diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 94a0453..35660b1 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -72,6 +72,16 @@ jobs:
           key: ${{ runner.os }}-shared-${{ hashFiles('native/shared/Cargo.lock') }}
           restore-keys: ${{ runner.os }}-shared-
 
+      - name: Select hosted Windows shader compiler
+        if: matrix.os == 'windows-latest'
+        shell: pwsh
+        run: |
+          # WARP's DXIL optimizer can crash during concurrent traversal shader
+          # compilation. Keep this software-renderer lane on explicit FXC;
+          # physical DX12/DXC qualification remains a separate requirement.
+          "WGPU_BACKEND=dx12" >> $env:GITHUB_ENV
+          "WGPU_DX12_COMPILER=fxc" >> $env:GITHUB_ENV
+
       - name: quick / shared-tests
         # Retain adapter identities and capability skips even when Rust reports
         # an early-returning GPU test as "ok".
diff --git a/docs/evidence/windows-camera-history-v1.md b/docs/evidence/windows-camera-history-v1.md
index 1ef4770..7c6eec3 100644
--- a/docs/evidence/windows-camera-history-v1.md
+++ b/docs/evidence/windows-camera-history-v1.md
@@ -51,11 +51,15 @@ ignored goldens, and two ignored documentation examples retain their status.
 Formatting, strict Clippy policy, and repository contracts also pass. The DX12
 run uses a process-local Vulkan loader override for older helper functions;
 some of those helpers explicitly use software adapters. The golden captures
-require a physical GPU and identify the Radeon/backend. Hosted validation is
-pending. The Windows hosted library access violation is separate and
-remains unresolved. This advances #135/#149/#140 without closing the wider
+require a physical GPU and identify the Radeon/backend. Hosted #163 passes the
+macOS shared suite, including all 93 goldens and the expanded camera-cut test,
+plus canonical Metal captures. Windows native builds and all 20 example links
+pass; its shared library stage still crashes before goldens. That access
+violation is separate and remains unresolved. This advances #135/#149/#140 without closing the wider
 performance, platform, representative-corpus, or hardware requirements.
 
 Source patches, commands, exact RGBA/PNG captures, changed-pixel coordinates,
 and results are retained under
 `tools/quality/out/windows-engine-plan/camera-cut-dx12/`.
+The [published archive](https://github.com/Bloom-Engine/engine/releases/tag/quality-evidence-camera-history-20260911)
+includes exact source-match receipts and the failed Windows hosted log.
diff --git a/docs/evidence/windows-warp-compiler-v1.md b/docs/evidence/windows-warp-compiler-v1.md
new file mode 100644
index 0000000..105b06a
--- /dev/null
+++ b/docs/evidence/windows-warp-compiler-v1.md
@@ -0,0 +1,44 @@
+# Hosted Windows software-renderer compiler
+
+The actual Windows shared job crashes with `0xc0000005` on #162 and #163.
+The native engine build and all 20 example links pass. The Windows crash occurs
+in the library stage, before golden tests execute; successful build jobs do not
+qualify those render tests.
+
+## Local diagnosis
+
+At unchanged #163 source `c643b85`, four-thread library execution also crashes
+when the virtual-geometry helpers select the Microsoft Basic Render Driver.
+An eight-thread run passes, so a passing rerun does not close the defect.
+Windows Event 1000 identifies `d3d10warp.dll` version `10.0.26100.9278`.
+
+The installed Windows debugger captures a second-chance access violation in
+`d3d10warp!JITBaseVariable::OptimizeCopy`, through the WARP DXIL shader-JIT
+destructor and compute-pipeline compilation, during a traversal queue submission.
+The affected Rust test refines atomic groups that straddle frustum planes.
+This identifies the failing driver/compiler path; it does not establish the
+underlying driver's root cause or prove that every hosted crash has this stack.
+
+That existing test passes twice alone with DXC and twice with FXC. The complete
+ten-test hierarchy group passes serially with DXC, crashes in both four-thread
+DXC controls, and passes with FXC and four threads. Complete library controls with four and eight threads also
+pass with FXC selected for environment-aware helpers (489 passed, one ignored).
+Older helpers ignored compiler/backend environment options during those controls;
+some explicitly select software adapters and others select the physical Radeon.
+
+## Compatibility change
+
+The hosted Windows shared lane explicitly selects DX12 and FXC. The remaining
+ordinary GPU test helpers now honor backend and compiler environment options,
+matching the visibility, virtual-geometry, and golden helpers. Adapter selection,
+capability requirements, ignored tests, assertions and thresholds are unchanged.
+The ray-query golden helper retains its deliberate DXC requirement.
+
+This is a software-renderer CI workaround. The WARP/DXIL access violation remains
+open, and physical DX12/DXC qualification remains required. The ordinary Windows
+engine compiler policy is unchanged. The candidate's library suite passes with
+four threads and explicit FXC (489 passed, one ignored). Complete local shared
+components and hosted validation are still running.
+
+Diagnostic commands, logs, debugger stacks, executable hashes and results are
+retained in `tools/quality/out/windows-engine-plan/windows-shared-crash/`.
diff --git a/docs/windows-engine-plan.md b/docs/windows-engine-plan.md
index 858c48a..f119e05 100644
--- a/docs/windows-engine-plan.md
+++ b/docs/windows-engine-plan.md
@@ -63,7 +63,12 @@ audit are saved in `tools/quality/out/windows-engine-plan/plan-requirements.json
    The expanded local DX12 goldens expose a [camera-history reset defect](evidence/windows-camera-history-v1.md);
    its read guard passes exact fresh/reset comparisons after eight and 40
    history frames on Vulkan and DX12. Both complete local shared components
-   now pass, including all 93 goldens; hosted validation remains required.
+   now pass, including all 93 goldens. Hosted #163 also passes all 93 macOS
+   goldens and the expanded cut check; its [evidence is published](https://github.com/Bloom-Engine/engine/releases/tag/quality-evidence-camera-history-20260911).
+   The Windows library crash reproduces locally inside WARP's DXIL shader
+   optimizer during concurrent traversal tests. An [explicit FXC hosted lane](evidence/windows-warp-compiler-v1.md)
+   and consistent test compiler selection are being validated. The underlying
+   WARP/DXIL defect and physical DX12/DXC acceptance remain separate.
 2. Finish all-example native linking, real starter/example startup, and clean
    Windows installation. The [native example gate](evidence/windows-example-gate-v1.md)
    passes all 20 links locally using Perry 0.5.1220 and one matching source-built
diff --git a/native/shared/src/cooked_texture_store_tests.rs b/native/shared/src/cooked_texture_store_tests.rs
index 1f31b4e..58681a1 100644
--- a/native/shared/src/cooked_texture_store_tests.rs
+++ b/native/shared/src/cooked_texture_store_tests.rs
@@ -432,7 +432,8 @@ fn temporary_store(label: &str) -> PathBuf {
 
 fn try_device(require_bc: bool) -> Option<(wgpu::Device, wgpu::Queue)> {
     let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-        backends: wgpu::Backends::all(),
+        backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+        backend_options: wgpu::BackendOptions::from_env_or_default(),
         ..wgpu::InstanceDescriptor::new_without_display_handle()
     });
     let adapter =
diff --git a/native/shared/src/renderer/gpu_driven.rs b/native/shared/src/renderer/gpu_driven.rs
index 82c27fe..7fac9e8 100644
--- a/native/shared/src/renderer/gpu_driven.rs
+++ b/native/shared/src/renderer/gpu_driven.rs
@@ -1816,7 +1816,8 @@ mod tests {
         use wgpu::util::DeviceExt as _;
 
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-            backends: wgpu::Backends::all(),
+            backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+            backend_options: wgpu::BackendOptions::from_env_or_default(),
             ..wgpu::InstanceDescriptor::new_without_display_handle()
         });
         let Ok(adapter) =
diff --git a/native/shared/src/renderer/impulse_field.rs b/native/shared/src/renderer/impulse_field.rs
index 65b9675..c501c19 100644
--- a/native/shared/src/renderer/impulse_field.rs
+++ b/native/shared/src/renderer/impulse_field.rs
@@ -314,7 +314,8 @@ mod tests {
     /// without storage textures" doc-comment contract).
     fn try_create_device() -> Option<(wgpu::Device, wgpu::Queue)> {
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-            backends: wgpu::Backends::all(),
+            backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+            backend_options: wgpu::BackendOptions::from_env_or_default(),
             ..wgpu::InstanceDescriptor::new_without_display_handle()
         });
         let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
diff --git a/native/shared/src/renderer/material_indirection.rs b/native/shared/src/renderer/material_indirection.rs
index ac807fb..40889fa 100644
--- a/native/shared/src/renderer/material_indirection.rs
+++ b/native/shared/src/renderer/material_indirection.rs
@@ -1541,7 +1541,11 @@ mod tests {
 
     #[cfg(not(target_arch = "wasm32"))]
     fn try_tier_a_device() -> Option<(wgpu::Device, wgpu::Queue)> {
-        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::new_without_display_handle());
+        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
+            backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+            backend_options: wgpu::BackendOptions::from_env_or_default(),
+            ..wgpu::InstanceDescriptor::new_without_display_handle()
+        });
         let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
             power_preference: wgpu::PowerPreference::HighPerformance,
             force_fallback_adapter: false,
diff --git a/native/shared/src/renderer/material_system_tests.rs b/native/shared/src/renderer/material_system_tests.rs
index 220ec51..2068012 100644
--- a/native/shared/src/renderer/material_system_tests.rs
+++ b/native/shared/src/renderer/material_system_tests.rs
@@ -40,7 +40,8 @@ mod tests {
     /// (test skips gracefully) when no GPU is available.
     fn try_create_device() -> Option<(wgpu::Device, wgpu::Queue)> {
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-            backends: wgpu::Backends::all(),
+            backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+            backend_options: wgpu::BackendOptions::from_env_or_default(),
             ..wgpu::InstanceDescriptor::new_without_display_handle()
         });
         let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
diff --git a/native/shared/src/renderer/occlusion.rs b/native/shared/src/renderer/occlusion.rs
index 01c290f..ad68bcc 100644
--- a/native/shared/src/renderer/occlusion.rs
+++ b/native/shared/src/renderer/occlusion.rs
@@ -482,7 +482,8 @@ mod tests {
 
     fn try_device() -> Option<(wgpu::Device, wgpu::Queue)> {
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-            backends: wgpu::Backends::all(),
+            backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+            backend_options: wgpu::BackendOptions::from_env_or_default(),
             ..wgpu::InstanceDescriptor::new_without_display_handle()
         });
         let adapter =
diff --git a/native/shared/src/renderer/planar_reflection.rs b/native/shared/src/renderer/planar_reflection.rs
index bb3bcf6..1b67ae1 100644
--- a/native/shared/src/renderer/planar_reflection.rs
+++ b/native/shared/src/renderer/planar_reflection.rs
@@ -408,7 +408,8 @@ mod tests {
     /// is available so the test skips gracefully on bare CI.
     fn try_create_device() -> Option<(wgpu::Device, wgpu::Queue)> {
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-            backends: wgpu::Backends::all(),
+            backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+            backend_options: wgpu::BackendOptions::from_env_or_default(),
             ..wgpu::InstanceDescriptor::new_without_display_handle()
         });
         let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
diff --git a/native/shared/src/renderer/post_pass.rs b/native/shared/src/renderer/post_pass.rs
index d918224..e2f0561 100644
--- a/native/shared/src/renderer/post_pass.rs
+++ b/native/shared/src/renderer/post_pass.rs
@@ -220,7 +220,8 @@ mod tests {
     /// `transient.rs` so tests run on machines without a real GPU.
     fn try_create_device() -> Option<(wgpu::Device, wgpu::Queue)> {
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-            backends: wgpu::Backends::all(),
+            backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+            backend_options: wgpu::BackendOptions::from_env_or_default(),
             ..wgpu::InstanceDescriptor::new_without_display_handle()
         });
         let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
diff --git a/native/shared/src/renderer/transient.rs b/native/shared/src/renderer/transient.rs
index 34526ea..3430bee 100644
--- a/native/shared/src/renderer/transient.rs
+++ b/native/shared/src/renderer/transient.rs
@@ -546,7 +546,8 @@ mod tests {
     /// need a device are skipped gracefully.
     fn try_create_device() -> Option<(wgpu::Device, wgpu::Queue)> {
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-            backends: wgpu::Backends::all(),
+            backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+            backend_options: wgpu::BackendOptions::from_env_or_default(),
             ..wgpu::InstanceDescriptor::new_without_display_handle()
         });
         let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
diff --git a/native/shared/src/virtual_shadow_gpu_receiver.rs b/native/shared/src/virtual_shadow_gpu_receiver.rs
index fea5c92..c0dca54 100644
--- a/native/shared/src/virtual_shadow_gpu_receiver.rs
+++ b/native/shared/src/virtual_shadow_gpu_receiver.rs
@@ -586,7 +586,8 @@ mod tests {
 
     fn try_device() -> Option<(wgpu::Device, wgpu::Queue)> {
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-            backends: wgpu::Backends::all(),
+            backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+            backend_options: wgpu::BackendOptions::from_env_or_default(),
             ..wgpu::InstanceDescriptor::new_without_display_handle()
         });
         let adapter =
diff --git a/native/shared/tests/render_targets.rs b/native/shared/tests/render_targets.rs
index 5dc38b9..0c2b311 100644
--- a/native/shared/tests/render_targets.rs
+++ b/native/shared/tests/render_targets.rs
@@ -22,7 +22,8 @@ use bloom_shared::scene::SceneGraph;
 
 fn try_renderer() -> Option<Renderer> {
     let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
-        backends: wgpu::Backends::all(),
+        backends: wgpu::Backends::from_env().unwrap_or(wgpu::Backends::all()),
+        backend_options: wgpu::BackendOptions::from_env_or_default(),
         ..wgpu::InstanceDescriptor::new_without_display_handle()
     });
     let adapter =