fix(auth): preserve cached auth flow state across activity recreation

Author: russellwheatley

auth/src/main/java/com/firebase/ui/auth/FirebaseAuthActivity.kt

@@ -72,15 +72,16 @@ class FirebaseAuthActivity : ComponentActivity() {
 
     private lateinit var authUI: FirebaseAuthUI
     private lateinit var configuration: AuthUIConfiguration
+    private var launchKey: String? = null
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
 
         // Extract configuration and auth instance from cache using UUID key
-        val launchKey = intent.getStringExtra(EXTRA_CONFIGURATION_KEY)
+        launchKey = intent.getStringExtra(EXTRA_CONFIGURATION_KEY)
         configuration = if (launchKey != null) {
-            configurationCache.remove(launchKey)
+            configurationCache[launchKey]
         } else {
             null
         } ?: run {
@@ -91,7 +92,7 @@ class FirebaseAuthActivity : ComponentActivity() {
         }
 
         authUI = if (launchKey != null) {
-            authUICache.remove(launchKey)
+            authUICache[launchKey]
         } else {
             null
         } ?: run {
@@ -159,11 +160,17 @@ class FirebaseAuthActivity : ComponentActivity() {
     }
 
     override fun onDestroy() {
-        super.onDestroy()
-        // Reset auth state when activity is destroyed
-        if (!isFinishing) {
+        if (isFinishing) {
+            launchKey?.let { key ->
+                configurationCache.remove(key)
+                authUICache.remove(key)
+            }
+        } else {
+            // Preserve cached launch state so the recreated activity can recover it.
             authUI.updateAuthState(AuthState.Idle)
         }
+
+        super.onDestroy()
     }
 
     companion object {

auth/src/test/java/com/firebase/ui/auth/FirebaseAuthActivityTest.kt

@@ -447,22 +447,28 @@ class FirebaseAuthActivityTest {
     // =============================================================================================
 
     @Test
-    fun `configuration is removed from cache after onCreate`() {
-        val intent1 = FirebaseAuthActivity.createIntent(applicationContext, configuration)
-        val configKey1 = intent1.getStringExtra("com.firebase.ui.auth.CONFIGURATION_KEY")
+    fun `launch state survives recreation and is cleared when activity finishes`() {
+        val intent = FirebaseAuthActivity.createIntent(applicationContext, configuration)
 
-        assertThat(configKey1).isNotNull()
+        val firstController = Robolectric.buildActivity(FirebaseAuthActivity::class.java, intent)
+        val firstActivity = firstController.create().start().resume().get()
+        assertThat(firstActivity.isFinishing).isFalse()
 
-        // Create activity - this should consume the configuration from cache
-        val controller1 = Robolectric.buildActivity(FirebaseAuthActivity::class.java, intent1)
-        controller1.create().get()
+        // Simulate recreation: the first activity is destroyed without finishing.
+        firstController.pause().stop().destroy()
+
+        val recreatedController = Robolectric.buildActivity(FirebaseAuthActivity::class.java, intent)
+        val recreatedActivity = recreatedController.create().start().resume().get()
+        assertThat(recreatedActivity.isFinishing).isFalse()
 
-        // Create another intent
-        val intent2 = FirebaseAuthActivity.createIntent(applicationContext, configuration)
-        val configKey2 = intent2.getStringExtra("com.firebase.ui.auth.CONFIGURATION_KEY")
+        // Once the recreated activity actually finishes, the cached launch state should be released.
+        recreatedActivity.finish()
+        recreatedController.pause().stop().destroy()
 
-        // Should be a different key
-        assertThat(configKey2).isNotEqualTo(configKey1)
+        val postFinishController = Robolectric.buildActivity(FirebaseAuthActivity::class.java, intent)
+        val postFinishActivity = postFinishController.create().get()
+        assertThat(postFinishActivity.isFinishing).isTrue()
+        assertThat(shadowOf(postFinishActivity).resultCode).isEqualTo(Activity.RESULT_CANCELED)
     }
 
     @Test