LaTeX Lab

LaTeX Lab is a zero‑setup, in‑browser workspace for typing math and seeing KaTeX render it live. The multiplayer build (branded LaTeX Salon) is live at https://latex.salon and runs entirely client‑side: peer‑to‑peer sync via Trystero, no accounts, no app server.

Multiplayer (LaTeX Salon)

• Join a room by name; anyone using the same code appears instantly.
• Edits sync peer‑to‑peer over WebRTC via Trystero (MQTT transport in this build).
• Host is elected by earliest join timestamp; the host sends full‑state syncs, everyone else sends deltas.
• Remote carets, selections, names, and color changes are broadcast live.
• Presence pills show participants with friendly color names (xkcd color list + nearest‑match).
• Local state persists (text, layout, theme, macros, cursor, scroll), so reconnects feel seamless.

Privacy & Threat Model

• No app backend stores your document. Single-player content stays in your browser unless you share it.
• Multiplayer rooms are collaborative by design: anyone with the same room code can read and edit the shared state.
• Room codes are not authenticated. Treat them as secrets and use hard-to-guess names for private sessions.
• Collaboration uses third-party relay infrastructure for peer discovery/signaling; network metadata (for example IP/timing) may be visible to those services and peers.
• Share links encode content and settings in the URL hash. Anyone with that link can read the encoded state.

What It Does Well

• Mixed mode (text + $inline$ / $$display$$) and Classic mode (each line is display math).
• Side‑by‑side editor + preview with synced line gutters and persistent split widths.
• High‑resolution PNG/PDF export with embedded fonts.
• Shareable links compress text, layout, theme, and macros into the URL.
• Matrix/table/cases builders and a macros manager for \newcommand shortcuts.
• Keyboard‑first editing: smart indent/outdent, paired delimiter insertion, Esc to close modals.

Repo & Hosting Notes

• Entry points: latex_lab_trystero.html (multiplayer) and latex_lab.html (single‑player).
• Entry pages are generated from templates/entry-page.template.html via node scripts/generate-entry-pages.mjs.
• _redirects maps / to multiplayer and /local to single‑player on the hosted site.
• Runtime code lives in assets/katex_backend.js; vendor libs and color data live in assets/vendor.
• Asset paths are absolute (/assets/...) for static hosting. If you serve from a sub‑path, adjust paths accordingly.

Runtime Dependencies

Static HTML that loads CDN‑hosted KaTeX, html‑to‑image, and html2canvas. No build step required; you just need a secure origin for WebRTC to enable multiplayer.

Testing

• Run all tests with node --test.
• Tests live in tests/katex_backend.test.cjs and execute assets/katex_backend.js in a mocked browser environment (tests/helpers/load-katex-backend.cjs).
• Playwright smoke tests (browser): LATEX_LAB_PLAYWRIGHT=1 node --test.
• Export golden tests only (browser + downloads): LATEX_LAB_EXPORT_GOLDEN=1 node --test tests/export_golden.test.cjs.
• PLAYWRIGHT=1 node --test also enables all Playwright tests, including export goldens.
• Browser tests require playwright to be installed locally. Export golden tests compare generated PNG/PDF exports against baselines in assets/images.

License

This project is licensed under GPL-3.0. See LICENSE.