github-auth

name	github-auth
description	Set up GitHub authentication for the agent using git (universally available) or the gh CLI. Covers HTTPS tokens, SSH keys, credential helpers, and gh auth — with a detection flow to pick the right method automatically.
version	1.1.0
author	Gauss Agent
license	MIT
metadata	{"gauss":{"tags":["GitHub","Authentication","Git","gh-cli","SSH","Setup"],"related_skills":["github-pr-workflow","github-code-review","github-issues","github-repo-management"]}}

GitHub Authentication Setup

This skill sets up authentication so the agent can work with GitHub repositories, PRs, issues, and CI. It covers two paths:

• git (always available) — uses HTTPS personal access tokens or SSH keys
• gh CLI (if installed) — richer GitHub API access with a simpler auth flow

Detection Flow

When a user asks you to work with GitHub, run this check first:

# Check what's available
git --version
gh --version 2>/dev/null || echo "gh not installed"

# Check if already authenticated
gh auth status 2>/dev/null || echo "gh not authenticated"
git config --global credential.helper 2>/dev/null || echo "no git credential helper"

Decision tree:

1. If gh auth status shows authenticated → you're good, use gh for everything
2. If gh is installed but not authenticated → use "gh auth" method below
3. If gh is not installed → use "git-only" method below (no sudo needed)

---

Method 1: Git-Only Authentication (No gh, No sudo)

This works on any machine with git installed. No root access needed.

Option A: HTTPS with Personal Access Token (Recommended)

This is the most portable method — works everywhere, no SSH config needed.

Step 1: Create a personal access token

Tell the user to go to: https://github.com/settings/tokens

• Click "Generate new token (classic)"
• Give it a name like "gauss-agent"
• Select scopes:
  • repo (full repository access — read, write, push, PRs)
  • workflow (trigger and manage GitHub Actions)
  • read:org (if working with organization repos)
• Set expiration (90 days is a good default)
• Copy the token — it won't be shown again

Step 2: Configure git to store the token

# Set up the credential helper to cache credentials
# "store" saves to ~/.git-credentials in plaintext (simple, persistent)
git config --global credential.helper store

# Now do a test operation that triggers auth — git will prompt for credentials
# Username: <their-github-username>
# Password: <paste the personal access token, NOT their GitHub password>
git ls-remote https://github.com/<their-username>/<any-repo>.git

After entering credentials once, they're saved and reused for all future operations.

Alternative: cache helper (credentials expire from memory)

# Cache in memory for 8 hours (28800 seconds) instead of saving to disk
git config --global credential.helper 'cache --timeout=28800'

Alternative: set the token directly in the remote URL (per-repo)

# Embed token in the remote URL (avoids credential prompts entirely)
git remote set-url origin https://<username>:<token>@github.com/<owner>/<repo>.git

Step 3: Configure git identity

# Required for commits — set name and email
git config --global user.name "Their Name"
git config --global user.email "[e-mail]"

Step 4: Verify

# Test push access (this should work without any prompts now)
git ls-remote https://github.com/<their-username>/<any-repo>.git

# Verify identity
git config --global user.name
git config --global user.email

Option B: SSH Key Authentication

Good for users who prefer SSH or already have keys set up.

Step 1: Check for existing SSH keys

ls -la ~/.ssh/id_*.pub 2>/dev/null || echo "No SSH keys found"

Step 2: Generate a key if needed

# Generate an ed25519 key (modern, secure, fast)
ssh-keygen -t ed25519 -C "[e-mail]" -f ~/.ssh/id_ed25519 -N ""

# Display the public key for them to add to GitHub
cat ~/.ssh/id_ed25519.pub

Tell the user to add the public key at: https://github.com/settings/keys

• Click "New SSH key"
• Paste the public key content
• Give it a title like "gauss-agent-"

Step 3: Test the connection

ssh -T [e-mail]
# Expected: "Hi <username>! You've successfully authenticated..."

Step 4: Configure git to use SSH for GitHub

# Rewrite HTTPS GitHub URLs to SSH automatically
git config --global url."[e-mail]:".insteadOf "https://github.com/"

Step 5: Configure git identity

git config --global user.name "Their Name"
git config --global user.email "[e-mail]"

---

Method 2: gh CLI Authentication

If gh is installed, it handles both API access and git credentials in one step.

Interactive Browser Login (Desktop)

gh auth login
# Select: GitHub.com
# Select: HTTPS
# Authenticate via browser

Token-Based Login (Headless / SSH Servers)

echo "<THEIR_TOKEN>" | gh auth login --with-token

# Set up git credentials through gh
gh auth setup-git

Verify

gh auth status

---

Using the GitHub API Without gh

When gh is not available, you can still access the full GitHub API using curl with a personal access token. This is how the other GitHub skills implement their fallbacks.

Setting the Token for API Calls

# Option 1: Export as env var (preferred — keeps it out of commands)
export GITHUB_TOKEN="<token>"

# Then use in curl calls:
curl -s -H "Authorization: token $GITHUB_TOKEN" \
  https://api.github.com/user

Extracting the Token from Git Credentials

If git credentials are already configured (via credential.helper store), the token can be extracted:

# Read from git credential store
grep "github.com" ~/.git-credentials 2>/dev/null | head -1 | sed 's|https://[^:]*:\([^@]*\)@.*|\1|'

Helper: Detect Auth Method

Use this pattern at the start of any GitHub workflow:

# Try gh first, fall back to git + curl
if command -v gh &>/dev/null && gh auth status &>/dev/null; then
  echo "AUTH_METHOD=gh"
elif [ -n "$GITHUB_TOKEN" ]; then
  echo "AUTH_METHOD=curl"
elif grep -q "github.com" ~/.git-credentials 2>/dev/null; then
  export GITHUB_TOKEN=$(grep "github.com" ~/.git-credentials | head -1 | sed 's|https://[^:]*:\([^@]*\)@.*|\1|')
  echo "AUTH_METHOD=curl"
else
  echo "AUTH_METHOD=none"
  echo "Need to set up authentication first"
fi

---

Troubleshooting

Problem	Solution
git push asks for password	GitHub disabled password auth. Use a personal access token as the password, or switch to SSH
remote: Permission to X denied	Token may lack repo scope — regenerate with correct scopes
fatal: Authentication failed	Cached credentials may be stale — run git credential reject then re-authenticate
ssh: connect to host github.com port 22: Connection refused	Try SSH over HTTPS port: add Host github.com with Port 443 and Hostname ssh.github.com to ~/.ssh/config
Credentials not persisting	Check git config --global credential.helper — must be store or cache
Multiple GitHub accounts	Use SSH with different keys per host alias in ~/.ssh/config, or per-repo credential URLs
gh: command not found + no sudo	Use git-only Method 1 above — no installation needed