Build design system — Nayara Marques

Build design system

A design system AI can build with

No system yet, or one AI keeps working around. I build the foundations, components and rules an agent reads first, and review what it invents so new parts join the system.

Handover or monthly.

What gets built

Four layers, in this order

Each layer is a set of parts. Each part is held by a rule, and most rules by a check that runs on every change.

  1. Foundations

    Colour, type, space, radius and motion as tokens named for their job, so an agent picks the right one, not the nearest number. Contrast checked on every pair.

    • Tokens named for their jobPage background, body text, muted text, the rule between sections. Pages use the role, never the raw value, and a check fails any hard-coded colour.

    • Scales, not free valuesType sizes, spacing, radii and elevations each come as a short, fixed set. A value between two steps is a finding for the owner.

    • Contrast, measured renderedText is measured against the ground it actually sits on, on the rendered page, and fails below AA.

    • One sourceThe token files in the repo are the source. The design tool is updated from them, never the other way round.

  2. Components and templates

    The parts your product uses, in code, with states, limits and usage rules. Templates for repeating screens, so AI starts from what exists.

    • Reuse before drawingAn agent looks for an existing component first, and changes it only through its props, never by copying its markup.

    • One structure per jobA problem, a step, a decision and a result each have one component, so the same kind of content looks the same on every page.

    • Limits written as rulesOne filled button per view, two card widths, big numbers only for results. Each rule has an ID and one line you can pass or fail.

    • Templates with a fixed orderRepeating screens start from a template whose sections come in a set order, so a new page starts complete.

  3. Drift review

    What AI invents is tagged and reviewed: it becomes a component with rules, or is replaced by one that exists. Drift is caught in the pull request, not in a redesign a year later.

    • Proposals, markedWhen nothing fits, the agent draws the part and marks it as a proposal: what it does, the components it considered, and why each was wrong.

    • Four verdictsThe owner rules on each proposal: promote it to the system, fold it into the component that already does the job, keep it on its page, or retire it.

    • Exact swaps, automaticA hard-coded value that equals a token is swapped without asking. One a few steps off goes to the owner, with the nearest token and a recommendation.

    • Checks on every changeThe source rules run first, then every page is rendered at desktop and phone width. A change is done when both pass.

  4. Docs an agent can read

    A docs site your team browses and a coding agent parses: every part, its contract, and what to use instead.

    • One rules fileEvery rule has an ID, one line and the check that holds it, so a person and an agent read the same thing.

    • A table from job to tokenAn agent looks up the job (page background, muted text) and gets the token, instead of matching a colour by eye.

    • A decisions logEvery verdict is written down the same day, with what it rules out, so a rejected idea does not come back.

    • A progress fileWhat is done, what waits on the owner and what comes next, so the next session starts where the last one stopped.

How the system is refined

  1. 01The owner rules on something that was built, and the verdict is written down the same day.
  2. 02If a machine can check it, the verdict becomes a rule with an ID and one line you can pass or fail.
  3. 03The rule gets a check. Checks run on every change: the source first, then the rendered pages at desktop and phone width.
  4. 04What AI invents stays a proposal until the owner rules on it, and that verdict starts the loop again.

How it runs

Two ways to run it

Same build either way, foundations first. The difference is what happens after.

Option 01 · Fixed end

Build and hand over

Scoped by layer, with an end date. I build it in your repo and leave your team able to run it.

  • Foundations, components, templates in code
  • Contribution and review rules, written
  • A walkthrough for whoever inherits it
  • A month of follow-up questions

Option 02 · Monthly

Keep it living

A system nobody owns drifts within a year, faster when AI builds on it. I stay on as its owner.

  • Monthly priorities, set together
  • New components as the roadmap needs them
  • Drift, contrast and motion checked before release
  • Rolling, one month's notice either way

Either way, work lands in your repo as it goes: one standing review, the rest asynchronous, docs written along the way.

Nayara Marques

Who runs it

I build systems that ship

Nine years designing products, lately also writing the code. Based in Barcelona, on US East Coast hours. Fintech, logistics and energy, from a seed startup to one of Latin America's largest investment banks.

I built the design system for an AI platform in private capital markets, in Claude Design: 48 components, 9 templates, tokens as the single source of truth, validation that catches drift. AI tools build most of its new UI; the system keeps them on it.

Read the case

Tell me what you are building on

Thirty minutes, no deck. Bring the repo as it stands; I will say what the first month should cover, or whether an audit is enough.

Book a call