docs: #459 resolved with validation proof; ledger notes the fix and the S4 draft

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/ISSUES.md

@@ -120,7 +120,7 @@ may be force-stopped after two failed graceful closes, and ACE then holds the se
 
 ## #459 — Five fragment shaders declare SPIR-V `DemoteToHelperInvocation` without the device feature (validation error at every launch)
 
-**Status:** OPEN — found 2026-09-03 by the first Vulkan-validation-layer self-gate of Campaign OVERHAUL v2 (S3 chunk 4 fix round 2's gate; the layer was forced through the loader with `VK_INSTANCE_LAYERS=VK_LAYER_KHRONOS_validation`, since `ACDREAM_DEVTOOLS=1` only adds the debug-utils extension — `VulkanInterop.cs:182-183` creates the instance with `EnabledLayerCount = 0`).
+**Status:** RESOLVED 2026-09-03 at `e33fd2472` — `shaderDemoteToHelperInvocation` is now read through the Vulkan 1.3 feature chain, enabled at device creation, and gated as required in `VulkanCapabilityRecord` (236 Vulkan tests + the hermetic lane green). Proof: the four-pose validation launch at that commit (`logs/selfgate-20260903-171009-fix459-validation`, `logs/vk-validation-459.log`) reports ZERO validation errors; only the ten pre-existing `WARNING-Shader-OutputNotConsumed` performance warnings remain (one pipeline declares a vertex attribute at location 1 its shader never reads — still to be identified; harmless). Found 2026-09-03 by the first Vulkan-validation-layer self-gate of Campaign OVERHAUL v2 (S3 chunk 4 fix round 2's gate; the layer was forced through the loader with `VK_INSTANCE_LAYERS=VK_LAYER_KHRONOS_validation`, since `ACDREAM_DEVTOOLS=1` only adds the debug-utils extension — `VulkanInterop.cs:182-183` creates the instance with `EnabledLayerCount = 0`).
 **Severity:** LOW today (every driver we run on accepts it), MEDIUM by the spec (undefined behavior: `VUID-VkShaderModuleCreateInfo-pCode-08740`)
 **Component:** `tools/ShaderCompiler` target environment / `VulkanGpuDevice` feature chain