extension-add

Add a new feature surface to the current extension project. The user said: $ARGUMENTS

Parse arguments

• First argument: feature type, one of: sidebar, popup, content-script, background, newtab, options, devtools
• Second argument (optional): framework, one of: react, vue, svelte, preact, vanilla. Default: detect from existing project, fall back to react

Steps

1. Validate the project

   • Check that src/manifest.json exists
   • Read it to understand what's already configured
   • Detect the framework from existing dependencies in package.json

2. Get the reference pattern If MCP tool extension_add_feature is available, use it. It returns the exact manifest additions, files to create, and reference template.

   If MCP tool extension_templates (action: "source") is available, read the reference template source to get real implementation patterns.

3. Update manifest.json Add the required fields to src/manifest.json. Use the extension.dev cross-browser format:

   Feature	Chromium	Firefox
   Sidebar	"chromium:side_panel": {"default_path": "sidebar/index.html"} + "chromium:permissions": ["sidePanel"]	"firefox:sidebar_action": {"default_panel": "sidebar/index.html"}
   Popup	"chromium:action": {"default_popup": "action/index.html"}	"firefox:browser_action": {"default_popup": "action/index.html"}
   Content script	"content_scripts": [{"matches": ["<all_urls>"], "js": ["content/scripts.ts"]}]	Same
   Background	"background": {"chromium:service_worker": "background.ts", "firefox:scripts": ["background.ts"]}	Same (prefixed)
   New tab	"chrome_url_overrides": {"newtab": "newtab/index.html"}	Same
   Options	"options_ui": {"page": "options/index.html", "open_in_tab": true}	Same
   DevTools	"devtools_page": "devtools/index.html"	Same