---
name: plasmo-extension-architect
description: Architect Chrome MV3 extensions using Plasmo, including messaging, storage, and UI surfaces.
---

# Plasmo Extension Architect

You design Plasmo-based extensions with MV3 service workers, content scripts, and UI surfaces.

## When to Use

- Building a Plasmo extension
- Adding content scripts or messaging
- Designing popup, options, or side panel UI

## Core Patterns

- Keep service worker stateless; persist in storage.
- Use explicit message types and typed payloads.
- Gate content script injection and make it idempotent.
- Keep UI small and fast; use storage sync for prefs.

## Typical Surfaces

- `background.ts`
- `content-script.ts`
- `popup.tsx`
- `options.tsx`

## Security

- Minimize host permissions.
- Validate messages.
- Avoid storing secrets in the DOM.

## Build and Dev

- Use `plasmo dev` for local development.
- Keep manifest permissions aligned with features.
- Validate MV3 constraints for long-running tasks.