Extension.js command guide

Choose the right command for the current phase of extension development, from first scaffold to production validation.

Command chooser

Goal	Command	Example
Scaffold a new project	`create`	`npx extension@latest create my-extension --template=new-react`
Develop with watch mode	`dev`	`extension dev --browser=firefox`
Build production artifacts	`build`	`extension build --browser=chrome,firefox --zip`
Build and launch production output	`start`	`extension start --browser=edge`
Launch existing build output only	`preview`	`extension preview --browser=chrome`
Get a shareable URL for a project	`publish`	`extension publish --ttl=4`
Install a managed browser runtime	`install`	`extension install chrome`
Remove a managed browser runtime	`uninstall`	`extension uninstall chrome`
Diagnose a running dev session	`doctor`	`extension doctor --browser=chromium`
Read or stream session logs	`logs`	`extension logs --follow --context background,content`
List tabs or inspect a DOM	`inspect`	`extension inspect --tab 412 --with-console`
Run code in a live context	`eval`	`extension eval "location.href" --context page`
Read or write extension storage	`storage`	`extension storage get --key settings`
Reload a context on demand	`reload`	`extension reload --context background`
Open a surface or replay an action	`open`	`extension open popup`
Handshake for scripts and agents	`capabilities`	`extension capabilities`

Running a bare extension with no command prints the full help and exits with code 0.

create to scaffold.
dev for iterative coding and reload cycles.
build for production artifacts.
preview or start for production-like validation.
install or uninstall when you need to manage Extension.js browser runtimes explicitly.
logs, inspect, eval, storage, reload, and open to observe and drive the running session.
doctor when a dev session or an automation verb talking to it stops responding.
capabilities first, when a script or agent drives the CLI instead of a human.

The telemetry command (enable / disable / status) manages anonymous telemetry consent. See Telemetry and privacy.