The built-in content collections and their lookup.
A collection is a directory, a schema, and routing rules (DESIGN.md §4). User-defined collections arrive in a later phase; the registry stays a compile-time map until then for the same reason the CLI registry does.
Summary
Functions
All {name, module} pairs in load order (sorted by name).
Looks up a collection module by name.
All collection names, sorted.
The portfolio collection names, sorted.