Format Anticipation

Format anticipation lets StreamMDX render inline formatting before closing delimiters arrive. The goal is a smoother, more "live" feel while still avoiding runaway parsing.

What it does

• Allows partial emphasis/strong/strike to render as soon as the opening marker is seen.
• Lets inline and block math render early (within safe bounds).
• Can be toggled per feature, so you keep the strict behavior where you need it.

Enable it

<StreamingMarkdown
  text={content}
  features={{
    formatAnticipation: {
      inline: true,
      mathInline: true,
      mathBlock: true,
      html: true,
      mdx: true,
      regex: false,
    },
  }}
/>

Inline and block math

The block math toggle is guarded by a newline threshold so unclosed blocks do not "capture" the rest of the article. Inline math is scoped to a single line.

Inline: $E = mc^2$ and $f(x) = x^2$

Block:

$$
\mathbf{J}_f(\mathbf{x}) = \nabla f(\mathbf{x})
$$

HTML and MDX

• HTML: only allowlisted tags are eligible for anticipation.
• MDX: anticipation applies to known component tags provided in mdxComponents.

This keeps the streaming state stable while letting rich components appear as early as possible.

When to keep it off

• Content with ambiguous markers (e.g., heavy use of stray * or $).
• Strict Markdown pipelines where you want the renderer to wait for a full, valid token.

Toggles and caveats

• Inline emphasis/strong: safest to enable; closes at line boundaries.
• Math blocks: guarded by a newline threshold (default 2) so unclosed blocks don’t swallow the document.
• HTML/MDX: limited to allowlisted tags/components to avoid invalid nesting.
• Regex plugins: require start/partial/full definitions to anticipate safely.

Debugging tips

• Toggle one flag at a time to see the effect.
• Use the demo page to compare strict vs anticipated rendering.