https://duan.ca/tag/programming/ <p>I've discovered a new hobby. It involves creating non-trivial libraries from scratch. (Not UI slop!) Except I don't write any code in editors. An agent does all of it.</p> <p>It goes like this:</p> <p>Set up an infinite loop so the coding agent that...</p> <ol> <li>has a clear guard for correctness (unit tests)</li> <li>has an objectively measurable, pass/fail outcome (performance benchmarks)</li> <li>has tools for styling (dead-code tool, formatter)</li> <li>leaves artifacts for future instances (commit changes on a branch, writes failure_analysis_SHA.md)</li> </ol> <p>... and watch number go up.</p> <p>You'll need a robust prompt, then just feed it to a single agent, over and over. No need to convince the agent instance it needs to repeat (doesn't hurt to try, but they usually give up after a while).</p> <p>It's more fun if you ask for a success artifact (benchmark_success_SHA.tsv) and have a script that monitors for new ones. I run this script with @steipete's VibeTunnel so I can watch the number go up on my phone.</p> <p><img src="/assets/2026/01/idle_monitoring.jpeg" alt="monitoring benchmark progress in terminal" /></p> <p>It may take some setup to get going. For example, at the beginning you want to import a large number of unit tests. You'll want to source some input for benchmarking. You'll want some infrastructure (SwiftPM project, Scripts directory, git).</p> <p>But quickly, it becomes an <a href="https://en.wikipedia.org/wiki/Incremental_game">idle game</a>. At first, you'll watch the number of unit tests go from 100% fail to 100% pass. Then, the performance benchmarks. Bonus points if you benchmark against existing libraries, and beat them in performance. This has happened on every project I've done.</p> <p>Codex btw.</p> <p>I should clarify: this is not serious software engineering. The goal is having fun. Although the end result usually is really useful, and because of robust unit testing + benchmarking, it might be good enough to use in production.</p> <p>We'll find out.</p> <p>My favorite idle game in 2026 so far.</p> Sat, 24 Jan 2026 11:52:04 -0800 https://duan.ca/2026/01/24/idle-coding/ https://duan.ca/2026/01/24/idle-coding/