extension_stop
Stop a session that extension_dev or extension_start is running: terminate the server and the browser it launched, and remove the live-preview carrier if extension_dev placed one.
Quick start
Stop the running session and close its browser
Asked to stop, the agent ends the session and names the server and browser it shut down.
How the agent uses it
The answer names the server pid and the browser pid the launcher recorded, each with whether it is gone (serverGone, browserGone), so a "close its browser" ask is settled by this answer with no process check by hand. This covers extension_start build:false too, which the registry records as a preview session. Call it when you are done verifying, so sessions do not accumulate.
Reference
| Group | local, on by default |
| Tier | Run |
| Needs | a live dev or start session |
| Read only | no |
| Destructive | yes |
| Idempotent | yes |
| Reaches the open web | no |
Inputs
| Input | Type | Required | Default | What it does |
|---|---|---|---|---|
projectPath | string | no | Extension project root | |
browser | string | no | Browser of the session to stop. Defaults to the single live session for this project rather than assuming chrome. | |
all | boolean | no | false | Stop every known session across projects and browsers, found from this server's registry AND the on-disk markers written by this server or by servers that are no longer running, so it still works after an MCP restart. A marker owned by another MCP server that is still running is left alone and listed under skippedForeign unless includeOtherServers is true. It also takes back every live-preview carrier still recorded on this machine, including one in a project whose session was never stopped. projectPath/browser are then ignored. |
includeOtherServers | boolean | no | false | With all: true, also stop sessions whose markers belong to another MCP server that is still running (the markers sit in a per-user directory every server shares). Off by default, since those sessions are someone else's. |
When it fails
- The call is refused because no session is live. Start one with
extension_devorextension_startand call again.
Next
- MCP server: install, the two groups and the session gates
- Install in your client
extension_dev: Run the extension while you edit it: dev build, hot module replacement, and a browser with the extension loaded.extension_start: Run the PRODUCTION build in a browser: build the project, serve it, and launch.extension_wait: Wait for a running dev or start session to be ready.