feat: add Gradle cache to Android release builds (#251)

Introduce androidBase() and firebaseBase() helpers that wrap setup() with
the Gradle named-cache volume, mirroring the pattern already used in
BuildAndroidDebugApks(). Use these in BuildAndroidRelease(), setupKeystore(),
and BuildAndroidDebugApks() so Gradle dependencies survive Dagger
execution-cache misses instead of being re-downloaded on every source change.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Taskfile.yml

@@ -224,7 +224,7 @@ tasks:
     desc: Build AAB via Dagger (cached, versionCode=1 placeholder) and export locally
     cmds:
       - mkdir -p build/app/outputs/bundle/release
-      - dagger call --progress=plain -q -m ci --source=. build-android-release -o build/app/outputs/bundle/release/app-release.aab
+      - HASH=$(git rev-parse --short HEAD) && dagger call --progress=plain -q -m ci --source=. build-android-release --commit-hash "$HASH" -o build/app/outputs/bundle/release/app-release.aab
 
   upload-android-bundle:
     desc: Upload AAB from build/ to Play Store via Dagger
@@ -247,7 +247,7 @@ tasks:
       - sh: test -n "$ANDROID_KEYSTORE_PASSWORD"
         msg: "ANDROID_KEYSTORE_PASSWORD is not set"
     cmds:
-      - dagger call --progress=plain -q -m ci --source=. publish-android --play-store-config env:PLAY_STORE_CONFIG_JSON --keystore-base64 env:ANDROID_KEYSTORE_BASE64 --keystore-password env:ANDROID_KEYSTORE_PASSWORD
+      - HASH=$(git rev-parse --short HEAD) && dagger call --progress=plain -q -m ci --source=. publish-android --play-store-config env:PLAY_STORE_CONFIG_JSON --keystore-base64 env:ANDROID_KEYSTORE_BASE64 --keystore-password env:ANDROID_KEYSTORE_PASSWORD --commit-hash "$HASH"
 
   deploy-apk:
     desc: Build and deploy Android APK via Dagger

ci/main.go

@@ -286,6 +286,21 @@ func (m *Ci) firebaseSrc() *dagger.Directory {
 	})
 }
 
+// androidBase wraps setup(androidSrc()) with the Gradle named-cache so that
+// Gradle dependencies survive across Dagger execution-cache misses.
+func (m *Ci) androidBase() *dagger.Container {
+	return m.setup(m.androidSrc()).
+		WithMountedCache("/home/ci/.gradle", dag.CacheVolume("gradle-cache"),
+			dagger.ContainerWithMountedCacheOpts{Owner: "ci"})
+}
+
+// firebaseBase wraps setup(firebaseSrc()) with the Gradle named-cache.
+func (m *Ci) firebaseBase() *dagger.Container {
+	return m.setup(m.firebaseSrc()).
+		WithMountedCache("/home/ci/.gradle", dag.CacheVolume("gradle-cache"),
+			dagger.ContainerWithMountedCacheOpts{Owner: "ci"})
+}
+
 // linuxSrc is the source subset for Linux builds and integration tests.
 func (m *Ci) linuxSrc() *dagger.Directory {
 	return m.Source.Filter(dagger.DirectoryFilterOpts{
@@ -584,9 +599,17 @@ func (m *Ci) BuildLinux() *dagger.Directory {
 }
 
 // BuildLinuxRelease builds the Linux release bundle.
-func (m *Ci) BuildLinuxRelease() *dagger.Directory {
+func (m *Ci) BuildLinuxRelease(
+	// Git commit hash injected as GIT_HASH dart-define so the About page can display it.
+	// +optional
+	commitHash string,
+) *dagger.Directory {
+	args := []string{"flutter", "build", "linux", "--release"}
+	if commitHash != "" {
+		args = append(args, "--dart-define=GIT_HASH="+commitHash)
+	}
 	return m.setup(m.linuxSrc()).
-		WithExec([]string{"flutter", "build", "linux", "--release"}).
+		WithExec(args).
 		Directory("build/linux/x64/release/bundle")
 }
 
@@ -599,7 +622,7 @@ func (m *Ci) DeployLinux(
 	sshHost string,
 	commitHash string,
 ) (string, error) {
-	bundle := m.BuildLinuxRelease()
+	bundle := m.BuildLinuxRelease(commitHash)
 
 	datePath := time.Now().Format("2006/01/02")
 	remoteDir := fmt.Sprintf("public_html/builds/%s", datePath)
@@ -615,16 +638,27 @@ func (m *Ci) DeployLinux(
 
 // setupKeystore decodes the base64 keystore into the android build container.
 func (m *Ci) setupKeystore(keystoreBase64 *dagger.Secret, keystorePassword *dagger.Secret) *dagger.Container {
-	return m.setup(m.androidSrc()).
+	return m.androidBase().
 		WithSecretVariable("ANDROID_KEYSTORE_BASE64", keystoreBase64).
 		WithSecretVariable("ANDROID_KEYSTORE_PASSWORD", keystorePassword).
 		WithExec([]string{"/bin/sh", "-c", `echo "$ANDROID_KEYSTORE_BASE64" | base64 -d > android/app/upload-keystore.jks`})
 }
 
 // BuildAndroidApk builds a release APK signed with the upload key.
-func (m *Ci) BuildAndroidApk(keystoreBase64 *dagger.Secret, keystorePassword *dagger.Secret, buildNumber string) *dagger.File {
+func (m *Ci) BuildAndroidApk(
+	keystoreBase64 *dagger.Secret,
+	keystorePassword *dagger.Secret,
+	buildNumber string,
+	// Git commit hash injected as GIT_HASH dart-define so the About page can display it.
+	// +optional
+	commitHash string,
+) *dagger.File {
+	args := []string{"flutter", "build", "apk", "--release", "--no-pub", "--build-number", buildNumber}
+	if commitHash != "" {
+		args = append(args, "--dart-define=GIT_HASH="+commitHash)
+	}
 	return m.setupKeystore(keystoreBase64, keystorePassword).
-		WithExec([]string{"flutter", "build", "apk", "--release", "--no-pub", "--build-number", buildNumber}).
+		WithExec(args).
 		File("build/app/outputs/flutter-apk/app-release.apk")
 }
 
@@ -640,7 +674,7 @@ func (m *Ci) DeployApk(
 	keystorePassword *dagger.Secret,
 	buildNumber string,
 ) (string, error) {
-	apk := m.BuildAndroidApk(keystoreBase64, keystorePassword, buildNumber)
+	apk := m.BuildAndroidApk(keystoreBase64, keystorePassword, buildNumber, commitHash)
 
 	datePath := time.Now().Format("2006/01/02")
 	remoteDir := fmt.Sprintf("public_html/builds/%s", datePath)
@@ -656,8 +690,7 @@ func (m *Ci) DeployApk(
 // BuildAndroidDebugApks builds the debug app APK and the androidTest APK needed for Firebase Test Lab.
 // Returns a flat directory with app-debug.apk and app-debug-androidTest.apk.
 func (m *Ci) BuildAndroidDebugApks() *dagger.Directory {
-	built := m.setup(m.firebaseSrc()).
-		WithMountedCache("/home/ci/.gradle", dag.CacheVolume("gradle-cache"), dagger.ContainerWithMountedCacheOpts{Owner: "ci"}).
+	built := m.firebaseBase().
 		WithExec([]string{"flutter", "build", "apk", "--debug", "--no-pub"}).
 		WithWorkdir("/src/android").
 		// --no-daemon avoids connecting to a stale daemon whose registry file was
@@ -716,9 +749,17 @@ func (m *Ci) TestAndroidFirebase(
 
 // BuildAndroidRelease builds the AAB with a fixed build-number so Dagger can cache it.
 // versionCode and signing are applied separately via StampAndroidVersionCode + SignAndroidBundle.
-func (m *Ci) BuildAndroidRelease() *dagger.File {
-	return m.setup(m.androidSrc()).
-		WithExec([]string{"flutter", "build", "appbundle", "--release", "--no-pub", "--build-number", "1"}).
+func (m *Ci) BuildAndroidRelease(
+	// Git commit hash injected as GIT_HASH dart-define so the About page can display it.
+	// +optional
+	commitHash string,
+) *dagger.File {
+	args := []string{"flutter", "build", "appbundle", "--release", "--no-pub", "--build-number", "1"}
+	if commitHash != "" {
+		args = append(args, "--dart-define=GIT_HASH="+commitHash)
+	}
+	return m.androidBase().
+		WithExec(args).
 		File("build/app/outputs/bundle/release/app-release.aab")
 }
 
@@ -790,9 +831,12 @@ func (m *Ci) PublishAndroid(
 	playStoreConfig *dagger.Secret,
 	keystoreBase64 *dagger.Secret,
 	keystorePassword *dagger.Secret,
+	// Git commit hash injected as GIT_HASH dart-define so the About page can display it.
+	// +optional
+	commitHash string,
 ) (string, error) {
 	versionCode := int(time.Now().Unix())
-	aab := m.BuildAndroidRelease()
+	aab := m.BuildAndroidRelease(commitHash)
 	stamped := m.StampAndroidVersionCode(aab, versionCode)
 	signed := m.SignAndroidBundle(stamped, keystoreBase64, keystorePassword)
 	return m.UploadToPlayStore(ctx, signed, playStoreConfig)