manifest-v3

# Manifest V3 Complete Reference

## Basic Structure

```json
{
  "manifest_version": 3,
  "name": "Extension Name",
  "version": "1.0.0",
  "description": "Brief description (max 132 chars for store)"
}
```

## Required Fields

| Field | Type | Description |
|-------|------|-------------|
| `manifest_version` | integer | Must be `3` |
| `name` | string | Extension name (max 45 chars) |
| `version` | string | Version string (e.g., "1.0.0") |

## Recommended Fields

| Field | Type | Description |
|-------|------|-------------|
| `description` | string | Brief description |
| `icons` | object | Extension icons |
| `action` | object | Toolbar button config |

---

## Icons

```json
{
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  }
}
```

| Size | Usage |
|------|-------|
| 16x16 | Favicon, toolbar |
| 32x32 | Windows computers |
| 48x48 | Extensions management page |
| 128x128 | Chrome Web Store |

---

## Background Service Worker

```json
{
  "background": {
    "service_worker": "background.js",
    "type": "module"
  }
}
```

| Property | Description |
|----------|-------------|
| `service_worker` | Path to service worker file |
| `type` | Set to `"module"` for ES module support |

**Key Differences from MV2:**
- No persistent background pages
- Service worker terminates after ~30s idle
- Must use `chrome.alarms` for periodic tasks
- Event listeners must be registered at top level

---

## Action (Toolbar Button)

```json
{
  "action": {
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png"
    },
    "default_title": "Click to activate",
    "default_popup": "popup.html"
  }
}
```

| Property | Description |
|----------|-------------|
| `default_icon` | Icon shown in toolbar |
| `default_title` | Tooltip text |
| `default_popup` | Popup HTML file |

**Note:** Replaces both `browser_action` and `page_action` from MV2.

---

## Content Scripts

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