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skills/a0-create-plugin/SKILL.md

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Agent Zero Plugin Development

[!IMPORTANT] Always create new plugins in /a0/usr/plugins/<plugin_name>/. The /a0/plugins/ directory is reserved for core system plugins.

Related skills: /a0/skills/a0-review-plugin/SKILL.md | /a0/skills/a0-contribute-plugin/SKILL.md | /a0/skills/a0-manage-plugin/SKILL.md

Primary references:

  • /a0/AGENTS.md (Full-stack architecture & AgentContext)
  • /a0/docs/agents/AGENTS.components.md (Component system deep dive)
  • /a0/docs/agents/AGENTS.modals.md (Modal system & CSS conventions)
  • /a0/docs/agents/AGENTS.plugins.md (Extension points, plugin.yaml, settings system, Plugin Index)
  • /a0/docs/developer/plugins.md (Developer lifecycle and publishing)

Step 0: Ask First — Local or Community Plugin?

Before starting, ask the user one question:

"Should this plugin be local only (stays in your Agent Zero installation) or a community plugin (published to the Plugin Index so others can install it)?"

  • Local plugin: Create it in /a0/usr/plugins/<plugin_name>/. No repository needed. Skip to the manifest section below.
  • Community plugin: The plugin must live in its own GitHub repository (runtime manifest at the repo root), and then a separate index submission PR is made to https://github.com/agent0ai/a0-plugins. Guide the user through both steps.

Plugin Manifest (plugin.yaml)

Every plugin must have a plugin.yaml or it will not be discovered.

yaml
name: my_plugin              # required for community plugins; must match dir name (^[a-z0-9_]+$)
title: My Plugin
description: What this plugin does.
version: 1.0.0
settings_sections:
  - agent
per_project_config: false
per_agent_config: false

name: lowercase, numbers, underscores only (^[a-z0-9_]+$). Required by CI when submitting to the Plugin Index - must exactly match the index folder name.

settings_sections controls which Settings tabs show a subsection for this plugin. Valid values: agent, external, mcp, developer, backup. Use [] for no subsection.

Activation defaults to ON when no toggle rule exists. Set per_project_config and/or per_agent_config to enable advanced per-scope switching. Core system plugins may also use always_enabled: true to lock the plugin permanently ON (reserved for framework use).

Mandatory Frontend Patterns

1. The "Store Gate" Template

To avoid race conditions and undefined errors, every component must use this wrapper:

html
<div x-data>
  <template x-if="$store.myPluginStore">
    <div x-init="$store.myPluginStore.onOpen()" x-destroy="$store.myPluginStore.cleanup()">
       <!-- Content goes here -->
    </div>
  </template>
</div>

2. Separate Store Module

Place store logic in a separate .js file. Do NOT use alpine:init listeners inside HTML.

javascript
// webui/my-store.js
import { createStore } from "/js/AlpineStore.js";
export const store = createStore("myPluginStore", {
    status: 'idle',
    init() { ... },
    onOpen() { ... },
    cleanup() { ... }
});

Import it in the HTML <head>:

html
<head>
  <script type="module" src="/plugins/<plugin_name>/webui/my-store.js"></script>
</head>

3. User Feedback: A0 Notifications Only

Do not show errors or success via inline boxes (e.g. a red <div> bound to store.error). Use the project notification system so toasts and history stay consistent.

  • Errors: toastFrontendError(message, "My Plugin") (or $store.notificationStore.frontendError(...))
  • Success: toastFrontendSuccess(message, "My Plugin")
  • Warnings/Info: toastFrontendWarning, toastFrontendInfo from /components/notifications/notification-store.js

Import and call from your store; do not render a dedicated error/success block in the template. See Notifications for the full API.

Plugin Settings

If your plugin needs user-configurable settings, add webui/config.html. The system detects it automatically and shows a Settings button in the relevant tabs (per settings_sections in plugin.yaml).

Settings modal contract

The modal provides Project + Agent profile context selectors. The plugin settings wrapper instantiates a local modal context from $store.pluginSettingsPrototype. Inside config.html, bind plugin fields to config.* and use context.* for modal-level state and actions:

html
<html>
<head>
  <title>My Plugin Settings</title>
  <script type="module">
    import { store } from "/components/plugins/plugin-settings-store.js";
  </script>
</head>
<body>
  <div x-data>
    <input x-model="config.my_key" />
    <input type="checkbox" x-model="config.feature_enabled" />
  </div>
</body>
</html>

The modal's Save button persists config to config.json in the correct scope (project/agent/global).

Sidebar Button (sidebar entry point)

  • Extension point: sidebar-quick-actions-main-start
  • Class: class="config-button"
  • Placement: x-move-after=".config-button#dashboard"
  • Action: @click="openModal('/plugins/<plugin_name>/webui/my-modal.html')"

Backend API & Context

Import Paths

  • Correct: from agent import AgentContext, AgentContextType
  • Correct: from initialize import initialize_agent
  • Correct for plugin-local Python modules under usr/plugins/<name>/: from usr.plugins.<name>.helpers.module import ...
  • Avoid sys.path hacks for plugin-local imports
  • Avoid symlink-dependent imports like from plugins.<name>... for user/community plugins in usr/plugins/

Sending Messages Proactively

python
from agent import AgentContext
from helpers.messages import UserMessage

context = AgentContext.use(context_id)
task = context.communicate(UserMessage("Message text"))
response = await task.result()

Reading Plugin Settings (backend)

python
from helpers.plugins import get_plugin_config, save_plugin_config

# Runtime (with running agent - resolves project/profile from context)
settings = get_plugin_config("my-plugin", agent=agent) or {}

# Explicit write target (project/profile scope)
save_plugin_config(
    "my-plugin",
    project_name="my-project",
    agent_profile="default",
    settings=settings,
)

Directory Layout

/a0/usr/plugins/<name>/
  plugin.yaml           # Required manifest
  execute.py            # Optional user-triggered setup, post-install, or maintenance script
  hooks.py              # Optional framework runtime hook functions
  default_config.yaml   # Optional default settings fallback
  README.md             # Optional locally; strongly recommended for community plugins
  LICENSE               # Optional locally (shown in Plugin List UI when present); required at repo root for Plugin Index submission
  agents/
    <profile>/agent.yaml # Optional plugin-distributed agent profile
  api/                  # API Handlers (ApiHandler base class)
  tools/                # Tool subclasses
  helpers/              # Shared Python logic
  prompts/              # Prompt templates
  conf/
    model_providers.yaml # Optional: add or override model providers
  extensions/
    python/<extension_point>/  # Named Python lifecycle extensions
    python/_functions/<module>/<qualname>/<start|end>/  # Implicit @extensible hooks
    webui/<point>/      # HTML/JS hook extensions
  webui/
    config.html         # Optional: plugin settings UI
    my-modal.html       # Full plugin pages
    my-store.js         # Alpine stores

Do not create the retired flattened extensible path form extensions/python/<module>_<qualname>_<start|end>/. The current runtime only resolves the deep _functions/<module>/<qualname>/<start|end> layout for implicit @extensible hooks.

Import rule for plugin-local Python code

Use the fully qualified usr.plugins.<plugin_name>... path for plugin-local imports. This lets plugins keep a normal helpers/ directory without renaming it to <name>_helpers, and it avoids both sys.path mutation and symlink installation steps.

Good:

python
from usr.plugins.my_plugin.helpers.runtime import do_work
import usr.plugins.my_plugin.helpers.state as state

Avoid:

python
sys.path.insert(0, ...)
from helpers.runtime import do_work

from plugins.my_plugin.helpers.runtime import do_work

Plugin Execution Script (execute.py)

If your plugin needs a user-triggered script for setup, post-install work, maintenance, or other manual operations, add an execute.py at the plugin root.

Good uses for execute.py include:

  • installing dependencies or downloading models/assets
  • running post-install steps after the plugin is copied into place
  • rebuilding caches, indexes, or generated files
  • applying migrations, repair steps, or sync jobs that the user may need to run again later
  • performing periodic maintenance tasks that should happen only when explicitly requested by the user

Use execute.py for user-initiated work. If the behavior is framework-internal or should happen automatically as part of plugin lifecycle handling, use hooks.py or lifecycle extensions instead.

First rule of plugin side effects: do not modify the system permanently in ways that outlive the plugin. When a plugin is deleted, there should be no leftover symlinks, unmanaged services, or stray files outside plugin-owned paths unless the user explicitly requested that behavior and the plugin documents how to clean it up.

python
import subprocess
import sys

def main():
    print("Installing plugin dependencies...")
    result = subprocess.run(
        [sys.executable, "-m", "pip", "install", "requests==2.31.0"],
        text=True,
    )
    if result.returncode != 0:
        print("ERROR: Installation failed")
        return result.returncode

    print("Refreshing plugin resources...")
    # Add post-install, repair, migration, or maintenance logic here.

    print("Done.")
    return 0

if __name__ == "__main__":
    sys.exit(main())

Users trigger it from the Plugins UI. Treat it as a manual, rerunnable operation: return 0 on success, non-zero on failure, and print progress so the user can understand what happened. When possible, make it safe to run more than once; if reruns are not safe, detect the state and print a clear message.

Runtime Hooks (hooks.py)

If your plugin needs framework-internal hook points, add a hooks.py file at the plugin root. The framework can call exported functions by name via helpers.plugins.call_plugin_hook(...).

  • hooks.py runs inside the Agent Zero framework runtime, not the separate agent execution environment.
  • Use it for things like install hooks, pre-update hooks, plugin registration work, cache setup, file preparation, or other internal framework operations.
  • Current built-in usage:
    • the plugin installer calls install() in hooks.py after placing a plugin in usr/plugins/
    • the plugin updater calls pre_update() in hooks.py immediately before pulling new plugin code into place
    • the plugin uninstaller calls uninstall() in hooks.py before deleting the plugin directory — use this to clean up any dependencies or state created by install()
  • Hook functions may be sync or async.
  • Hooks should be reversible and cleanup-safe. Prefer framework-managed state and plugin-owned paths over permanent system modifications.

Environment targeting rules

  • If hooks.py runs sys.executable -m pip install ..., it installs into the same Python environment that is running Agent Zero.
  • That is correct for dependencies needed by the plugin inside the framework runtime.
  • If the dependency is meant for the separate agent runtime or for OS-level tools, do not assume the current environment is correct.

Instead, explicitly switch targets in a subprocess:

  • invoke the exact Python interpreter for the target runtime
  • activate the target virtualenv in the subprocess before running pip
  • run the relevant OS package manager from a subprocess configured for the intended environment

In Docker, this usually means hooks.py affects /opt/venv-a0 unless you intentionally target /opt/venv or another environment.

Community Plugin: GitHub Repo + Plugin Index Submission

If the user chose a community plugin, follow these additional steps after building and testing the plugin locally.

1. Repository Structure

The plugin must live in its own GitHub repository with the plugin contents at the repository root (not inside a subfolder):

text
your-plugin-repo/          ← GitHub repository root
├── plugin.yaml            ← runtime manifest (must include name field!)
├── default_config.yaml
├── README.md
├── LICENSE                ← required at repo root before Plugin Index submission
├── api/
├── tools/
├── extensions/
└── webui/

The runtime plugin.yaml at the repo root must include a name field matching the index folder name:

yaml
name: my_plugin            # REQUIRED - must match index folder name exactly
title: My Plugin
description: What this plugin does.
version: 1.0.0

Help the user create this repository and push the plugin files to it.

2. Index manifest (different from runtime manifest)

The Plugin Index (https://github.com/agent0ai/a0-plugins) uses a separate index.yaml file that only describes discoverability — it is NOT the same as the runtime plugin.yaml and has a different schema:

yaml
title: My Plugin
description: What this plugin does.
github: https://github.com/yourname/your-plugin-repo
tags:
  - tools
  - example
screenshots:                # optional, up to 5 full image URLs
  - https://raw.githubusercontent.com/yourname/your-plugin-repo/main/docs/screen1.png

Required fields: title, description, github. Optional: tags (up to 5), screenshots (up to 5 URLs). See the recommended tag list at https://github.com/agent0ai/a0-plugins/blob/main/TAGS.md.

Important: CI also checks that your remote plugin.yaml contains a name field matching the index folder name exactly.

3. Submission steps

  1. Fork https://github.com/agent0ai/a0-plugins.
  2. Create the folder plugins/<your_plugin_name>/ in the fork.
    • Folder name: lowercase letters, numbers, underscores only (^[a-z0-9_]+$) - no hyphens
    • Must exactly match the name field in your remote plugin.yaml
  3. Add index.yaml inside it (and optionally a square thumbnail ≤ 20 KB named thumbnail.png, thumbnail.jpg, or thumbnail.webp).
  4. Open a Pull Request. The PR must add exactly one new plugin folder.
  5. CI validates automatically. A maintainer reviews and merges.

Submission constraints:

  • Folder name: unique, stable, ^[a-z0-9_]+$
  • Folders starting with _ are reserved for internal use
  • title max 50 characters, description max 500 characters
  • index.yaml max 2000 characters total

For a fully guided contribution flow (including git operations), read /a0/skills/a0-contribute-plugin/SKILL.md.

Plugin Index & Plugin Hub

The Plugin Index is the community hub at https://github.com/agent0ai/a0-plugins.

Agent Zero now exposes indexed plugins through the built-in Plugin Hub. Users can open it from the Plugins dialog either through the Browse tab or through the Install button, then inspect plugin details and install directly from the UI.