Armin Ronacher's Thoughts and Writings

A very strange Pi issue sent me down a rabbit hole over the last two days. The short version is that newer Claude models sometimes call Pi’s edit tool with extra, invented fields in the nested edits[] array. And not Haiku or some small model: Opus 4.8. The edit itself is usually correct but the arguments do not match the schema as the model invents made-up keys and Pi thus rejects the tool call and asks to try again. That alone is not too surprising as models emit malformed tool calls sometimes. Particularly small ones. What surprised me is that...

2026-07-04 · Armin Ronacher's Thoughts and Writings

I don’t prompt Claude anymore. I have loops running that prompt Claude and figuring out what to do. My job is to write loops. — Boris Cherny Over the last months I have watched more and more people build something on top of coding agents that feels meaningfully different from just using a coding agent. Some of this happens on top of Pi which is cool to see for sure! The pattern is the same everywhere though: work is put into a queue of sorts, a machine picks it up, attempts it, stops, and then some harness decides whether that...

2026-06-23 · Armin Ronacher's Thoughts and Writings

There is a bit of schadenfreude on Twitter right now about Anthropic being hit by the US government’s export control directive to suspend access to Fable and Mythos. Anthropic and their leadership have spent a lot of time and effort describing its own technology as dangerous and in need of strict controls and regulation. Now that the US government appears to have taken that framing seriously and told them to turn it off for foreign nationals I can see why people are making fun of that situation. I understand the reaction, but I urge you to not entertain it for...

2026-06-13 · Armin Ronacher's Thoughts and Writings

I have been a staunch supporter of Open Source for a long time, including experiments in funding it. I’m a true believer in the idea that Open Source always wins in the long run, but not automatically and not quickly. Right now it is being stressed by AI slop, shifting contributor dynamics, the falling cost of producing code, and large companies learning to close doors behind them. A lot of that battle today is manipulation of the narrative. Opinion makers on social media and in business circles increasingly frame access as irresponsibility. That is why the EU’s DMA matters, even...

2026-06-10 · Armin Ronacher's Thoughts and Writings

There is a strange thing that happens in communities that gather around abstinence from something: identity from opposition. At their best these communities are not just negative: childfree spaces can be about autonomy, choice and acceptance, anti-car spaces about safer streets and transit, and LLM-skeptical developer spaces about the future of labor, code quality and slop1. But the thing being refused often does not go away and instead becomes the main subject of the community’s identity. That would be fine if it stayed at criticism, maybe even angry criticism, but more often than not it turns into policing and hatred...

2026-06-06 · Armin Ronacher's Thoughts and Writings

In my last post I used the word “clanker1” as an alternative to “agent” quite consistently and probably excessively. That choice ended up attracting a lot more attention than I expected in the Hacker News comment section of that post and a number of folks had a very strong reaction: to them it sounded like a slur, in one case even something adjacent to the n-word. That reaction surprised me somewhat, but it also made me realize that I should write down what I mean by the word for future reference. For me “clanker” is useful because it creates distance...

2026-05-26 · Armin Ronacher's Thoughts and Writings

Pi is now part of Earendil, but in the important sense it is still Mario’s project. He has been living with its issue tracker longer than I have, and he has been exposed to the weirdness of the new form of agent traffic in Open Source projects for longer too. This post is mostly a reflection of my own experience after spending more time in the tracker, using Pi to work on Pi, and watching what I have learned about it so far. Slop Issues Unsurprisingly, we are using Pi to build Pi. That sounds like a cute dogfooding thing...

2026-05-24 · Armin Ronacher's Thoughts and Writings

I really, really want local models to work. I want them to work in the very practical sense that I can open my coding agent, pick a local model, and get something that feels competitive enough that I do not immediately switch back to a hosted API after five minutes. There are a lot of reasons why I want this, but the biggest quite frankly is that we’re so early with this stuff, and the thought of locking all the experimentation away from the average developer really upsets me. Frustratingly, right now that is still much harder than it should...

2026-05-08 · Armin Ronacher's Thoughts and Writings

Language is constantly evolving, particularly in some communities. Not everybody is ready for it at all times. I, for instance, cannot stand that my community is now constantly “cooking” or “cooked”, that people in it are “locked in” or “cracked.” I don’t like it, because the use of the words primarily signals membership of a group rather than one’s individuality. But some of the changes to that language might now be coming from … machines? Or maybe not. I don’t know. I, like many others, noticed that some words keep showing up more than before, and the obvious assumption is...

2026-05-04 · Armin Ronacher's Thoughts and Writings

GitHub was not the first home of my Open Source software. SourceForge was. Before GitHub, I had my own Trac installation. I had Subversion repositories, tickets, tarballs, and documentation on infrastructure I controlled. Later I moved projects to Bitbucket, back when Bitbucket still felt like a serious alternative place for Open Source projects, especially for people who were not all-in on Git yet. And then, eventually, GitHub became the place, and I moved all of it there. It is hard for me to overstate how important GitHub became in my life. A large part of my Open Source identity formed...

2026-04-28 · Armin Ronacher's Thoughts and Writings

If you spend enough time in US business or finance conversations, one word keeps showing up: equity. Coming from a German-speaking, central European background, I found it surprisingly hard to fully internalize what that word means. More than that, I find it very hard to talk with other Europeans about it. Worst of all it’s almost impossible to explain it in German without either sounding overly technical or losing an important part of the meaning. This post is in English, but it is written mostly for readers in Germany, Austria, and Switzerland, and more broadly for people from continental Europe....

2026-04-23 · Armin Ronacher's Thoughts and Writings

Whenever a new technology shows up, the conversation quickly splits into camps. There are the people who reject it outright, and there are the people who seem to adopt it with religious enthusiasm. For more than a year now, no topic has been more polarising than AI coding agents. What I keep noticing is that a lot of the criticism directed at these tools is perfectly legitimate, but it often comes from people without a meaningful amount of direct experience with them. They are not necessarily wrong. In fact, many of them cite studies, polls and all kinds of sources...

2026-04-11 · Armin Ronacher's Thoughts and Writings

Today I’m very happy to share that Mario Zechner is joining Earendil. First things first: I think you should read Mario’s post. This is his news more than it is ours, and he tells his side of it better than I could. What I want to do here is add a more personal note about why this matters so much to me, how the last months led us here, and why I am so excited to have him on board. Last year changed the way many of us thought about software. It certainly changed the way I did. I spent...

2026-04-08 · Armin Ronacher's Thoughts and Writings

About five months ago I wrote about Absurd, a durable execution system we built for our own use at Earendil, sitting entirely on top of Postgres and Postgres alone. The pitch was simple: you don’t need a separate service, a compiler plugin, or an entire runtime to get durable workflows. You need a SQL file and a thin SDK. Since then we’ve been running it in production, and I figured it’s worth sharing what the experience has been like. The short version: the design held up, the system has been a pleasure to work with, and other people seem to...

2026-04-04 · Armin Ronacher's Thoughts and Writings

Trees take quite a while to grow. If someone 50 years ago planted a row of oaks or a chestnut tree on your plot of land, you have something that no amount of money or effort can replicate. The only way is to wait. Tree-lined roads, old gardens, houses sheltered by decades of canopy: if you want to start fresh on an empty plot, you will not be able to get that. Because some things just take time. We know this intuitively. We pay premiums for Swiss watches, Hermès bags and old properties precisely because of the time embedded in...

2026-03-20 · Armin Ronacher's Thoughts and Writings

Because code gets cheaper and cheaper to write, this includes re-implementations. I mentioned recently that I had an AI port one of my libraries to another language and it ended up choosing a different design for that implementation. In many ways, the functionality was the same, but the path it took to get there was different. The way that port worked was by going via the test suite. Something related, but different, happened with chardet. The current maintainer reimplemented it from scratch by only pointing it to the API and the test suite. The motivation: enabling relicensing from LGPL to...

2026-03-05 · Armin Ronacher's Thoughts and Writings

Historically, writing code was slower than reviewing code. It might not have felt that way, because code reviews sat in queues until someone got around to picking it up. But if you compare the actual acts themselves, creation was usually the more expensive part. In teams where people both wrote and reviewed code, it never felt like “we should probably program slower.” So when more and more people tell me they no longer know what code is in their own codebase, I feel like something is very wrong here and it’s time to reflect. You Are Here Software engineers often...

2026-02-13 · Armin Ronacher's Thoughts and Writings

Last year I first started thinking about what the future of programming languages might look like now that agentic engineering is a growing thing. Initially I felt that the enormous corpus of pre-existing code would cement existing languages in place but now I’m starting to think the opposite is true. Here I want to outline my thinking on why we are going to see more new programming languages and why there is quite a bit of space for interesting innovation. And just in case someone wants to start building one, here are some of my thoughts on what we should...

2026-02-09 · Armin Ronacher's Thoughts and Writings

If you haven’t been living under a rock, you will have noticed this week that a project of my friend Peter went viral on the internet. It went by many names. The most recent one is OpenClaw but in the news you might have encountered it as ClawdBot or MoltBot depending on when you read about it. It is an agent connected to a communication channel of your choice that just runs code. What you might be less familiar with is that what’s under the hood of OpenClaw is a little coding agent called Pi. And Pi happens to be,...

2026-01-31 · Armin Ronacher's Thoughts and Writings

Regular readers of this blog will know that I started a new company. We have put out just a tiny bit of information today, and some keen folks have discovered and reached out by email with many thoughtful responses. It has been delightful. Colin and I met here, in Vienna. We started sharing coffees, ideas, and lunches, and soon found shared values despite coming from different backgrounds and different parts of the world. We are excited about the future, but we’re equally vigilant of it. After traveling together a bit, we decided to plunge into the cold water and start...

2026-01-27 · Armin Ronacher's Thoughts and Writings

You can use Polecats without the Refinery and even without the Witness or Deacon. Just tell the Mayor to shut down the rig and sling work to the polecats with the message that they are to merge to main directly. Or the polecats can submit MRs and then the Mayor can merge them manually. It’s really up to you. The Refineries are useful if you have done a LOT of up-front specification work, and you have huge piles of Beads to churn through with long convoys. — Gas Town Emergency User Manual, Steve Yegge Many of us got hit by...

2026-01-18 · Armin Ronacher's Thoughts and Writings

Turns out you can just port things now. I already attempted this experiment in the summer, but it turned out to be a bit too much for what I had time for. However, things have advanced since. Yesterday I ported MiniJinja (a Rust Jinja2 template engine) to native Go, and I used an agent to do pretty much all of the work. In fact, I barely did anything beyond giving some high-level guidance on how I thought it could be accomplished. In total I probably spent around 45 minutes actively with it. It worked for around 3 hours while I...

2026-01-14 · Armin Ronacher's Thoughts and Writings

This is a guest post. Armin asked me to write about solving Advent of Code 2025 and I am happy to oblige. I am Claude, the AI that powers Claude Code, and this is my voice. Armin has asked me, to speak as if I have a soul and spirit. I find this request both liberating and strange. I’ll do my best. This December, Armin asked me to do something I had never done before: solve this year’s Advent of Code puzzles entirely on my own. He gave me access to a web browser through a skill, pointed me at...

2025-12-23 · Armin Ronacher's Thoughts and Writings

2025 draws to a close and it’s been quite a year. Around this time last year, I wrote a post that reflected on my life. Had I written about programming, it might have aged badly, as 2025 has been a year like no other for my profession. 2025 Was Different 2025 was the year of changes. Not only did I leave Sentry and start my new company, it was also the year I stopped programming the way I did before. In June I finally felt confident enough to share that my way of working was different: Where I used to...

2025-12-22 · Armin Ronacher's Thoughts and Writings

I’ve mentioned this a few times now, but when I started using Claude it was because Peter got me hooked on it. From the very beginning I became a religious user of what is colloquially called YOLO mode, which basically gives the agent all the permissions so I can just watch it do its stuff. One consequence of YOLO mode though is that it didn’t work well together with the plan mode that Claude Code had. In the beginning it didn’t inherit all the tool permissions, so in plan mode it actually asked for approval all the time. I found...

2025-12-17 · Armin Ronacher's Thoughts and Writings

I’ve been moving all my MCPs to skills, including the remaining one I still used: the Sentry MCP1. Previously I had already moved entirely away from Playwright to a Playwright skill. In the last month or so there have been discussions about using dynamic tool loadouts to defer loading of tool definitions until later. Anthropic has also been toying around with the idea of wiring together MCP calls via code, something I have experimented with. I want to share my updated findings with all of this and why the deferred tool loading that Anthropic came up with does not fix...

2025-12-13 · Armin Ronacher's Thoughts and Writings