Feature request: Normalize `\(...\)` and `\[...\]` to `$$ ... $$`

[shloimy-wiesel]

Bug Description

According to the docs, Streamdown only renders mathematical expressions when they are wrapped in double dollar signs ($$).
However, AI-generated content (and many LaTeX sources) commonly use \(...\) for inline math and \[...\] for block math.

As a result, valid mathematical expressions produced by AI models are not rendered unless manually converted to $$.

This creates a mismatch between Streamdown’s expected syntax and common AI/LaTeX output.

Steps to Reproduce

1. Use Streamdown with the default math configuration.
2. Generate mathematical content using an AI model, for example openai/gpt-oss-120b, without explicitly specifying the required math delimiter format.
3. The AI may output math using common LaTeX conventions, such as:

## Inline math with \(...\)

This is inline math: \(x = \frac{1}{2}\) and another one \(E = mc^2\).

## Block math with \[...\]

\[
\int_{0}^{\infty} e^{-x^2} dx = \frac{\sqrt{\pi}}{2}
\]

4. Render the generated Markdown using Streamdown.
5. Observe how the mathematical expressions are displayed.

Expected Behavior

Streamdown should render mathematical expressions correctly, including those using LaTeX-style delimiters (\(...\) for inline math and \[...\] for block math), without requiring manual conversion to $$ ... $$.

Actual Behavior

• Mathematical expressions wrapped with \(...\) and \[...\] are rendered as plain text.
• KaTeX is not invoked for these expressions.
• Only expressions wrapped with $$ ... $$ are detected and rendered as math.

Code Sample

function normalizeMathDelimiters(input: string): string[] {
  return [
    input
      .replace(/\\\[/g, `$$$`)
      .replace(/\\\]/g, `$$$`)
      .replace(/\\\(/g, `$$$`)
      .replace(/\\\)/g, `$$$`)
  ];
}

Streamdown Version

1.6.10

React Version

19.2.3

Node.js Version

24.12.0

Browser(s)

No response

Operating System

None

Additional Context

See: vercel/ai-chatbot#716

[andreastande]

Duplicate of #194

[shloimy-wiesel]

closing as duplicated of #194