Named registries mapping a node's type string to its component module.

A host app almost always ends up with more than one palette. A page builder and, say, a broadcast-overlay editor both want Athanor components, but neither wants the other's modules showing up in its palette or resolvable from its trees. So a registry is always named, and every lookup says which one it means.

Configuration

config :athanor, :registries,
  page_builder: [
    components: [MyApp.Components.Hero, MyApp.Components.Card],
    fallback_resolver: {MyApp.LegacyResolver, :resolve_type}
  ],
  channel_overlays: [
    components: [MyApp.Overlays.Text, MyApp.Overlays.MarqueeText]
  ]

:components is a list of modules implementing Athanor.Component. Lookup matches node["type"] against each module's metadata().type.

:fallback_resolver is an optional {module, function} tuple, scoped to its registry. When a type is not found in that registry's :components, the resolver is called as module.function(type_string) and may return a module or nil — how a consumer keeps existing dispatch wired in during a gradual migration.

Config is read at call time via Application.get_env/2, so test setup can swap registries per scenario.

Naming a registry at each call site

Rendering reads the name off Athanor.Ctx (ctx.registry), which Athanor.Renderer threads through dispatch. Editor consumers declare it once as the required registry: option of use Athanor.Editor.Live.

Errors are loud

An unknown registry name raises rather than resolving to an empty list: a typo that silently turned every component into "Unknown component type" would be far harder to diagnose than a crash naming the registries that do exist.