Hacking Tauri for Designer

wdym?

← →

You might be thinking..

1. Why it is something to do with the Designer? Tauri is somekind fo Devtool, no?
2. Tauri is using Webview, so running it in any type of browser should work out-of-the-box, no?

The idea: designers shouldn't be isolated inside Figma. They should work primarily inside the codebase, using AI agents to iterate on design directly — not just in mockups.

• The problem with Tauri: even though you're using the same frontend tech (e.g. React), the Tauri webview has __TAURI_INTERNALS__ globals that don't exist in a normal browser. Things like invoke (calling Rust commands) and event subscriptions break immediately outside the managed webview.
• So you can't just open it in Chrome and start iterating. Until now.

motivation

Ryo Lu @ryolu_

update: baby cursor can now simulate multi-agent chats & tab tab tab sequences, from a single json

if you want to be in our demos
drop screenshot / screen recording of you building with cursor below 👇 https://t.co/svgyorvrJd pic.twitter.com/b4wLebLwUZ

August 21, 2025

Rick Astley - Never Gonna Give You Up (Official Video) (4K R…

The lines got burry. Designer / Developer.

• Marketers → purely async. Write a spec, hand it off to an async coding agent (Devin, background agents, etc.), done. No need to run a live dev environment.
• Designers → purely iterative. You can't spec your way to a good design without seeing visuals first. Sketchbooks exist for a reason.
• Engineers → both. Maintenance and refactors can be async; product work is iterative. As agents get more capable, more of the async slice shifts to them.

Designer work is iterative by nature → they need a live dev environment, same as engineers. That's why the line is blurry.

implementation details

fastrepl/char#4007 to support.

How the Relay plugin works:

• Intercepts __TAURI_INTERNALS__.invoke calls inside the managed webview and replaces them with a shim.js injected via a Vite plugin.
• The shim routes commands to the Relay plugin, which runs the actual Rust handler — no Tauri globals needed in the browser.
• Events (emit/listen) are bridged over WebSocket.
• End result: the full Tauri UI runs inside Chrome or Cursor's embedded browser, not just the isolated desktop webview.

flowchart LR
  Designer -- writes --> Excalidraw
  Excalidraw -- exports --> JSON
  JSON -- injected into --> Tauri
  Tauri -- renders --> App

DX is DX

"DX(developer experience) is UX(user experience)" was kind of OG. I heard some people saying "AX(Agent) is DX(Developer)". But here I wanna say "DX(developer) is DX(designer)". Within the team.

It is all same thing. same apply to Agents...

we need more babies

Cursor has an internal tool called Baby Cursor — a simplified, minified simulation of the Cursor UI that their designer iterates on, because the real Cursor codebase is too complex to design against directly.

• Baby Cursor exists as a workaround for drift. The production codebase is too unwieldy, so a controlled sandbox was built.
• Our approach is different: the Relay plugin lets you run the actual production UI in the browser with no simplification. No controlled environment, no drift.
• Ideally, a dev environment should have minimal difference from prod. The more they drift, the less useful iteration is. Baby Cursor implicitly acknowledges that Cursor's codebase has too much drift to work around — ours doesn't need that compromise.
• Think of it as Baby Char — but it's just Char, running in your browser.

AI makes it cheap to spin up variants directly on top of real code. Code can be reused and pattern-matched far better than Figma mockups. We should be living in a world with more of these babies.