person
Sureffi
Software developer, Finland. .NET, Go, Rust. Products that run, and the tools coding agents work with. Available for work.
- where
- Finland
- company
- Lumio Software Oy
- sureffi@proton.me
- github
- github.com/Sureffi
what I do
I build software with coding agents, and I build the tools the agents work with. Both halves are on this site. The products are a Finnish invoicing SaaS with its first pilot onboarding, a website factory that reads a company's site and rebuilds it, and the shop that sells the rebuild. The tools are a Claude Agent SDK for .NET, a terminal renderer for graphs, UI automation for desktop apps, a bench for instruction files, and the OSINT stack the factory runs on: a page reader, API clients, a digest with sources.
how I work
- The .NET libraries here were each cut in a Claude Code session from a document that says what the thing is, and checked on a bench that a cold reader builds the same thing from it.
- .NET 10 on the back, Avalonia on the desktop, Go and Rust where a single binary is the right shape, Next.js where it was the fastest way to a paying user.
- Libraries over frameworks. One package per concern. The answer as the wire sent it, nothing folded in.
public code
- drawer, Go, MIT. A Claude Code plugin.
- CienceTerminal, .NET 8 and React 19 on AWS. Ran in production in 2025.
- inbox. An event inbox for a Claude Code session: any program on the machine sends it an event, the session wakes.
- Motion and Curse, two GTA V mod menus in Lua, written at 14 and 16. Curse has its own immediate-mode UI framework.
The rest is private. Ask, and I will walk you through any of it.