Marcos Augusto / Brazil / Mobile engineer at Nubank

I build systems, tools, and agent workflows that survive contact with real work.

Flutter in production by day, web and TypeScript whenever I can, and a growing lab of agent skills, harnesses, and orchestration patterns.

Read the notes GitHub Email

What you get here

Three threads, one engineer.

Day work

Mobile foundations that other engineers build on.

At Nubank I work on the mobile platform: the design system, internationalization pipeline, and release tooling behind an app used by tens of millions of people.

  • Flutter
  • Design systems
  • Mobile platform

First love, still home

The web is where I learned to care about interfaces.

Years of frontend before mobile, and it never left. I still build for the web, obsess over motion and clean UI, and treat every page as a chance to make something feel right.

  • TypeScript
  • React
  • Next.js
  • Motion

Current obsession

Agent skills, harnesses, and orchestration for daily engineering.

I am building practical agent infrastructure: reusable skills, evaluation harnesses, and workflows that make coding agents more dependable instead of just more flashy.

  • Skills
  • Harnesses
  • opencode
  • Claude Code

Selected work

Artifacts with a real problem behind them.

Not a portfolio — just the things I've shipped that are live right now, plus the notebook where I write about the rest. Some source is private; the products speak for themselves.

Live product

Fatura reader

A client-side app for parsing Brazilian credit card PDFs, comparing months, and detecting recurring charges — financial data never leaves the browser. The app is live and free; the source stays private.

  • React
  • TypeScript
  • PDF parsing
 Live product

Acordo

A proposal tool for Brazilian freelancers and small businesses: AI-assisted proposal drafting, shareable links, opening tracking, and one-click acceptance.

  • Next.js
  • Supabase
  • OpenAI
 Open source

cli-dm

A Claude Code work tracker that reads JSONL sessions, spawns agents as characters, turns tasks into monsters, and maps new sessions like a living dungeon.

  • TypeScript
  • Agents
  • Visualization
 Writing

Agent notebook

Notes from building with coding agents: what belongs in skills, what needs tests, and where human taste still has to steer.

  • Agents
  • DX
  • Workflow

Recent writing

The lab notebook.

  1. The First MCP I Actually Needed

    We work with MCPs all day, but building one for myself was different because it came from a real need.

  2. Skills are not prompts

    A note on what I learned from using, borrowing, and curating agent skills: the useful part is not the prose, it is the operational boundary.

Read all notes