Restore Sparkle, add Homebrew tap auto-update to release workflow

Sparkle remains for direct-download users. Release workflow now also
updates Pribess/homebrew-tap cask formula with new version and SHA256.
Requires HOMEBREW_TAP_TOKEN secret (PAT with repo scope).

Author: Pribess

.github/workflows/release.yml

@@ -13,6 +13,8 @@ jobs:
     runs-on: macos-15
     permissions:
       contents: write
+      pages: write
+      id-token: write
     env:
       REPOSITORY_NAME: ${{ github.event.repository.name }}
     steps:
@@ -21,15 +23,15 @@ jobs:
       - name: Configure GitHub Pages
         uses: actions/configure-pages@v5
 
-      - name: Build release app bundle
+      - name: Build
         run: |
           version="${GITHUB_REF_NAME#v}"
           owner="$(printf '%s' "$GITHUB_REPOSITORY_OWNER" | tr '[:upper:]' '[:lower:]')"
           export APP_VERSION="$version"
           export SU_FEED_URL="https://${owner}.github.io/${REPOSITORY_NAME}/appcast.xml"
           bash macos/scripts/build.sh
 
-      - name: Package and verify release artifacts
+      - name: Package
         env:
           EXPECT_FEED_URL: '1'
         run: |
@@ -47,36 +49,6 @@ jobs:
             -f tag_name="${GITHUB_REF_NAME}" \
             --jq '.body' > dist/release-notes.md
 
-          python3 - <<'PY'
-          import json
-          import os
-          import urllib.request
-
-          with open("dist/release-notes.md", "r", encoding="utf-8") as fh:
-              markdown = fh.read()
-
-          request = urllib.request.Request(
-              "https://api.github.com/markdown",
-              data=json.dumps({
-                  "text": markdown,
-                  "mode": "gfm",
-                  "context": os.environ["GITHUB_REPOSITORY"],
-              }).encode("utf-8"),
-              headers={
-                  "Authorization": f"Bearer {os.environ['GH_TOKEN']}",
-                  "Accept": "application/vnd.github+json",
-                  "X-GitHub-Api-Version": "2022-11-28",
-              },
-              method="POST",
-          )
-
-          with urllib.request.urlopen(request) as response:
-              html = response.read().decode("utf-8")
-
-          with open("dist/archives/UsageKit.html", "w", encoding="utf-8") as fh:
-              fh.write(html)
-          PY
-
       - name: Create release
         uses: softprops/action-gh-release@v2
         with:
@@ -90,8 +62,8 @@ jobs:
           SPARKLE_PRIVATE_KEY: ${{ secrets.SPARKLE_PRIVATE_KEY }}
         run: |
           if [[ -z "${SPARKLE_PRIVATE_KEY:-}" ]]; then
-            echo "::error::Missing SPARKLE_PRIVATE_KEY repository secret."
-            exit 1
+            echo "::warning::Missing SPARKLE_PRIVATE_KEY, skipping appcast generation"
+            exit 0
           fi
 
           cp macos/UsageKit.zip dist/archives/UsageKit.zip
@@ -105,20 +77,31 @@ jobs:
               -o dist/site/appcast.xml
 
       - name: Upload appcast for GitHub Pages
+        if: hashFiles('dist/site/appcast.xml') != ''
         uses: actions/upload-pages-artifact@v4
         with:
           path: dist/site
 
-  deploy_appcast:
-    needs: release
-    runs-on: ubuntu-latest
-    permissions:
-      pages: write
-      id-token: write
-    environment:
-      name: github-pages
-      url: ${{ steps.deployment.outputs.page_url }}
-    steps:
       - name: Deploy appcast
-        id: deployment
+        if: hashFiles('dist/site/appcast.xml') != ''
         uses: actions/deploy-pages@v4
+
+      - name: Update Homebrew tap
+        env:
+          GH_TOKEN: ${{ secrets.HOMEBREW_TAP_TOKEN }}
+        run: |
+          if [[ -z "${GH_TOKEN:-}" ]]; then
+            echo "::warning::Missing HOMEBREW_TAP_TOKEN, skipping tap update"
+            exit 0
+          fi
+
+          version="${GITHUB_REF_NAME#v}"
+          sha=$(shasum -a 256 macos/UsageKit.dmg | awk '{print $1}')
+
+          gh repo clone Pribess/homebrew-tap /tmp/homebrew-tap
+          printf 'cask "usagekit" do\n  version "%s"\n  sha256 "%s"\n\n  url "https://github.com/Pribess/UsageKit/releases/download/v#{version}/UsageKit.dmg"\n  name "UsageKit"\n  desc "Menu bar app that tracks Claude and Codex usage"\n  homepage "https://github.com/Pribess/UsageKit"\n\n  depends_on macos: ">= :sonoma"\n\n  app "UsageKit.app"\n\n  zap trash: [\n    "~/.config/usagekit",\n  ]\nend\n' "$version" "$sha" > /tmp/homebrew-tap/Casks/usagekit.rb
+
+          cd /tmp/homebrew-tap
+          git add Casks/usagekit.rb
+          git commit -m "Update UsageKit to $version"
+          git push