| 1 | # Create A Small Plugin |
| 2 | |
| 3 | The fastest way to understand Agent Zero plugins is to make one small enough to |
| 4 | hold in your head. |
| 5 | |
| 6 | This guide walks through a real example: a local plugin named `unread_dot` that |
| 7 | adds a pulsing dot beside a chat when that chat receives new activity while you |
| 8 | are looking somewhere else. |
| 9 | |
| 10 |  |
| 11 | |
| 12 | For architecture and source-linked internals, use |
| 13 | [DeepWiki for Agent Zero](https://deepwiki.com/agent0ai/agent-zero). This page |
| 14 | stays practical: what to ask, where files appear, what to check, and how to know |
| 15 | the plugin actually works. |
| 16 | |
| 17 | ## What You Are Making |
| 18 | |
| 19 | `unread_dot` is intentionally tiny: |
| 20 | |
| 21 | - it does not add a server endpoint; |
| 22 | - it adds no tool; |
| 23 | - it installs no package; |
| 24 | - it makes no network calls; |
| 25 | - it touches only the Web UI and one browser `localStorage` key. |
| 26 | |
| 27 | That makes it a good first plugin. You can see the whole shape without learning |
| 28 | every plugin feature at once. |
| 29 | |
| 30 | ## Ask Agent Zero To Build It |
| 31 | |
| 32 | Open a new chat and give Agent Zero a very specific plugin task: |
| 33 | |
| 34 | ```text |
| 35 | Use the a0-create-plugin skill. |
| 36 | |
| 37 | Create a local-only plugin named unread_dot in /a0/usr/plugins/unread_dot. |
| 38 | The plugin should show a pulsing dot in the chat list whenever a non-selected |
| 39 | chat receives new agent activity. |
| 40 | |
| 41 | Keep it minimal and frontend-only: |
| 42 | - no external dependencies; |
| 43 | - no backend API; |
| 44 | - no tools; |
| 45 | - no network calls. |
| 46 | |
| 47 | If the plugin already exists, improve it instead of creating a duplicate. |
| 48 | When finished, run the a0-review-plugin skill on unread_dot and summarize |
| 49 | PASS/WARN/FAIL. Do not run CodeRabbit. |
| 50 | ``` |
| 51 | |
| 52 | The important part is not the exact wording. The important part is giving Agent |
| 53 | Zero the plugin name, the location, the visible behavior, and the boundaries. |
| 54 | |
| 55 | ## Where The Files Go |
| 56 | |
| 57 | Local plugins live under `/a0/usr/plugins/<plugin_name>/` inside the running |
| 58 | Agent Zero instance. For this example, the final plugin shape is: |
| 59 | |
| 60 | ```text |
| 61 | /a0/usr/plugins/unread_dot/ |
| 62 | ├── plugin.yaml |
| 63 | ├── README.md |
| 64 | ├── extensions/ |
| 65 | │ └── webui/ |
| 66 | │ ├── apply_snapshot_before/ |
| 67 | │ │ └── track-unread.js |
| 68 | │ └── initFw_end/ |
| 69 | │ └── bootstrap-unread-dot.js |
| 70 | └── webui/ |
| 71 | ├── unread-dot.css |
| 72 | └── unread-dot-store.js |
| 73 | ``` |
| 74 | |
| 75 | `plugin.yaml` is the plugin's name tag: |
| 76 | |
| 77 | ```yaml |
| 78 | name: unread_dot |
| 79 | title: Unread Dot |
| 80 | description: Shows a pulsing dot beside chats that received new activity while you were elsewhere. |
| 81 | version: 1.0.0 |
| 82 | settings_sections: [] |
| 83 | per_project_config: false |
| 84 | per_agent_config: false |
| 85 | ``` |
| 86 | |
| 87 | The two Web UI extension files are the little doorways into the running |
| 88 | interface: |
| 89 | |
| 90 | - `initFw_end/bootstrap-unread-dot.js` loads the store and stylesheet after the Web UI starts. |
| 91 | - `apply_snapshot_before/track-unread.js` watches state snapshots so the plugin can notice when another chat changes. |
| 92 | |
| 93 | The store keeps the unread state. The CSS draws the dot. |
| 94 | |
| 95 | ## Try It For Real |
| 96 | |
| 97 | After creating or changing a plugin, restart Agent Zero so the Web UI extension |
| 98 | list is rebuilt. |
| 99 | |
| 100 | Then test the behavior: |
| 101 | |
| 102 | 1. Open a fresh chat. |
| 103 | 2. Send a short prompt, such as: |
| 104 | |
| 105 | ```text |
| 106 | Please reply with one short sentence: unread dot live test complete. |
| 107 | ``` |
| 108 | |
| 109 | 3. Immediately switch to another chat. |
| 110 | 4. Wait for Agent Zero to keep working in the first chat. |
| 111 | 5. Look at the chat list. |
| 112 | |
| 113 | If the first chat receives new activity while it is not selected, the dot appears. |
| 114 | When you open that chat again, the dot clears. |
| 115 | |
| 116 | This example watches for chat activity. In normal use, that means "the agent did |
| 117 | something in a chat you were not watching." It does not read every message in |
| 118 | every other chat. |
| 119 | |
| 120 | ## Review It |
| 121 | |
| 122 | Run the plugin review skill before treating the plugin as done: |
| 123 | |
| 124 | ```text |
| 125 | Use the a0-review-plugin skill to review /a0/usr/plugins/unread_dot. |
| 126 | Report PASS/WARN/FAIL by phase. |
| 127 | ``` |
| 128 | |
| 129 | For this example, the review result is: |
| 130 | |
| 131 | | Phase | Result | Notes | |
| 132 | | --- | --- | --- | |
| 133 | | Manifest | PASS | `plugin.yaml` is valid, named correctly, and uses simple local settings. | |
| 134 | | Structure | PASS with WARN | The layout is standard. `LICENSE` is absent, which is fine locally but blocks Plugin Index submission. | |
| 135 | | Code patterns | PASS with WARN | The store uses Agent Zero's `createStore` pattern. The unread signal is chat activity, not a parsed message-author check. | |
| 136 | | Security and index | PASS with WARN | No secrets, subprocesses, dependencies, or outbound calls. The community index already has a related `Chat Status Marklet` plugin, so treat this as a learning example unless you make it clearly different. | |
| 137 | |
| 138 | Status: ready as a local demo plugin. Not ready as a new community submission |
| 139 | until it has a license and a reason to exist separately from similar plugins. |
| 140 | |
| 141 | ## Make The Example Yours |
| 142 | |
| 143 | Once the small version works, change only one thing at a time: |
| 144 | |
| 145 | - move the dot to a different place in the row; |
| 146 | - use a badge instead of a dot; |
| 147 | - add a plugin setting for color or animation; |
| 148 | - show a different status for running chats and finished chats; |
| 149 | - turn the plugin into a publishable project with a `LICENSE`, screenshots, and a clearer README. |
| 150 | |
| 151 | Small plugins are good teachers. You can see the whole machine turning without |
| 152 | standing inside the engine. |
| 153 | |
| 154 | ## Related |
| 155 | |
| 156 | - [Usage Guide](usage.md#plugins-and-plugin-hub): where plugins appear in the Web UI. |
| 157 | - [DeepWiki for Agent Zero](https://deepwiki.com/agent0ai/agent-zero): source-linked architecture when you need it. |
| 158 | - [Contributing Guide](contribution.md): expectations before sharing changes upstream. |