Play Store release build: signing, R8, versioning, listing assets

.gitignore

@@ -7,3 +7,11 @@ local.properties
 .DS_Store
 captures/
 .kotlin/
+CLAUDE.md
+
+# Release signing — never commit keystores or their credentials.
+store-assets/
+app/keystore.properties
+*.jks
+*.keystore
+*.pepk

app/build.gradle.kts

@@ -1,3 +1,5 @@
+import java.util.Properties
+
 plugins {
     // AGP 9 built-in Kotlin (see :metawear-core) — org.jetbrains.kotlin.android
     // must NOT be applied. The Compose compiler Gradle plugin (2.2.10, matching
@@ -6,6 +8,21 @@ plugins {
     alias(libs.plugins.kotlin.compose)
 }
 
+// Release signing reads from an UNTRACKED file so no secret ever enters git.
+// Create app/keystore.properties (gitignored) with:
+//   storeFile=/absolute/path/to/mbientlab_android_apps.jks
+//   storePassword=…
+//   keyAlias=…
+//   keyPassword=…
+// When the file is absent (CI, fresh clones) the release build type still
+// assembles — unsigned — so the AAB task exists everywhere and only a machine
+// holding the upload key can produce a signed artifact.
+val keystoreProperties = Properties().apply {
+    val f = rootProject.file("app/keystore.properties")
+    if (f.exists()) f.inputStream().use { load(it) }
+}
+val hasReleaseKeystore = keystoreProperties.getProperty("storeFile") != null
+
 // Jetpack Compose MetaWear app: scanning, live streaming with ring-buffer
 // decimation, on-device logging + download, session history with CSV export,
 // LED/haptic controls, device settings, and firmware updates.
@@ -17,8 +34,53 @@ android {
         applicationId = "com.mbientlab.metawear.app"
         minSdk = 26
         targetSdk = 36
-        versionCode = 1
-        versionName = "1.0"
+        // This package already ships on Google Play (the previous-generation
+        // app reached versionCode 25 / 4.0.0). Play rejects any upload whose
+        // versionCode is not higher than the live one, so the new app line
+        // starts at 100 / 5.0.0 — clear headroom above the old series and an
+        // unmistakable major bump for existing users.
+        versionCode = 100
+        versionName = "5.0.0"
+    }
+
+    signingConfigs {
+        if (hasReleaseKeystore) {
+            create("release") {
+                storeFile = file(keystoreProperties.getProperty("storeFile"))
+                storePassword = keystoreProperties.getProperty("storePassword")
+                keyAlias = keystoreProperties.getProperty("keyAlias")
+                keyPassword = keystoreProperties.getProperty("keyPassword")
+            }
+        }
+    }
+
+    buildTypes {
+        release {
+            // R8: shrink + obfuscate. Keep rules for Room, the Nordic BLE/DFU
+            // libraries, and Compose live in proguard-rules.pro.
+            isMinifyEnabled = true
+            isShrinkResources = true
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro",
+            )
+            // Without an upload keystore on this machine, sign with the debug
+            // key so the minified build can still be installed and smoke-tested
+            // on a device. Play never sees this artifact — the store AAB is
+            // produced only where keystore.properties exists.
+            signingConfig = if (hasReleaseKeystore) signingConfigs.getByName("release") else signingConfigs.getByName("debug")
+        }
+        debug {
+            // Distinct id so a debug build can sit beside the store app.
+            applicationIdSuffix = ".debug"
+            versionNameSuffix = "-debug"
+        }
+    }
+
+    bundle {
+        // Let Play deliver per-device splits; language splits stay off so
+        // the app is fully usable offline in any locale (single-language app).
+        language.enableSplit = false
     }
 
     buildFeatures {

app/proguard-rules.pro

@@ -0,0 +1,32 @@
+# R8 keep rules for the MetaWear app release build.
+
+# --- Room ---------------------------------------------------------------
+# Entities / DAOs are reached via generated code and reflection-free, but the
+# @Database subclass and its generated _Impl are located by name.
+-keep class * extends androidx.room.RoomDatabase { <init>(); }
+-keep @androidx.room.Entity class * { *; }
+-dontwarn androidx.room.paging.**
+
+# --- Nordic Kotlin BLE library + Android DFU library --------------------
+# The DFU library instantiates the app's DfuBaseService subclass by name and
+# talks to it over broadcasts; the BLE library uses reflection-free coroutines
+# but ships some optional pieces R8 warns about.
+-keep class com.mbientlab.metawear.firmware.MetaWearDfuService { *; }
+-keep class no.nordicsemi.android.dfu.** { *; }
+-dontwarn no.nordicsemi.android.**
+
+# --- kotlinx.coroutines / datetime ---------------------------------------
+-dontwarn kotlinx.coroutines.**
+-keepnames class kotlinx.coroutines.internal.MainDispatcherFactory
+-keepnames class kotlinx.coroutines.CoroutineExceptionHandler
+-keepclassmembers class kotlinx.coroutines.** { volatile <fields>; }
+-dontwarn kotlinx.datetime.**
+
+# --- App: keep the persisted-record codec's data classes stable ------------
+# LogSessionRecord / RememberedDevice round-trip through hand-rolled string
+# codecs (no reflection), so nothing here needs keeping — listed for clarity.
+
+# --- General ---------------------------------------------------------------
+-keepattributes *Annotation*, Signature, InnerClasses, EnclosingMethod
+-keepattributes SourceFile, LineNumberTable
+-renamesourcefileattribute SourceFile