ChannelResponseModel and BulkChannelRequests DTOs lacked file-scoped #nullable enable, so the OpenAPI generator emitted every string property as a ["null","string"] union (project Nullable default is disable), polluting SPA typegen with needless `| null` unions. ChannelStateResponseModel already complied with this convention (precedent: PlayoutResponseModel). All properties in both files are always populated (never null in practice), so no property needed to become explicitly optional/nullable - just adding #nullable enable was sufficient to clean up the generated schema. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>