I use Claude Code as my primary dev environment. It generates a lot of markdown. Planning docs, architecture notes, task lists. I wanted something purpose-built for reading markdown. Not a browser tab, not a preview pane in an editor. A real app I can launch from the terminal.

VS Code's markdown preview is fine but I don't really use VS Code. I wanted something Claude Code could launch for me and get a nice readable window.

So I built attn. One command, OS webview window, under 20MB. No Electron, no bundled Chromium.

Some things that ended up being useful:

npx attnmd README.md and it just works. Rust binary distributed through npm so you don't need cargo or a homebrew tap.

Live reload. I'm reading a plan while the agent is still writing it. Save the file, see it update.

Full ProseMirror editor with syntax highlighting, math, and mermaid. I annotate plans inline without opening another tool.

Mermaid diagrams render inline. Agents love generating mermaid.

Stack: Rust (wry/tao wrapping the OS webview — WebKit on macOS, WebKitGTK on Linux), Svelte 5 + ProseMirror frontend compiled by Vite and embedded into the binary at build time.

npx attnmd README.md to try it, cargo install attn to build from source. MIT licensed, source at github.com/lightsofapollo/attn.