OpenAI aren't talking about it yet, but it turns out they've adopted Anthropic's brilliant "skills" mechanism in a big way Skills are now live in both ChatGPT and their Codex CLI tool, I wrote up some detailed notes on how they work so far here:
Simon Willison’s Weblog
OpenAI are quietly adopting skills, now available in ChatGPT and Codex CLI
One of the things that most excited me about Anthropic’s new Skills mechanism back in October is how easy it looked for other platforms to implem...
Just pushed a new release of my LLM Python library and CLI tool for interacting with Large Language Models, adding support for GPT 5.1 and GPT 5.2 plus a few smaller bug fixes
Changelog - LLM
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Initial notes on GPT-5.2 - I'm excited to see the knowledge cut-off bump up to August 2025, interesting that it's priced at 1.4x over GPT-5.1
Simon Willison’s Weblog
GPT-5.2
OpenAI reportedly declared a “code red” on the 1st of December in response to increasingly credible competition from the likes of Google’s Ge...
I put together a detailed collection of useful patterns I've collected after vibe-coding 150 different single-file HTML tools over the past couple of years
Simon Willison’s Weblog
Useful patterns for building HTML tools
I’ve started using the term HTML tools to refer to HTML applications that I’ve been building which combine HTML, JavaScript, and CSS in a singl...
I've never been particularly invested in light mode v.s. dark mode but I got enough complaints from people that my blog was "blinding" that I had Claude Code knock out a dark mode theme for it, and it seems to work pretty well
Simon Willison’s Weblog
Dark mode
I've never been particularly invested dark v.s. light mode but I get enough people complaining that this site is "blinding" that I decided to see i...
Put together some notes on Mistral Vibe, Mistral's new CLI coding agent (think Claude Code / OpenAI Codex) which is Apache 2 licensed, written in Python+Pydantic+Textual and has a neat set of system and tool definition prompts that are fun to read
Simon Willison’s Weblog
mistralai/mistral-vibe
Here's the Apache 2.0 licensed source code for Mistral's new "Vibe" CLI coding agent, released today alongside Devstral 2. It's a neat implementati...