I'm John Enrique — João Henrique Barbosa on paper and on GitHub — a senior full-stack engineer in Brazil (UTC−3), nine years into shipping web systems end to end. TypeScript and React/Next.js pay the bills; Rust is where I go when correctness and performance are the point; lately a large share of my work is AI agent systems — harnesses, tool loops and session infrastructure, both in production and in public.
How I work
Three habits run through everything on this site.
The truth is in the code. I describe my work by less rather than by more, and every number I publish — test counts, stars, merged PRs — is measured against the source before it goes anywhere. If a claim can't be verified, I don't make it.
Test instead of infer. The bugs I'm proudest of finding were caught by installing and running, not by reading and assuming. A package that compiles isn't a package that works; the fiscal-rs npm entrypoint bug shipped broken for three releases precisely because nobody exercised it.
When I want to understand a mechanism, I implement the mechanism. That's why the same layout algorithm exists three times in my repos (pardal in TypeScript, cobogo in Rust), why there's a reactive framework in Go whose deliverable was proving the idea wrong, and why my agent work starts from a while loop instead of a framework.
What the work looks like
Maintainer of fiscal-rs — reviewing community PRs, holding a security bar, coordinating releases on crates.io and npm with signed provenance. Author of FinOpenPOS, an open-source POS with a full Brazilian fiscal module (81★). Twelve PRs merged into NestJS core, plus 370 tests contributed upstream to sped-nfe. The complete list, with an honest story for each repo, lives in Writing.
Off the clock
I draw with colored pencils, study the math under machine learning on paper, and once synthesized a Candomblé rhythm in pure Python to understand why it swings.
Now
I'm looking for a senior remote role — full-stack, platform, or Rust/TypeScript-heavy — on a team that values verifiable work. The fastest way to reach me is email; I reply within a day.