feat(editor): support markdown adapter preprocessed with latex delimiters (#11431)

To close [BS-2870](https://linear.app/affine-design/issue/BS-2870/支持识别-和-[-包裹内容为公式)

## Add Markdown Preprocessor Extension and Enhanced LaTeX Support

### Markdown Preprocessor Extension
This PR introduces a new preprocessor extension for Markdown adapters that allows preprocessing of content before conversion:

Adds a new PreprocessorManager for handling text transformations
Introduces extensible preprocessor interface that supports different processing levels (block/slice/doc)

Integrates preprocessor extension into the existing Markdown adapter workflow

### LaTeX Support Enhancement
Extends LaTeX support to handle both traditional and alternative syntax:
Adds support for backslash LaTeX syntax:

Block math: ```\[...\] ``` alongside existing ```$$...$$```
Inline math: ```\(...\) ``` alongside existing ```$...$```

Implements LaTeX preprocessor to standardize syntax before conversion

Updates tests to cover both syntax variants

blocksuite/affine/shared/src/adapters/markdown/delta-converter.ts

@@ -10,7 +10,7 @@ import {
   type ASTToDeltaMatcher,
   DeltaASTConverter,
   type InlineDeltaMatcher,
-} from '../types/adapter.js';
+} from '../types/delta-converter.js';
 import type { MarkdownAST } from './type.js';
 
 export type InlineDeltaToMarkdownAdapterMatcher =

blocksuite/affine/shared/src/adapters/markdown/index.ts

@@ -1,4 +1,5 @@
 export * from './block-adapter.js';
 export * from './delta-converter.js';
 export * from './markdown.js';
+export * from './preprocessor.js';
 export * from './type.js';

blocksuite/affine/shared/src/adapters/markdown/markdown.ts

@@ -37,6 +37,7 @@ import {
   MarkdownDeltaConverter,
 } from './delta-converter';
 import { remarkGfm } from './gfm';
+import { MarkdownPreprocessorManager } from './preprocessor';
 import type { Markdown, MarkdownAST } from './type';
 
 type MarkdownToSliceSnapshotPayload = {
@@ -167,6 +168,7 @@ export class MarkdownAdapter extends BaseAdapter<Markdown> {
   };
 
   deltaConverter: MarkdownDeltaConverter;
+  preprocessorManager: MarkdownPreprocessorManager;
 
   readonly blockMatchers: BlockMarkdownAdapterMatcher[];
 
@@ -187,6 +189,7 @@ export class MarkdownAdapter extends BaseAdapter<Markdown> {
       inlineDeltaToMarkdownAdapterMatchers,
       markdownInlineToDeltaMatchers
     );
+    this.preprocessorManager = new MarkdownPreprocessorManager(provider);
   }
 
   private _astToMarkdown(ast: Root) {
@@ -273,7 +276,11 @@ export class MarkdownAdapter extends BaseAdapter<Markdown> {
   async toBlockSnapshot(
     payload: ToBlockSnapshotPayload<Markdown>
   ): Promise<BlockSnapshot> {
-    const markdownAst = this._markdownToAst(payload.file);
+    const markdownFile = this.preprocessorManager.process(
+      'block',
+      payload.file
+    );
+    const markdownAst = this._markdownToAst(markdownFile);
     const blockSnapshotRoot = {
       type: 'block',
       id: nanoid(),
@@ -297,7 +304,8 @@ export class MarkdownAdapter extends BaseAdapter<Markdown> {
   async toDocSnapshot(
     payload: ToDocSnapshotPayload<Markdown>
   ): Promise<DocSnapshot> {
-    const markdownAst = this._markdownToAst(payload.file);
+    const markdownFile = this.preprocessorManager.process('doc', payload.file);
+    const markdownAst = this._markdownToAst(markdownFile);
     const blockSnapshotRoot = {
       type: 'block',
       id: nanoid(),
@@ -356,67 +364,11 @@ export class MarkdownAdapter extends BaseAdapter<Markdown> {
   async toSliceSnapshot(
     payload: MarkdownToSliceSnapshotPayload
   ): Promise<SliceSnapshot | null> {
-    let codeFence = '';
-    payload.file = payload.file
-      .split('\n')
-      .map(line => {
-        if (line.trimStart().startsWith('-')) {
-          return line;
-        }
-        let trimmedLine = line.trimStart();
-        if (!codeFence && trimmedLine.startsWith('```')) {
-          codeFence = trimmedLine.substring(
-            0,
-            trimmedLine.lastIndexOf('```') + 3
-          );
-          if (codeFence.split('').every(c => c === '`')) {
-            return line;
-          }
-          codeFence = '';
-        }
-        if (!codeFence && trimmedLine.startsWith('~~~')) {
-          codeFence = trimmedLine.substring(
-            0,
-            trimmedLine.lastIndexOf('~~~') + 3
-          );
-          if (codeFence.split('').every(c => c === '~')) {
-            return line;
-          }
-          codeFence = '';
-        }
-        if (
-          !!codeFence &&
-          trimmedLine.startsWith(codeFence) &&
-          trimmedLine.lastIndexOf(codeFence) === 0
-        ) {
-          codeFence = '';
-        }
-        if (codeFence) {
-          return line;
-        }
-
-        trimmedLine = trimmedLine.trimEnd();
-        if (!trimmedLine.startsWith('<') && !trimmedLine.endsWith('>')) {
-          // check if it is a url link and wrap it with the angle brackets
-          // sometimes the url includes emphasis `_` that will break URL parsing
-          //
-          // eg. /MuawcBMT1Mzvoar09-_66?mode=page&blockIds=rL2_GXbtLU2SsJVfCSmh_
-          // https://www.markdownguide.org/basic-syntax/#urls-and-email-addresses
-          try {
-            const valid =
-              URL.canParse?.(trimmedLine) ?? Boolean(new URL(trimmedLine));
-            if (valid) {
-              return `<${trimmedLine}>`;
-            }
-          } catch (err) {
-            console.log(err);
-          }
-        }
-
-        return line.replace(/^ /, '&#x20;');
-      })
-      .join('\n');
-    const markdownAst = this._markdownToAst(payload.file);
+    const markdownFile = this.preprocessorManager.process(
+      'slice',
+      payload.file
+    );
+    const markdownAst = this._markdownToAst(markdownFile);
     const blockSnapshotRoot = {
       type: 'block',
       id: nanoid(),

blocksuite/affine/shared/src/adapters/markdown/preprocessor.ts

@@ -0,0 +1,40 @@
+import {
+  createIdentifier,
+  type ServiceIdentifier,
+  type ServiceProvider,
+} from '@blocksuite/global/di';
+import type { ExtensionType } from '@blocksuite/store';
+
+import {
+  type AdapterPreprocessor,
+  PreprocessorManager,
+} from '../types/preprocessor';
+import type { Markdown } from './type';
+
+export type MarkdownAdapterPreprocessor = AdapterPreprocessor<Markdown>;
+
+const MarkdownPreprocessorIdentifier =
+  createIdentifier<MarkdownAdapterPreprocessor>('MarkdownPreprocessor');
+
+export const MarkdownPreprocessorExtension = (
+  preprocessor: MarkdownAdapterPreprocessor
+): ExtensionType & {
+  identifier: ServiceIdentifier<MarkdownAdapterPreprocessor>;
+} => {
+  const identifier = MarkdownPreprocessorIdentifier(preprocessor.name);
+  return {
+    setup: di => {
+      di.addImpl(identifier, () => preprocessor);
+    },
+    identifier,
+  };
+};
+
+export class MarkdownPreprocessorManager extends PreprocessorManager<
+  Markdown,
+  MarkdownAdapterPreprocessor
+> {
+  constructor(provider: ServiceProvider) {
+    super(provider, MarkdownPreprocessorIdentifier);
+  }
+}