feat: bump Homebrew cask on release

.github/workflows/release.yml

@@ -320,4 +320,61 @@ jobs:
           # Assets use tauri-action's default versioned naming (e.g.
           # Gridline_0.7.5_aarch64.dmg, Gridline-0.7.5-1.x86_64.rpm) and the
           # README download tables link to them statically per release —
-          # remember to update both README tables when cutting a new version.
+          # remember to update both README tables when cutting a new version.
+
+  # After the installers are uploaded, refresh the Homebrew cask in the
+  # AdrianBonpin/homebrew-gridline tap: hash the freshly-published DMGs,
+  # render Casks/gridline.rb from the template, and push it. Users then get
+  # the new version via `brew upgrade --cask gridline`.
+  #
+  # Requires the HOMEBREW_TAP_TOKEN secret (a PAT with `repo` scope on the tap
+  # repo — the default GITHUB_TOKEN cannot push to a different repo). The job
+  # no-ops until that secret is set, so releases stay green before this is
+  # configured.
+  bump-cask:
+    needs: publish
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Resolve version and DMG checksums
+        id: meta
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          VERSION="${GITHUB_REF_NAME#v}"
+          gh release download "$GITHUB_REF_NAME" -p "Gridline_${VERSION}_aarch64.dmg" -O /tmp/arm.dmg
+          gh release download "$GITHUB_REF_NAME" -p "Gridline_${VERSION}_x64.dmg" -O /tmp/intel.dmg
+          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
+          echo "sha_arm=$(shasum -a 256 /tmp/arm.dmg | cut -d' ' -f1)" >> "$GITHUB_OUTPUT"
+          echo "sha_intel=$(shasum -a 256 /tmp/intel.dmg | cut -d' ' -f1)" >> "$GITHUB_OUTPUT"
+
+      - name: Checkout tap repo
+        uses: actions/checkout@v4
+        with:
+          repository: AdrianBonpin/homebrew-gridline
+          token: ${{ secrets.HOMEBREW_TAP_TOKEN }}
+          path: tap
+
+      - name: Render and push cask
+        env:
+          VERSION: ${{ steps.meta.outputs.version }}
+          SHA_ARM: ${{ steps.meta.outputs.sha_arm }}
+          SHA_INTEL: ${{ steps.meta.outputs.sha_intel }}
+        run: |
+          mkdir -p tap/Casks
+          ./scripts/render-cask.sh "$VERSION" "$SHA_ARM" "$SHA_INTEL" > tap/Casks/gridline.rb
+          cat tap/Casks/gridline.rb
+          cd tap
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add Casks/gridline.rb
+          if git diff --cached --quiet; then
+            echo "cask already up to date"
+          else
+            git commit -m "gridline $VERSION"
+            git push
+          fi