+        index: 2,
+        new_block: {
+          type: 'paragraph',
+          content: 'This is a new paragraph inserted after deletion.',
+        },
+      },
+      {
+        op: 'delete',
+        block_id: 'block-002',
+      },
+    ]);
+  });
+});
diff --git a/packages/frontend/core/src/blocksuite/ai/utils/apply-model/apply-patch-to-doc.ts b/packages/frontend/core/src/blocksuite/ai/utils/apply-model/apply-patch-to-doc.ts
new file mode 100644
index 0000000000..114e89ff2c
--- /dev/null
+++ b/packages/frontend/core/src/blocksuite/ai/utils/apply-model/apply-patch-to-doc.ts
@@ -0,0 +1,54 @@
+import type { Store } from '@blocksuite/store';
+
+import { insertFromMarkdown } from '../../../utils';
+import type { PatchOp } from './markdown-diff';
+
+/**
+ * Apply a list of PatchOp to the page doc (children of the first note block)
+ * @param doc The page document Store
+ * @param patch Array of PatchOp
+ */
+export async function applyPatchToDoc(
+  doc: Store,
+  patch: PatchOp[]
+): Promise<void> {
+  // Get all note blocks
+  const notes = doc.getBlocksByFlavour('affine:note');
+  if (notes.length === 0) return;
+  // Only handle the first note block
+  const note = notes[0].model;
+
+  // Build a map from block_id to BlockModel for quick lookup
+  const blockIdMap = new Map<string, any>();
+  note.children.forEach(child => {
+    blockIdMap.set(child.id, child);
+  });
+
+  for (const op of patch) {
+    if (op.op === 'delete') {
+      // Delete block
+      doc.deleteBlock(op.block_id);
+    } else if (op.op === 'replace') {
+      // Replace block: delete then insert
+      const oldBlock = blockIdMap.get(op.block_id);
+      if (!oldBlock) continue;
+      const parentId = note.id;
+      const index = note.children.findIndex(child => child.id === op.block_id);
+      if (index === -1) continue;
+      doc.deleteBlock(op.block_id);
+      // Insert new content
+      await insertFromMarkdown(undefined, op.new_content, doc, parentId, index);
+    } else if (op.op === 'insert_at') {
+      // Insert new block
+      const parentId = note.id;
+      const index = op.index;
+      await insertFromMarkdown(
+        undefined,
+        op.new_block.content,
+        doc,
+        parentId,
+        index
+      );
+    }
+  }
+}
diff --git a/packages/frontend/core/src/blocksuite/ai/utils/apply-model/markdown-diff.ts b/packages/frontend/core/src/blocksuite/ai/utils/apply-model/markdown-diff.ts
new file mode 100644
index 0000000000..c5a2c8dcac
--- /dev/null
+++ b/packages/frontend/core/src/blocksuite/ai/utils/apply-model/markdown-diff.ts
@@ -0,0 +1,111 @@
+export type Block = {
+  block_id: string;
+  type: string;
+  content: string;
+};
+
+type NewBlock = Omit<Block, 'block_id'>;
+
+export type PatchOp =
+  | { op: 'replace'; block_id: string; new_content: string }
+  | { op: 'delete'; block_id: string }
+  | { op: 'insert_at'; index: number; new_block: NewBlock };
+
+export function parseMarkdownToBlocks(markdown: string): Block[] {
+  const lines = markdown.split(/\r?\n/);
+  const blocks: Block[] = [];
+  let currentBlockId: string | null = null;
+  let currentType: string | null = null;
+  let currentContent: string[] = [];
+
+  for (const line of lines) {
+    const match = line.match(/^<!--\s*block_id=(.*?)\s+type=(.*?)\s*-->/);
+    if (match) {
+      // If there is a block being collected, push it into blocks first
+      if (currentBlockId && currentType) {
+        blocks.push({
+          block_id: currentBlockId,
+          type: currentType,
+          content: currentContent.join('\n').trim(),
+        });
+      }
+      // Start a new block
+      currentBlockId = match[1];
+      currentType = match[2];
+      currentContent = [];
+    } else {
+      // Collect content
+      if (currentBlockId && currentType) {
+        currentContent.push(line);
+      }
+    }
+  }
+  // Collect the last block
+  if (currentBlockId && currentType) {
+    blocks.push({
+      block_id: currentBlockId,
+      type: currentType,
+      content: currentContent.join('\n').trim(),
+    });
+  }
+  return blocks;
+}
+
+function diffBlockLists(oldBlocks: Block[], newBlocks: Block[]): PatchOp[] {
+  const patch: PatchOp[] = [];
+  const oldMap = new Map<string, { block: Block; index: number }>();
+  oldBlocks.forEach((b, i) => oldMap.set(b.block_id, { block: b, index: i }));
+  const newMap = new Map<string, { block: Block; index: number }>();
+  newBlocks.forEach((b, i) => newMap.set(b.block_id, { block: b, index: i }));
+
+  // Mark old blocks that have been handled
+  const handledOld = new Set<string>();
+
+  // First process newBlocks in order
+  newBlocks.forEach((newBlock, newIdx) => {
+    const old = oldMap.get(newBlock.block_id);
+    if (old) {
+      handledOld.add(newBlock.block_id);
+      if (old.block.content !== newBlock.content) {
+        patch.push({
+          op: 'replace',
+          block_id: newBlock.block_id,
+          new_content: newBlock.content,
+        });
+      }
+    } else {
+      patch.push({
+        op: 'insert_at',
+        index: newIdx,
+        new_block: {
+          type: newBlock.type,
+          content: newBlock.content,
+        },
+      });
+    }
+  });
+
+  // Then process deleted oldBlocks
+  oldBlocks.forEach(oldBlock => {
+    if (!newMap.has(oldBlock.block_id)) {
+      patch.push({
+        op: 'delete',
+        block_id: oldBlock.block_id,
+      });
+    }
+  });
+
+  return patch;
+}
+
+export function diffMarkdown(
+  oldMarkdown: string,
+  newMarkdown: string
+): PatchOp[] {
+  const oldBlocks = parseMarkdownToBlocks(oldMarkdown);
+  const newBlocks = parseMarkdownToBlocks(newMarkdown);
+
+  const patch: PatchOp[] = diffBlockLists(oldBlocks, newBlocks);
+
+  return patch;
+}
diff --git a/yarn.lock b/yarn.lock
index 9aff707fe3..e692a9875f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -399,6 +399,7 @@ __metadata:
     "@affine/templates": "workspace:*"
     "@affine/track": "workspace:*"
     "@blocksuite/affine": "workspace:*"
+    "@blocksuite/affine-shared": "workspace:*"
     "@blocksuite/icons": "npm:^2.2.13"
     "@blocksuite/std": "workspace:*"
     "@dotlottie/player-component": "npm:^2.7.12"
@@ -3731,6 +3732,8 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@blocksuite/affine-shared@workspace:blocksuite/affine/shared"
   dependencies:
+    "@blocksuite/affine": "workspace:*"
+    "@blocksuite/affine-ext-loader": "workspace:*"
     "@blocksuite/affine-model": "workspace:*"
     "@blocksuite/global": "workspace:*"
     "@blocksuite/icons": "npm:^2.2.12"