flux-md

Zero-dep streaming markdown for the browser. A Rust→WASM core with one pooled Web Worker per stream, incremental parse with speculative closure for mid-stream constructs, and stable block identities so unchanged blocks never re-reconcile.

Wire each LLM stream to a FluxClient and the markdown renders incrementally off the main thread, block by block — so many concurrent streams render without melting the UI thread. 100% CommonMark 0.31 + GFM.

Live demo · Full docs & API → · Changelog

npm i flux-md

import { FluxMarkdown } from "flux-md/react";

// `stream` is an AsyncIterable<string> (SSE deltas), a Response, or a ReadableStream
<FluxMarkdown stream={stream} />;

Highlights

• Off the main thread — a pooled Web Worker per stream; the parser re-parses only the active tail on each token, and heavy renderers (highlighting, math, mermaid) defer until a block closes.
• SSR-safe — imports and renderToString cleanly on the server across React, Vue, Solid, and Svelte; the worker is created lazily on the client.
• Structured block.data channel (opt-in, default off) — tables, headings, code, math, and lists are exposed as typed, streaming data on block.kind.data, so you build toolbars (sort/filter/CSV), tables of contents, charts, and copy buttons from data — no HTML re-parsing, no AST tree to walk.
• Renderers for every stack — React, Vue 3, Svelte (4 & 5), Solid, a framework-agnostic <flux-markdown> Web Component, and a vanilla DOM mount.
• Zero runtime dependencies. The whole engine is one WASM binary plus a small TypeScript client.

See the package README for the full API, per-stream config, framework bindings, security model, and scaling helpers (virtualize, stickToBottom).

Repository layout

Path	What
packages/flux-md	The published npm package — TS client + renderers, and the full docs.
crates/flux-md-core	The Rust parser/renderer compiled to WASM (built on demand; not committed).
web	The live demo / playground (md.hsingh.app).

Development

bun install
bun run build:wasm        # compile the Rust core → WASM
cd packages/flux-md && bun test

CI enforces the CommonMark 652/652 + GFM conformance floors, the JS test suite, a fresh-process SSR cold-import check, and that the published tarball ships the WASM.

License

MIT