diff --git a/src/AcDream.App/Rendering/Gpu/Vk/VulkanCapabilityRecord.cs b/src/AcDream.App/Rendering/Gpu/Vk/VulkanCapabilityRecord.cs
index 5e9d5d42..e78874a0 100644
--- a/src/AcDream.App/Rendering/Gpu/Vk/VulkanCapabilityRecord.cs
+++ b/src/AcDream.App/Rendering/Gpu/Vk/VulkanCapabilityRecord.cs
@@ -84,6 +84,17 @@ internal sealed record VulkanDeviceFeatureSupport
     /// <summary>Relaxed shader interface rules for the dual-legal GLSL sources.</summary>
     public required bool Maintenance4 { get; init; }
 
+    /// <summary>
+    /// #459: the shader compiler targets Vulkan 1.3 / SPIR-V 1.6, where glslang
+    /// lowers every fragment <c>discard</c> to <c>OpDemoteToHelperInvocation</c>
+    /// (five committed modules declare the capability — sky, mesh_detail,
+    /// mesh_atmospheric and both directional-shadow cutout fragments). A module
+    /// that declares the capability without the feature enabled is invalid
+    /// usage (<c>VUID-VkShaderModuleCreateInfo-pCode-08740</c>), so the feature
+    /// is required and enabled, never optional.
+    /// </summary>
+    public required bool ShaderDemoteToHelperInvocation { get; init; }
+
     /// <summary>
     /// Every feature present. The starting point for the forced-unsupported gate
     /// knob and for tests that assert one specific absence at a time.
@@ -108,6 +119,7 @@ internal sealed record VulkanDeviceFeatureSupport
         DynamicRendering = true,
         Synchronization2 = true,
         Maintenance4 = true,
+        ShaderDemoteToHelperInvocation = true,
     };
 
     /// <summary>
@@ -139,6 +151,7 @@ internal sealed record VulkanDeviceFeatureSupport
             var n when Is(n, nameof(DynamicRendering)) => this with { DynamicRendering = false },
             var n when Is(n, nameof(Synchronization2)) => this with { Synchronization2 = false },
             var n when Is(n, nameof(Maintenance4)) => this with { Maintenance4 = false },
+            var n when Is(n, nameof(ShaderDemoteToHelperInvocation)) => this with { ShaderDemoteToHelperInvocation = false },
             _ => null,
         };
 
@@ -521,6 +534,8 @@ internal static class VulkanCapabilityRequirements
             failures.Add("synchronization2 is required; every barrier in the frame is a barrier2.");
         if (!features.Maintenance4)
             failures.Add("maintenance4 is required for the relaxed shader interface rules the shared GLSL relies on.");
+        if (!features.ShaderDemoteToHelperInvocation)
+            failures.Add("shaderDemoteToHelperInvocation is required; the SPIR-V 1.6 fragment modules lower discard to OpDemoteToHelperInvocation (#459).");
 
         VulkanDeviceLimitSupport limits = capabilities.Limits;
         if (limits.MaxPushConstantsSize < GpuBindingModel.PushConstantBytes)
diff --git a/src/AcDream.App/Rendering/Gpu/Vk/VulkanInterop.cs b/src/AcDream.App/Rendering/Gpu/Vk/VulkanInterop.cs
index 3dae155b..5788a292 100644
--- a/src/AcDream.App/Rendering/Gpu/Vk/VulkanInterop.cs
+++ b/src/AcDream.App/Rendering/Gpu/Vk/VulkanInterop.cs
@@ -330,6 +330,7 @@ internal static unsafe class VulkanPhysicalDeviceInspector
             DynamicRendering = vulkan13.DynamicRendering,
             Synchronization2 = vulkan13.Synchronization2,
             Maintenance4 = vulkan13.Maintenance4,
+            ShaderDemoteToHelperInvocation = vulkan13.ShaderDemoteToHelperInvocation,
         };
     }
 
@@ -609,6 +610,12 @@ internal sealed unsafe class VulkanLogicalDeviceFactory
             DynamicRendering = true,
             Synchronization2 = true,
             Maintenance4 = true,
+            // #459: the SPIR-V 1.6 fragment modules declare
+            // DemoteToHelperInvocation (glslang's lowering of `discard` for a
+            // Vulkan 1.3 target); declaring it without the feature is invalid
+            // usage (VUID-VkShaderModuleCreateInfo-pCode-08740). Gated as
+            // required in VulkanCapabilityRecord, so this is never speculative.
+            ShaderDemoteToHelperInvocation = true,
         };
         var vulkan12 = new PhysicalDeviceVulkan12Features
         {