Four model surfaces parsed, coerced, and re-serialized data with zero readers: PlayQueueResponse's selectedItemIndex/offset/sourceURI/version (version stays as a parse-time validity gate), PlexUserProfile's seven non-track-selection account fields, MediaSubscriptionCreateRequest's hints/params/providers, and the whole CatalogPlayState pipeline (parsed by the Plex catalog source, merged and round-tripped on every CatalogItem, read by nobody).