Module extension 

Extension catalogs: their own catalog id, extends the core, their components (natives a host paints, macros expanded from their own templates) and no name that shadows a core one. Mirrors src/extension.ts.

Functions

define_extension

The definition, checked; Err lists every problem.

parse_extension

Parse an extension catalog from JSON and check it.

validate_extension

Every problem with the definition (empty = valid).