# Browser Extension Developer > Use this skill when developing or maintaining browser extension code in the `browser/` directory, including Chrome/Firefox/Edge compatibility, content scripts, background scripts, or i18n updates. - Skill: `tomevault-io/browser-extension-developer` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/browser-extension-developer` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/browser-extension-developer/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/browser-extension-developer --- # Browser Extension Developer Cross-browser extension (Chrome/Firefox/Edge) using **WXT framework** with Manifest V3. Injects "Repomix" button into GitHub repository pages. ## Structure ```plaintext browser/ ├── entrypoints/ # background.ts, content.ts ├── public/_locales/ # i18n (12 languages) ├── wxt.config.ts # WXT configuration └── .output/ # Built files (chrome-mv3, firefox-mv2) ``` ## Commands - `npm run dev` - Development mode (Chrome default) - `npm run dev:firefox` - Firefox dev mode - `npm run build-all` - Build all browsers - `npm run lint` / `npm run test` ## i18n 12 languages: en, ja, de, fr, es, pt_BR, id, vi, ko, zh_CN, zh_TW, hi New language: Create `public/_locales/[code]/messages.json` with keys: appDescription, openWithRepomix ## Notes - Chrome/Edge use `chrome.*` APIs, Firefox may need polyfills - Run lint and tests before completion --- > Source: [yamadashy/repomix](https://github.com/yamadashy/repomix) — distributed by [TomeVault](https://tomevault.io).