RollCage / A design workbench for real software
Design software by making software
RollCage is a workbench for product designers who make real, running software with their coding agent. Refine the smallest interface detail or shape a whole system, without stopping at mockups and handoffs.
Your design decisions stay in the repository as rules, reasoning, and checks, so they keep guiding the work as it grows.
What you can do
Work at the level you design
You and your coding agent make it together, in the running product. You bring the design judgment and direct the work. The agent writes the code and checks it.
Refine the details
Work on real components, states, tokens, accessibility, and interactions, not just mockups of them. Switch a page between states, like slow or failing data, and each one is checked for accessibility.
Shape the whole system
Work out flows, data, permissions, and how the parts connect, in the software itself. States that only appear partway through a flow are reached, checked, and photographed too.
The work remembers
Make decisions that keep working
A good design decision shouldn't vanish when the session ends. When a decision should last, and only when you say so, your agent writes it into the repository in your words: a rule, a check, or a ticket that keeps the why.
Ordinary files in your repository
The next session starts with the records of the prior decisions.
Any agent can follow them
Claude Code, Codex, or another agent that works in a repo reads the same record. Where it's a check, work that breaks it fails.
They stay yours
When you change your mind, the history of why stays. Nothing depends on an account with us.
Three ways in
Real enough to trust Safe enough to break
Learn with the example app
A working React app with nine states to switch between, from slow and failing to another user's view. Change it, break it, put it back.
Build on a new workbench
React, Vue, Svelte, or Angular, with every instrument already running.
Join your existing app
RollCage adds the method and lists every change. Your package.json, build, CI, and Git history stay as they were. The instruments come with a new workbench.