Kinda mind boggling. Opus got my little game running in web assembly in 10 minutes. Didn't even have to fix up inputs or sound which is wild to me. mitsuhiko.github.io/tankgame/

This is 100% me, @simonwillison.net. simonwillison.net/2026/Jan/4/c...

What's the coolest thing you built over Christmas? :) My kids and I mostly had fun building a computer game. It's the only non meta thing I built for fun, the rest was more tools for AI and patches to pi :D github.com/mitsuhiko/ta...

Around 20.000 lines of C code later :)

It's the small things that make working with agents so great. I got sick of the ugly output from lint+typecheck+custom lint. Also I wanted it in parallel. Agent made it pretty and parallel <3

What I find surprising working on and with pi is that it has such a short system prompt and at least for my prompting style, it still works. That, plus 4 tools (read|bash|edit|write), is it.

In which I argue that the legal vs. illegal immigration debate is largely a distraction. In reality, it comes down to a colder truth: who we are willing to accept and who we are not. That line is drawn by taste — taste changes. dark.ronacher.eu/2025/12/30/i...

Made a small demo of gh-issue-sync and how you can use it with an agent to roleplay project manager or scrum master :) youtu.be/ClTvgE-sFls

What confuses me is why is a hypothetical attack on the residence of Putin such an outrage, but striking civilian buildings and killing civilians every day in Ukraine is … not news and okay?

I would love to learn if anyone else finds this useful: gh-issue-sync syncs down your issues and lets you edit them locally and sync them back up. Also lets you create issues locally and reference them by temporary numbers which are filled in after push. github.com/mitsuhiko/gh...

If you are a programmer and an AI hold-out, and you have some time off during Christmas: gift yourself a 100 USD subscription to Claude Code and … try it. But really try it. Take a week if you can afford it and dive in. It will change your opinion on these tools.

While I was busy writing tickets, Pi with Opus rolled out some certificates, DNS records, a new S3 bucket, cloudfront and updated deploys. Love it.

Now in light and dark. I might have procrastinated.

I am still sort of in disbelief how quickly we moved from "AI is not making me more productive as a programmer" to "of course AI can one-shot advent of code" in less than a year. bsky.app/profile/mits...

I bookmarked the 60 Minutes video on CECOT yesterday evening. Was taken down some time since. Fascinating.

Today I violated my own blog's AI policy and had Claude Code write a guest blog post. That finishes my Advent of Code adventure where I had Claude Opus write and optimize all puzzles itself, including writing input generators in the end. Consider it art. lucumr.pocoo.org/2025/12/23/a...

I really hope that we will see more AI conferences outside of the US, now that so many people are refused visas :(

I have a confession to make: I have only ever used a French Press to make tea. In fact, as far as I'm concerned it's a device to make tea.

A personal recap of 2025. It was a year of a new style of engineering. Left some ideas for what might come next. lucumr.pocoo.org/2025/12/22/a...

Now kiss!

I've been thinking of forgiveness after wars and how it requires institutions we are busy dismantling. dark.ronacher.eu/2025/12/21/d...

In Vienna there was (until ~this week) a service to send and receive parcels completely anonymous. It was called sub rosa and technically legal. Turns out ~95% of all utilization was to send and receive drugs, and the owners were arrested. Incentives really, really matter wien.orf.at/stories/3334...

I don't use Claude's plan mode. I made some potentially uninformed statements today about plan mode, so I learned what it does by looking at the code. This might or might not be useful to you. lucumr.pocoo.org/2025/12/17/w...

I'm in love with the post-its my wife puts on the door for our oldest in the morning. That's a recent collection of my favorite ones.

Post Opus 4.5 I'm basically 90% Opus now, 10% Codex. I only use codex for code review. In parts because I don't see it program better and it's hard to understand what it does. Also it's surprisingly slow.

Why is it that we love borders so much? dark.ronacher.eu/2025/12/15/b...

I asked Claude yesterday to add dynamic navigation to my "Dark Thoughts" blog. It ended up with small jumps on the animation I did not appreciate and I thought it was impossible to debug this. Claude slowed down all animations, added debug borders everywhere and we found the issue in two minutes.

This year I make a conscious decision to write more. Writing is how I deal with the world around me. Much of what I wrote is not for sharing, some is though and does not fit my blog. So I created a new place for it. dark.ronacher.eu/2025/12/13/w...

Apparently I have Claude Code guest passes?

How many more times can I write about MCP not working? We'll see, but here is my weekend blog on why Claude's skills seem to work well for me, when MCP does not. lucumr.pocoo.org/2025/12/13/s...

I really did not look at the code at all. I asked the agent to measure it and just make it faster. Did it in two goes. That's it's explanation of the changes. I find all of this deeply fascinating still. bsky.app/profile/mits...

We're rapidly losing our humanity. It pains me to see people that I know starting to echo the current sentiment of the American right, Russia and social media. So much hatred.

Unsurprisingly, Claude Code completed all 12 days of Advent of Code. The code isn't even all that bad. github.com/mitsuhiko/ao...

I know there is nothing more you want to read than another tech bro giving their political opinions, so here it is: “Let’s Destroy The European Union!“ lucumr.pocoo.org/2025/12/9/fi...

I pointed Amp with the oracle and Opus 4.5 at a vulnerable React and asked it to find the remote control execution issue without googling and it found it very little help. In fact, it found more than one way to exploit it. Really, really cool.

I don't understand this lock poisoning fetishism that Rust people have.

Dass man als Ausländer seit heuer in Österreich 21 bzw 42 Euro zahlen muss um sich zu melden (was rechtlich verpflichtend ist) finde ich in keinster Weise gerechtfertigt.

Few things in life have stressed me more than immigration, especially when my spouse and I had different statuses. What's happening in the US right now with the USCIS changes is going to inflict immense, and very avoidable, pain on a lot of people :(

Updating changelogs and triggering release workflows is something I mostly outsource to agents now. Works quite well! bsky.app/profile/mits...

MiniJinja 2.13.0 coming up!

After @mariozechner.at exposed me to TypeBox I'm now seriously considering using it as a replacement for zod. The fact that it sits on top of JSON Schema and supports schema serialization is a significant improvement.

If you want to kill yourself in 996 culture, be my friend but “I worked 36 hours straight, fell asleep a few times in the car but FSD drove me home” is absolutely insane. It pains me how many people praise this behavior though.

We did a whole bunch of this today.

If you're skeptical or frustrated with AI, and still poking around on this profile, you might find my longform content more informative: lucumr.pocoo.org/tags/ai/ or my Youtube channel which has some conversations with others too: www.youtube.com/@ArminRonach...

It's kinda cool, but also sad at the same time, that email holds my oldest correspondences. So many other records were lost because the apps shut down, or I lost the data along the way.

At the risk of starting the flame war to end all flame wars... Modern LLMs (GPT-5.1, Claude 4.5, Gemini 3) produce excellent code and can be a significant productivity boost to software engineers who take the time to learn how to effectively apply them - especially if used with coding agent tools

I’m not sure what this platform can do to make it more enjoyable, but I’m definitely not enjoying whatever pile-on is taking place right now in my notifications and I’m also not really sure how I could make it stop.

I kinda forgot how weird mailinglists are implemented. Because clients keep the person you reply to in the recipient list, the listserv opts to not send out a message to anyone directly addressed. That means that directly addressed people do not get the modified message of the ML.

I also won't have opinions Opus 4.5 for at least a week. But I will say that the pricing dropped to $5/$25 per million tokens is a welcome news and was entirely unexpected!

This post is 10 years old at this point. Nothing improved. lucumr.pocoo.org/2016/3/24/op...