skill-installer

name	skill-installer
description	Install a skill package into the local agent client from a GitHub repository, local folder, or archive. Use when the user says "install this skill", "add skill from GitHub", or "list available skills". Do not use for creating new skills (use skill-creator), packaging skills for distribution (use skill-packaging), or improving already-installed skills (use skill-improver).

Purpose

Install a skill package into the local agent client's skill directory so it becomes discoverable on next restart. Supports GitHub repos, local folders, and tarballs/zips.

When to use

• User says "install this skill", "add skill from GitHub", "list available skills"
• Installing from a GitHub repo by owner/repo or URL
• Installing from a local folder or archive
• Listing what skills are available vs already installed

Do NOT use when:

• Creating a new skill from scratch → skill-creator
• Packaging a skill for distribution → skill-packaging
• Improving an already-installed skill → skill-improver
• Reconfiguring or removing an already-installed skill (manual task)

Client skill paths

Client	Path
OpenCode	.opencode/skills/<name>/
Copilot	.github/skills/<name>/ or .vscode/skills/<name>/
Claude Code	.claude/skills/<name>/ (project) or ~/.claude/skills/<name>/ (user)
Gemini CLI	.gemini/skills/<name>/

Operating procedure

Install from GitHub

1. Run: scripts/install-skill-from-github.py --repo <owner>/<repo> --path <path/to/skill>
   • Or by URL: --url https://github.com/<owner>/<repo>/tree/<ref>/<path>
2. Script downloads via zip (public repos) or falls back to git sparse checkout on auth errors
3. Pass --dest <path> to override the default install location for the target client
4. Confirm the installed folder contains SKILL.md
5. Tell user: "Restart the agent client to pick up the new skill"

Install from local source

1. Folder: Verify SKILL.md exists, then copy to the client skill path
2. Archive (tar.gz / zip): Extract to temp dir, verify SKILL.md, copy to client skill path
3. Never overwrite an existing destination — abort and ask the user first

List available skills

1. Run: scripts/list-skills.py (or --format json for machine output)
2. Present results with "(already installed)" annotations
3. Ask user which skills to install

Script reference

Network required — these scripts make GitHub API calls. Request sandbox escalation if running in a restricted environment.

Script	Purpose
scripts/install-skill-from-github.py	Download and install from any GitHub path
scripts/list-skills.py	List available skills with install status

Safety

• Overwrite protection: Scripts abort if the destination directory already exists. Never force-overwrite without explicit user confirmation.
• Path traversal: Scripts validate that skill paths are relative and inside the target directory. Do not bypass this by constructing absolute paths.
• Source trust: Only install skills from repositories the user explicitly identifies. Do not auto-discover and install skills without user approval.
• Pre-install verification (URL/GitHub sources):
  1. Verify the repository is not archived (archived repos receive no maintenance).
  2. Check the SKILL.md has valid YAML frontmatter (name and description fields present and non-empty).
  3. If the skill has a scripts/ directory, scan each script file for: shell commands with sudo, network calls to non-origin URLs, file operations outside the skill directory. Flag any found and ask user to confirm before proceeding.
• Post-install verification: Run cat SKILL.md | head -5 to confirm frontmatter parsed correctly. Check that the skill directory appears at the expected client skill path.
• If verification fails: Remove the installed skill directory immediately. Report which specific check failed and stop.
• Archive extraction: The zip extractor rejects archives containing paths that escape the destination directory.
• Credentials: Scripts use GITHUB_TOKEN / GH_TOKEN if set. Never log or echo token values.

Output contract

After a successful install, report exactly:

## Installed: <skill-name>

**Location**: <full path to installed skill directory>
**Source**: <GitHub URL or local path>

Verified:
- SKILL.md present
- No overwrite conflict

Restart the agent client to pick up the new skill.

On failure, report the specific error (see Failure handling) and stop — do not partially install.

Failure handling

Condition	Action
Destination already exists	Abort. Ask user: overwrite, skip, or rename?
No SKILL.md in source	Abort: "Not a valid skill package — no SKILL.md found"
HTTP 401/403/404 on download	Fall back to git sparse checkout; if that also fails, tell user to set GITHUB_TOKEN
Archive contains path-traversal entries	Abort: "Archive rejected — contains paths outside destination"
Network unavailable	Report the error and suggest sandbox escalation or manual download

Next steps

After installing a skill:

• If imported from external source → run skill-provenance to record origin and trust
• If imported from untrusted source → run skill-safety-review before use
• Verify the skill works → skill-evaluation