Engineering notes by Michał Gacek
Notes from real projects: testing strategy, TypeScript systems, product architecture, developer workflows, and practical uses of AI beyond demos.
Featured article
A practical case study of using Redis in a small Hono + TypeScript API — caching, counters, rate limiting, and short-lived state. Patterns that solve real backend problems, not abstract SET foo bar tutorials.
Flaky E2E tests are silent killers of team velocity. Here is how I turned an LLM from a code generator into a participant in a diagnostic process — using local skills, knowledge files, and anti-flake rules grounded in a real Playwright + Qase regression suite.
CPQ and EAV are two of the most debated patterns in business systems. Here is when they actually make sense, when they are overkill, and why they so often end up in the same codebase.
A deep dive into building a real AI agent from scratch in TypeScript — no LangChain, no CrewAI, just a loop, the OpenAI API, and a few small libraries. Learn the architecture, the decisions, and the lessons that frameworks hide from you.
In the age of AI, seniority is becoming less about writing code fast and more about making high-quality decisions in complex contexts.
MCP Is Not Dead. Most Teams Just Haven't Learned How to Evaluate It
Hard Negative Mining: A Practical Guide for Senior Developers
TypeScript's `satisfies` Operator: When and How to Use It
Mastering Git: From Basics to Advanced Techniques
First post to start my journey