ClosedBit error docs

CB_ERR_GPU_BACKEND

GPU backend failure. The Direct3D/GPU runtime path failed while creating or running work.

Why it happens

The Direct3D/GPU runtime path failed while creating or running work.

How to fix it

Check drivers, GPU availability, VRAM budget, and the exact backend message.

Copy-paste fix pattern
compile cba render.cbp render.cba graphics threaded
Runtime and Studio now show this kind of page from the error dialog: plain message first, stable code second, original details third.