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If you’ve been using coding agents like Claude Code or OpenAI Codex and constantly wondering “am I doing this right?”, Simon Willison just dropped exactly what you need. His [Agentic Engineering Patterns](https://simonwillison.net/guides/agentic-engineering-patterns/) guide is a growing collection of hard-won patterns for actually getting good results out of these tools, and it’s blowing up across the developer internet right now.

For those unfamiliar, Simon Willison is the co-creator of Django and one of the most thoughtful voices on practical AI tooling. He’s been deep in the weeds with coding agents for a while, and this guide distills what he’s learned into something genuinely useful. He draws a clear line between what he calls “agentic engineering” — professional developers using agents to amplify their work — and casual vibe coding. The distinction matters, and the patterns reflect that.

The guide currently spans five sections covering principles, testing strategies, code comprehension, and annotated prompts. The chapters on [Red/green TDD](https://simonwillison.net/guides/agentic-engineering-patterns/) and “First run the tests” are particularly worth your time — turns out test-driven development pairs absurdly well with coding agents. There’s also a fascinating section on having agents build interactive explanations of complex code, which I hadn’t considered before. Willison publishes about one or two chapters a week and treats the whole thing as living documentation that gets updated over time, inspired loosely by the classic 1994 *Design Patterns* book format.

What makes this stand out is the honesty. Willison [wrote about his motivations](https://simonwillison.net/2026/Feb/23/agentic-engineering-patterns/) openly — he wanted to answer “how do I get good results out of this stuff” in one place. And in a nice bit of meta-irony, much of the Django code powering the guide itself was written by Claude running in Claude Code.

The response has been massive. It hit [#1 on Hacker News](https://news.ycombinator.com/item?id=47243272) with 229 points and over 109 comments, got picked up on [daily.dev](https://app.daily.dev/posts/agentic-engineering-patterns-a-guide-to-enhancing-software-development-with-ai-rqvhbu0uq), and Willison shared it across [Twitter/X](https://x.com/simonw/status/2025990408514523517) and [Mastodon](https://fedi.simonwillison.net/@simon/116121189986896177) where it spread fast. The comment threads alone are worth reading — lots of experienced devs sharing their own patterns and pushing back on certain ideas in productive ways.

If you’re spending any real time with coding agents, bookmark this one. It’s the most organized, experience-backed resource on the topic I’ve come across, and it’s only going to get better as Willison keeps adding chapters.