Models

An app's own domain types, written as Swift from one compact line a type, shipped as a Granite agent package. A call says each type the way a person would jot it down; the package writes a file a type into the folder the call names, each one Codable, Hashable and Sendable, Identifiable when it has an id, with an explicit initializer and a preview value for SwiftUI previews and tests.

It is one of the Rao Craft Agents: independent packages that, tagged in prompts along the life of a project, build an app of Loom's quality. models writes the values every other layer shares: the records a service keeps, the choices a setting offers, and one type that unifies several APIs' types.

How an app finds it

ModelsAgent is a GraniteAgentPackage, and it carries a record in its binary:

@used @section("__DATA_CONST,__granite")
let modelsRecord: GraniteRoster.Record = { GraniteRoster.record(ModelsAgent.self) }

In Craft, install it from the Agent Store or with craft agents add https://github.com/Rao-Craft-Agents/ModelsAgent.git, then say $models in a request:

$models the recipe app's types: a Recipe with an id, title, minutes (30 by default), its cook,
its steps and tags; a Cook; a Step; and a Course that is a starter, main or dessert

The model writes the lines; the call shows on Craft's agent map as models-1, and the files it names are built and tested with the turn.

What a call takes and answers

The answer is a ModelsResult: every file written (path, paths, absolute), the types, which have a preview, and a sentence for anything left out.

The line

Recipe "a dish someone saved": id String, title String, minutes Int = 30, author Cook?, steps [Step], added Date
Cook: id UUID, name String, avatar URL?, recipes [Recipe] = []
Course: starter | main | dessert = "pudding"
Media: photo(URL) | video(url URL, seconds Double) | none

• A struct is a name, an optional doc in quotes, a colon, and its fields split by commas. A field is a name and a type; ? makes it optional, = value gives a default, @json_key names its JSON key, a trailing quoted string documents it. title: String reads the same as title String, and string, int, bool, url and date are read as the Swift types.
• An enum is its cases split by bars. A case may carry values (video(url URL, seconds Double)) or have a raw value (= "pudding", = 2), never both in one enum. enum Size: small, large says enum when there is one case or commas.
• A line it cannot read is refused with the reason, every bad line at once, and nothing is written.

How the types are made

No model is asked: the same lines make the same files every time.

Testing

swift test                    # the record, the schema, the line, the files, a call through the roster
MODELS_BUILD=1 swift test     # the files compiled in a package and run: JSON missing every default decodes

MIT licensed.