Work with me
I am Lucas Firmo, a senior iOS engineer with 13 years in Swift. I currently work on Pray.com, a US consumer
subscription app. I also design the AI agent systems my production work now runs through.
Two kinds of work
Track one
I lead large, risky iOS changes in small reviewable steps. Swift, SwiftUI, UIKit and Swift 6 concurrency, on consumer apps with real traffic.
Recent proof
- Moved a production app to Swift 6 language mode in 10 days, with zero strict-concurrency warnings across the app, widget, watch and notification targets.
- Grew the unit suite by 25% during that same migration, with no big-bang change.
- Rebuilt the analytics pipeline as a Swift actor and kept the sent payloads byte-identical, pinned by tests written first.
- Fixed the paywall showing fallback prices at cold launch by rebuilding how StoreKit prices are resolved.
Track two
I design and run multi-agent coding systems on production code. I work close to the people using the system, find where it fails, and turn each failure into a tested guard.
Recent proof
- Designed the delivery system my production work runs through: agents work tickets in parallel lanes, each in its own worktree.
- Built a cross-model review gate in code. A pull request cannot open until a separate AI session signs a passing review of that exact commit.
- Made proof a merge requirement: a screenshot, captured output, or the same check failing before the fix and passing after it.
- Kept agents safe around production by default-deny. Deploys, production data and messages sent as me always wait for a human.
The two tracks meet in one place: I ran that Swift 6 migration as four parallel agent lanes, split so they never
touched the same files. The full write-up is in
How I run AI agents on production code.
Something you can try
Side project · built solo
A social app for live football matches. Every match opens a live room where fans chat, post their takes and vote
on the best ones while the game is on. Live in Brazil, in Portuguese.
I built every part of it myself: the iOS and Android apps in React Native and Expo, the backend on Supabase
(Postgres, realtime chat, auth, storage and edge functions), the database, push notifications and image moderation.
How I work
- Remote
- Based in São Paulo, Brazil. Fully remote.
- US hours
- I overlap with US working hours.
- Contractor or EOR
- Ready to start as a contractor or through an employer of record.
- No visa needed
- Nothing to sponsor. English at a professional level.
What you can expect from me
- Small, reviewable steps over big-bang rewrites.
- A test that fails before the fix, then passes after it.
- Measure before and after, and show the numbers.
- Own the problem end to end, across iOS, backend and web.