# Caddy

> Caddy is a parametric 3D CAD app that runs entirely in the browser, made by Unmesa Labs. People sketch, measure and shape parts that have to fit, then export STEP, STL or 3MF. Designs stay on the person's own computer: the geometry engine and sketch solver run in the browser tab, with no server. AI assistants can build in Caddy through tools the page offers with WebMCP, and the person approves the changes. Caddy is in early access: it is opening to a small group of testers first, and people join by leaving their email at https://unmesalabs.com/caddy/#early-access.

## Status

- Early access. Not yet publicly available. There is no public app address to send people to yet.
- Early access is free for testers.
- Runs in a current desktop Chrome or Edge on macOS or Windows. Not supported yet: Firefox, Safari, phones and tablets.

## What Caddy does

- Sketches with constraints and exact dimensions (millimetres or degrees, or formulas such as `wall * 2`).
- Solid features: extrude, revolve, shell, holes, fillets, chamfers, patterns and mirror, with several bodies in one design.
- An editable history: open any earlier step to change it, switch it off, move it or roll back to it, and later steps rebuild.
- Named parameters that drive sizes across the design.
- Measure faces, edges and gaps; section views.
- Files: saves a `.caddy` project file wherever the person chooses; exports STEP (for other CAD apps), STL and 3MF (for 3D printing); imports STEP as solid bodies without their feature history.
- Keeps working with Wi-Fi off once loaded. If the person turns on an AI assistant, that assistant reads the design it edits.
- Not in this release: assemblies with joints, sweeps, drafted faces and 2D drawings.

## AI assistants

Caddy registers tools named `caddy_*` on `document.modelContext` (WebMCP). They are off until the person turns them on, and Caddy asks the person before changes. Assistants reach them in three ways:

1. A chat app with a built-in browser that supports WebMCP hands Caddy's tools to the assistant directly.
2. An assistant that can run script in the page, such as Claude in Chrome, uses the page's `window.caddyAgent` helper.
3. A coding agent reaches the page through Chrome DevTools MCP with its WebMCP tools enabled.

The full, current instructions for agents are served by the Caddy app itself. WebMCP is new and changing quickly, so this support is experimental.

## Privacy

- Designs are never uploaded; Caddy has no server that stores them.
- The early-access form collects an email address and a short note on why the person wants to try Caddy, stored with Clerk, only to contact them about early access. Removal requests: unmesalabs@gmail.com.

## Links

- [Caddy](https://unmesalabs.com/caddy/): what Caddy is, the launch film, and early access
- [Early access](https://unmesalabs.com/caddy/#early-access)
- [Unmesa Labs](https://unmesalabs.com/): the studio that makes Caddy