Publish a build

Ask your AI agent to publish, and it returns your build's page on extension.dev, with a download and a run command for each browser. Reach for it when a tester, a reviewer or a teammate needs a build the platform already made.

Quick start

Start the MCP server with --features=local,platform, log in, and ask the agent:

Publish my latest build and give me the link

The agent calls extension_publish. The answer carries link, the link to send, tellThem, one sentence to send with it, and previewCommands, one run command per browser the build targets.

How it works

extension_publish uploads nothing. It links a build the platform recorded, so the project needs one completed build first. Without buildSha the link is the newest successful build's page, https://<workspace>.extension.dev/<project>/builds/<sha>. With buildSha it is the build you name. When the build list cannot be read, the link falls back to the project page.

The build page has a download for each browser with the install steps beside it, and the answer adds a run command per browser. To hand out the bytes in your own dist/ right now, upload them instead: Share an unpublished build for review. Sending an extension to a store is Publishing.

Build links and channel links

There are two links. A build link opens one build's page and always shows that build. A channel link, https://<workspace>.extension.dev/<project>/channels/<channel>, always opens the newest build on the channel and never expires. On a public project, or a public channel, send the channel link. Otherwise send the build link and say when it stops working. tellThem says it for you. See Build links and channel links.

A public project's build link has no token and no expiry. A private project's build link adds a ?share= token. The token lives 7 days unless the agent passes ttlHours, up to the plan's share window, 30 days on Free and 365 days on Pro. The page opens for whoever holds the link while it lasts. Visibility is a setting of the extension.dev project, not of its GitHub repository.

Which project answers

The token decides the project, not the folder you stand in. Log in with the extension_auth tool and action: "login", or run npx @extension.dev/mcp login --project <workspace>/<project>, then approve the printed code at extension.dev/device in a browser signed in to extension.dev. The token lands in ~/.config/extension-dev/auth.json, under $XDG_CONFIG_HOME if you set one, or %APPDATA%\extension-dev\auth.json on Windows. See Access tokens.

The tool reads EXTENSION_DEV_TOKEN, then the stored login. With several logins stored, its project argument or EXTENSION_DEV_PROJECT picks one, and that login wins over EXTENSION_DEV_TOKEN.

From a script

The tool posts to POST /api/cli/publish with the project token in the Authorization header. A script can make the same call. The body carries only ttlHours and buildSha, so no path, manifest or repository name leaves your machine. See the HTTP API.

Reference

extension_publish input	What it does	Default
buildSha	Link that build's page. A sha with no completed build is refused	The newest successful build
ttlHours	Token lifetime on a private project, up to the plan's share window. Ignored on a public project	168 (7 days)
project	Which stored login to use, as <workspace>/<project>	EXTENSION_DEV_TOKEN, then the most recent login
api	Platform base URL	https://www.extension.dev

Answer field	Meaning
link	The link to send: kind (build or channel), url, expiresAt, pointsAt and audience
tellThem	One sentence to send with the link
shareUrl	The build page address
visibility	Whether the project is public or private
buildSha, version, builtAt	The build the link serves
previewCommands	One run command per browser the build targets
expiresAt	When a private project's build link stops working

Code	Status	Meaning
BAD_TOKEN	401	The token is wrong or expired
TOKEN_IN_QUERY	401	The token was sent in the query string instead of the header
TOKEN_REVOKED	401	The token was revoked
PROJECT_NOT_FOUND	404	The token's project does not exist here
UNKNOWN_BUILD	404	The buildSha is not a build of this project

When it fails

• The agent has no extension_publish tool: the server started without platform tools. Start it with --features=local,platform. See Platform tools.
• An auth error: the token is missing, wrong or expired. Device login tokens live at most seven days. Log in again with extension_auth.
• The URL names a project you did not expect: the platform answered for the token's project. Read the slug in the URL before you send it, and pass project for the one you mean.
• UNKNOWN_BUILD: the buildSha has no completed build. Leave it out to link the newest successful build.
• PROJECT_NOT_FOUND: the platform does not know the project. Import the repository first, or push a local folder to GitHub and then import it.
• You expected a store listing: this tool links a build page. Store submission starts at Publishing.
• You expected a link that outlives the token: send a channel link. A workspace owner or admin makes a channel public, or makes the project public. See Build links and channel links.

Next

• Share an unpublished build for review uploads a local dist/ instead
• Build links and channel links for which link to send
• Public project pages for the pages a public project gets
• Access tokens covers minting and scoping tokens