[v2.15.20](https://github.com/ash-project/ash/compare/v2.15.19...v2.15.20) (2023-10-24)
Bug Fixes:
* Change heading levels in generated livebook to have only one H1 (#747)
* code gen interfaces check type first argument (#749)
* properly support `get` in `Ash`
* add back in accidentally removed transformer
* properly determine resource from `Ash.get!/2`
* cast functional default values
* temporarily omit overzealous validation
* properly honor `max_concurrency` option
* support tenant option in api.can
* properly use constraints when casting expression values
* don't re-case constraints in the `type` function
Improvements:
* add `Ash.Test.assert_has_error` and `Ash.Test.refute_has_error`
* support `to_error_class` taking changeset/query/input
* add "filename" parameter to the livebook generator. (#746)
* support an `api` option to `use Ash.Resource` (#715)
* support an `api` option to `use Ash.Resource`
* add functions to `Ash` for resources w/ configured apis
* default code_interface.define_for to resource's ash api
* cast_input for default values at compile time
* optimize bulk creates where results are not returned
* rewrite bulk creates, optimize changeset functions (#744)
* better storage_type handling, undo function change