Versioning
The template is versioned like a library. A change that requires every service to act is a major version; a new optional capability is a minor one. forge new always uses the latest version, and an existing service records the version it was generated from.
Rollout
A template change is proved on the platform team's own service first. It reaches other services only through forge upgrade, which is a pull request, never a push.
Deprecations
A removed convention gets one release of forge check warnings before it disappears from the template. The warning names the replacement, so the upgrade path is in the output rather than in a wiki page.
Ownership
The platform team owns the template; product teams own their generated services. A bug in generated code is fixed in the template and rolled forward, not patched into each repository.