What is textfox AGENTS.md?

Repository instructions for textfox, a Firefox theme made from CSS, SVG icons, shell scripts, and Nix configuration. Nix is a tool for reproducible development environments and builds.

Use them when editing textfox styles, icons, installation scripts, or Nix files, and when checking the result in Firefox.

They explain how the theme is structured, how its settings are overridden, and how to validate changes when there is no automated test suite.

How adriankarlen/textfox configures Codex and OpenCode

About the project

textfox is a Firefox theme designed for people who prefer a terminal-inspired visual style.

adriankarlen/textfox · 1,707 stars · on GitHub · matrix.to

Reuse

Borrowing it

Nothing to install: this file belongs to adriankarlen/textfox. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/adriankarlen/textfox/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/adriankarlen/textfox

Made for: Codex, OpenCode.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/adriankarlen/textfox/agents-md/github.svg)](https://agentmods.dev/instructions/adriankarlen/textfox/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/adriankarlen/textfox/agents-md"><img src="https://agentmods.dev/badge/instructions/adriankarlen/textfox/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/adriankarlen/textfox/agents-md"><img src="https://agentmods.dev/badge/instructions/adriankarlen/textfox/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 927 This file is loaded in full into every session.

When invoked 927 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00927	$0.00927
Opus 5.5	$0.00371	$0.00371
Sonnet 5.5	$0.00185	$0.00185
Haiku 4.5	$0.00093	$0.00093

Measured 2mo ago against content hash cbd875db8f39, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

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 2mo 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.

AGENTS.md · 71 lines

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 defaults
overwrites.css — Firefox internal style resets
navbar.css, urlbar.css, sidebar.css, tabs.css, findbar.css, menus.css, browser.css — per-component styles
icons.css — icon overrides (references SVGs in chrome/icons/)
content/newtab.css, content/about.css → loaded into userContent.css

Nix layer

The flake exposes two delivery mechanisms:

home-manager module (nix/modules/home-manager.nix):

Copies chrome/ directory into the Firefox profile via home.file
Writes a generated config.css (from textfox.configCss) into chrome/config.css
Injects user.js prefs via programs.firefox.profiles.<name>.extraConfig

Read the full file on GitHub · 71 lines

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.

2mo ago First seen · 71 lines · 927 tokens per session scan A cbd875db8f39

Subscribe to this mod's changes

textfox AGENTS.md is an instructions file published in the GitHub repository adriankarlen/textfox (1,707 stars, last pushed 14d ago), licensed MPL-2.0. It adds 927 tokens to every session, about $0.0037 per session on Opus 5.5. 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.

CSS and styling Frontend css firefox firefox-css rice

textfox AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
textfox AGENTS.mdadriankarlen/textfox	Instructions file	1.7k	14d ago	MPL-2.0	A	927	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	today	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

textfox: Instructions file for Codex