D030 - Backend seams are enforced by crate boundaries, not discipline

decided · 2026-08-19

orbistoun-gpu holds command-stream and shader translation and does not depend on ash at all. orbistoun-gpu-vulkan is the only crate that knows Vulkan exists.

Leaking the host API into the translator is then not discouraged but impossible - the dependency is not there to leak, and cargo enforces it rather than code review. A future second backend is a new crate rather than surgery. Audio gets the same treatment when it lands.

Done before the code exists, because restructuring costs nothing now and everything later.