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This guide gets a designed, working screen out of a coding agent without leaving it. You type one request in Claude Code or Cursor, the Polymet Agent builds the screen on a canvas, and your coding agent reads the code back. The example is a settings page for Relay, a made-up team inbox app.

The same flow on a small store: add the server, ask for a page, open the canvas link, send a change. The runs are sped up, and the one-time sign-in is skipped.

  • Who it is for: a developer who works in a coding agent and wants to see a design before writing it into a codebase.
  • What it costs: the settings page below was built in under four minutes. It ran next to a second example, and the two used 145 credits together. The one fix after it used 7 credits and took under a minute. Every organization gets 500 free credits every 30 days, at most 250 a day.
  • What you need: a Polymet account, and Claude Code, Claude, Cursor or VS Code. The run below was made from Claude Code.

1. Add the Polymet MCP server

In Claude Code, run this once, then sign in to Polymet in the browser window that opens:
For Cursor, Claude and VS Code, the steps are in Use Polymet from your coding agent. You’re done with this step when your coding agent lists tools named create_project, send_prompt and get_status.

2. Ask for the screen

Say what you want in your coding agent, and say to use Polymet. Describe the product and the screen, not the code: the Polymet Agent writes the code.
“Do not ask me questions” matters here. The Polymet Agent may stop to ask Quick questions, and a coding agent cannot answer them for you. You would have to open the canvas.

3. Watch what your coding agent does

It makes three kinds of call. These are the ones from this run, with the long ids shortened:
send_prompt returns at once. Your coding agent then asks get_status until it says completed. This run was generating for under four minutes. Open the canvas link while it runs. You see the same project a teammate would: the agent’s steps in the chat and the screen on the canvas.

4. Read what it built

When the generation ends, your coding agent can read the Polymet Agent’s summary with get_conversation and the files with get_files. This run’s summary said, in part:
The files it wrote: one page (src/polymet/pages/settings.tsx), four components (profile, billing and notification settings, and a shared section), and one data file with every name and number in it. Read the summary before you trust the screen. It tells you what was added that you did not ask for, and what the agent did not check: this one said it had not looked at the page at phone width.

5. Fix what is off, from the same place

Reading the data file showed one thing wrong. The prompt said “no real names”, and the names were made up, but the profile photo was loaded from a real person’s GitHub account. One more request fixed it:
That generation used 7 credits and finished in under a minute. Your coding agent can then show exactly what changed with get_changes. Here, two files: the photo’s address became empty in the data file, and the avatar now falls back to initials on an indigo tint. Check generated sample data for real people before you show a screen to anyone. An instruction not to use real names does not cover a photo.

6. Take the design further

  • Keep designing on the canvas. Open the canvas link, click Select, point at an element and say what to change. See Select and edit with AI.
  • Bring the code into your codebase. Ask your coding agent to read the page and its components with get_files and adapt them to your project. On a paid plan it can download the whole repository instead.
  • Keep the two in step. Link the project to a GitHub repository, and every change made in Polymet is pushed to it. See Sync a project with a repository.

You’re done when

  • Your coding agent has given you a canvas link, and the link opens the project with the screen on it.
  • The three tabs switch, and Save changes is disabled until you edit a field.
  • get_changes after your fix shows only the files you expected.

If it goes wrong

  • get_status says the generation is waiting for you. The Polymet Agent asked a question or needs an approval, such as a database change. Open the canvas link and answer there. Your coding agent cannot.
  • send_prompt is refused while a generation is running. One generation runs per branch at a time. Wait for completed, then send again.
  • A generation never finishes. A generation stops after 25 minutes. Ask for a smaller piece.
  • download_repository returns an error about a paid plan. Downloading the whole repository needs one. get_files works on every plan.

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