oa::PresentationMode

controls what graphics surface the engine is built for. None — compute-only engine. No graphics queue, no swapchain. Headless training, batch ML inference, CI. Headless — graphics queue requested, but no VK_KHR_swapchain extension and no surface ever attached. hasGraphics=true, hasPresent =false permanently. Render-farm worker, server-side rendering, batch image-sequence export, CI for graphics code paths. Sinks: saveImage / encodeFrame. Swapchain — graphics queue + swapchain extension. surface attached via two-phase init (initPresentation). GUI mode. Sinks: present (+ optionally saveImage / encodeFrame).