xterm-js

xterm-js is a skill for Claude Code, Codex from tincopper/neeko. It costs 127 tokens per session (4,385 once invoked), scanned A, original, Apache-2.0.

A browser-based terminal emulator: a component that displays and accepts terminal commands inside a web page or Electron app. It only provides the terminal interface and must connect to another program to actually run commands.

In plain words
What is it for?
It is for building web terminals, WebSSH interfaces, and terminal views in Electron applications, with optional add-ons for tasks such as fitting, searching, and connecting.
Why use it?
It helps when an application needs an in-browser command line instead of opening a separate terminal window.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

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/tincopper/neeko/xterm-js
Any agent
npx skills add tincopper/neeko --skill xterm-js
Clone the repo
git clone --depth 1 https://github.com/tincopper/neeko

Made for: Claude Code, Codex.

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.

agentmods badge for xterm-js

README.md
[![agentmods](https://agentmods.dev/badge/skills/tincopper/neeko/xterm-js.svg)](https://agentmods.dev/skills/tincopper/neeko/xterm-js)
Your own site
<a href="https://agentmods.dev/skills/tincopper/neeko/xterm-js"><img src="https://agentmods.dev/badge/skills/tincopper/neeko/xterm-js.svg" alt="Measured on agentmods" height="20"></a>
Per session 127 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,385 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 5.1 $0.00127 $0.04385
Opus 5 $0.00063 $0.02193
Sonnet 5 $0.00025 $0.00877
Haiku 4.5 $0.00013 $0.00439

Measured 6d ago against content hash 6aa9e631e252, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

xterm-js 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 6d 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/skills/xterm-js/SKILL.md · 516 lines

How it starts

The opening of the file, as written. The whole thing — 516 lines — stays where its author put it; the contents beside it link to each section on GitHub.

xterm.js Development Skill

xterm.js (@xterm/xterm) is a full-featured terminal emulator that runs in the browser or Electron. It is NOT a shell — it must be connected to a backend process (e.g. via node-pty + WebSocket) to execute commands.


1. Installation

npm install @xterm/xterm
# Required addons (install only what you need):
npm install @xterm/addon-fit @xterm/addon-attach @xterm/addon-web-links \
            @xterm/addon-search @xterm/addon-webgl @xterm/addon-clipboard \
            @xterm/addon-web-fonts @xterm/addon-unicode11

Always import the CSS:

<link rel="stylesheet" href="node_modules/@xterm/xterm/css/xterm.css" />

Or in JS/TS:

import '@xterm/xterm/css/xterm.css';

2. Basic Setup

import { Terminal } from '@xterm/xterm';

const term = new Terminal({
  cols: 80,
  rows: 24,
  cursorBlink: true,
  scrollback: 5000,
  fontFamily: '"Cascadia Code", Menlo, monospace',
  fontSize: 14,
  theme: {
    background: '#1e1e1e',
    foreground: '#d4d4d4',
    cursor: '#d4d4d4',
  },
});

term.open(document.getElementById('terminal')!);
term.write('Hello from \x1B[1;32mxterm.js\x1B[0m\r\n$ ');

Critical: Always call term.open(element) AFTER the element is in the DOM. Use \r\n (not just \n) for newlines when writing directly.


3. Official Addons

Addon Package Purpose
FitAddon @xterm/addon-fit Resize terminal to fill its container
AttachAddon @xterm/addon-attach Connect to a WebSocket backend
SearchAddon @xterm/addon-search In-terminal text search
WebglAddon @xterm/addon-webgl GPU-accelerated WebGL2 renderer
WebLinksAddon @xterm/addon-web-links Clickable URLs
ClipboardAddon @xterm/addon-clipboard Browser clipboard integration
WebFontsAddon @xterm/addon-web-fonts Wait for web fonts before rendering
Unicode11Addon @xterm/addon-unicode11 Unicode 11 character width support
LigaturesAddon @xterm/addon-ligatures Font ligature support (canvas renderer only)

Read the full file on GitHub · 516 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.

  1. 6d ago First seen · 516 lines · 127 tokens per session scan A 6aa9e631e252

Subscribe to this mod's changes

xterm-js is a skill published in the GitHub repository tincopper/neeko (11 stars, last pushed yesterday), licensed Apache-2.0. It adds 127 tokens to every session and 4,385 once invoked, about $0.0006 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 2026-08-31.

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