Fix Windows numeric NGX feature discovery and quick-test launches

patches/optiscaler/0004-serialize-device-hook-installation.patch

@@ -0,0 +1,34 @@
+diff --git a/OptiScaler/hooks/D3D12_Hooks.cpp b/OptiScaler/hooks/D3D12_Hooks.cpp
+index 3b757be..05fc194 100644
+--- a/OptiScaler/hooks/D3D12_Hooks.cpp
++++ b/OptiScaler/hooks/D3D12_Hooks.cpp
+@@ -2217,11 +2217,20 @@ static HRESULT hkD3D12GetInterface(REFCLSID rclsid, REFIID riid, void** ppvDebug
+     return result;
+ }
+ 
++// Device discovery and NGX initialization can overlap. Installing d4r's
++// command hooks can also create a device and re-enter this function. Never
++// overwrite live Detours trampolines from a second installation attempt.
++static std::recursive_mutex deviceHookMutex;
++static bool deviceHookInstalling = false;
+ static void HookToDevice(ID3D12Device* InDevice)
+ {
+-    if (o_CreateSampler != nullptr || InDevice == nullptr)
++    std::lock_guard<std::recursive_mutex> lock(deviceHookMutex);
++    if (o_CreateSampler != nullptr || InDevice == nullptr || deviceHookInstalling)
+         return;
+ 
++    deviceHookInstalling = true;
++    struct InstallationGuard { ~InstallationGuard() { deviceHookInstalling = false; } } installationGuard;
++
+     LOG_DEBUG("Dx12");
+ 
+     // Get the vtable pointer
+@@ -2334,6 +2343,7 @@ static void HookToDevice(ID3D12Device* InDevice)
+ 
+ static void UnhookDevice()
+ {
++    std::lock_guard<std::recursive_mutex> lock(deviceHookMutex);
+     LOG_FUNC();
+ 
+     DetourTransactionBegin();

patches/optiscaler/0005-forward-numeric-init-errors.patch

@@ -0,0 +1,22 @@
+diff --git a/OptiScaler/inputs/NVNGX_DLSS_Dx12.cpp b/OptiScaler/inputs/NVNGX_DLSS_Dx12.cpp
+index 1f723f1..ef5ec77 100644
+--- a/OptiScaler/inputs/NVNGX_DLSS_Dx12.cpp
++++ b/OptiScaler/inputs/NVNGX_DLSS_Dx12.cpp
+@@ -184,6 +184,8 @@ NVSDK_NGX_API NVSDK_NGX_Result NVSDK_NGX_D3D12_Init_Ext(unsigned long long InApp
+ 
+             if (result == NVSDK_NGX_Result_Success)
+                 NVNGXProxy::SetDx12Inited(true);
++            else if (State::Instance().dlssExternalBackend)
++                return result;
+         }
+         else
+         {
+@@ -254,6 +256,8 @@ NVSDK_NGX_API NVSDK_NGX_Result NVSDK_NGX_D3D12_Init(unsigned long long InApplica
+ 
+             if (result == NVSDK_NGX_Result_Success)
+                 NVNGXProxy::SetDx12Inited(true);
++            else if (State::Instance().dlssExternalBackend)
++                return result;
+         }
+     }
+ 

patches/optiscaler/README.md

@@ -1,6 +1,18 @@
 # Explicit Windows d4r backend
 
 Base: OptiScaler `45a2001303ddff632e279f77aef85ceede5832cb` (2026-09-30).
+
+`0004` serializes D3D12 device hook installation/removal and guards recursive
+device discovery while the d4r command backend installs. The previous frontend
+can start two installations, fail a Detours transaction with `0x10dd`, clear
+live original-function pointers and call null. This was reproduced in the
+numeric-ID standalone harness; no game was required.
+
+`0005` propagates numeric Init/Init_Ext failures for the explicitly selected
+external backend, matching the existing ProjectID behavior. FeatureNotFound
+must fail initialization instead of being hidden until repeated CreateFeature
+attempts. `Libraries.NvngxDlssPath` takes a directory, not the DLL filename;
+the Windows installer and standalone runner now use that directory.
 The modifications to OptiScaler are GPL-3.0, matching its upstream license.
 No NVIDIA DLL is supplied or patched.