allowing the user to edit their email address after starting the verfication process

- the email verification screen is no longer a hard exit during the standard account creation flow, however if a authentication session is restored eg the app is killed and reopened whilst waiting for email verifcation, then pressing back will cause the flow to be restarted

vector/src/main/java/im/vector/app/features/onboarding/OnboardingViewModel.kt

@@ -348,9 +348,10 @@ class OnboardingViewModel @AssistedInject constructor(
                             overrideNextStage?.invoke() ?: _viewEvents.post(OnboardingViewEvents.DisplayStartRegistration)
                         }
                         RegistrationActionHandler.Result.UnsupportedStage -> _viewEvents.post(OnboardingViewEvents.DisplayRegistrationFallback)
-                        is RegistrationActionHandler.Result.SendEmailSuccess -> _viewEvents.post(
+                        is RegistrationActionHandler.Result.SendEmailSuccess -> {
-                                OnboardingViewEvents.OnSendEmailSuccess(it.email, isRestoredSession = false)
+                            _viewEvents.post(OnboardingViewEvents.OnSendEmailSuccess(it.email, isRestoredSession = false))
-                        )
+                            setState { copy(registrationState = registrationState.copy(email = it.email)) }
+                        }
                         is RegistrationActionHandler.Result.SendMsisdnSuccess -> _viewEvents.post(OnboardingViewEvents.OnSendMsisdnSuccess(it.msisdn.msisdn))
                         is RegistrationActionHandler.Result.Error -> _viewEvents.post(OnboardingViewEvents.Failure(it.cause))
                         RegistrationActionHandler.Result.MissingNextStage -> {

vector/src/main/java/im/vector/app/features/onboarding/OnboardingViewState.kt

@@ -101,6 +101,7 @@ data class SelectedAuthenticationState(
 
 @Parcelize
 data class RegistrationState(
+        val email: String? = null,
         val isUserNameAvailable: Boolean = false,
         val selectedMatrixId: String? = null,
 ) : Parcelable

vector/src/main/java/im/vector/app/features/onboarding/ftueauth/FtueAuthEmailEntryFragment.kt

@@ -25,6 +25,8 @@ import im.vector.app.core.extensions.associateContentStateWith
 import im.vector.app.core.extensions.autofillEmail
 import im.vector.app.core.extensions.clearErrorOnChange
 import im.vector.app.core.extensions.content
+import im.vector.app.core.extensions.editText
+import im.vector.app.core.extensions.hasContent
 import im.vector.app.core.extensions.isEmail
 import im.vector.app.core.extensions.setOnImeDoneListener
 import im.vector.app.core.extensions.toReducedUrl
@@ -61,6 +63,10 @@ class FtueAuthEmailEntryFragment @Inject constructor() : AbstractFtueAuthFragmen
 
     override fun updateWithState(state: OnboardingViewState) {
         views.emailEntryHeaderSubtitle.text = getString(R.string.ftue_auth_email_subtitle, state.selectedHomeserver.userFacingUrl.toReducedUrl())
+
+        if (!views.emailEntryInput.hasContent()) {
+            views.emailEntryInput.editText().setText(state.registrationState.email)
+        }
     }
 
     override fun onError(throwable: Throwable) {

vector/src/main/java/im/vector/app/features/onboarding/ftueauth/FtueAuthVariant.kt

@@ -414,18 +414,20 @@ class FtueAuthVariant(
     }
 
     private fun openWaitForEmailVerification(email: String, isRestoredSession: Boolean) {
-        supportFragmentManager.popBackStack(FRAGMENT_REGISTRATION_STAGE_TAG, FragmentManager.POP_BACK_STACK_INCLUSIVE)
         when {
             vectorFeatures.isOnboardingCombinedRegisterEnabled() -> addRegistrationStageFragmentToBackstack(
                     FtueAuthWaitForEmailFragment::class.java,
                     FtueAuthWaitForEmailFragmentArgument(email, isRestoredSession),
             )
-            else -> addRegistrationStageFragmentToBackstack(
+            else -> {
+                supportFragmentManager.popBackStack(FRAGMENT_REGISTRATION_STAGE_TAG, FragmentManager.POP_BACK_STACK_INCLUSIVE)
+                addRegistrationStageFragmentToBackstack(
                         FtueAuthLegacyWaitForEmailFragment::class.java,
                         FtueAuthWaitForEmailFragmentArgument(email, isRestoredSession),
                 )
             }
         }
+    }
 
     private fun openMsisdnConfirmation(msisdn: String) {
         supportFragmentManager.popBackStack(FRAGMENT_REGISTRATION_STAGE_TAG, FragmentManager.POP_BACK_STACK_INCLUSIVE)

vector/src/main/java/im/vector/app/features/onboarding/ftueauth/FtueAuthWaitForEmailFragment.kt

@@ -49,6 +49,8 @@ class FtueAuthWaitForEmailFragment @Inject constructor(
     private val params: FtueAuthWaitForEmailFragmentArgument by args()
     private var inferHasLeftAndReturnedToScreen = false
 
+    override fun backIsHardExit() = params.isRestoredSession
+
     override fun getBinding(inflater: LayoutInflater, container: ViewGroup?): FragmentFtueWaitForEmailVerificationBinding {
         return FragmentFtueWaitForEmailVerificationBinding.inflate(inflater, container, false)
     }
@@ -89,6 +91,11 @@ class FtueAuthWaitForEmailFragment @Inject constructor(
     }
 
     override fun resetViewModel() {
-        viewModel.handle(OnboardingAction.ResetAuthenticationAttempt)
+        when {
+            backIsHardExit() -> viewModel.handle(OnboardingAction.ResetAuthenticationAttempt)
+            else -> {
+                // delegate to the previous step
+            }
+        }
     }
 }