Use nix flake for macos builds

Author: danrmiller

.github/workflows/build.yaml

@@ -313,30 +313,18 @@ jobs:
           echo "version=${VERSION}" >> $GITHUB_OUTPUT
           echo "build_number=${BUILD_NUMBER}" >> $GITHUB_OUTPUT
 
-      - uses: subosito/flutter-action@v2
-        with:
-          flutter-version: '3.38.1'
-          channel: 'stable'
-
-      - uses: actions/setup-go@v5
+      - uses: cachix/install-nix-action@v27
         with:
-          go-version: '1.24.13'
-
-      - uses: dtolnay/rust-toolchain@stable
-
-      - name: Install required Rust toolchains
-        run: |
-          rustup toolchain install 1.85.1
-          rustup target add aarch64-apple-darwin --toolchain stable
-          rustup target add aarch64-apple-darwin --toolchain 1.85.1
+          extra_nix_config: |
+            experimental-features = nix-command flakes
 
       - name: Decode secrets
         env:
           CHANGE_NOW: ${{ secrets.CHANGE_NOW }}
         run: echo "$CHANGE_NOW" | base64 --decode > lib/external_api_keys.dart
 
       - name: Build
-        run: make build-macos VERSION="${{ steps.ver.outputs.version }}" BUILD_NUM="${{ steps.ver.outputs.build_number }}"
+        run: nix develop --command make build-macos VERSION="${{ steps.ver.outputs.version }}" BUILD_NUM="${{ steps.ver.outputs.build_number }}"
 
       - name: Package
         run: |

.github/workflows/test.yaml

@@ -90,30 +90,13 @@ jobs:
         with:
           submodules: recursive
 
-      - name: Install Flutter
-        uses: subosito/flutter-action@v2
+      - uses: cachix/install-nix-action@v27
         with:
-          flutter-version: '3.38.1'
-          channel: 'stable'
-
-      - name: Setup Rust
-        uses: dtolnay/rust-toolchain@stable
-
-      - name: Install macOS build dependencies
-        run: ./scripts/install_macos_build_tools.sh
-
-      - name: Select Xcode
-        run: |
-          XCODE_PATH=$(find /Applications -maxdepth 1 -name 'Xcode*.app' -type d | head -1)
-          if [ -n "$XCODE_PATH" ]; then
-            sudo xcode-select --switch "$XCODE_PATH"
-            echo "Using Xcode at: $XCODE_PATH"
-          else
-            echo "Xcode not found" && exit 1
-          fi
+          extra_nix_config: |
+            experimental-features = nix-command flakes
 
       - name: Fresh clone smoke build (macOS)
-        run: make build-macos VERSION=0.0.1 BUILD_NUM=1
+        run: nix develop --command make build-macos VERSION=0.0.1 BUILD_NUM=1
 
       - name: MWC FFI integration test
-        run: make test-mwc
+        run: nix develop --command make test-mwc