feat: enhance Milkdown editor and file system functionality

- Normalize line endings in Markdown export for DOCX files.
- Improve selection serialization to Markdown with better handling of empty documents.
- Add a new `updateFile` function to the file system for updating file properties.
- Introduce video transcoding capabilities using FFmpeg, supporting various video formats.
- Update AGENTS.md for clearer plugin structure and responsibilities.
- Add scoped styles for TreeNodeItem component to improve UI consistency.
- Implement cross-origin isolation headers in Vite configuration for enhanced security.
- Remove obsolete test_cross.py file.

src/utils/docBlock.js

@@ -5,6 +5,17 @@ export const DOC_CONTEXT_LIMIT = 32 * 1024
 const IMAGE_MD_RE = /!\[[^\]]*]\([^)]+\)/g
 const IMAGE_HTML_RE = /<img\b[^>]*>/gi
 const HEADER_SEPARATOR = '\n---\n'
+const FENCED_DOC_BLOCK_RE = /(^|\n)(`{3,})llm-file[^\n]*\n([\s\S]*?)\n\2(?=\n|$)/g
+const LEGACY_DOC_BLOCK_RE = /<doc_type="[^"]+"\s+doc_name="[^"]+"\s+upload_time="[^"]+"(?:\s+collapsed="[^"]+")?>[\s\S]*?<\/doc_end>/g
+
+function normalizeMarkdownText(markdown = '') {
+  return String(markdown || '').replace(/\r\n?/g, '\n')
+}
+
+function clipDocContext(content = '', limit = 0) {
+  if (!limit || content.length <= limit) return content
+  return `${content.slice(0, limit)}...`
+}
 
 export function normalizeDocType(value = '') {
   const lower = String(value || '').trim().toLowerCase()
@@ -54,12 +65,9 @@ export function isSupportedDocFile(file) {
 }
 
 export function sanitizeDocContent(markdown = '') {
-  return String(markdown || '')
-    .replace(/\r\n?/g, '\n')
+  return normalizeMarkdownText(markdown)
     .replace(IMAGE_MD_RE, '')
     .replace(IMAGE_HTML_RE, '')
-    .replace(/\n{3,}/g, '\n\n')
-    .trim()
 }
 
 function quoteMeta(value = '') {
@@ -102,7 +110,7 @@ export function buildDocBlockValue(attrs = {}) {
 }
 
 export function parseDocBlockValue(raw = '') {
-  const normalized = String(raw || '').replace(/\r\n?/g, '\n')
+  const normalized = normalizeMarkdownText(raw)
   const separatorIndex = normalized.indexOf(HEADER_SEPARATOR)
   const headerText = separatorIndex >= 0 ? normalized.slice(0, separatorIndex) : ''
   const bodyText = separatorIndex >= 0 ? normalized.slice(separatorIndex + HEADER_SEPARATOR.length) : normalized
@@ -150,7 +158,8 @@ export function buildLegacyDocBlock(attrs = {}) {
 }
 
 export function parseLegacyDocBlock(raw = '') {
-  const match = String(raw || '').match(/^<doc_type="([^"]+)"\s+doc_name="([^"]+)"\s+upload_time="([^"]+)"(?:\s+collapsed="([^"]+)")?>\n?([\s\S]*?)\n?<\/doc_end>$/)
+  const normalized = normalizeMarkdownText(raw)
+  const match = normalized.match(/^<doc_type="([^"]+)"\s+doc_name="([^"]+)"\s+upload_time="([^"]+)"(?:\s+collapsed="([^"]+)")?>\n?([\s\S]*?)\n?<\/doc_end>$/)
   if (!match) return null
   return {
     docType: normalizeDocType(match[1]),
@@ -161,33 +170,57 @@ export function parseLegacyDocBlock(raw = '') {
   }
 }
 
+export function extractDocBlockContextFromMarkdown(markdown = '', contentLimit = 0) {
+  const normalized = normalizeMarkdownText(markdown)
+  const contexts = []
+  const appendContext = (attrs) => {
+    if (!attrs) return
+    const rawContent = String(attrs.content || '')
+    if (!rawContent.trim()) return
+    contexts.push(buildDocContextFence({
+      docType: attrs.docType,
+      content: clipDocContext(rawContent, contentLimit),
+    }))
+  }
+
+  normalized.replace(FENCED_DOC_BLOCK_RE, (_full, _prefix, _fence, value) => {
+    appendContext(parseDocBlockValue(value))
+    return _full
+  })
+
+  normalized.replace(LEGACY_DOC_BLOCK_RE, (full) => {
+    appendContext(parseLegacyDocBlock(full))
+    return full
+  })
+
+  return contexts.join('\n\n')
+}
+
 export function transformDocBlockMarkdownForClipboard(markdown = '') {
-  const pattern = /(^|\n)(`{3,})llm-file[^\n]*\n([\s\S]*?)\n\2(?=\n|$)/g
-  const replacedFence = String(markdown || '').replace(pattern, (full, prefix, _fence, value) => {
+  const normalized = normalizeMarkdownText(markdown)
+  const replacedFence = normalized.replace(FENCED_DOC_BLOCK_RE, (full, prefix, _fence, value) => {
     const attrs = parseDocBlockValue(value)
     return `${prefix}${buildDocContextFence(attrs)}`
   })
-  return replacedFence.replace(/<doc_type="[^"]+"\s+doc_name="[^"]+"\s+upload_time="[^"]+"(?:\s+collapsed="[^"]+")?>[\s\S]*?<\/doc_end>/g, (full) => {
+  return replacedFence.replace(LEGACY_DOC_BLOCK_RE, (full) => {
     const attrs = parseLegacyDocBlock(full)
     return attrs ? buildDocContextFence(attrs) : full
   })
 }
 
 export function stripDocBlockMarkdown(markdown = '') {
-  const pattern = /(^|\n)(`{3,})llm-file[^\n]*\n[\s\S]*?\n\2(?=\n|$)/g
-  return String(markdown || '').replace(pattern, '$1').replace(/\n{3,}/g, '\n\n').trim()
+  return normalizeMarkdownText(markdown).replace(FENCED_DOC_BLOCK_RE, '$1')
 }
 
 export function transformLegacyDocBlocksForExport(markdown = '') {
-  return String(markdown || '').replace(/<doc_type="[^"]+"\s+doc_name="[^"]+"\s+upload_time="[^"]+"(?:\s+collapsed="[^"]+")?>[\s\S]*?<\/doc_end>/g, (full) => {
+  return normalizeMarkdownText(markdown).replace(LEGACY_DOC_BLOCK_RE, (full) => {
     const attrs = parseLegacyDocBlock(full)
     return attrs ? buildDocBlockMarkdown(attrs) : full
   })
 }
 
 export function transformSpecialDocBlocksToLegacy(markdown = '') {
-  const pattern = /(^|\n)(`{3,})llm-file[^\n]*\n([\s\S]*?)\n\2(?=\n|$)/g
-  return String(markdown || '').replace(pattern, (full, prefix, _fence, value) => {
+  return normalizeMarkdownText(markdown).replace(FENCED_DOC_BLOCK_RE, (full, prefix, _fence, value) => {
     const attrs = parseDocBlockValue(value)
     return `${prefix}${buildLegacyDocBlock(attrs)}`
   })