Release version 6.0.0-alpha.0 of the npm package.
This is an alpha release so should only be used for experimentation. There is a known issue when migrating from v5 which will be fixed in the v6.0.0 release. #1558
The main new features are support for ACP and notifications. The notification implementation conforms to v0.1.0 of the notification specification. The v6.0.0 release will contain the latest version instead.