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A virtual waiting room that absorbs traffic spikes on Nota Carioca and the SuperApp.
Search that reads "I want to quit smoking" and finds the city's anti-smoking program.
The Go backend behind course enrollments and job listings in the SuperApp.
1.1 million requests against five services, using 7,500 valid CPFs.
A BigQuery → Oracle load 31 to 33x faster, in production a few days after the first test.
From a fee that jumped over 6,000x to an automatic breaker for runaway APIs.
The bridge between citizens on WhatsApp and the city's AI agents.
One package so every IplanRio developer can use a coding agent safely and within budget.
Incident triage in Discord and change approval with AI risk assessment.
The webhooks that let the city chatbot issue property tax slips, open 1746 service requests and point to the nearest hospital.
Python webhooks to look up and download property tax slips with short links, query properties over VPN with encrypted tokens, open 1746 service requests with data validation and find the nearest health units by location, filtered by complexity. I also built the share.dados.rio URL shortener in Django REST with JWT.
29 merged PRs between late 2024 and early 2025, my first deliveries at IplanRio.
A rewrite of the transactional email worker, with automatic fallback to the Gmail API.
The Python worker kept stalling on the proxy tunnel to the city's SMTP relay. I rewrote it in Go consuming from RabbitMQ, with an unbuffered HTTP/1.0 tunnel reader and a Gmail API fallback when the SMTP network hangs. If the AMQP channel drops, the process exits on purpose so Kubernetes restarts it.
Two synchronized screens showing city indicators in the City Hall executive meeting room.
Merged two separate apps into a single Next.js app with one route per screen, transitions without black frames and a 6-second rotation. CI runs with zero react-doctor warnings.
Practice management for doctors and psychologists, with AI in the medical record and paying clinics.
An issue lands on the board, one agent implements, another reviews and a third validates in staging. If it breaks, the revert is automatic.
Social security case analysis for law firms, in use at two firms.
Six fiscal and finance robots became one platform, and then the product was sold.
Read-only and data-driven, to answer why CPU spikes and why deploys hang.
A public housing consultation turned into a game, used in live sessions in Bahia.
Where companies find the solar installers trained by Revolusolar.
Architecture support for a data engineering consultancy's data platform.
Kubernetes on Talos on a dedicated server, Argo Workflows pipelines, dbt on PostgreSQL with pg_duckdb, Helm charts and reproducible environments with Nix.
Short-term rental management with Airbnb calendar sync and a digital guest guide.
Restructured the project as a Turborepo monorepo, fixed the API build with esbuild and refined the year-over-year revenue view and onboarding.
Ten Elixir agents that read WhatsApp, email and calendar, and only act once you approve.
Transcribes voice notes, detects narratives and pings Telegram when a topic heats up.
A Node.js bridge on Baileys keeps one WhatsApp session per user, with the QR code streamed over SSE. FastAPI receives the events, and Celery transcribes voice notes with Gemini, scores group activity and runs narrative detection hourly without repeating topics from the last 24 h. Phone login with TOTP. 40 commits, all mine, in two weeks.
Finance, contracts, people, tasks and Gmail in one place.
Fastify, Prisma and PostgreSQL with 20 models (revenue, expenses, contracts, subscriptions, projects, documents, tasks and calendar), MinIO for files, Google and WhatsApp integrations and per-route permissions. I moved state that lived in the browser's localStorage into the API and got it ready for production.
A wagering wallet in Go where the database itself guarantees the balance never drifts from the ledger.
The server this site runs on, with one-command HTTPS previews and ops bots.
A hardened VM with Terraform, UFW, Fail2ban and an iptables chain that stops Docker from bypassing the firewall. Caddy publishes any local service on *.lab.fredzol.io with one command. A health watcher runs every 30 minutes, plus LLM spend tracking and SOPS-managed secrets. Before it, I ran a declarative NixOS homelab.
A surgery practical exam simulator, with examiner and student on separate devices.
Real-time rooms with Hono and WebSockets, a server-owned clock (1 minute to read, 5 to answer), student join by QR code and exams released by the examiner. The student never receives the answer key or an unreleased image. 100 stations, 52 of them with verbatim source content audited across 555 excerpts.
An honest test of whether atomic questions and deterministic rules can grade Brazil's national exam essays.
19 atomic questions across the 5 competencies, with all of the official rubric math in code and none in the model. Each competency is routed by confidence to automatic, a cascade to a reasoning model, or a human, and an essay is only zeroed at 90% confidence. It produced zero false zeros and a 20.7-point mean error on competency 1, but the total error was 197 points against an 80-point target. The call was to stop before spending on UI and billing.
A browser arcade where the server replays the whole match before accepting a score.
The server issues a seeded session, the client records inputs per tick, and on submit the server re-simulates the match in one of 5 engines (snake, tetris, invaders, breakout and pong), computes score and state hash and logs any mismatch. Login by wallet signature (EIP-191).
An autonomous search engine for AI agents, later adopted by the city.
Searches and crawls the web and returns ready-to-use context for the agent. It became a city service and the search tool on the MCP server.