What an application may ask for (§45, §62): "auto" for §62's ordered
preference, or one RendererBackend by name.
§45's literal union omits "null"; this one keeps it, because the headless
tier is a real §62 backend and naming it is how a determinism or CI run asks
for "a renderer that draws nothing" without importing one. It is never
chosen by "auto" — see AUTO_RENDERER_ORDER.
What an application may ask for (§45, §62):
"auto"for §62's ordered preference, or one RendererBackend by name.§45's literal union omits
"null"; this one keeps it, because the headless tier is a real §62 backend and naming it is how a determinism or CI run asks for "a renderer that draws nothing" without importing one. It is never chosen by"auto"— see AUTO_RENDERER_ORDER.