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.
npx agentmods add instructions/adriankarlen/textfox/agents-mdgit clone --depth 1 https://github.com/adriankarlen/textfoxWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/adriankarlen/textfox/agents-md)<a href="https://agentmods.dev/instructions/adriankarlen/textfox/agents-md"><img src="https://agentmods.dev/badge/instructions/adriankarlen/textfox/agents-md.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00927 | $0.00927 |
| Opus 5 | $0.00464 | $0.00464 |
| Sonnet 5 | $0.00185 | $0.00185 |
| Haiku 4.5 | $0.00093 | $0.00093 |
Grade A, and why
textfox AGENTS.md 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 4d ago.
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.
How it starts
The opening of the file, as written. The whole thing — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
What this is
textfox is a Firefox userChrome CSS theme for TUI enthusiasts. No JavaScript framework, no bundler — just CSS files, SVG icons, shell scripts, and a Nix flake.
Commands
Nix formatting (CI enforced):
nix run nixpkgs#nixfmt-tree # format all Nix files
nix run nixpkgs#nixfmt-tree -- --check # check only (what CI runs)
Install/uninstall (manual testing):
sh tf-install.sh # interactive install to a Firefox profile
sh tf-uninstall.sh # interactive uninstall
No test suite exists. Changes are validated by loading Firefox with the theme applied.
Architecture
CSS layer
chrome/userChrome.css is the entry point — it @imports every other CSS file and applies global font/body rules. Load order matters: defaults.css must come before config.css (user overrides).
All theming flows through CSS custom properties prefixed --tf-*, defined in chrome/defaults.css. Users customize by creating chrome/config.css which overrides those variables. Never hard-code colors; always reference --tf-* vars or Firefox's own theme vars (e.g. var(--lwt-accent-color)).
CSS file responsibilities:
defaults.css— canonical--tf-*variable definitions and their defaultsoverwrites.css— Firefox internal style resetsnavbar.css,urlbar.css,sidebar.css,tabs.css,findbar.css,menus.css,browser.css— per-component stylesicons.css— icon overrides (references SVGs inchrome/icons/)content/newtab.css,content/about.css→ loaded intouserContent.css
Nix layer
The flake exposes two delivery mechanisms:
home-manager module (nix/modules/home-manager.nix):
- Copies
chrome/directory into the Firefox profile viahome.file - Writes a generated
config.css(fromtextfox.configCss) intochrome/config.css - Injects
user.jsprefs viaprograms.firefox.profiles.<name>.extraConfig
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.
- 4d ago First seen · 71 lines · 927 tokens per session scan A cbd875db8f39
textfox AGENTS.md is an instructions file published in the GitHub repository adriankarlen/textfox (1,692 stars, last pushed 3mo ago), licensed MPL-2.0. It adds 927 tokens to every session, about $0.0046 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.
Other instructions, from other repositories
skelet AGENTS.md
Instructions for Selekkt/skelet, covering agents.md — developing skelet.css, what skelet is, source of truth, repo map and rules of engagement (framework dev).
shadow-plugin AGENTS.md
Instructions for flornkm/shadow-plugin, covering shadow agent instructions, dev environment tips, css (tailwind) class instructions and avoid double borders.
css-noop-checker CLAUDE.md
Instructions for purupurupu/css-noop-checker, covering claude.md, project overview, commands, tech stack and architecture.
weapp-tailwindcss CLAUDE.md
Claude Code instructions for sonofmagic/weapp-tailwindcss, covering claude.md, project overview, monorepo structure, common development commands and build.
gsap-skills scrolltrigger.instructions.md
Instructions for greensock/gsap-skills: When writing or suggesting scroll-linked GSAP code (ScrollTrigger).
nextarter-tailwind AGENTS.md
AGENTS.md instructions for agustinusnathaniel/nextarter-tailwind, covering next.js: always read docs before coding, ai agent guidance: nextarter-tailwind, 1. mental model for agents, implementation delegation and tooling strategy.