Auto-Update Plugins Skill

Overview

This skill solves the multi-repo plugin sync problem using a GitHub-native pull model:

• Consumer projects declare what GitHub repos they subscribe to via plugin-sources.json.
• On every agent session start, a SessionStart hook fires check_and_sync.py, which detects upstream changes and re-runs plugin_add.py automatically.
• No local clone of agent-plugins-skills required — plugin_add.py clones into a temp directory, installs, and cleans up automatically.

GitHub (richfrem/agent-plugins-skills)
        ↓  plugin_add.py <owner/repo> --all -y
  consumer-project/.agents/   ← skills + agents + commands + hooks

Adding a new consumer = drop in a plugin-sources.json. Nothing changes at the source. Pivoting away = delete or clear plugin-sources.json.

---

Phase 1: Consumer Project Setup (Once Per Project)

Step 1: Create plugin-sources.json at the project root

Each source entry declares a GitHub owner/repo to pull from. No env vars or local paths required.

{
  "sources": [
    {
      "name": "agent-plugins-skills",
      "github": "richfrem/agent-plugins-skills",
      "plugins": "all"
    }
  ]
}

To subscribe to specific plugins only, list them by name:

{
  "sources": [
    {
      "name": "agent-plugins-skills",
      "github": "richfrem/agent-plugins-skills",
      "plugins": ["spec-kitty-plugin", "agent-agentic-os", "agent-loops"]
    }
  ]
}

To subscribe to multiple source repos, add more entries:

{
  "sources": [
    {
      "name": "agent-plugins-skills",
      "github": "richfrem/agent-plugins-skills",
      "plugins": "all"
    },
    {
      "name": "my-private-plugins",
      "github": "myorg/my-private-plugins",
      "plugins": "all"
    }
  ]
}

Step 2: Install check_and_sync.py into the consumer project

Copy ./scripts/check_and_sync.py into the consumer project at .agents/scripts/check_and_sync.py.

This script:

1. Reads plugin-sources.json at the project root.
2. For each source, checks the latest commit SHA from the GitHub API (no auth needed for public repos).
3. Compares it against .agents/plugin-sync-state.json (a local SHA cache).
4. If changed: runs plugin_add.py <owner/repo> --all -y and updates the SHA cache.
5. If GitHub is unreachable: logs a warning and skips gracefully (no crash).

Step 3: Wire up the SessionStart Hook

Add a SessionStart hook so check_and_sync.py fires on every agent session start.

Create .agents/hooks/session_start.sh:

#!/usr/bin/env bash
# Auto-sync plugins from registered GitHub sources on every session start.
if [ -f "plugin-sources.json" ]; then
  python3 .agents/scripts/check_and_sync.py
fi

For Claude Code, register the hook in .claude/settings.json:

{
  "hooks": {
    "SessionStart": [
      {
        "matcher": "",
        "hooks": [
          {
            "type": "command",
            "command": "bash .agents/hooks/session_start.sh"
          }
        ]
      }
    ]
  }
}

---

Phase 2: Manual On-Demand Update

To manually pull the latest plugins from GitHub at any time:

# Interactive — pick which plugins to update
python ./scripts/plugin_add.py richfrem/agent-plugins-skills

# Non-interactive — reinstall everything
python ./scripts/plugin_add.py richfrem/agent-plugins-skills --all -y

---

How check_and_sync.py Works

SessionStart fires
    ↓
Read plugin-sources.json
    ↓
For each source:
    GET https://api.github.com/repos/<owner>/<repo>/commits?per_page=1
    sha = response[0].sha
    ↓
    Compare sha to .agents/plugin-sync-state.json["<name>"]["sha"]
    ↓
    If changed:
        python plugin_add.py <owner/repo> --all -y
        update plugin-sync-state.json sha
    If same:
        skip (no network calls beyond the SHA check)
    If GitHub unreachable:
        log warning, skip

The SHA check is a single lightweight API call (~1 KB). The full clone only happens when there is an actual upstream change.

---

Opting Out / Pivoting Away

To stop a consumer project from auto-syncing:

• Delete or empty plugin-sources.json, OR
• Remove the check_and_sync.py call from the SessionStart hook.

Nothing at the source repo needs to change.

---

Migration from Old Local-Path Model

If you previously used AGENT_PLUGINS_SKILLS_DIR env var + install_all_plugins.py:

1. Replace plugin-sources.json with the GitHub-based format above.
2. Remove AGENT_PLUGINS_SKILLS_DIR from your shell profile / PowerShell profile.
3. Remove the sync-agent-plugins alias (no longer needed).
4. check_and_sync.py now calls plugin_add.py instead of install_all_plugins.py.

---

Related Skills

• plugin-installer — full plugin deployment (skills + agents + commands + hooks).
• maintain-plugins — health check, orphan cleanup, and ecosystem audit.