fix: remove Android Gson usage to avoid R8 incompatibility (#126)

## Changes
Android widget rendering still used Gson in a few renderer parsing
paths, which made the Android release build vulnerable to R8
incompatibility.

- replace remaining Android renderer-side Gson parsing with shared
`kotlinx.serialization` / `JsonElement` helpers
- remove dead Gson leftovers and delete the Android Gson dependency
- add Android tests covering renderer JSON decoding and chart mark
parsing regressions

## Outcome
Android no longer depends on Gson, release builds complete with R8
enabled, and the existing JS wire format remains unchanged.

## Test plan
- [x] `npm run format:kotlin:fix`
- [x] `npm run test:kotlin`
- [x] `./gradlew app:assembleRelease`

Author: V3RON

packages/voltra/android/build.gradle

@@ -102,9 +102,6 @@ dependencies {
   // Google Tink (encryption for credential storage)
   implementation "com.google.crypto.tink:tink-android:1.19.0"
 
-  // JSON parsing
-  implementation "com.google.code.gson:gson:2.10.1"
-
   // Coroutines
   implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.8.1"
 
@@ -114,4 +111,5 @@ dependencies {
   // Unit tests
   testImplementation "junit:junit:4.13.2"
   testImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:1.8.1"
+  testImplementation "org.robolectric:robolectric:4.14.1"
 }

packages/voltra/android/src/main/java/voltra/glance/GlanceFactory.kt

@@ -9,7 +9,7 @@ import voltra.models.VoltraNode
 class GlanceFactory(
     private val widgetId: String,
     private val sharedElements: List<VoltraNode>? = null,
-    private val sharedStyles: List<Map<String, Any>>? = null,
+    private val sharedStyles: List<Map<String, Any?>>? = null,
     private val widgetSize: DpSize? = null,
 ) {
     @Composable

packages/voltra/android/src/main/java/voltra/glance/RemoteViewsGenerator.kt

@@ -62,7 +62,7 @@ object RemoteViewsGenerator {
         context: Context,
         node: VoltraNode,
         sharedElements: List<VoltraNode>?,
-        sharedStyles: List<Map<String, Any>>?,
+        sharedStyles: List<Map<String, Any?>>?,
         size: DpSize,
     ): RemoteViews {
         // Create a new GlanceRemoteViews instance each time to avoid caching issues

packages/voltra/android/src/main/java/voltra/glance/StyleUtils.kt

@@ -17,8 +17,8 @@ data class ResolvedStyle(
 
 @Composable
 fun resolveAndApplyStyle(
-    props: Map<String, Any>?,
-    sharedStyles: List<Map<String, Any>>?,
+    props: Map<String, Any?>?,
+    sharedStyles: List<Map<String, Any?>>?,
 ): ResolvedStyle {
     val resolvedStyle = resolveStyle(props, sharedStyles)
     val compositeStyle =
@@ -42,9 +42,9 @@ fun resolveAndApplyStyle(
  * or {"s": {...}} for inline styles.
  */
 private fun resolveStyle(
-    props: Map<String, Any>?,
-    sharedStyles: List<Map<String, Any>>?,
-): Map<String, Any>? {
+    props: Map<String, Any?>?,
+    sharedStyles: List<Map<String, Any?>>?,
+): Map<String, Any?>? {
     if (props == null) return null
 
     val styleRef = props["style"]
@@ -58,7 +58,7 @@ private fun resolveStyle(
         is Map<*, *> -> {
             // It's already an inline style
             @Suppress("UNCHECKED_CAST")
-            styleRef as? Map<String, Any>
+            styleRef as? Map<String, Any?>
         }
 
         else -> {
@@ -82,7 +82,7 @@ private fun resolveStyle(
 @Composable
 fun applyClickableIfNeeded(
     modifier: GlanceModifier,
-    props: Map<String, Any>?,
+    props: Map<String, Any?>?,
     elementId: String?,
     widgetId: String,
     componentType: Int,

packages/voltra/android/src/main/java/voltra/glance/VoltraRenderContext.kt

@@ -7,7 +7,7 @@ import voltra.models.VoltraNode
 data class VoltraRenderContext(
     val widgetId: String,
     val sharedElements: List<VoltraNode>? = null,
-    val sharedStyles: List<Map<String, Any>>? = null,
+    val sharedStyles: List<Map<String, Any?>>? = null,
     val widgetSize: DpSize? = null,
 )
 

packages/voltra/android/src/main/java/voltra/glance/renderers/ButtonRenderers.kt

@@ -13,17 +13,13 @@ import androidx.glance.appwidget.components.OutlineButton
 import androidx.glance.appwidget.components.SquareIconButton
 import androidx.glance.layout.Box
 import androidx.glance.unit.ColorProvider
-import com.google.gson.Gson
 import voltra.glance.LocalVoltraRenderContext
 import voltra.glance.applyClickableIfNeeded
 import voltra.glance.resolveAndApplyStyle
 import voltra.models.VoltraElement
 import voltra.styling.JSColorParser
 import voltra.styling.toColorProvider
 
-private const val TAG = "ButtonRenderers"
-private val gson = Gson()
-
 @Composable
 fun RenderButton(
     element: VoltraElement,

packages/voltra/android/src/main/java/voltra/glance/renderers/ChartBitmapRenderer.kt

@@ -6,13 +6,10 @@ import android.graphics.DashPathEffect
 import android.graphics.Paint
 import android.graphics.Path
 import android.graphics.RectF
-import android.util.Log
 import androidx.compose.ui.graphics.toArgb
 import voltra.styling.JSColorParser
 import voltra.styling.VoltraColorValue
 
-private const val TAG = "ChartBitmapRenderer"
-
 private val DEFAULT_PALETTE =
     intArrayOf(
         0xFF4E79A7.toInt(), // blue
@@ -46,24 +43,19 @@ data class SectorPoint(
 )
 
 fun parseMarksJson(marksJson: String): List<WireMark> {
-    return try {
-        val gson = com.google.gson.Gson()
-        val type = object : com.google.gson.reflect.TypeToken<List<List<Any>>>() {}.type
-        val outer: List<List<Any>> = gson.fromJson(marksJson, type)
-        outer.mapNotNull { row ->
-            if (row.size < 3) return@mapNotNull null
-            val markType = row[0] as? String ?: return@mapNotNull null
-
-            @Suppress("UNCHECKED_CAST")
-            val data = row[1] as? List<List<Any>>
-
-            @Suppress("UNCHECKED_CAST")
-            val props = (row[2] as? Map<String, Any>) ?: emptyMap()
-            WireMark(markType, data, props)
-        }
-    } catch (e: Exception) {
-        Log.w(TAG, "Failed to parse marks JSON", e)
-        emptyList()
+    return parseMarksTuples(marksJson).mapNotNull { row ->
+        if (row.size < 3) return@mapNotNull null
+        val markType = row[0] as? String ?: return@mapNotNull null
+
+        @Suppress("UNCHECKED_CAST")
+        val data =
+            (row[1] as? List<*>)?.mapNotNull { point ->
+                (point as? List<*>)?.toList() as? List<Any>
+            }
+
+        @Suppress("UNCHECKED_CAST")
+        val props = row[2] as? Map<String, Any> ?: emptyMap()
+        WireMark(markType, data, props)
     }
 }
 

packages/voltra/android/src/main/java/voltra/glance/renderers/ChartRenderers.kt

@@ -152,16 +152,7 @@ fun RenderChart(
 
 @Composable
 private fun parseForegroundStyleScale(json: String?): Map<String, Int>? {
-    if (json.isNullOrEmpty()) return null
-    val pairs: List<List<String>> =
-        try {
-            val gson = com.google.gson.Gson()
-            val type = object : com.google.gson.reflect.TypeToken<List<List<String>>>() {}.type
-            gson.fromJson(json, type)
-        } catch (e: Exception) {
-            Log.w(TAG, "Failed to parse foregroundStyleScale", e)
-            return null
-        }
+    val pairs = parseForegroundStyleScaleEntries(json) ?: return null
 
     val map = mutableMapOf<String, Int>()
     for (pair in pairs) {

packages/voltra/android/src/main/java/voltra/glance/renderers/ComplexRenderers.kt

@@ -9,7 +9,6 @@ import androidx.glance.LocalContext
 import androidx.glance.appwidget.components.Scaffold
 import androidx.glance.appwidget.components.TitleBar
 import androidx.glance.text.FontFamily
-import com.google.gson.Gson
 import voltra.glance.LocalVoltraRenderContext
 import voltra.glance.applyClickableIfNeeded
 import voltra.glance.resolveAndApplyStyle
@@ -19,9 +18,6 @@ import voltra.payload.ComponentTypeID
 import voltra.styling.JSColorParser
 import voltra.styling.toColorProvider
 
-private const val TAG = "ComplexRenderers"
-private val gson = Gson()
-
 @Composable
 fun RenderTitleBar(
     element: VoltraElement,

packages/voltra/android/src/main/java/voltra/glance/renderers/LazyListRenderers.kt

@@ -132,15 +132,15 @@ fun RenderLazyVerticalGrid(
     }
 }
 
-private fun extractHorizontalAlignment(props: Map<String, Any>?): Alignment.Horizontal =
+private fun extractHorizontalAlignment(props: Map<String, Any?>?): Alignment.Horizontal =
     when (props?.get("horizontalAlignment") as? String) {
         "start" -> Alignment.Horizontal.Start
         "center-horizontally" -> Alignment.Horizontal.CenterHorizontally
         "end" -> Alignment.Horizontal.End
         else -> Alignment.Horizontal.Start
     }
 
-private fun extractVerticalAlignment(props: Map<String, Any>?): Alignment.Vertical =
+private fun extractVerticalAlignment(props: Map<String, Any?>?): Alignment.Vertical =
     when (props?.get("verticalAlignment") as? String) {
         "top" -> Alignment.Vertical.Top
         "center" -> Alignment.Vertical.CenterVertically