ci: add release workflow for dual-arch macOS builds

Builds aarch64 and x86_64 binaries on tag push, uploads to GitHub
release, and auto-updates the Homebrew tap formula.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Alan Shum

.github/workflows/release.yml

@@ -0,0 +1,117 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - "v*"
+
+permissions:
+  contents: write
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        include:
+          - target: aarch64-apple-darwin
+            os: macos-latest
+          - target: x86_64-apple-darwin
+            os: macos-13
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: ${{ matrix.target }}
+      - name: Build
+        run: cargo build --release --target ${{ matrix.target }}
+      - name: Package
+        run: |
+          cd target/${{ matrix.target }}/release
+          tar -czf semantic-diff-${{ github.ref_name }}-${{ matrix.target }}.tar.gz semantic-diff
+          shasum -a 256 semantic-diff-${{ github.ref_name }}-${{ matrix.target }}.tar.gz > semantic-diff-${{ github.ref_name }}-${{ matrix.target }}.tar.gz.sha256
+      - uses: actions/upload-artifact@v4
+        with:
+          name: semantic-diff-${{ matrix.target }}
+          path: |
+            target/${{ matrix.target }}/release/semantic-diff-${{ github.ref_name }}-${{ matrix.target }}.tar.gz
+            target/${{ matrix.target }}/release/semantic-diff-${{ github.ref_name }}-${{ matrix.target }}.tar.gz.sha256
+
+  release:
+    needs: build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          merge-multiple: true
+      - name: Create or update release
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_REPO: ${{ github.repository }}
+        run: |
+          # Upload binaries to the existing release (created by tag push)
+          gh release upload ${{ github.ref_name }} \
+            semantic-diff-${{ github.ref_name }}-aarch64-apple-darwin.tar.gz \
+            semantic-diff-${{ github.ref_name }}-aarch64-apple-darwin.tar.gz.sha256 \
+            semantic-diff-${{ github.ref_name }}-x86_64-apple-darwin.tar.gz \
+            semantic-diff-${{ github.ref_name }}-x86_64-apple-darwin.tar.gz.sha256 \
+            --clobber
+
+  update-homebrew:
+    needs: release
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          merge-multiple: true
+      - name: Read SHA256 sums
+        id: sha
+        run: |
+          echo "arm64=$(cat semantic-diff-${{ github.ref_name }}-aarch64-apple-darwin.tar.gz.sha256 | awk '{print $1}')" >> "$GITHUB_OUTPUT"
+          echo "x86_64=$(cat semantic-diff-${{ github.ref_name }}-x86_64-apple-darwin.tar.gz.sha256 | awk '{print $1}')" >> "$GITHUB_OUTPUT"
+      - uses: actions/checkout@v4
+        with:
+          repository: alankyshum/homebrew-tap
+          token: ${{ secrets.HOMEBREW_TAP_TOKEN }}
+      - name: Update formula
+        env:
+          VERSION: ${{ github.ref_name }}
+          SHA_ARM64: ${{ steps.sha.outputs.arm64 }}
+          SHA_X86: ${{ steps.sha.outputs.x86_64 }}
+        run: |
+          VER="${VERSION#v}"
+          cat > Formula/semantic-diff.rb << FORMULA
+          class SemanticDiff < Formula
+            desc "Terminal diff viewer with AI-powered semantic grouping via Claude CLI"
+            homepage "https://github.com/alankyshum/semantic-diff"
+            version "${VER}"
+            license "MIT"
+
+            on_macos do
+              if Hardware::CPU.arm?
+                url "https://github.com/alankyshum/semantic-diff/releases/download/${VERSION}/semantic-diff-${VERSION}-aarch64-apple-darwin.tar.gz"
+                sha256 "${SHA_ARM64}"
+              elsif Hardware::CPU.intel?
+                url "https://github.com/alankyshum/semantic-diff/releases/download/${VERSION}/semantic-diff-${VERSION}-x86_64-apple-darwin.tar.gz"
+                sha256 "${SHA_X86}"
+              end
+            end
+
+            def install
+              bin.install "semantic-diff"
+            end
+
+            test do
+              assert_match "semantic-diff", shell_output("#{bin}/semantic-diff --help")
+            end
+          end
+          FORMULA
+          # Remove leading whitespace from heredoc
+          sed -i 's/^          //' Formula/semantic-diff.rb
+      - name: Commit and push
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add Formula/semantic-diff.rb
+          git commit -m "Update semantic-diff to ${{ github.ref_name }}"
+          git push