https://www.mediawiki.org/wiki/Requests_for_comment/Streamlining_Composer_usage
Next steps in any order:
T125343: Upgrade integration/composer to 1.6.5 stable
Create a CI job that creates an update to a branch including a build of vendor (T101123) that can be deployed to beta which is similar to what for production a new wmf branch normal is done for. See the work flow example in the RFC.