ci: add simd on/off test

.github/workflows/test.yml

@@ -23,6 +23,7 @@ jobs:
       - build-snap
       - build-windows
       - test
+      - test-simd
       - test-gtk
       - test-sentry-linux
       - test-macos
@@ -601,6 +602,41 @@ jobs:
             -Dgtk-x11=${{ matrix.x11 }} \
             -Dgtk-wayland=${{ matrix.wayland }}
 
+  test-simd:
+    strategy:
+      fail-fast: false
+      matrix:
+        simd: ["true", "false"]
+    name: Build -Dsimd=${{ matrix.simd }}
+    runs-on: namespace-profile-ghostty-sm
+    needs: test
+    env:
+      ZIG_LOCAL_CACHE_DIR: /zig/local-cache
+      ZIG_GLOBAL_CACHE_DIR: /zig/global-cache
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+
+      - name: Setup Cache
+        uses: namespacelabs/nscloud-cache-action@a289cf5d2fcd6874376aa92f0ef7f99dc923592a # v1.2.17
+        with:
+          path: |
+            /nix
+            /zig
+
+      # Install Nix and use that to run our tests so our environment matches exactly.
+      - uses: cachix/install-nix-action@a809471b5c7c913aa67bec8f459a11a0decc3fce # v31.6.2
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+      - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
+        with:
+          name: ghostty
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+
+      - name: Test
+        run: |
+          nix develop -c zig build test -Dsimd=${{ matrix.simd }}
+
   test-sentry-linux:
     strategy:
       fail-fast: false