What is the real admission gate for a new bitsandbytes backend?

[RyanX0198]

Hi maintainers — I’m Rui from Psync.labs. Recent work on 4-bit correctness and supported-platform documentation raises a question about adding a new hardware path.

Low-bit support appears useful only when kernels, numerical regression, installation, fallback behavior and release maintenance form one supported path. Which item is the real admission gate for a new backend, and which one is commonly underestimated after the first demo?

For multi-step coding or retrieval workloads, what task-level evidence should sit beside model metrics before a low-bit result is treated as usable? @TimDettmers @matthewdouglas

— Rui, Psync.labs