Software Engineer — based in Brazil. Building production software — SaaS platforms, e-commerce storefronts, serverless data pipelines, and ERP integrations.

I started in Electrical Engineering and ended up deep in software, drawn by the same thing: building systems that work precisely and reliably. I like the parts of the job most people avoid — distributed state, third-party API complexity, schema design that has to survive real-world load.

Curated collection of 23 agent skills shipped in two formats from the same SKILL.md files — a Claude Code plugin marketplace (/plugin marketplace add mqmalagris/agent-skills) or bunx skills add mqmalagris/agent-skills, which installs into any of 75+ agents. Headline is a nine-skill feature-delivery pipeline — dev-flow → grill-me → to-prd → compass → heist → maestro → pr-craft → babysit-prs — taking a feature from vague idea to merged PR, each stage consuming the prior stage's artifact and refusing to proceed on thin context; babysit-prs then drives the PR through bot and human review on its own loop until it merges. Also ships code-craft (language/framework idioms across 7 languages and 12 frameworks, with a PostToolUse hook that flips reviewer rules on automatically), a deterministic LLM-first seo audit suite, and OWASP WSTG security testing. Every skill is versioned independently with CI-validated manifests, and all use progressive disclosure: a SKILL.md router plus workflows, topics, and reference tables loaded on demand.

Pure-Rust fixed-income library: piecewise linear, natural cubic spline (C² via Thomas tridiagonal solver), PCHIP monotone Hermite, Nelson-Siegel (1987), Svensson (1994) — plus bond pricing (duration, convexity, par yield), compounding and implied-forward-rate conversion, and a zero-dependency date toolkit (ISDA 2006 day counts, business-day calendars incl. Brazil BUS/252, coupon schedules). No third-party numerical crates — bundles its own Nelder-Mead simplex optimizer. unsafe_code = "forbid", post-fit sanity checks with deterministic spline fallback, SLSA Level 3 provenance on every crates.io release.

Local-first, git-friendly API client spanning REST, GraphQL, SOAP, WebSocket, and gRPC in a single TOML collection format — a Postman/Bruno alternative. Dynamic gRPC via .proto reflection with no protoc dependency; JS pre/post-request hooks via boa_engine. CLI-first (pglot) test runner with JUnit/TAP output and CI-correct exit codes, data-driven testing (CSV/JSON), JSON Schema assertions, and snapshot testing — the same engine powers a native egui desktop app that self-updates from GitHub Releases. OpenAPI specs import straight into a TOML collection with spec tree search for picking endpoints. Tagged releases auto-publish to npm and crates.io via Trusted Publishing, with SLSA build provenance.

Flutter chord-pad synthesizer built on the Nashville Number System — tap diatonic pads or twist a joystick to morph chord quality (maj7, sus4, dim, aug). Three instrument engines (SF2 soundfont, subtractive synth, chromatic WAV sampler), a reorderable effects chain (Freeverb reverb, delay, low-pass filter), looper, arpeggiator, and a low-latency 512-frame PCM audio path with a FluidSynth fallback on desktop and web. The whole audio engine was since ported from Dart to a Rust crate behind flutter_rust_bridge + cargokit, shipped in three parts — FX chain, then the synth and sampler, then SF2 playback onto rustysynth — each landing dormant behind a render boundary and cut over only after byte-exact parity with the Dart implementation. EN/ES/FR/pt-BR i18n, RevenueCat freemium gate, v1.2.0 on Google Play via GitHub Actions signed-release CD with R8 gated in CI.

Records two or more USB microphones on one computer in sync. Each USB mic runs on its own crystal clock, so over a long take they drift apart and desync — the standard reason multi-mic setups on a single machine fall apart. The first mic listed becomes the master clock and every other mic is linear-resampled to its exact sample count over the take, correcting nominal sample-rate mismatch and drift in one step, so all tracks come out equal-length. Rust with cpal capture, lock-free rtrb ring buffers to the writer, and one WAV per mic plus a mix via hound. Zero-config CLI: bare invocation lists numbered devices, record 0,1 captures until Enter, with optional fixed duration, --normalize, and per-mic --gain. Shipped as a prebuilt Windows zip on GitHub Releases.

Public freemium REST + GraphQL API (Indicadores-BR) aggregating Brazilian and international economic data — BCB, IBGE SIDRA, Tesouro Nacional, FRED, ECB — into normalized endpoints with complete history and aggressive caching. Rust + Axum with compile-time-checked sqlx queries, apalis ingestion workers with retry and circuit breakers, real-time PTAX over WebSocket, HMAC-signed webhooks and alerts, and financial calculators (SAC/Price amortization, monetary correction, CDB/LCI/LCA comparison). Yield-curve endpoints are backed by my own yield-curves crate. Single binary on Fly.io; OpenAPI docs and Swagger UI at api.economapy.com/docs.

Languages

Frontend

Mobile

Backend

Databases

Cloud & Infra

Tooling & Testing

B.Eng. Electrical Engineering — CEFET-RJ, Brazil. The engineering mindset stuck: understand the system, find the constraint, fix it properly.

• Email — matheus@malagris.dev