Simon Willison’s Weblog

29th March 2026

Tool Pretext — Under the Hood — Explore how pure-JavaScript text measurement and line breaking work through an interactive visualization of the Pretext library's pipeline. This tool demonstrates each stage from raw text input through whitespace normalization, word segmentation, canvas-based width measurement, and arithmetic-based line breaking, with live verification against actual DOM rendering.

See my notes on Pretext here.

Posted 29th March 2026 at 7:59 pm

Recent articles

New release of LLM adds support for reasoning traces, OpenAI Responses, server-side tools, and smarter logging - 4th August 2026
Stateless MCP has recaptured my interest (and inspired mcp-explorer and datasette-mcp) - 31st July 2026
OpenAI’s accidental cyberattack against Hugging Face is science fiction that happened - 22nd July 2026

This is a beat by Simon Willison, posted on 29th March 2026.

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