The @streamdown/cjk plugin improves handling of CJK (Chinese, Japanese, Korean) text with proper emphasis formatting and autolink handling. This is particularly important for AI-generated content, where language models naturally place emphasis markers around phrases that include or end with punctuation.

• Correct emphasis formatting near ideographic punctuation (bold, italic, strikethrough)
• Splits autolinks at CJK punctuation boundaries to prevent URLs from swallowing trailing punctuation
• Uses remark-cjk-friendly and remark-cjk-friendly-gfm-strikethrough for proper parsing

Tailwind v4

Add the following @source directive to your globals.css or main CSS file:

@source "../node_modules/@streamdown/cjk/dist/*.js";

The path must be relative from your CSS file to the node_modules folder containing @streamdown/cjk. In a monorepo, adjust the number of ../ segments to reach the root node_modules.

Tailwind v3

Add @streamdown/cjk to your content array in tailwind.config.js:

module.exports = {
  content: [
    "./app/**/*.{js,ts,jsx,tsx,mdx}",
    "./node_modules/@streamdown/cjk/dist/*.js",
  ],
  // ... rest of your config
};

In a monorepo, adjust the path to reach the root node_modules:

module.exports = {
  content: [
    "./app/**/*.{js,ts,jsx,tsx,mdx}",
    "../../node_modules/@streamdown/cjk/dist/*.js",
  ],
  // ... rest of your config
};

import { cjk } from '@streamdown/cjk';

<Streamdown plugins={{ cjk }}>
  {markdown}
</Streamdown>

For advanced configuration, use createCjkPlugin:

import { Streamdown } from "streamdown";
import { createCjkPlugin } from "@streamdown/cjk";

const cjk = createCjkPlugin();

export default function Page() {
  return (
    <Streamdown plugins={{ cjk }}>
      {markdown}
    </Streamdown>
  );
}

The CommonMark/GFM specification has a limitation where emphasis markers (** or *) adjacent to ideographic punctuation marks occasionally fail to be recognized. This causes formatting to break in CJK text:

**この文は太字になりません（This won't be bolded）。**この文のせいで（It is due to this sentence）。

Without CJK-friendly parsing, the text above would render as plain text instead of bold because the closing ** appears next to the Japanese period.

Bold Text with Punctuation

Works correctly with all ideographic punctuation marks:

**日本語の文章（括弧付き）。**この文が後に続いても大丈夫です。
**中文文本（带括号）。**这句子继续也没问题。
**한국어 구문(괄호 포함)**을 강조.

Japanese: 日本語の文章（括弧付き）。この文が後に続いても大丈夫です。

Chinese: 中文文本（带括号）。这句子继续也没问题。

Korean: 한국어 구문(괄호 포함)을 강조.

Italic Text with Punctuation

*これは斜体のテキストです（括弧付き）。*この文が後に続いても大丈夫です。
*这是斜体文字（带括号）。*这句子继续也没问题。
*이 텍스트(괄호 포함)*는 기울임꼴입니다.

Japanese: これは斜体のテキストです（括弧付き）。この文が後に続いても大丈夫です。

Chinese: 这是斜体文字（带括号）。这句子继续也没问题。

Korean: 이 텍스트(괄호 포함)는 기울임꼴입니다.

Strikethrough with Punctuation

Streamdown includes remark-cjk-friendly-gfm-strikethrough for proper strikethrough support:

~~削除されたテキスト（括弧付き）。~~この文は正しいです。
~~删除的文字（带括号）。~~这个句子是正确的。
~~이 텍스트(괄호 포함)~~를 삭제합니다.

Japanese: 削除されたテキスト（括弧付き）。この文は正しいです。

Chinese: 删除的文字（带括号）。这个句子是正确的。

Korean: 이 텍스트(괄호 포함)를 삭제합니다。

Mixed Content

CJK and English text work seamlessly together:

**重要提示（Important Notice）：**请注意。

Result: 重要提示（Important Notice）：请注意。

The plugin handles all common ideographic punctuation marks:

• Parentheses: （）
• Brackets: 【】「」〈〉
• Periods: 。．
• Commas: ，、
• Questions: ？
• Exclamations: ！
• Colons: ：

Language models generate markdown naturally, often placing emphasis markers around phrases that include punctuation. Without CJK-friendly parsing, AI-generated content in Chinese, Japanese, or Korean would have broken formatting.

❌ Without CJK support:

• The model writes: **この用語（読み方など）**について説明します。- The user sees: **この用語（読み方など）**について説明します。 (not bold!)

✅ With CJK support:

• The model writes: **この用語（読み方など）**について説明します。- The user sees: この用語（読み方など）について説明します。 (properly bolded!)

The CJK plugin also prevents autolinks from swallowing trailing CJK punctuation. When a URL ends with CJK punctuation characters, the plugin splits the link so the punctuation appears as regular text.

Example:

Check out https://example.com。这是一个链接。

Without CJK support, the trailing 。 would be included in the URL. With the plugin, the link ends at https://example.com and the period is rendered as text.

Supported boundary characters:

。．，、？！：；（）【】「」『』〈〉《》

The CJK plugin provides remark plugins in a specific order for proper integration:

interface CjkPlugin {
  // Plugins that run BEFORE remarkGfm (e.g., remark-cjk-friendly)
  remarkPluginsBefore: Pluggable[];

  // Plugins that run AFTER remarkGfm (e.g., autolink boundary, strikethrough)
  remarkPluginsAfter: Pluggable[];

  // @deprecated - Use remarkPluginsBefore and remarkPluginsAfter instead
  remarkPlugins: Pluggable[];
}

Streamdown automatically handles the plugin ordering. If integrating manually, ensure:

1. remarkPluginsBefore runs before remarkGfm (modifies emphasis handling)
2. remarkPluginsAfter runs after remarkGfm (enhances autolinks and strikethrough)