extension-manifest

name	extension-manifest
description	Generate and validate manifest.json with optimal permissions for Chrome MV3 extensions. Analyzes code to determine minimum permissions. Use when: manifest, permissions, manifest.json.

Extension Manifest & Permissions Generator

Generate the best manifest.json based on current extension implementation. Analyze code to determine minimum permissions following Chrome docs and best practices.

Workflow

1. Detect framework: check for wxt.config.ts, plasmo.config.ts, or raw manifest.json
2. Scan the extension codebase for Chrome API usage
3. Map each API call to its required permission (see references/api-permission-map.md)
4. Generate manifest.json with minimum required permissions
5. Validate against Chrome docs and CWS policies
6. Report permission warnings users will see

Plasmo projects: Manifest is auto-generated from code and package.json. Override via plasmo.config.ts. See https://docs.plasmo.com/

Docs References

• Manifest reference: https://developer.chrome.com/docs/extensions/reference/manifest
• Permissions list: https://developer.chrome.com/docs/extensions/reference/permissions-list

Quick Manifest Template

{
  "manifest_version": 3,
  "name": "Extension Name",
  "version": "1.0.0",
  "description": "Brief description. Max 132 chars for CWS.",
  "icons": { "16": "icons/icon16.png", "48": "icons/icon48.png", "128": "icons/icon128.png" },
  "action": { "default_popup": "popup.html", "default_icon": { "16": "icons/icon16.png" } },
  "permissions": [],
  "host_permissions": [],
  "background": { "service_worker": "background.js", "type": "module" }
}

Permission Analysis Steps

1. Grep codebase for chrome. API calls
2. Map each to permission using references/api-permission-map.md
3. Prefer activeTab over tabs + host_permissions when possible
4. Use optional permissions for non-essential features
5. Check warning text in references/permission-warnings.md

Common Mistakes

Error	Fix
host_permissions inside permissions	Move URLs to separate host_permissions array
Using <all_urls>	Narrow to specific domain patterns
Missing activeTab	Add when only needing current tab on user click
tabs permission overuse	Only needed for tab URL/title; use activeTab instead
content_security_policy as string	Must be object: { "extension_pages": "..." }
web_accessible_resources as string[]	Use object with resources + matches

Key MV3 Rules

1. host_permissions is separate from permissions
2. Service workers replace background pages (no DOM, no window)
3. content_security_policy is an object, not string
4. Remote code execution banned (no eval, no CDN scripts)
5. web_accessible_resources requires matches array
6. Use chrome.scripting.executeScript() not tabs.executeScript()

References

• references/manifest-fields-reference.md - All manifest fields with types and examples
• references/manifest-templates.md - Ready-to-use templates (popup, content script, sidepanel, devtools)
• references/manifest-validation-checklist.md - Pre-submission validation
• references/api-permission-map.md - Chrome API → permission mapping
• references/permission-warnings.md - User-facing warning text per permission
• references/permission-strategies.md - Optional permissions, activeTab, escalation patterns

Related Skills

• extension-create - Full project scaffolding
• extension-analyze - Security audit and best practices