From AS/400s to AI Agent Swarms

Mon, 30 Mar 2026 20:54:15 +0000

I've spent 16 years building software — starting on IBM WebSphere Commerce platforms for major retailers, eventually leading architecture at companies like Hertz, DaVita, Chick-fil-A, Wayfair, and Kohl's, and now running a fractional CTO practice out of Austin.

I wanted to introduce myself to the CoderLegion community because I've been writing more this year, and the response has been eye-opening. My post about building a 35-agent AI coding swarm got more engagement in a week than anything I'd published in years. Turns out people want to read about what actually happens in production — not the sanitized conference-talk version, but the real decisions, trade-offs, and scars.

So that's what I write about.

What I've Been Working On

My most recent deep-dive was about the architecture behind a 6,000% throughput improvement at Hertz. The short version: their rate engine was doing 300 requests per second with p90 latency over a minute. We rebuilt it with CQRS, CDC-powered caching, and Kinesis streaming. The result was 3,000+ reads/sec at p95 under 30ms. The post walks through every architectural decision and why we made it — including the ones that didn't work the first time.

Before that, I wrote about orchestrating a swarm of 35 AI coding agents that run overnight — spawning specialized agents for different tasks, coordinating them through a hierarchical topology, and waking up to pull requests that are actually useful. It's the kind of thing that sounds like science fiction until you see the git log.

What I Build Day to Day

Right now I split my time between:

Fractional CTO work — leading platform rebuilds, defining architecture, running weekly executive checkins for clients who need senior technical leadership without a full-time hire
Enterprise commerce — about a decade of IBM WebSphere Commerce, plus Magento, Shopify, and BigCommerce across major retailers and enterprise brands
AI/ML in production — not just prototypes, but edge AI video pipelines feeding vision models on Raspberry Pis, agentic workflows that actually ship code, and real-time analysis at the edge
Distributed systems — the Hertz work, DaVita's 100+ microservices, Chick-fil-A's offline-first POS system across 3,000+ locations

What I'll Be Writing About

I've got a backlog of posts in various stages of done:

"Your Custom Cache Is a Bug Factory" — a follow-up to the Hertz piece about the caching anti-patterns I see in almost every codebase I audit
"Eventual Consistency Isn't Lazy — It's Architecture" — why most teams default to strong consistency out of fear, not necessity, and what it costs them
"Why You Probably Don't Need a Full-Time CTO" — the case for fractional technical leadership, from someone who does it

If you're interested in production architecture, real-world scaling problems, or what it actually looks like to lead engineering at companies that move millions of dollars through their software every day — I think you'll find something useful here.

I'm Mathew. Good to meet you all.

Find me at mdostal.com or connect on LinkedIn. If you're dealing with a scaling problem or making an architecture bet that could use a second opinion, I do free 30-minute calls.

Coder Legion - Recent posts tagged fractional-cto

From AS/400s to AI Agent Swarms

What I've Been Working On

What I Build Day to Day

What I'll Be Writing About