About

Hi, I'm Serguei — a software engineer with 15 years of experience building web systems. My focus is accretive application state — systems where past states are preserved, not overwritten — and I write about that, similar concepts (such as "pseudotime", message passing) and functional thinking.

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Background

I started at Pivotal Labs (San Francisco), pair programming with hundreds of engineers and consultants across 15+ client projects — that collaborative, disciplined approach influenced me early on. I then spent 8 years building web applications in health-tech startups (Omada Health and Maximus) and spent a few years on connected-vehicle data systems at Autonomic.

Accretive Application State

My main technical interest is what I'd call "accretive application state" (by which I mean first-class, accessible past state). Think "time-travel" debugging or reporting, built-in audit trails, reduced concurrency bugs, and an occasional "undo" feature. I've spent 7 years running event-sourced systems in production. You'll hear me use pseudotime to refer to an application's own sense of time, driven by state changes rather than the clock — as a related concept.

Functional inclination

Even though I've happily spent more than half of my career with Ruby on Rails, there's a strong functional theme in everything I build — immutability, "functional core, imperative shell", separating pure calculations from side effects. I use Elixir in my side projects and I attend Elixir or Clojure meetups when I can. And if you like to nerd out about Rich Hickey talks or Alan Kay scholarship, we have a lot in common.

Get in touch

If my work overlaps with your interests — personally or for your team — contact me at serguei@filimonov.ca. I'd be happy to hear from you.