Stefan Rusek

Principal engineer. I build systems — and systems that build systems.

Twenty years of shipping — a production compiler at Fog Creek, a three-continent 80-server network at Cheezburger, marketplace platforms at Updater and TaskRabbit. Since February 2026 I have operated in a different gear: I design and run dark factories — multi-agent AI orchestration frameworks of my own construction that turn rigorous specifications into tested, production-grade software while I sleep.

The output is held to a bar most human teams don't attempt: 100% enforced test coverage, formal invariants, generated-from-code API contracts, spec-first development under a written engineering constitution. The receipts are in git, and this resume is built so that both humans and AI reviewing agents can check every number.

108K LOCproduction platform, TypeScript + Go, built solo in ~8 weeks
62K LOCparental-control system, 100% coverage, built in one 13-hour day
98%of Sugar Maple commits carry AI co-author trailers — by design
300K+ MAUon a donation-funded app I've run since 2010
20 yrsshipping: compilers → global infra → platforms → AI orchestration

All figures verified against git on 2026-07-12 · details & methodology in the portfolio

How I work

Dark factory orchestration

I run two competing multi-agent frameworks I built and benchmark against each other — with a three-tier test harness, per-agent-role evals, ground-truth scored benchmark fixtures, and pre-registered A/B experiments with per-dispatch token telemetry. Daily driver since February 2026 (first on Augment Code, rebuilt on Claude Code that April).

Spec-driven development

Specification, plan, and task decomposition before a line of code — so agents (and humans) can implement unattended and be gated mechanically. 31 features shipped this way on Sugar Maple alone; the same method I champion at TaskRabbit.

Trust through gates — at a fraction of the cost

100% coverage thresholds, property-based tests, formal invariants, constitutions enforced by hooks — gates that don't care which model wrote the line. So the bulk of implementation runs on Haiku- and Sonnet-class models (97% of Sugar Maple's 739 model trailers; the frontier tier is reserved for judgment), outrunning big-agents-for-everything on both speed and spend.

Experience

Sugar Maple · Sugar Maple Labs, Inc. 2026 – present
Founder & sole engineer nights & weekends, building toward first revenue
TypeScript · Go · Kafka · gRPC · Kubernetes · Cloudflare Workers · OpenTofu · Postgres · MCP
TaskRabbit (an IKEA company) Aug 2024 – present
Solutions Architect Sep 2025 – present
Senior Staff Engineer, Dolly division Aug 2024 – Sep 2025
TypeScript · Kafka · event-driven microservices · API design · spec-driven AI development
Updater 2021 – 2024
Principal Software Engineer 2022 – 2024 · contract 2021–22
TypeScript · C# · Ruby · Kotlin · Rust · Go · Terraform · Auth0
Ergon Labs 2013 – 2022
Technical Consultant
TypeScript · C# · Python · Java · Objective-C · React · Angular · Django · Unity
Cheezburger Network 2008 – 2013
Director of Technology 2011 – 2013
Lead Software Engineer 2008 – 2011
C# · SQL Server · distributed infrastructure · CDN
Fog Creek Software 2005 – 2008
Member of Technical Staff
Fog Creek is the company that later created Trello and co-founded Stack Overflow.
C# · compilers · PHP · SQL Server

Selected projects

Dark Factory

AI orchestration · daily since Feb 2026

Two competing multi-agent frameworks for unattended, overnight implementation of specced features — with agent evals, ground-truth benchmarks, and pre-registered A/B experiments.

Sugar Maple

108K LOC · 8 weeks · AI-built

Collaborative docs platform where AI agents are first-class editors. TS + Go + Kafka + K8s. Live PoC deployment.

family-time

62K LOC · one 13-hour day · AI-built

Parental-control system: Windows agent, Chrome extension, backend, AI content judge. 100% coverage, property tests, deployed on Fly.io.

Ο Μαθητής

47K LOC Dart · 4 weeks · AI-built

Reader for Greek & Latin classics on the Perseus corpus, live on the web — the dark factory's first proving ground.

Unfasten

hand-written · unfasten.app

Intermittent-fasting app (Flutter + Firebase) for iOS, Android, and web. Thirteen releases; I use it every day.

OI LOGOI

hand-written · live on the web

Reader for ancient Greek New Testament manuscripts, with a custom round-trip-tested markup parser and manuscript databases.

Rusek Ministries

2010 – present · 300K+ MAU

Daily Bible-study app for iOS and Android, single Flutter codebase, donation-supported nonprofit run with my brother.

Education & community

B.S. Physics & Computer Science — Middle Tennessee State University 2003 – 2005

3.9 GPA · mathematics minor · Sigma Pi Sigma physics honor society · undergraduate research in photonic band-gap crystals and Bayesian question generation. Earlier coursework at Southern Adventist University, where I taught C# and object-oriented design in the M.S. Software Engineering program.

Community: school board member 2017–2020 (including a year as interim school director) and nonprofit treasurer 2021–2023.