# Pretext

Use when building creative browser demos with @chenglou/pretext, DOM-free text layout...

- Repository: https://github.com/mateaix/mateclaw (1176 stars)
- Category: Design
- License: Apache-2.0
- Last updated: 2026-10-30
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add mateaix/mateclaw --skill pretext -g -a claude-code -y`
Codex: `npx skills add mateaix/mateclaw --skill pretext -g -a codex -y`
Cursor: `npx skills add mateaix/mateclaw --skill pretext -g -a cursor -y`
Gemini CLI: `npx skills add mateaix/mateclaw --skill pretext -g -a gemini-cli -y`

## Description

Use when building creative browser demos with @chenglou/pretext, DOM-free text layout for ASCII art, typographic flow around obstacles, text-as-geometry games, kinetic typography, and text-powered generative art. Produces single-file HTML demos by default.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Pretext Creative Demos

## Overview

[`@chenglou/pretext`](https://github.com/chenglou/pretext) is a 15KB zero-dependency TypeScript library by Cheng Lou (React core, ReasonML, Midjourney) for **DOM-free multiline text measurement and layout**. It does one thing: given `(text, font, width)`, return the line breaks, per-line widths, per-grapheme positions, and total height, all via canvas measurement, no reflow.

That sounds like plumbing. It is not. Because it is fast and geometric, it is a **creative primitive**: you can reflow paragraphs around a moving sprite at 60fps, build games whose level geometry is made of real words, drive ASCII logos through prose, shatter text into particles with exact per-grapheme starting positions, or pack shrink-wrapped multiline UI without any `getBoundingClientRect` thrash.

This skill exists so the agent can make **cool demos** with it, the kind people post to X. See `pretext.cool` and `chenglou.me/pretext` for the community demo corpus.

## When to Use

Use when the user asks for:
- A "pretext demo" / "cool pretext thing" / "text-as-X"
- Text flowing around a moving shape (hero sections, editorial layouts, animated long-form pages)
- ASCII-art effects using **real words or prose**, not monospace rasters
- Games where the playfield / obstacles / bricks are made of text (Tetris-from-letters, Breakout-of-prose)
- Kinetic typography with per-glyph physics (shatter, scatter, flock, flow)
- Typographic generative art, especially with non-Latin scripts or mixed scripts
- Multiline "shrink-wrap" UI (smallest container width that still fits the text)
- Anything that would require knowing line breaks *before* rendering

Don't use for:
- Static SVG/HTML pages where CSS already solves layout, just use CSS
- Rich text editors, general inline formatting engines (pretext is intentionally narrow)
- Image → text (use `ascii-art` / `ascii-video` skills)
- Pure canvas generative art with no text role, use `p5js`

## Creative Standard

The rest: https://github.com/mateaix/mateclaw/blob/HEAD/mateclaw-server/src/main/resources/skills/pretext/SKILL.md