Fix lifecycle of regV5 scratch storage.

app/src/main/java/org/thoughtcrime/securesms/registration/v2/AppRegistrationStorageController.kt

@@ -67,7 +67,6 @@ import org.whispersystems.signalservice.api.link.TransferArchiveResponse
 import java.io.File
 import java.io.IOException
 import java.time.LocalDateTime
-import kotlin.time.Duration.Companion.minutes
 
 /**
  * Implementation of [StorageController] that bridges to the app's existing storage infrastructure.
@@ -77,7 +76,6 @@ class AppRegistrationStorageController(private val context: Context) : StorageCo
   companion object {
     private val TAG = Log.tag(AppRegistrationStorageController::class)
     private const val TEMP_PROTO_FILENAME = "registration-in-progress.proto"
-    private val TEMP_PROTO_TIMEOUT = 15.minutes
     private val MODERN_BACKUP_PATTERN = Regex("^signal-backup-(\\d{4})-(\\d{2})-(\\d{2})-(\\d{2})-(\\d{2})-(\\d{2})$")
     private val LEGACY_BACKUP_PATTERN = Regex("^signal-(\\d{4})-(\\d{2})-(\\d{2})-(\\d{2})-(\\d{2})-(\\d{2})\\.backup$")
   }
@@ -155,13 +153,6 @@ class AppRegistrationStorageController(private val context: Context) : StorageCo
   override suspend fun readInProgressRegistrationData(): RegistrationData = withContext(Dispatchers.IO) {
     val file = File(context.cacheDir, TEMP_PROTO_FILENAME)
     if (file.exists()) {
-      val age = System.currentTimeMillis() - file.lastModified()
-      if (age > TEMP_PROTO_TIMEOUT.inWholeMilliseconds) {
-        Log.w(TAG, "In-progress registration data is stale (${age}ms old), discarding.")
-        file.delete()
-        return@withContext RegistrationData()
-      }
-
       try {
         RegistrationData.ADAPTER.decode(file.readBytes())
       } catch (e: Exception) {
@@ -537,7 +528,8 @@ class AppRegistrationStorageController(private val context: Context) : StorageCo
   }
 
   private suspend fun writeRegistrationData(data: RegistrationData) = withContext(Dispatchers.IO) {
+    val stamped = data.newBuilder().lastUpdatedMillis(System.currentTimeMillis()).build()
     val file = File(context.cacheDir, TEMP_PROTO_FILENAME)
-    file.writeBytes(RegistrationData.ADAPTER.encode(data))
+    file.writeBytes(RegistrationData.ADAPTER.encode(stamped))
   }
 }

demo/registration/src/main/java/org/signal/registration/sample/dependencies/DemoStorageController.kt

@@ -440,7 +440,8 @@ class DemoStorageController(private val context: Context) : StorageController {
   }
 
   private suspend fun writeRegistrationData(data: RegistrationData) = withContext(Dispatchers.IO) {
+    val stamped = data.newBuilder().lastUpdatedMillis(System.currentTimeMillis()).build()
     val file = File(context.filesDir, TEMP_PROTO_FILENAME)
-    file.writeBytes(RegistrationData.ADAPTER.encode(data))
+    file.writeBytes(RegistrationData.ADAPTER.encode(stamped))
   }
 }

feature/registration/src/main/java/org/signal/registration/RegistrationRepository.kt

@@ -798,6 +798,22 @@ class RegistrationRepository(val context: Context, val networkController: Networ
     storageController.clearLocalDataAndRestart()
   }
 
+  /**
+   * Deletes all in-progress registration data. Called once registration is fully complete, so the scratch data is
+   * never reused by a later flow.
+   */
+  suspend fun clearInProgressRegistrationData() = withContext(Dispatchers.IO) {
+    storageController.clearAllData()
+  }
+
+  /**
+   * The time the in-progress registration data was last written, as epoch milliseconds, or null if nothing has been
+   * written yet. Read from the in-progress data's `lastUpdatedMillis`, which is stamped on every write.
+   */
+  suspend fun getInProgressRegistrationDataLastUpdated(): Long? = withContext(Dispatchers.IO) {
+    storageController.readInProgressRegistrationData().lastUpdatedMillis.takeIf { it > 0 }
+  }
+
   /**
    * Clears any persisted flow state JSON from the in-progress registration data.
    */

feature/registration/src/main/java/org/signal/registration/RegistrationViewModel.kt

@@ -181,7 +181,7 @@ class RegistrationViewModel(private val repository: RegistrationRepository, save
       is RegistrationFlowEvent.ResetState -> repository.clearFlowState()
       is RegistrationFlowEvent.NavigateToScreen -> {
         if (event.route is RegistrationRoute.FullyComplete) {
-          repository.clearFlowState()
+          repository.clearInProgressRegistrationData()
         } else {
           repository.saveFlowState(_state.value)
         }
@@ -195,7 +195,7 @@ class RegistrationViewModel(private val repository: RegistrationRepository, save
       is RegistrationFlowEvent.RestoreMethodTokenReceived,
       is RegistrationFlowEvent.UserSuppliedAepSubmitted,
       is RegistrationFlowEvent.UserSuppliedAepVerified -> repository.saveFlowState(_state.value)
-      is RegistrationFlowEvent.RegistrationComplete -> repository.clearFlowState()
+      is RegistrationFlowEvent.RegistrationComplete -> repository.clearInProgressRegistrationData()
 
       // No need to persist anything new, fields accounted for in proto already
       is RegistrationFlowEvent.Registered,

feature/registration/src/main/java/org/signal/registration/screens/verificationcode/VerificationCodeScreen.kt

@@ -50,6 +50,8 @@ import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.input.KeyboardType
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.compose.LifecycleEventEffect
 import kotlinx.coroutines.delay
 import org.signal.core.ui.compose.AllDevicePreviews
 import org.signal.core.ui.compose.Previews
@@ -146,6 +148,10 @@ fun VerificationCodeScreen(
     focusRequesters[0].requestFocus()
   }
 
+  LifecycleEventEffect(Lifecycle.Event.ON_RESUME) {
+    onEvent(VerificationCodeScreenEvents.Foregrounded)
+  }
+
   Scaffold(
     snackbarHost = { SnackbarHost(snackbarHostState) },
     modifier = modifier

feature/registration/src/main/java/org/signal/registration/screens/verificationcode/VerificationCodeScreenEvents.kt

@@ -35,4 +35,10 @@ sealed class VerificationCodeScreenEvents {
    * Event to update countdown timers. Should be triggered periodically (e.g., every second).
    */
   data object CountdownTick : VerificationCodeScreenEvents()
+
+  /**
+   * The screen returned to the foreground. Used to check whether the in-progress registration data (and thus the
+   * verification session) has grown too stale to keep waiting on, in which case we restart the flow.
+   */
+  data object Foregrounded : VerificationCodeScreenEvents()
 }

feature/registration/src/main/java/org/signal/registration/screens/verificationcode/VerificationCodeViewModel.kt

@@ -41,6 +41,7 @@ import org.signal.registration.screens.util.navigateTo
 import org.signal.registration.screens.verificationcode.VerificationCodeState.OneTimeEvent
 import kotlin.time.Duration
 import kotlin.time.Duration.Companion.milliseconds
+import kotlin.time.Duration.Companion.minutes
 import kotlin.time.Duration.Companion.seconds
 
 class VerificationCodeViewModel(
@@ -54,6 +55,12 @@ class VerificationCodeViewModel(
   companion object {
     private val TAG = Log.tag(VerificationCodeViewModel::class)
 
+    /**
+     * How old the in-progress registration data can be before we assume the verification session has expired and
+     * restart the flow. Checked whenever the screen is foregrounded.
+     */
+    private val IN_PROGRESS_DATA_TIMEOUT = 15.minutes
+
     /**
      * Cold [Flow] of verification codes automatically retrieved from incoming SMS messages via the Play Services SMS
      * retriever. Registers a [BroadcastReceiver] for [SmsRetriever.SMS_RETRIEVED_ACTION] while collected, and
@@ -123,10 +130,27 @@ class VerificationCodeViewModel(
       is VerificationCodeScreenEvents.HavingTrouble -> throw NotImplementedError("having trouble flow") // TODO [registration] - Having trouble flow
       is VerificationCodeScreenEvents.ConsumeInnerOneTimeEvent -> state.copy(oneTimeEvent = null)
       is VerificationCodeScreenEvents.CountdownTick -> applyCountdownTick(state)
+      is VerificationCodeScreenEvents.Foregrounded -> applyForegrounded(state)
     }
     stateEmitter(result)
   }
 
+  /**
+   * If the in-progress registration data has grown older than [IN_PROGRESS_DATA_TIMEOUT], the verification session has
+   * likely expired server-side. Rather than let the user enter a code only to fail, restart the flow from the beginning.
+   */
+  private suspend fun applyForegrounded(state: VerificationCodeState): VerificationCodeState {
+    val lastUpdated = repository.getInProgressRegistrationDataLastUpdated() ?: return state
+    val age = (clock() - lastUpdated).milliseconds
+
+    if (age >= IN_PROGRESS_DATA_TIMEOUT) {
+      Log.w(TAG, "[Foregrounded] In-progress registration data is stale (${age.inWholeMilliseconds}ms old). Restarting the flow.")
+      parentEventEmitter(RegistrationFlowEvent.ResetState)
+    }
+
+    return state
+  }
+
   @VisibleForTesting
   fun applyParentState(state: VerificationCodeState, parentState: RegistrationFlowState): VerificationCodeState {
     if (parentState.sessionMetadata == null || parentState.sessionE164 == null) {

feature/registration/src/main/protowire/Registration.proto

@@ -39,7 +39,11 @@ message RegistrationData {
   bool fetchesMessages = 23;
 
   string flowStateJson = 24;
-  // Next: 25
+
+  // Epoch milliseconds of the last write to this data. Used to detect data that has grown too stale to trust (e.g. an
+  // expired verification session). Stamped on every write.
+  int64 lastUpdatedMillis = 25;
+  // Next: 26
 }
 
 message SvrCredential {

feature/registration/src/test/java/org/signal/registration/RegistrationViewModelTest.kt

@@ -201,7 +201,7 @@ class RegistrationViewModelTest {
   }
 
   @Test
-  fun `onEvent NavigateToScreen FullyComplete clears flow state`() = runTest(testDispatcher) {
+  fun `onEvent NavigateToScreen FullyComplete clears in-progress registration data`() = runTest(testDispatcher) {
     coEvery { mockRepository.restoreFlowState() } returns null
     coEvery { mockRepository.getPreExistingRegistrationData() } returns null
 
@@ -211,7 +211,7 @@ class RegistrationViewModelTest {
     viewModel.onEvent(RegistrationFlowEvent.NavigateToScreen(RegistrationRoute.FullyComplete))
     advanceUntilIdle()
 
-    coVerify { mockRepository.clearFlowState() }
+    coVerify { mockRepository.clearInProgressRegistrationData() }
   }
 
   @Test
@@ -257,7 +257,7 @@ class RegistrationViewModelTest {
   }
 
   @Test
-  fun `onEvent RegistrationComplete commits final data and clears flow state`() = runTest(testDispatcher) {
+  fun `onEvent RegistrationComplete commits final data and clears in-progress registration data`() = runTest(testDispatcher) {
     coEvery { mockRepository.restoreFlowState() } returns null
     coEvery { mockRepository.getPreExistingRegistrationData() } returns null
 
@@ -268,7 +268,7 @@ class RegistrationViewModelTest {
     advanceUntilIdle()
 
     coVerify { mockRepository.commitFinalRegistrationData() }
-    coVerify { mockRepository.clearFlowState() }
+    coVerify { mockRepository.clearInProgressRegistrationData() }
   }
 
   // ==================== applyEvent Tests (Navigation & State Reducers) ====================

feature/registration/src/test/java/org/signal/registration/screens/verificationcode/VerificationCodeViewModelTest.kt

@@ -37,6 +37,7 @@ import org.signal.registration.RegistrationFlowEvent
 import org.signal.registration.RegistrationFlowState
 import org.signal.registration.RegistrationRepository
 import org.signal.registration.RegistrationRoute
+import kotlin.time.Duration.Companion.minutes
 import kotlin.time.Duration.Companion.seconds
 
 @OptIn(ExperimentalCoroutinesApi::class)
@@ -869,6 +870,40 @@ class VerificationCodeViewModelTest {
     assertThat(emittedStates.last().oneTimeEvent).isEqualTo(VerificationCodeState.OneTimeEvent.UnableToSendSms)
   }
 
+  // ==================== applyEvent: Foregrounded Tests ====================
+
+  @Test
+  fun `Foregrounded emits ResetState when in-progress data is older than the timeout`() = runTest {
+    val now = 100.minutes.inWholeMilliseconds
+    coEvery { mockRepository.getInProgressRegistrationDataLastUpdated() } returns now - 16.minutes.inWholeMilliseconds
+
+    val vm = VerificationCodeViewModel(mockRepository, parentState, parentEventEmitter, clock = { now })
+    vm.applyEvent(VerificationCodeState(), VerificationCodeScreenEvents.Foregrounded, stateEmitter)
+
+    assertThat(emittedEvents).hasSize(1)
+    assertThat(emittedEvents.first()).isEqualTo(RegistrationFlowEvent.ResetState)
+  }
+
+  @Test
+  fun `Foregrounded does not emit ResetState when in-progress data is within the timeout`() = runTest {
+    val now = 100.minutes.inWholeMilliseconds
+    coEvery { mockRepository.getInProgressRegistrationDataLastUpdated() } returns now - 14.minutes.inWholeMilliseconds
+
+    val vm = VerificationCodeViewModel(mockRepository, parentState, parentEventEmitter, clock = { now })
+    vm.applyEvent(VerificationCodeState(), VerificationCodeScreenEvents.Foregrounded, stateEmitter)
+
+    assertThat(emittedEvents).hasSize(0)
+  }
+
+  @Test
+  fun `Foregrounded does not emit ResetState when there is no in-progress data`() = runTest {
+    coEvery { mockRepository.getInProgressRegistrationDataLastUpdated() } returns null
+
+    viewModel.applyEvent(VerificationCodeState(), VerificationCodeScreenEvents.Foregrounded, stateEmitter)
+
+    assertThat(emittedEvents).hasSize(0)
+  }
+
   // ==================== Helper Functions ====================
 
   private fun createSessionMetadata(