Simon Willison — Week of 2026-05-08 to 2026-05-15#

Highlight of the Week#

The standout development this week is Simon’s rapid adaptation to the latest frontier model capabilities, most notably releasing llm 0.32a2 to expose and visualize the new interleaved reasoning tokens of GPT-5 class models directly in the terminal. This perfectly pairs with his hands-on explorations of embedding LLM calls deeply into developer workflows, such as executing prompts via script shebangs and leveraging models to output rich HTML rather than just Markdown.

Simon Willison — Week of 2026-05-22 to 2026-05-29#

Highlight of the Week#

This week’s most significant milestone is the release of Datasette 1.0a31, which fundamentally shifts the project’s paradigm by introducing UI support for executing write queries directly against the database. This officially bridges Datasette from a purely read-only tool to one that embraces secure data mutation, allowing developers to save and template insert, update, and delete operations.

Key Posts#

[I think Anthropic and OpenAI have found product-market fit] · Source Simon analyzes the shift in enterprise pricing to argue that AI coding agents have crossed the threshold into massive usage and real revenue generation. He points to Anthropic’s staggering $1.25 billion monthly compute spend and notes that labs are pivoting to capture enterprise value directly from heavy agent users rather than relying on middlemen.

Simon Willison — 2026-05-08#

Highlight#

Simon re-evaluates his long-standing habit of asking LLMs for Markdown output, sparked by Anthropic’s Thariq Shihipar advocating for the rich capabilities of HTML. He tests this out practically by using his llm CLI to generate an interactive HTML explanation of a newly discovered Linux security exploit.

Posts#

[Using Claude Code: The Unreasonable Effectiveness of HTML] · Source Simon reflects on a piece by Thariq Shihipar (from Anthropic’s Claude Code team) that argues for requesting HTML instead of Markdown from Claude. While Markdown’s token-efficiency was a strict necessity during the 8,192-token GPT-4 days, modern LLMs can leverage HTML to output SVG diagrams, interactive widgets, and rich in-page navigation. Simon tests this technique by piping an obfuscated Python exploit from copy.fail into gpt-5.5 via his llm CLI tool, successfully prompting the model to generate a fully styled, interactive HTML explanation of the code.

Simon Willison — 2026-05-23#

Highlight#

Today’s update features a practical web standards TIL (Today I Learned) about the <dl> HTML element, proving there are still useful nuances to uncover in foundational markup regarding structure, styling, and accessibility.

Posts#

[On the dl] · Source Simon shares a few structural and historical insights regarding HTML description lists, prompted by an article by Ben Meyer. For practical formatting, he highlights that a single <dt> can be followed by multiple <dd> elements and that pairs can be grouped strictly inside a <div> for easier CSS styling. He also notes the 2008 HTML5 nomenclature shift from “definition lists” to “description lists” and includes a valuable link to Adrian Roselli concerning screen reader accessibility and ARIA labeling.

Simon Willison — 2026-06-29#

Highlight#

Today’s standout piece is a hands-on exploration of Ornith-1.0, a newly released family of open-weights models specifically optimized for agentic coding. Simon tests its local execution capabilities and tool-calling proficiency, signaling another practical step forward for open-source AI developer tooling.

Posts#

Ornith-1.0: Self-Scaffolding LLMs for Agentic Coding Simon goes hands-on with Ornith-1.0, a new MIT-licensed model family from DeepReinforce built on top of Gemma 4 and Qwen 3.5. Testing the 35B MoE variant locally via LM Studio, he finds it highly proficient at executing agent harnesses and running tool calls against a Datasette checkout. He highlights that the underlying models use clean Apache 2.0 licenses, successfully avoiding the “janky” terms of use that affected earlier Gemma models.

Simon Willison — Week of 2026-06-25 to 2026-07-03#

Highlight of the Week#

The single most impactful release this week was Simon’s launch of llm-coding-agent 0.1a0, which successfully turns his popular llm library into a full-fledged coding agent capable of file manipulation and command execution. Bootstrapped entirely using Claude Fable 5 via test-driven development, this represents a massive leap forward for his CLI ecosystem and a brilliant showcase of using frontier models to build the very tools that will orchestrate them.