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carbon-badge — Claude Code skill: what it does, how to install

Creates a shields.io badge showing your monthly Claude Code carbon footprint. Best suited for personal project READMEs and GitHub developer profiles.

Install into Claude Code · Skills CLI (Vercel) All methods and platforms ↓
npx skills add gwittebolle/claude-carbon --skill carbon-badge -a claude-code
Open on GitHub

What carbon-badge does

This skill executes a Bash script that discovers the claude-carbon package inside your configuration directory, status line configuration, or plugin cache. It converts Windows paths using cygpath and relies on jq to read config files.

The execution prints raw badge URLs alongside ready-to-paste Markdown and methodology notes. Output stays untouched by the agent: numbers, dates, and links remain strictly as the script produced them.

The generated badge represents individual developer metrics rather than team usage. Because shields.io serves a static asset tied to a specific month, refreshing your statistics requires re-running /carbon-badge.

What it helps with

  • add a carbon footprint badge to your GitHub profile README
  • generate a shields.io snippet with Claude Code emission figures
  • refresh monthly environmental metrics for a personal project

Example prompts for the agent

  • Run /carbon-badge to generate a README badge
  • Create my carbon footprint shields.io snippet using /carbon-badge
  • Get the markdown badge for my Claude Code emissions

How to install carbon-badge

1Skills CLI (Vercel)

npx skills add gwittebolle/claude-carbon --skill carbon-badge -a claude-code

2Manually: put the files in place

~/.claude/skills/carbon-badge/SKILL.md

Copy the whole skill folder; for one project use .claude/skills/carbon-badge/

Step by step, with commands for each platform: How to install skills in Claude Code: five ways

Questions about carbon-badge

How to install carbon-badge in Claude Code?

Run npx skills add gwittebolle/claude-carbon --skill carbon-badge -a claude-code in your terminal to register the skill.

Where should the carbon badge be displayed?

The badge reflects a single developer total, so it belongs in a personal profile README or a solo repository rather than shared team organizations.

What should you do if the generator script is missing?

If your installation predates the badge feature and cannot locate generate-badge.sh, run /carbon-update first to fetch current scripts.

Source text

SKILL.md · MIT
---
name: carbon-badge
description: Generate a shields.io badge of your Claude Code carbon footprint for your READMEs
---

Run the following bash script and present the output to the user.

```bash
#!/usr/bin/env bash
# Locate the install wired into the status line (honours CLAUDE_CONFIG_DIR),
# then fall back to CLAUDE_PLUGIN_ROOT / CLAUDE_CARBON_DIR / the default path.
# Windows (Git Bash): CLAUDE_* variables and the paths stored in settings.json can
# arrive in the native "C:\Users\..." spelling, which bash cannot open. cygpath
# ships with Git for Windows; everywhere else this is the identity function.
ccp() {
  case "${OSTYPE:-}" in msys*|cygwin*) ;; *) printf '%s' "$1"; return 0 ;; esac
  case "$1" in
    [A-Za-z]:[\\/]*|*\\*) cygpath -u "$1" 2>/dev/null || printf '%s' "$1" ;;
    *) printf '%s' "$1" ;;
  esac
}
CFG="$(ccp "${CLAUDE_CONFIG_DIR:-$HOME/.claude}")"
# A jq the installer fetched into the data folder (a Mac older than macOS 15 has none)
if ! command -v jq >/dev/null 2>&1 && [ -x "$CFG/claude-carbon/bin/jq" ]; then PATH="$CFG/claude-carbon/bin:$PATH"; fi
REPO_DIR=""
if command -v jq >/dev/null 2>&1 && [ -f "$CFG/settings.json" ]; then
  SL_CMD="$(jq -r '.statusLine.command // empty' "$CFG/settings.json" 2>/dev/null)"
  # statusLine.command stores a path, shell-escaped, or in double quotes on Windows:
  # unquote, expand ~ and unescape spaces
  SL_CMD="${SL_CMD#\"}"; SL_CMD="${SL_CMD%\"}"
  SL_CMD="${SL_CMD//\\ / }"; SL_CMD="${SL_CMD/#\~/$HOME}"; SL_CMD="$(ccp "$SL_CMD")"
  [ -n "$SL_CMD" ] && [ -f "$SL_CMD" ] && REPO_DIR="$(cd "$(dirname "$SL_CMD")/.." 2>/dev/null && pwd)"
fi
[ -z "$REPO_DIR" ] && [ -n "${CLAUDE_PLUGIN_ROOT:-}" ] && REPO_DIR="$(ccp "$CLAUDE_PLUGIN_ROOT")"
[ -z "$REPO_DIR" ] && [ -n "${CLAUDE_CARBON_DIR:-}" ] && REPO_DIR="$(ccp "$CLAUDE_CARBON_DIR")"
if [ -z "$REPO_DIR" ]; then
  # Pure marketplace installs reach here: no statusLine.command in settings.json and
  # no CLAUDE_PLUGIN_ROOT in a skill's bash env. Pick the newest cached plugin copy,
  # keeping only candidates that ship the badge script.
  CACHE_LATEST=""
  for D in "$CFG/plugins/cache"/*/claude-carbon/*/; do
    [ -f "${D}scripts/generate-badge.sh" ] || continue
    if [ -z "$CACHE_LATEST" ] || [ "$(printf '%s\n%s\n' "$CACHE_LATEST" "$D" | sort -V | tail -1)" = "$D" ]; then
      CACHE_LATEST="$D"
    fi
  done
  [ -n "$CACHE_LATEST" ] && REPO_DIR="${CACHE_LATEST%/}"
fi
[ -z "$REPO_DIR" ] && REPO_DIR="$HOME/code/claude-carbon"

bash "$REPO_DIR/scripts/generate-badge.sh"
```

The script prints a ready-to-paste markdown snippet, the raw badge URL and a short note on where the badge belongs. Show all of it exactly as printed — never recompute, reformat or re-escape the number, the month or the URL. The badge is one developer's total, dated with the month it was generated, and it links to the methodology. It belongs in the user's profile README or a personal project, not in a team or organisation repository. The badge is a static image, so re-running `/carbon-badge` is how they refresh the figure and its month.

If the script is missing (an install that predates the badge), suggest `/carbon-update`.

© gwittebolle · MIT · gwittebolle/claude-carbon

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