Michael Czeiszperger

Multi-LLM Spec-Driven Software Development

Wed, 22 Apr 2026 10:00:00 -0400

Over the past year I have shipped around twenty major revisions of a 25-year-old, 550,000-line codebase using a workflow that seems obvious to me (and a growing number of professional software engineers) and foreign to many working programmers I talk to. Either they are still in the Cursor-style inner loop: small prompts, small edits, small completions, or trying to one-shot complex instructions. They are not running an agentic system at full capability, and they are paying for it in slow, flaky, one-model output. It’s impossible to quantify, but my unscientific impression is I’ve made more changes to this product in the past 12 months than previous teams of four could have achieved over several years.

Modernizing a 550K-Line Java Codebase with AI-Assisted Development

Tue, 31 Mar 2026 10:00:00 -0400

Web Performance Load Tester has been in continuous development for over 25 years. I designed the original architecture and wrote the first version. Over the years, a dozen developers have contributed to what is now 550,000 lines of hand-written Java. Longer than the entire Lord of the Rings trilogy. Today I’m the sole developer again, and for version 7.0, I modernized the platform and started moving the product to the cloud.

Building Agentic AI Systems for Web Performance Load Tester 7.0

Thu, 26 Mar 2026 10:00:00 -0400

Configuring a web load test by hand is one of those tasks that’s just interesting enough to require expertise and just tedious enough to make you resent having it. After 25 years of tediously pouring through HTTP headers, I decided to teach an AI to do the work instead. Then I built a second system to handle the part nobody enjoys: staring at load test metrics for hours and condensing them into a client report that will almost certainly be read no further than the executive summary.

Building an AI Financial Analysis System for Copilot Money

Thu, 09 Jan 2025 10:00:00 -0800

Is it cheaper for two people to go to the movies at Red Cinemas or Golden Ticket?

Copilot Money (which I strongly recommend for personal financial management) can tell you exactly what you spent at each theater, down to the penny. What it can’t do is group those transactions by visit, include the Fandango ticket purchases and parking fees that belong to the same outing, and compare the all-in cost per person across venues. Its budget-vs.-actuals only works for the current month. Custom analysis means exporting to a spreadsheet.