Why streaming AI chat needs a renderer for incomplete Markdown

Simon He — Mon, 20 Jul 2026 07:56:55 +0000

When an AI answer arrives token by token, it spends most of its life as an incomplete Markdown document.

A code fence may be open, a table may have only its header, a formula may be half-written, or a nested list may still be taking shape. Most Markdown renderers are optimized for complete documents, so an AI chat interface can flicker between raw syntax and formatted output while the answer streams.

What a streaming-aware renderer needs to handle

A useful renderer for this state should keep partially generated content readable without pretending it is already final:

preserve stable output while an open code block is still receiving tokens;
render progressively without repeatedly rebuilding a long response;
handle Markdown structures that arrive in pieces, including tables, lists, math, and diagrams;
work with server rendering and the framework used by the chat interface.

Markstream

I maintain Markstream, an MIT-licensed renderer focused on this exact UI problem. It is intended for AI chat and LLM streaming interfaces, and has integrations for Vue/Nuxt, React/Next.js, Svelte/SvelteKit, and Angular.

It supports streaming code blocks, Mermaid diagrams, KaTeX, long responses, SSR, and safe HTML rendering. The goal is simple: keep an answer usable while it is still being written.

Live demo: https://markstream-vue.simonhe.me/
Source code: https://github.com/Simon-He95/markstream-vue

If you build streaming AI interfaces, I would be interested in the Markdown edge cases that still feel awkward in your product.

DEV Community: Simon He

Why streaming AI chat needs a renderer for incomplete Markdown

What a streaming-aware renderer needs to handle

Markstream