pretext

A tool for measuring and arranging multiline text in a browser without placing it on the page. Given text, a font, and a width, it calculates line breaks, widths, character positions, and total height.

In plain words
What is it for?
Use it to wrap text around moving shapes, create word-based game geometry, build ASCII effects from real text, position individual characters, or size multiline interface elements.
Why use it?
It avoids repeatedly measuring visible page elements when text changes or moves. That makes text-based visual effects and animated layouts easier to calculate.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/nousresearch/hermes-agent/pretext
Any agent
npx skills add NousResearch/hermes-agent --skill pretext
Clone the repo
git clone --depth 1 https://github.com/NousResearch/hermes-agent

Made for: Claude Code, Codex.

Per session 13 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,465 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00013 $0.03465
Opus 5 $0.00006 $0.01733
Sonnet 5 $0.00003 $0.00693
Haiku 4.5 $0.00001 $0.00347

Measured yesterday against content hash c09691f63543, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

pretext scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

8 near-identical copies found in the catalogue:

  • pretext — 95% identical, 6 lines differ
  • pretext — 94% identical, 14 lines differ
  • pretext — 92% identical, 16 lines differ
  • pretext — 92% identical, 8 lines differ
  • pretext — 92% identical, 8 lines differ
  • pretext — 91% identical, 9 lines differ
  • pretext — 91% identical, 14 lines differ
  • pretext — 89% identical, 31 lines differ
optional-skills/creative/pretext/SKILL.md · 221 lines

How it starts

The opening of the file, as written. The whole thing — 221 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Pretext Creative Demos

Overview

@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 Hermes 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

This is visual art rendered in a browser. Pretext returns numbers; you draw the thing.

Read the full file on GitHub · 221 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 221 lines · 13 tokens per session scan A c09691f63543

Subscribe to this mod's changes

pretext is a skill published in the GitHub repository NousResearch/hermes-agent (238,457 stars, last pushed yesterday), licensed MIT. It adds 13 tokens to every session and 3,465 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

storybook

Storybook is the fidelity oracle, not the runtime. The converter bundles the package's compiled dist/ into dsbundle.js - the same bundle the claude.ai/design agent builds with - and generates each preview by compiling the story source module itself (hooks, fixtures, local helpers - the whole closure comes along), with…

asgeirtj/system_prompts_leaks · 0 tokens

save-as-pdf

Reformat the current HTML design into a paginated, paper-ready PDF. The "Instant" export already gives the user a PDF at the design's native pixel size — this path is for when they want real pages.

asgeirtj/system_prompts_leaks · 9 tokens

vscode-visual-regression

Write Storybook stories and visual regression tests for the Kilo VS Code extension webview UI.

Kilo-Org/kilocode · 25 tokens

9router-web-fetch

Fetch URL → markdown / text / HTML via 9Router /v1/web/fetch using Firecrawl / Jina Reader / Tavily Extract / Exa Contents. Use when the user wants to scrape a webpage, extract URL content, read article, or convert a URL to markdown.

decolua/9router · 63 tokens

claude-in-chrome

Automates your Chrome browser to interact with web pages - clicking elements, filling forms, capturing screenshots, reading console logs, and navigating sites. Opens pages in new tabs within your existing Chrome session. Requires site-level permissions before executing (configured in the extension).

asgeirtj/system_prompts_leaks · 57 tokens

verify

Verify that a code change actually does what it's supposed to by exercising it end-to-end and observing behavior — drive the affected flow, not just tests or typecheck. Run before committing nontrivial changes; bootstraps this repo's project verify skill if none exists yet. Don't invoke it on a diff that only touches…

asgeirtj/system_prompts_leaks · 95 tokens