legacy skia build next to impeller arm64

.github/workflows/build.yml

@@ -147,9 +147,13 @@ jobs:
           IPTPROXY_SOURCE: ${{ runner.temp }}/IPtProxy
         run: melos run build-go-runtime --no-select
 
-      - name: Build APK (Alpha)
+      - name: Build APK (Alpha, Impeller)
         if: steps.build-type.outputs.is_prerelease == 'true'
-        run: melos run build-browser-alpha --no-select
+        run: melos run build-browser-alpha-impeller --no-select
+
+      - name: Build APK (Alpha, Legacy renderer)
+        if: steps.build-type.outputs.is_prerelease == 'true'
+        run: melos run build-browser-alpha-legacy --no-select
 
       - name: Build APK (Stable)
         if: steps.build-type.outputs.is_prerelease == 'false'
@@ -164,7 +168,7 @@ jobs:
         if: steps.build-type.outputs.is_prerelease == 'true'
         uses: ncipollo/release-action@v1.17.0
         with:
-          artifacts: "apps/weblibre/build/app/outputs/apk/alpha/release/*.apk"
+          artifacts: "apps/weblibre/build/app/outputs/apk/alphaImpeller/release/*.apk,apps/weblibre/build/app/outputs/apk/alphaLegacy/release/*.apk"
           prerelease: true
 
       - name: Create github artifact release (Full)

apps/weblibre/android/app/build.gradle

@@ -43,6 +43,10 @@ android {
         targetSdk = 37
         versionCode = flutterVersionCode.toInteger()
         versionName = flutterVersionName
+        // Whether the Flutter engine renders via Impeller or the legacy Skia
+        // backend. Read by io.flutter.embedding.android.EnableImpeller in
+        // AndroidManifest.xml. Overridden per-flavor below.
+        manifestPlaceholders = [enableImpeller: "true"]
     }
 
     flavorDimensions "track"
@@ -51,11 +55,32 @@ android {
             dimension "track"
             manifestPlaceholders = [appName: "WebLibre"]
         }
-        alpha {
+        // Same alpha release slot (applicationId/versionName suffix), split into
+        // two variants so Impeller and the legacy Skia renderer can be compared
+        // side by side. The renderer is chosen at Flutter engine startup via a
+        // manifest meta-data flag and cannot be switched at runtime, hence two
+        // separate builds rather than a single toggle.
+        alphaImpeller {
             dimension "track"
             applicationIdSuffix ".alpha"
             versionNameSuffix "-alpha"
-            manifestPlaceholders = [appName: "WebLibre Alpha"]
+            manifestPlaceholders = [appName: "WebLibre Alpha", enableImpeller: "true"]
+        }
+        alphaLegacy {
+            dimension "track"
+            applicationIdSuffix ".alpha"
+            versionNameSuffix "-alpha"
+            manifestPlaceholders = [appName: "WebLibre Alpha (Legacy)", enableImpeller: "false"]
+        }
+    }
+
+    sourceSets {
+        // Both alpha variants share the existing alpha launcher icon/branding.
+        alphaImpeller {
+            res.srcDirs += 'src/alpha/res'
+        }
+        alphaLegacy {
+            res.srcDirs += 'src/alpha/res'
         }
     }
 

apps/weblibre/android/app/src/main/AndroidManifest.xml

@@ -271,7 +271,7 @@
 
         <meta-data
             android:name="io.flutter.embedding.android.EnableImpeller"
-            android:value="true" />
+            android:value="${enableImpeller}" />
 
         <!-- HCPP (Hybrid Composition++) is still experimental and mis-maps
              platform-view touch coordinates when the activity runs in a resized

pubspec.yaml

@@ -94,9 +94,15 @@ melos:
         set -e
         cd apps/weblibre
         flutter build apk --release --flavor stable --target-platform android-arm,android-arm64 --split-per-abi --no-tree-shake-icons
-    build-browser-alpha:
+    build-browser-alpha-impeller:
-      description: Build alpha release APK split per ABI (side-by-side installable with stable)
+      description: Build arm64 alpha release APK with Impeller enabled (side-by-side installable with stable)
       run: |
         set -e
         cd apps/weblibre
-        flutter build apk --release --flavor alpha --target-platform android-arm,android-arm64 --split-per-abi --no-tree-shake-icons
+        flutter build apk --release --flavor alphaImpeller --target-platform android-arm64 --no-tree-shake-icons
+    build-browser-alpha-legacy:
+      description: Build arm64 alpha release APK with the legacy Skia renderer (side-by-side installable with stable)
+      run: |
+        set -e
+        cd apps/weblibre
+        flutter build apk --release --flavor alphaLegacy --target-platform android-arm64 --no-tree-shake-icons