Simon Willison — Week of 2026-04-04 to 2026-04-10#

Highlight of the Week#

Anthropic’s decision to delay the general release of their highly capable Claude Mythos model under “Project Glasswing” marks a significant turning point in the AI industry. The move underscores a massive shift in frontier model capabilities, as models evolve from generating text to autonomously chaining multiple minor vulnerabilities into sophisticated exploits, requiring a new level of security safeguards before release.

Simon Willison — Week of 2026-06-18 to 2026-06-25#

Highlight of the Week#

This week’s absolute standout is the launch of the datasette-apps plugin, which fundamentally transforms how we build micro-applications over local databases. By utilizing tightly constrained iframe sandboxes and Content-Security-Policy headers, developers and LLMs alike can safely run custom HTML/JS interfaces against a persistent Datasette backend. It brilliantly merges Simon’s ongoing experiments with AI-assisted “vibe coding” and robust security architectures into a core ecosystem feature, effectively bridging the gap between Claude Artifacts and secure data environments.

Simon Willison — 2026-07-14#

Highlight#

Simon’s deep-dive into creating a custom animated desktop “pet” using Codex and GPT-5.6 Sol is a fantastic look at AI-driven asset generation. He documents the exact multi-stage prompts used to create perfect sprite sheets with magenta chroma-key backgrounds, showing how generative models can reliably output structured, game-ready images.

Posts#

simonw/pedalican Simon accidentally activated a Codex Desktop pet and immediately set out to build his own: a pelican riding a bicycle. He details the pipeline of using GPT-5.6 Sol and gpt-image-2 to generate the required sprite sheets, including the precise prompts used to keep the character consistent on a flat magenta background. It’s a great practical example of using text-to-image models to generate functional, game-ready assets.

Simon Willison — 2026-04-04#

Highlight#

Simon highlights a staggering growth in developer activity on GitHub, pointing to massive recent surges in both commit volume and GitHub Actions usage. This brief but potent link post captures the sheer scale of how rapidly AI-assisted programming and automated workflows are accelerating platform activity.

Posts#

[Quoting Kyle Daigle] · Source Simon shares a striking quote from GitHub COO Kyle Daigle that reveals an explosive surge in overall platform activity. Commit rates have jumped to 275 million per week, which is on pace for 14 billion this year compared to just 1 billion total commits in 2025. Additionally, GitHub Actions usage has skyrocketed to 2.1 billion minutes in just the current week alone, up from 1 billion minutes per week in 2025 and 500 million in 2023. This massive scale-up highlights the unprecedented velocity at which code is currently being generated, integrated, and tested across the developer ecosystem.

Simon Willison — 2026-06-24#

Highlight#

Today’s most interesting post is Simon’s creation of browser-compat-db, demonstrating a clever mix of AI-assisted programming to convert Mozilla’s MDN compatibility data into a SQLite database, along with a neat CI/CD trick for hosting it. It perfectly encapsulates his workflow of using frontier models like Opus 4.8 and GPT-5.5 to rapidly build, deploy, and explore small, sharp data tools.

Posts#

simonw/browser-compat-db · Source Inspired by Mozilla’s new MDN Model Context Protocol (MCP) service, Simon used Claude Code for web (Opus 4.8) to write a script that converts the comprehensive browser compatibility repository into a ~66MB SQLite database. To bypass the fact that GitHub Releases do not provide open CORS headers, he utilized Codex Desktop (GPT-5.5) to build a GitHub Actions workflow that force-pushes the database to an “orphan” branch. This deployment strategy allows the database to be served via GitHub’s CDN with open CORS headers, enabling immediate exploration directly in the browser via Datasette Lite.