diff --git a/.github/workflows/wai-quantum-webgpu.yml b/.github/workflows/wai-quantum-webgpu.yml
index dc3bf3178..ae59fb27e 100644
--- a/.github/workflows/wai-quantum-webgpu.yml
+++ b/.github/workflows/wai-quantum-webgpu.yml
@@ -339,9 +339,59 @@ jobs:
             "$RUNNER_TEMP/browser-webgpu.log" \
             || { echo "::error::no GPU member certified bit-exact 4 of 4, per-gate and in tile runs, in the browser"; exit 1; }
 
-# Windows, when its runner is back (DX12, translator naga+dxbc, and Vulkan, as separate members):
-#   member-windows:
-#     runs-on: windows
-#     env: { WAI_QUANTUM_WEBGPU_EXPECT: "<keys from the first run>" }
-#     steps: checkout; Set-ExecutionPolicy Bypass; run the script with `shell: bash`
-#     (Git Bash on PATH). Not a required status.
+  # Windows reaches both of this host's GPUs through both backends, so one job
+  # certifies five adapters rather than one per backend: the member test
+  # enumerates every adapter in the one process, and the DX12 keys exercise the
+  # WGSL -> HLSL path (naga) that no other member covers. Not a required status.
+  member-windows:
+    name: member · DX12 and Vulkan (cbio-windows)
+    runs-on: windows
+    timeout-minutes: 150
+    env:
+      # The key list this host's first run printed:
+      #   gpu-dx12-10de    discrete NVIDIA, DX12
+      #   gpu-dx12-8086    integrated Intel, DX12
+      #   gpu-vulkan-10de  discrete NVIDIA, Vulkan
+      #   gpu-vulkan-8086  integrated Intel, Vulkan
+      #   swgpu-dx12-1414  Microsoft's software adapter (WARP), class Cpu
+      # Adding or removing a driver changes this set, and the member test fails
+      # until this line matches it again.
+      WAI_QUANTUM_WEBGPU_EXPECT: gpu-dx12-10de,gpu-dx12-8086,gpu-vulkan-10de,gpu-vulkan-8086,swgpu-dx12-1414
+    steps:
+      - uses: actions/checkout@v5
+      # The runner writes an unsigned .ps1 per step, which the default policy
+      # refuses. pwsh, not Windows PowerShell: the 5.1 parser rejects the PS7
+      # syntax this repo's scripts use.
+      - name: Allow the runner's generated scripts to run
+        shell: pwsh
+        run: Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass -Force
+      # `bash` on this host resolves to the WindowsApps WSL stub, and the machine
+      # PATH carries Git\cmd (git.exe) but not Git\bin (bash.exe). Without this
+      # every `shell: bash` step below would run under WSL, which reaches none of
+      # the Windows GPU drivers.
+      - name: Put Git Bash on PATH
+        shell: pwsh
+        run: |
+          $gitBash = 'C:\Program Files\Git\bin'
+          if (-not (Test-Path "$gitBash\bash.exe")) { throw "Git Bash is missing at $gitBash" }
+          $gitBash | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+      - name: The shell is Git Bash, not WSL
+        shell: bash
+        run: |
+          set -euo pipefail
+          command -v bash
+          # A WSL bash reports Linux; Git Bash reports MINGW or MSYS.
+          case "$(uname -s)" in
+            MINGW*|MSYS*) ;;
+            *) echo "::error::bash is $(uname -s), not Git Bash"; exit 1 ;;
+          esac
+      - name: The member's tests
+        shell: bash
+        run: scripts/wai-quantum-webgpu-member.sh
+      # wai-rs is built with --no-default-features here for the same reason as the
+      # other GPU members: its default `codecs` feature links system codec
+      # libraries this host does not have, and the corpus needs none of them.
+      - name: The conformance corpus through the member
+        shell: bash
+        working-directory: wai/wai-rs
+        run: cargo run --locked --no-default-features --features quantum_fabric_webgpu --bin wai_quantum_vectors -- verify ../quantum-conformance --webgpu