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 and similar concepts of "pseudotime" 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) with a detour into connected-vehicle data systems at Autonomic for a few years.

Accretive Application State

My main technical interest is what I'd call "accretive application state" — designing systems where past states are preserved rather than overwritten. 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 unifying concept for these ideas.

Functional bend

Even though I've happily spent more than half of my career with Ruby on Rails, there's a strong "functional" bend in everything I build — immutability, "functional core", separating pure calculations from side effects. I'm using Elixir in my side projects and attend Elixir or Clojure meetups when I can.

Get in touch

If you find my pursuits and experience overlap with yours personally, or your team at work, reach me at serguei@filimonov.ca. I'd be happy to hear from you.