feat: make explicit DXVK mode strict and prevent WineD3D fallback

- Implemented strict DLL overrides (`=n`) in `build_dll_overrides` to prevent Wine from falling back to built-in WineD3D when DXVK is explicitly requested.
- Enhanced pre-launch validation in `ResolveDllProvidersStage` to include `d3d10core` and fail if any required DXVK DLLs are missing for the target architecture.
- Updated the launch pipeline to treat backend policy violations as a `Failure` state when DXVK is requested.
- Added a `STRICT_DXVK_POLICY_VIOLATION` diagnostic warning to `LaunchInvariantValidator` when WineD3D usage is observed despite a DXVK request.
- Updated sanity checks and unit tests to reflect and verify the strict enforcement policy.
- Maintained existing permissive behavior for `Auto` mode.

Co-authored-by: weter11 <14630689+weter11@users.noreply.github.com>

Author: google-labs-jules[bot]

src/infra/logging/session.rs

@@ -290,10 +290,10 @@ pub fn check_environment_sanity(
                 });
             }
             if let Some(overrides) = env_vars.get("WINEDLLOVERRIDES") {
-                if !overrides.contains("d3d11=n") && !overrides.contains("dxgi=n") && !overrides.contains("d3d9=n") {
+                if !overrides.contains("d3d11=n") && !overrides.contains("dxgi=n") && !overrides.contains("d3d9=n") && !overrides.contains("d3d8=n") && !overrides.contains("d3d10core=n") {
                      warnings.push(crate::launch::pipeline::CompatibilityWarning {
                         code: "SANITY_MISSING_DXVK_OVERRIDE".to_string(),
-                        message: "DXVK is enabled but WINEDLLOVERRIDES does not appear to contain native overrides for D3D11/DXGI/D3D9.".to_string(),
+                        message: "DXVK is enabled but WINEDLLOVERRIDES does not appear to contain native overrides for D3D11/DXGI/D3D9/D3D8/D3D10CORE.".to_string(),
                         context: [("overrides".to_string(), overrides.clone())].into_iter().collect(),
                     });
                 }

src/infra/runners/tests.rs

@@ -127,7 +127,9 @@ mod tests {
         ctx_dxvk.user_config = Some(user_config_dxvk);
         let env_dxvk = runner.build_env(&ctx_dxvk).await.unwrap();
         let overrides_dxvk = env_dxvk.get("WINEDLLOVERRIDES").unwrap();
-        assert!(overrides_dxvk.contains("d3d11=n,b"));
+        // Strict mode uses 'n', not 'n,b'
+        assert!(overrides_dxvk.contains("d3d11=n"));
+        assert!(!overrides_dxvk.contains("d3d11=n,b"));
     }
 
     #[tokio::test]

src/infra/runners/wine_tkg.rs

@@ -314,12 +314,12 @@ impl Runner for WineTkgRunner {
         );
 
         // 1. Resolve DX8-11 policy (GraphicsBackendPolicy) - CONSERVATIVE
-        let (policy_dxvk, force_builtin) = match glc.graphics_backend_policy {
+        let (policy_dxvk, force_builtin, strict_dxvk) = match glc.graphics_backend_policy {
             // Auto is now conservative: it does NOT automatically enable DXVK
             // even if detected on disk. It prefers default Wine behavior.
-            crate::models::GraphicsBackendPolicy::Auto => (false, false),
-            crate::models::GraphicsBackendPolicy::WineD3D => (false, true),
-            crate::models::GraphicsBackendPolicy::DXVK => (true, false),
+            crate::models::GraphicsBackendPolicy::Auto => (false, false, false),
+            crate::models::GraphicsBackendPolicy::WineD3D => (false, true, false),
+            crate::models::GraphicsBackendPolicy::DXVK => (true, false, true),
         };
 
         // Manual override takes precedence if enabled
@@ -346,6 +346,7 @@ impl Runner for WineTkgRunner {
             no_overlay,
             force_builtin_d3d,
             Some(&game_working_dir),
+            strict_dxvk,
         );
 
         // Enhance overrides with resolved DLL providers

src/launch/pipeline.rs

@@ -494,7 +494,11 @@ impl LaunchPipeline {
         }
 
         if !policy_satisfied && final_result == LaunchResult::Success {
-             final_result = LaunchResult::Degraded;
+             if ctx.graphics_stack.requested_backend == "DXVK" {
+                 final_result = LaunchResult::Failure;
+             } else {
+                 final_result = LaunchResult::Degraded;
+             }
         }
 
         self.write_summary_if_possible(ctx, final_result, failing_stage, total_start.elapsed().as_millis(), stage_durations);

src/launch/stages/resolve_dll_providers.rs

@@ -76,7 +76,7 @@ impl PipelineStage for ResolveDllProvidersStage {
             let backend_policy = &config.graphics_layers.graphics_backend_policy;
 
             if *backend_policy == crate::models::GraphicsBackendPolicy::DXVK {
-                let dxvk_dlls = ["d3d11", "dxgi", "d3d9", "d3d8"];
+                let dxvk_dlls = ["d3d11", "dxgi", "d3d9", "d3d8", "d3d10core"];
                 let mut missing = Vec::new();
 
                 for dll in dxvk_dlls {

src/launch/validators/invariants.rs

@@ -180,6 +180,14 @@ impl LaunchValidator for LaunchInvariantValidator {
             ));
         }
 
+        // Additional check for WineD3D usage when DXVK was requested
+        if ctx.graphics_stack.requested_backend == "DXVK" && ctx.graphics_stack.runtime_evidence.wined3d.evidence_found {
+            warnings.push((
+                "STRICT_DXVK_POLICY_VIOLATION",
+                "DXVK was explicitly requested, but WineD3D usage was observed in logs.".into(),
+            ));
+        }
+
         if ctx.graphics_stack.effective_d3d12_provider == "vkd3d-proton" && !ctx.graphics_stack.runtime_evidence.vkd3d_proton.evidence_found {
              let meta = &ctx.graphics_stack.runtime_evidence.scan_metadata;
              let suffix = if !meta.file_exists { " (Wine log missing)" } else if meta.line_count == 0 { " (Wine log empty)" } else { "" };

src/utils.rs

@@ -650,6 +650,7 @@ pub fn build_dll_overrides(
     no_overlay: bool,
     force_builtin_d3d: bool, // NEW — for WineD3D policy
     game_dir: Option<&std::path::Path>, // check for game-local DLLs
+    strict_dxvk: bool,
 ) -> String {
     let mut overrides: Vec<String> = vec![
         "vstdlib_s=n".into(),
@@ -704,11 +705,13 @@ pub fn build_dll_overrides(
             "dxgi.dll",
         ] {
             let stem = dll.trim_end_matches(".dll");
-            if !game_has(dll) {
-                overrides.push(format!("{stem}=n,b"));
+            let mode = if strict_dxvk { "n" } else { "n,b" };
+
+            if strict_dxvk || !game_has(dll) {
+                overrides.push(format!("{stem}={mode}"));
             }
-            // If the game ships it locally, leave Wine's default search order
-            // alone — exe-dir native wins automatically.
+            // If the game ships it locally and we are not in strict mode,
+            // leave Wine's default search order alone — exe-dir native wins automatically.
         }
     }
 

tests/dll_override_tests.rs

@@ -3,7 +3,7 @@ use steamflow::utils::build_dll_overrides;
 #[test]
 fn test_build_dll_overrides_baseline() {
     // Default case: no graphics layers, no overlay
-    let overrides = build_dll_overrides(false, false, false, false, false, None);
+    let overrides = build_dll_overrides(false, false, false, false, false, None, false);
 
     // Essential Steam integration should be present
     assert!(overrides.contains("vstdlib_s=n"));
@@ -21,7 +21,7 @@ fn test_build_dll_overrides_baseline() {
 
 #[test]
 fn test_build_dll_overrides_dxvk_active() {
-    let overrides = build_dll_overrides(true, false, false, true, false, None);
+    let overrides = build_dll_overrides(true, false, false, true, false, None, false);
 
     // DXVK keys should be present
     assert!(overrides.contains("d3d9=n,b"));
@@ -34,7 +34,7 @@ fn test_build_dll_overrides_dxvk_active() {
 
 #[test]
 fn test_build_dll_overrides_vkd3d_active() {
-    let overrides = build_dll_overrides(false, true, false, true, false, None);
+    let overrides = build_dll_overrides(false, true, false, true, false, None, false);
 
     // VKD3D keys should be present
     assert!(overrides.contains("d3d12=n,b"));
@@ -49,10 +49,39 @@ fn test_build_dll_overrides_local_dll_skip() {
     let d3d11_path = tmp.path().join("d3d11.dll");
     std::fs::write(&d3d11_path, "fake dll").unwrap();
 
-    let overrides = build_dll_overrides(true, false, false, true, false, Some(tmp.path()));
+    let overrides = build_dll_overrides(true, false, false, true, false, Some(tmp.path()), false);
 
     // d3d11 should be skipped because it exists locally
     assert!(!overrides.contains("d3d11=n,b"));
     // other dxvk keys should still be present
     assert!(overrides.contains("d3d9=n,b"));
 }
+
+#[test]
+fn test_build_dll_overrides_strict_dxvk() {
+    let overrides = build_dll_overrides(true, false, false, true, false, None, true);
+
+    // DXVK keys should use 'n' (native only) in strict mode
+    assert!(overrides.contains("d3d9=n"));
+    assert!(overrides.contains("d3d11=n"));
+    assert!(overrides.contains("dxgi=n"));
+    assert!(overrides.contains("d3d8=n"));
+    assert!(overrides.contains("d3d10core=n"));
+
+    // They should NOT contain 'n,b'
+    assert!(!overrides.contains("d3d9=n,b"));
+    assert!(!overrides.contains("d3d11=n,b"));
+}
+
+#[test]
+fn test_build_dll_overrides_strict_dxvk_ignores_local() {
+    let tmp = tempfile::tempdir().unwrap();
+    let d3d11_path = tmp.path().join("d3d11.dll");
+    std::fs::write(&d3d11_path, "fake dll").unwrap();
+
+    let overrides = build_dll_overrides(true, false, false, true, false, Some(tmp.path()), true);
+
+    // In strict mode, even if d3d11.dll exists locally, we should still add the override
+    // and it should be 'n' (native only)
+    assert!(overrides.contains("d3d11=n"));
+}