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Armin Ronacher

@mitsuhiko.at
49K followers 223 following 2.4K posts

Creator of Flask • earendil.com ♥︎ writing and giving talks • Excited about AI • Husband and father of three • Inhabits Vienna; Liberal Spirit • “more nuanced in person” • More AI content on x.com/mitsuhiko More stuff: ronacher.eu

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Armin Ronacher @mitsuhiko.at · 15/09/2026
Lobsters broke their Anubis rollout and now you can't upvote or message the moderators. Thankfully codex does not give a shit and found a way to solve Anubis and send a message to the moderators.
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Armin Ronacher @mitsuhiko.at · 14/09/2026
David Sacks' complaint about Pangram giving his longform tweet a 100% AI rating motivated me to figure out how it actually works and if you can (easily) edit your way out of it's AI detection. lucumr.pocoo.org/2026/9/14/in...
lucumr.pocoo.org
Interpreting Pangram
What is AI generated text anyways?
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Armin Ronacher @mitsuhiko.at · 12/09/2026
This is the type of post I might regret later, but I really had an urge to rant about the current discourse around pacing the frontier. lucumr.pocoo.org/2026/9/12/pd...
lucumr.pocoo.org
P(doom)
Are we all going to die?
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Armin Ronacher @mitsuhiko.at · 09/09/2026
This is almost comedic. I created a structure for it to place shaders. Astra did not give a shit, wrote a README.md there that it did not place shaders there because they are not needed and then shits unreadable shaders inline into multiple files.
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Armin Ronacher @mitsuhiko.at · 09/09/2026
Astra is really, really cool but I cannot current trust it for my present day engineering. At least until I have adjusted. Some random thoughts including code samples of what I recovered from my traces. lucumr.pocoo.org/2026/9/7/ast...
lucumr.pocoo.org
Astra for Coding: Why Are We Doing This Again?
Some thoughts on Astra and newfangled long-horizon models.
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Armin Ronacher @mitsuhiko.at · 08/09/2026
Rumors of one of the labs having a solution to a Millennium Prize problem were going around for a few days already, which is why I'm a lot less surprised than I should be. But still it's worth reflecting on how little we're surprised now that we are now able to solve it. openai.com/index/navier...
openai.com
On the Navier–Stokes Millennium Prize Problem
We’re sharing an AI-generated solution to the Navier–Stokes Millennium Prize Problem, including a writeup and a formal proof in Lean.
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Armin Ronacher @mitsuhiko.at · 06/09/2026
Future language designers please don't make the mistake of Python to use indentation based syntax. There is just not good syntax to make lexically scoped variables work in that world.
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Armin Ronacher @mitsuhiko.at · 05/09/2026
Have you too started hacking on hardware projects because of LLMs? Some weekend thoughts on our newfound powers. lucumr.pocoo.org/2026/9/5/lat...
lucumr.pocoo.org
Latent Powers
Are we all discovering the same things at once?
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Armin Ronacher @mitsuhiko.at · 03/09/2026
If you look at a release like Astra I feel like you can only draw the conclusion that cool shit is happening. So far we haven't really slowed down with what these models do and I don't think it's going to stop right now.
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Armin Ronacher @mitsuhiko.at · 24/08/2026
Some thoughts of anger vs anxiety for people in tech when it comes to what AI does to the industry in response to a comment I read that made if think. lucumr.pocoo.org/2026/8/24/an...
lucumr.pocoo.org
Anger, Anxiety and Agency
Who is the AI villain we should be angry at?
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Armin Ronacher @mitsuhiko.at · 22/08/2026
Some weekend thoughts on how LLMs change the way we start new projects. lucumr.pocoo.org/2026/8/22/fa...
lucumr.pocoo.org
Fast and Hard Code
People pick languages differently with LLMs.
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Armin Ronacher @mitsuhiko.at · 22/08/2026
Minecraft and pi are a good match. My oldest has been burning GTP tokens the last two days self directed. Fun to watch.
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Armin Ronacher @mitsuhiko.at · 19/08/2026
I finished one post. Why does changing reasoning effort trash your KV cache, how does it work and why can CoT traces leak? lucumr.pocoo.org/2026/8/19/wh...
lucumr.pocoo.org
What Is Reasoning
A short summary of how reasoning traces work.
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Armin Ronacher @mitsuhiko.at · 09/08/2026
Stories that did not happen for 100. Claude or others do not randomly spit out complete clones of projects blog.terrygodier.com/2026/08/09/m...
blog.terrygodier.com
Mea Culpa - Dark Hours
Last week I launched a project called Dark Hours, which was a website utility to give you an idea of what could be seen in the sky that night. A developer who …
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Armin Ronacher @mitsuhiko.at · 02/08/2026
Rust serde people, what do you think of this? gist.github.com/mitsuhiko/f0...
gist.github.com
custom_extension.rs
GitHub Gist: instantly share code, notes, and snippets.
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Armin Ronacher @mitsuhiko.at · 01/08/2026
Absolutely wild things are happening in the world of AI agents and SOTA models. I really think a lot will change in our world soon as a result of this. openai.com/index/ten-ad...
openai.com
Ten advances in mathematics and theoretical computer science
OpenAI shares new results on long-standing open problems in mathematics and theoretical computer science, including advances in geometry, cryptography, and complexity.
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Armin Ronacher @mitsuhiko.at · 26/07/2026
Do you think you will work in or run a software factory in two years for most of your software development?
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Armin Ronacher @mitsuhiko.at · 24/07/2026
I promise I will shut up about Codeberg after this :) lucumr.pocoo.org/2026/7/24/co...
lucumr.pocoo.org
Codeberg Divides
Codeberg drew a democratic, but suboptimal line.
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Armin Ronacher @mitsuhiko.at · 23/07/2026
We've recently made Pi's cache behavior more visible. This site has been debating whether agent harnesses are helping or quietly torching their caches. That seemed like a good excuse to explain how KV caches actually work and how Pi helps (or doesn't). earendil.com/posts/prompt...
earendil.com
Prompt Caching In Agents | EARENDIL
How prompt caching shapes the cost, latency, tools, and architecture of coding agents, and what Pi does to keep cache behavior visible.
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Armin Ronacher @mitsuhiko.at · 23/07/2026
I think this is a very bad move, and the people behind Codeberg should re-consider there stance. blog.codeberg.org/protecting-o...
blog.codeberg.org
Protecting our FLOSS commons from LLMs — Codeberg News
.codeberg-design ul { padding-left: revert !important; } In Brief: Two...
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Armin Ronacher @mitsuhiko.at · 21/07/2026
dark.ronacher.eu/2026/7/21/ne...
dark.ronacher.eu
Never Enough
Comparison is the thief of joy.
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Armin Ronacher @mitsuhiko.at · 20/07/2026
"Story removed by a moderator: End-running the ban on twitter by linking to a forum is not cool. Let's wait a day or two for the inevitable expert writeup." — hilarious. Can't discuss topics if they originate on Twitter on Lobsters.
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Armin Ronacher @mitsuhiko.at · 17/07/2026
I appreciate DHH's thoughts, but I disagree on where Europe's problems are, and from where I'm sitting it's not immigration. Thus I wrote a response to his post. dark.ronacher.eu/2026/7/17/li...
dark.ronacher.eu
Europe Won’t Live By Deporting
A case for focusing on Europe’s actual problems.
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Armin Ronacher @mitsuhiko.at · 16/07/2026
I wrote this earlier today on lobsters, but the thread was deleted. I feel like I had a conversation of that sort multiple times, so I figured I leave my thoughts on that issue for others to read. It's on the question of not having kids because of the state of the world.
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Armin Ronacher @mitsuhiko.at · 16/07/2026
After the Linus post I read a bit more how people judge AI on mastodon and I feel like I'm living in a parallel universe.
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Armin Ronacher @mitsuhiko.at · 16/07/2026
I wonder if this will make people reconsider their stance or become even more defensive.
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Armin Ronacher @mitsuhiko.at · 14/07/2026
Some late weekend thoughts: What can the bible tell us about vibecoding? lucumr.pocoo.org/2026/7/13/th...
lucumr.pocoo.org
The Tower Keeps Rising
Vibecoding and the possible collapse of a shared language.
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Armin Ronacher @mitsuhiko.at · 10/07/2026
Shitty personal attacks in a blog post are one thing, but when people reply “now I like zig even more” really makes me wonder what went wrong in our communities.
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Armin Ronacher @mitsuhiko.at · 09/07/2026
One thing I notice more and more is that people think verbal abuse and personal attacks are acceptable, if they are directed at people who don't have a dismissive attitude towards AI and LLMs.
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Armin Ronacher @mitsuhiko.at · 05/07/2026
I guess the argument against invite trees as practices on lobsters is the monoculture of opinion that comes from it. Good idea, but suboptimal outcomes in practice if you don't fully align with the vibes.
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Reposted by Armin Ronacher
Andrey Okonetchnikov @okonet.dev · 05/07/2026
It feels incredible to me that something that started as a joke during a lunch with a few other nerds like me turned out to be one of the best european coffee shops. theworlds100bestcoffeeshops.com/locales-euro...
theworlds100bestcoffeeshops.com
Kaffemik - Top 100 Best Coffee Shops
Since 2014, Kaffemik has been more than a spot for coffee, it’s been their way of creating connection in the community. Inspired by the Greenlandic tradition of open‑door hospitality, the founders wan...
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Armin Ronacher @mitsuhiko.at · 04/07/2026
I had some vibes that Opus 4.8 was performing worse than older ones for some of uses that are off distribution and now I have the receipts. Latest Opus/Sonnet are causing tool invocation failures on Pi's edit tool when older ones did not! I wrote about it. lucumr.pocoo.org/2026/7/4/bet...
lucumr.pocoo.org
Better Models: Worse Tools
About an aggravating tool-calling regression in newer Claude models.
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Armin Ronacher @mitsuhiko.at · 26/06/2026
A new post for my other blog. Musings about cycling on the danube island at night and the value of public spaces. dark.ronacher.eu/2026/6/26/te...
dark.ronacher.eu
The Texture of Civilization
Some of reality’s hidden detail lives inside other people’s lives.
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Armin Ronacher @mitsuhiko.at · 26/06/2026
Das radikalisiert mich.
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Armin Ronacher @mitsuhiko.at · 25/06/2026
How it started, how it's going.
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Armin Ronacher @mitsuhiko.at · 24/06/2026
Cool! Someone posted my article to lobsters … oh. I guess I should not be annoyed by that but I really stinks that instead of reading some interesting comments you just get stuff like this.
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Armin Ronacher @mitsuhiko.at · 23/06/2026
Some more thoughts on looping in coding agents. lucumr.pocoo.org/2026/6/23/th...
lucumr.pocoo.org
The Coming Loop
Loops, harnesses, and why even loop skeptics may end up with them.
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Armin Ronacher @mitsuhiko.at · 20/06/2026
People of pi, enjoy a little weekend update! /new with lots of extensions should now be slightly faster. Fixed GLM-5.2 configs on some providers, added a new way to configure reasoning on VLLM and others. edit tool's fuzzy algorithm is no longer touching non-modified lines.
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Armin Ronacher @mitsuhiko.at · 17/06/2026
I really like reading Europeans positive experiences with the US during this worldcup. We gotta rebuild relationships, not tear things further down. The US does a lot of stuff right, sport being one of those things.
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Armin Ronacher @mitsuhiko.at · 13/06/2026
When I struggle to structure my thoughts about what's happening I turn to writing. Today about the recent US Anthropic ban news, what it says about power and dependency, and what it should mean for Europeans and citizens of the world. It's a long one. lucumr.pocoo.org/2026/6/13/am...
lucumr.pocoo.org
Dangerous Technology For Americans Only
AI nationalism, safety and European weakness.
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Armin Ronacher @mitsuhiko.at · 10/06/2026
Some thoughts of mine that nobody asked for on the EU's fight with Apple and my worries related to Mythos and Fable. lucumr.pocoo.org/2026/6/10/ga...
lucumr.pocoo.org
Gaslighting Openness
Control is safety. Openness is danger.
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Armin Ronacher @mitsuhiko.at · 07/06/2026
I wrote this almost exactly one year ago: lucumr.pocoo.org/2025/6/4/cha...
lucumr.pocoo.org
AI Changes Everything
From fear to optimism: why I am convinced AI is worth embracing.
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Armin Ronacher @mitsuhiko.at · 06/06/2026
Some weekend thoughts of recent mob behaviors. lucumr.pocoo.org/2026/6/6/com...
lucumr.pocoo.org
Communities of Not
On the strange hostility that grows in communities built around abstinence.
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Armin Ronacher @mitsuhiko.at · 03/06/2026
In case you are in the camp of “Andrew Tridgell is vibefucking rsync” please read this.l and adjust your priors. medium.com/@tridge60/rs...
medium.com
rsync and outrage
I gave up blogging a long time ago (apart from an occasional thing about ArduPilot), I tend to just write code and hope people find it…
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Armin Ronacher @mitsuhiko.at · 26/05/2026
More musings after some people got upset about the word clanker. lucumr.pocoo.org/2026/5/26/cl...
lucumr.pocoo.org
Clanker: A Word For The Machine
Why I like the word clanker and why machines are not people.
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Armin Ronacher @mitsuhiko.at · 24/05/2026
Has been a while since I wrote about agentic engineering, so this time around some learnings of maintaining Pi as a junior maintainer to @mariozechner.at lucumr.pocoo.org/2026/5/24/pi...
lucumr.pocoo.org
Building Pi With Pi
Learnings from post-AI Open Source and how we’re approaching this so far.
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Armin Ronacher @mitsuhiko.at · 23/05/2026
Sharing this post once more given recent news: “… it would be much more honest to just recognize that we did not quite move past the point of dividing immigration into the people we like, and the people we don’t like, and that tastes are subject to change.” dark.ronacher.eu/2025/12/30/i...
dark.ronacher.eu
Immigration
Legal immigration is a fugazi.
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Armin Ronacher @mitsuhiko.at · 14/05/2026
Jarred rewrite Bun in Rust in a week with clankers. Say what you want about it, but that’s impressive. github.com/oven-sh/bun/...
github.com
Rewrite Bun in Rust by Jarred-Sumner · Pull Request #30412 · oven-sh/bun
Blog post with details coming soon. It passes Bun's pre-existing test suite on all platforms (and fixes several memory leaks and flaky tests), the binary size shrinks by 3 MB - 8 MB, the benchm...
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Armin Ronacher @mitsuhiko.at · 08/05/2026
I think @antirez ds4.c is important! I wrote down my thoughts on why I built pi-ds4 and why we need to focus our local model efforts stronger than we do currently. lucumr.pocoo.org/2026/5/8/loc...
lucumr.pocoo.org
Pushing Local Models With Focus And Polish
Local models need focus and polish.
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Armin Ronacher @mitsuhiko.at · 04/05/2026
Five minutes after reporting a bun bug. Both cool and disturbing :D
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