Simon Willison (@simonw) header
Simon Willison (@simonw) profile picture

Creator @datasetteproj, co-creator Django. PSF board. Hangs out with @natbat. He/Him. Mastodon: https://xitter.twitterapi.xyz/t.co/t0MrmnJW0K Bsky: https://xitter.twitterapi.xyz/t.co/OnWIyhX4CH

San Francisco, CA
Joined November 2006
Photo by Simon Willison (@simonw)Photo by Simon Willison (@simonw)Photo by Simon Willison (@simonw)Photo by Simon Willison (@simonw)Photo by Simon Willison (@simonw)Photo by Simon Willison (@simonw)Photo by Simon Willison (@simonw)Photo by Simon Willison (@simonw)Photo by Simon Willison (@simonw)Photo by Simon Willison (@simonw)
When Anthropic release a new model it's always worth taking a look at their updated prompting guide - here's an entertaining tip to make Fable 5.2 less likely to be cautious in how it improves existing code: tell it "This codebase is yours" platform.claude.com/docs/en/…
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Huh, they've changed the recommended prompt to "You are the owner and long-term maintainer of this codebase, and its design is up to you."
Replying to @simonw
FYI they updated the prompt to: You are the owner and long-term maintainer of this codebase, and its design is up to you.
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Gemini 4 Carbon is good at pelican SVGs, but that's nothing new for Gemini "Make a three js animation where yonkers stands up as a big mech (cool stand up motion) and stomps around manhattan and queens and Brooklyn, use openstreetmap mapping data" simonwillison.net/2026/Nov/1…
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The Gemini 4 Carbon pelican is still pretty cute
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Google had a whole lot more fun with Carbon and pelicans on bicycles than I did xitter.twitterapi.xyz/sundarpichai/status/21…
Carbon made a pelican demo so you don't have to 😅 fun test of long-horizon coding and the new /swarm feature in Google @Antigravity. Builder and critic subagents ran iterative loops across Blender and Three.js - checking their own renders to build a playable 3D game of a pelican biking around our Mountain View campus.
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Something I enjoy about these prompting guides is that it's VERY clear from reading them that Anthropic are just as surprised by the idiosyncrasies of their new models as we are
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There is a mysterious intermittent beep coming from somewhere in your room of unopened boxes. Do you: 1. Open boxes methodically until you find it 2. Vibe code software to triangulate it using two laptops, two iPads and a phone all listening at once simonwillison.net/2026/Nov/9…
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I've recently started hiding the bulk of my AI-generated GitHub PR descriptions behind a collapsed <details><summary> HTML tag (thankfully supported by GitHub Markdown) and I think it's a useful pattern for making PR slop a little bit less exhausting simonwillison.net/2026/Nov/9…
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... today I learned that Twitter preview cards can't handle HTML tags in post titles!
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There's a buzzy new paper about GPT-6 Astra being able to directly interpret model weights (prompts full of floating point numbers) - I tried it with Qwen 3.8 27B on my laptop and found that, after 45+ minutes, that model could achieve the same thing simonwillison.net/2026/Nov/3…
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In updating a graphic showing U.S. company AI adoption over time according to a long-running U.S. Census Bureau survey, I found out that the Bureau's work has been sullied by that asinine "Super Intelligence" executive order simonwillison.net/2026/Nov/2…
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Simon Willison retweeted
X should have a zero tolerance policy for AI replies Like you do one and your account is suspended for life Replies are a nightmare now and it's never ever been this bad AI replies are an an existential threat to the future of this platform, because people will simply stop using it if the vast majority of replies are AI bots
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Fascinating case study of the sharpest edge of what you can do with agentic engineering in the Fable era - my eyebrows raised at least a dozen times while reading this
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Inspired me to try out spawn.co on my phone. Here's me flying a dragon around a castle, I prompted both the castle and the dragon into existence using the in-game "Savi" chatbot
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the secret to becoming an expert is embarrassingly boring: build in public, write down what you learned and the process behind it, teach all that to someone, help them ship repeat for a few years, and you're solid – at Weehawken, NJ
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Simon Willison retweeted
very weird thing happening rn technical people are sad, they think their skills are now useless non-technical people are desperately wishing they were more technical so they could use agents better
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These ones are pretty great!
Replying to @benjedwards
Apple II Agent (Opus 5.5) drew a pretty good pelican riding a bicycle (cc: @simonw) on the Apple Ii Seen here in both color and monochrome
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