How to use Mateo with Claude Code, Cursor or Codex

← All guidesOctober 28, 2026 · 2 min read

The difference between AI-built UI that looks generic and UI that looks designed is almost entirely context. The Rebuild Package gives your coding agent that context as files. Here is the workflow, step by step.

1. Capture the page

Sign in, paste the public URL of a site you own or have permission to reproduce, and press Capture. When the capture finishes, Mateo prepares the Rebuild Package automatically. Wait for it to show as ready.

2. Export the Rebuild Package

Open Export and choose Rebuild Package. You get a zip with a folder named <domain>-rebuild/ containing:

REBUILD.md: the build specification
evidence.json: every measured value
screenshots/: visual ground truth
assets/: the site's original downloadable assets
DESIGN.md: the design language reference
AGENT_PROMPT.md: the ready-to-paste agent prompt

3. Unzip it into your project

Unzip the package into your project root, or open the folder directly. Then open the project in Claude Code, Cursor, Codex or another coding agent. The agent needs to read the files, so they have to be in its workspace.

4. Paste the agent prompt

Use Copy agent prompt in the Export menu, or open AGENT_PROMPT.md, and paste it into your agent. The prompt tells the agent to:

read REBUILD.md first
treat the screenshots as ground truth
use the files in assets/ directly
let evidence.json win whenever anything is ambiguous
ask you about anything marked (inferred) or listed under Unknowns
finish the self-validation loop in REBUILD.md §9

5. Let the agent run the self-validation loop

Section 9 of REBUILD.md is a self-validation loop: the agent compares its build against the screenshots, the measured values and the acceptance criteria, then fixes what doesn't match. Let it finish before you review. Agents are better at checking work against a document than at holding every rule while they write.

6. Iterate on known gaps

Expect a strong first pass, not a finished page. Every capture lists its known gaps: what Mateo could not verify. Your agent will ask about those instead of guessing. Answer its questions, then ask it to run the loop again.

Borrowing a look instead of rebuilding

If the site isn't yours, don't use the Rebuild Package. Export DESIGN.md instead, add it to your project, and tell your agent that all UI work follows it. You get the design language without the source's content or assets.