Markdown Translator

English | 中文

Immersive bilingual Markdown translation for VSCode — read any Markdown document side-by-side in your native language without modifying the source file.

MVP Behavior

• Enhances VSCode's built-in Markdown Preview without modifying the source .md file.
• Adds a translate button to the official Markdown Preview editor title bar.
• Inserts translated text below each source block using a quote-style display.
• Supports Google Web and DeepL Free translation without an API key.
• Supports source/target language settings.

Technical Route

The project uses VSCode's official Markdown Preview as the rendering surface.

1. The user opens the built-in Markdown Preview.
2. Markdown Translator: Translate Preview is contributed to the preview editor title bar.
3. The command resolves the source Markdown document, including the webview-panel: case from preview title buttons.
4. The extension host collects translatable Markdown blocks with markdown-it.
5. The selected provider translates those blocks. Google Web uses the mobile /m endpoint; DeepL Free uses the DeepL web JSON-RPC endpoint.
6. Results are cached in memory by document URI for the current session.
7. A markdown.markdownItPlugins contribution injects translated DOM during official Markdown rendering.
8. Each completed batch updates the in-memory translation store and calls markdown.api.reloadPlugins, so long documents can progressively render translated blocks.

This keeps the source document untouched while avoiding a custom preview webview.

Interaction Rules

• If a document has no translations, the translate button starts translation.
• If a document is currently translating, clicking translate is a no-op.
• If a document is already translated, clicking translate is a no-op.
• If translation failed, clicking translate retries.
• If translations are cleared, clicking translate starts a new translation.

Commands

• Markdown Translator: Translate Preview
  • Translates the current Markdown document and refreshes the official Markdown Preview.
• Markdown Translator: Clear Preview Translations
  • Clears in-memory translations for the current Markdown Preview and refreshes the official preview.
• Markdown Translator: Select Translation Provider
  • Switches between Google Web and DeepL Free, then clears current in-memory translations.

Settings

• markdownTranslator.sourceLanguage
  • Default: auto
• markdownTranslator.targetLanguage
  • Default: zh-CN
• markdownTranslator.provider
  • Default: googleWeb
  • Options: googleWeb, deeplFree
• markdownTranslator.debugLogging
  • Default: false
  • Set to true only when collecting diagnostics. It logs block collection, provider batching, fallback behavior, and final translation mapping to the Markdown Translator output channel.
• markdownTranslator.deeplFree.requestDelayMs
  • Default: 5000
  • Increase this if DeepL Free returns rate-limit errors on long documents. Rate limits fail fast by default; click translate again later to continue unfinished blocks.
• markdownTranslator.deeplFree.retryDelayMs
  • Default: 0
• markdownTranslator.deeplFree.maxBatchTexts
  • Default: 1
• markdownTranslator.deeplFree.maxBatchCharacters
  • Default: 400

Development

npm install
npm test
npm run typecheck
npm run compile
npm run host

npm run host compiles the extension and opens a VSCode Extension Development Host window with /tmp/markdown-translator-smoke as the test workspace.

Installation

From VSCode Marketplace

Search for Markdown Translator in the Extensions view (Ctrl+Shift+X / Cmd+Shift+X), or install from the Marketplace page.

Local VSIX Install

Build a local VSIX package:

npm run package

Install it into VSCode:

code --install-extension md-immersive-translate-1.0.1.vsix

Or install from the VSCode UI:

1. Open Extensions.
2. Open the ... menu.
3. Choose Install from VSIX....
4. Select md-immersive-translate-1.0.1.vsix.

After installing, open a Markdown file, run Markdown: Open Preview to the Side, and use the Markdown Translator buttons in the preview title bar.

Notes

Current scope:

• Translate headings, paragraphs, list items, and blockquotes.
• Skip fenced code blocks, inline code, formulas, YAML front matter, HTML blocks, and tables.
• Switch between Google Web and DeepL Free from the command palette.
• Batch multiple Google Web mobile translations with stable markers, progressively render completed batches, and fall back to per-block requests if a batch result cannot be split safely.
• Send DeepL Free translations in small batches with configurable delays and retry backoff.
• Protect inline code with placeholders during translation and restore it after translation.
• Prevent concurrent translation runs for the same document.
• Keep translation state bounded in memory and clear it when Markdown documents change or close.
• Keep only current-session in-memory translation state.
• Keep detailed diagnostic logging off by default; enable markdownTranslator.debugLogging when investigating incorrect or misaligned translations.
• Keep Google Web domain and retry behavior internal for now.

Next route:

1. Install the local VSIX in daily VSCode and validate it against real Markdown documents.
2. Tune long-document batch sizing and rate-limit handling around Google Web /m limits with real documents.