Refactor Android build process to support update-compatible APKs and add shared debug keystore configuration

.github/workflows/android-build.yml

@@ -26,16 +26,10 @@ jobs:
       - name: Set up Gradle
         uses: gradle/actions/setup-gradle@v4
 
-      - name: Cache Android debug keystore
-        uses: actions/cache@v4
-        with:
-          path: ~/.android/debug.keystore
-          key: android-debug-keystore-${{ runner.os }}
-
       - name: Make Gradle wrapper executable
         run: chmod +x gradlew
 
-      - name: Build debug APK
+      - name: Build update-compatible APK
         run: ./gradlew assembleDebug -PciVersionCode=${{ github.run_number }} -PciVersionName=1.0.${{ github.run_number }}
 
       - name: Prepare release assets

app/build.gradle

@@ -4,11 +4,21 @@ plugins {
 
 def ciVersionCode = providers.gradleProperty("ciVersionCode").getOrNull()
 def ciVersionName = providers.gradleProperty("ciVersionName").getOrNull()
+def sharedDebugKeystore = file("signing/bible-daily-debug.keystore")
 
 android {
     namespace "com.bibliadiaria.app"
     compileSdk 35
 
+    signingConfigs {
+        sharedDebug {
+            storeFile sharedDebugKeystore
+            storePassword "android"
+            keyAlias "androiddebugkey"
+            keyPassword "android"
+        }
+    }
+
     defaultConfig {
         applicationId "com.bibliadiaria.app"
         minSdk 23
@@ -17,6 +27,14 @@ android {
         versionName ciVersionName != null ? ciVersionName : "1.0"
     }
 
+    buildTypes {
+        debug {
+            if (sharedDebugKeystore.exists()) {
+                signingConfig signingConfigs.sharedDebug
+            }
+        }
+    }
+
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_17
         targetCompatibility JavaVersion.VERSION_17

app/signing/README.md

@@ -0,0 +1,3 @@
+This debug keystore is intentionally shared by local and GitHub Actions builds so sideloaded APK updates keep the same Android signing identity.
+
+Do not use this key for Play Store or production release signing.