Monday, 23rd February 2026
Red/green TDD
"Use red/green TDD" is a pleasingly succinct way to get better results out of a coding agent.
TDD stands for Test Driven Development. It's a programming style where you ensure every piece of code you write is accompanied by automated tests that demonstrate the code works.
The most disciplined form of TDD is test-first development. You write the automated tests first, confirm that they fail, then iterate on the implementation until the tests pass. [... 348 words]
Nothing humbles you like telling your OpenClaw “confirm before acting” and watching it speedrun deleting your inbox. I couldn’t stop it from my phone. I had to RUN to my Mac mini like I was defusing a bomb.
I said “Check this inbox too and suggest what you would archive or delete, don’t action until I tell you to.” This has been working well for my toy inbox, but my real inbox was too huge and triggered compaction. During the compaction, it lost my original instruction 🤦♀️
The latest scourge of Twitter is AI bots that reply to your tweets with generic, banal commentary slop, often accompanied by a question to "drive engagement" and waste as much of your time as possible.
I just found out that the category name for this genre of software is reply guy tools. Amazing.
The paper asked me to explain vibe coding, and I did so, because I think something big is coming there, and I'm deep in, and I worry that normal people are not able to see it and I want them to be prepared. But people can't just read something and hate you quietly; they can't see that you have provided them with a utility or a warning; they need their screech. You are distributed to millions of people, and become the local proxy for the emotions of maybe dozens of people, who disagree and demand your attention, and because you are the one in the paper you need to welcome them with a pastor's smile and deep empathy, and if you speak a word in your own defense they'll screech even louder.
— Paul Ford, on writing about vibe coding for the New York Times
Writing code is cheap now
The biggest challenge in adopting agentic engineering practices is getting comfortable with the consequences of the fact that writing code is cheap now.
Code has always been expensive. Producing a few hundred lines of clean, tested code takes most software developers a full day or more. Many of our engineering habits, at both the macro and micro level, are built around this core constraint.
At the macro level we spend a great deal of time designing, estimating and planning out projects, to ensure that our expensive coding time is spent as efficiently as possible. Product feature ideas are evaluated in terms of how much value they can provide in exchange for that time - a feature needs to earn its development costs many times over to be worthwhile! [... 661 words]
Writing about Agentic Engineering Patterns
I’ve started a new project to collect and document Agentic Engineering Patterns—coding practices and patterns to help get the best results out of this new era of coding agent development we find ourselves entering.
[... 554 words]Ladybird adopts Rust, with help from AI (via) Really interesting case-study from Andreas Kling on advanced, sophisticated use of coding agents for ambitious coding projects with critical code. After a few years hoping Swift's platform support outside of the Apple ecosystem would mature they switched tracks to Rust their memory-safe language of choice, starting with an AI-assisted port of a critical library:
Our first target was LibJS , Ladybird's JavaScript engine. The lexer, parser, AST, and bytecode generator are relatively self-contained and have extensive test coverage through test262, which made them a natural starting point.
I used Claude Code and Codex for the translation. This was human-directed, not autonomous code generation. I decided what to port, in what order, and what the Rust code should look like. It was hundreds of small prompts, steering the agents where things needed to go. [...]
The requirement from the start was byte-for-byte identical output from both pipelines. The result was about 25,000 lines of Rust, and the entire port took about two weeks. The same work would have taken me multiple months to do by hand. We’ve verified that every AST produced by the Rust parser is identical to the C++ one, and all bytecode generated by the Rust compiler is identical to the C++ compiler’s output. Zero regressions across the board.
Having an existing conformance testing suite of the quality of test262 is a huge unlock for projects of this magnitude, and the ability to compare output with an existing trusted implementation makes agentic engineering much more of a safe bet.