Resource groups
Azure-style grouping of resources (the surveyer's group column generalized): user-defined folders/groups in the explorer list.
Why deferred
Nothing groups resources today, and the explorer's type facets + search cover current volumes. Carrying a group column "just in case" on every resource would be speculative schema.
Revisit when
A user's flat resource list with type facets and search is no longer sufficient to find things — that is the signal to design proper resource groups (a first-class grouping entity, not a text column). If tags usage grows into "give me a folder", that is this trigger.
A portal group is a containment relationship — a resource is inside exactly one — and our resources have no container at all, the same fact that keeps the breadcrumb from deriving ancestry (breadcrumb trail). That is why the service menu copied the portal's shape but gave tags the route a Groups entry would have taken.
