Enforce change number post registration delay.

app/src/main/java/org/thoughtcrime/securesms/components/settings/app/changenumber/ChangeNumberEnterCodeFragment.kt

@@ -33,6 +33,7 @@ import org.thoughtcrime.securesms.registration.sms.ReceivedSmsEvent
 import org.thoughtcrime.securesms.util.concurrent.AssertedSuccessListener
 import org.thoughtcrime.securesms.util.navigation.safeNavigate
 import org.thoughtcrime.securesms.util.visible
+import kotlin.math.ceil
 import kotlin.time.Duration.Companion.milliseconds
 
 /**
@@ -168,7 +169,7 @@ class ChangeNumberEnterCodeFragment : LoggingFragment(R.layout.fragment_change_n
       is ChangeNumberResult.RegistrationLocked -> presentRegistrationLocked(result.timeRemaining)
       is ChangeNumberResult.AuthorizationFailed -> presentIncorrectCodeDialog()
       is ChangeNumberResult.AttemptsExhausted -> presentAccountLocked()
-      is ChangeNumberResult.RateLimited -> presentRateLimitedDialog()
+      is ChangeNumberResult.RateLimited -> presentRateLimitedDialog(result.timeRemaining)
 
       else -> presentGenericError(result)
     }
@@ -195,13 +196,25 @@ class ChangeNumberEnterCodeFragment : LoggingFragment(R.layout.fragment_change_n
     )
   }
 
-  private fun presentRateLimitedDialog() {
+  private fun presentRateLimitedDialog(retryAfterSeconds: Long = 0) {
     binding.codeEntryLayout.keyboard.displayFailure().addListener(
       object : AssertedSuccessListener<Boolean?>() {
         override fun onSuccess(result: Boolean?) {
           MaterialAlertDialogBuilder(requireContext()).apply {
             setTitle(R.string.RegistrationActivity_too_many_attempts)
-            setMessage(R.string.RegistrationActivity_you_have_made_too_many_attempts_please_try_again_later)
+            if (retryAfterSeconds > 0) {
+              val minutes = ceil(retryAfterSeconds / 60.0).toInt().coerceAtLeast(1)
+              setMessage(
+                if (minutes >= 60) {
+                  val hours = ceil(minutes / 60.0).toInt()
+                  resources.getQuantityString(R.plurals.ChangeNumberEnterCodeFragment__too_many_attempts_try_again_in_hours, hours, hours)
+                } else {
+                  resources.getQuantityString(R.plurals.ChangeNumberEnterCodeFragment__too_many_attempts_try_again_in_minutes, minutes, minutes)
+                }
+              )
+            } else {
+              setMessage(R.string.RegistrationActivity_you_have_made_too_many_attempts_please_try_again_later)
+            }
             setPositiveButton(android.R.string.ok) { _: DialogInterface?, _: Int ->
               binding.codeEntryLayout.callMeCountDown.visibility = View.VISIBLE
               binding.codeEntryLayout.resendSmsCountDown.visibility = View.VISIBLE

app/src/main/java/org/thoughtcrime/securesms/components/settings/app/changenumber/ChangeNumberFragment.kt

@@ -23,7 +23,6 @@ import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.res.vectorResource
-import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
 import androidx.navigation.NavController
@@ -34,7 +33,10 @@ import org.signal.core.ui.compose.DayNightPreviews
 import org.signal.core.ui.compose.Previews
 import org.signal.core.ui.compose.Scaffolds
 import org.thoughtcrime.securesms.R
+import org.thoughtcrime.securesms.keyvalue.SignalStore
+import org.thoughtcrime.securesms.util.RemoteConfig
 import org.thoughtcrime.securesms.util.navigation.safeNavigate
+import kotlin.time.Duration.Companion.milliseconds
 
 class ChangeNumberFragment : ComposeFragment() {
 
@@ -46,10 +48,25 @@ class ChangeNumberFragment : ComposeFragment() {
         navController.popBackStack()
       },
       onContinueClick = {
-        navController.safeNavigate(ChangeNumberFragmentDirections.actionChangePhoneNumberFragmentToEnterPhoneNumberChangeFragment())
+        val remainingWaitSeconds = remainingPostRegistrationWaitSeconds()
+        if (remainingWaitSeconds > 0) {
+          ChangeNumberPostRegistrationWaitSheet.show(parentFragmentManager, remainingWaitSeconds)
+        } else {
+          navController.safeNavigate(ChangeNumberFragmentDirections.actionChangePhoneNumberFragmentToEnterPhoneNumberChangeFragment())
+        }
       }
     )
   }
+
+  private fun remainingPostRegistrationWaitSeconds(): Long {
+    val registeredAt = SignalStore.account.registeredAtTimestamp
+    if (registeredAt <= 0) {
+      return 0
+    }
+    val waitingPeriodSeconds = RemoteConfig.changeNumberPostRegistrationWaitingPeriodSeconds
+    val elapsedSeconds = (System.currentTimeMillis() - registeredAt).milliseconds.inWholeSeconds
+    return (waitingPeriodSeconds - elapsedSeconds).coerceAtLeast(0)
+  }
 }
 
 @Composable
@@ -73,7 +90,7 @@ fun ChangeNumberScreen(
         .padding(horizontal = 32.dp)
     ) {
       Image(
-        painter = painterResource(id = R.drawable.change_number_hero_image),
+        painter = painterResource(id = R.drawable.change_number),
         contentDescription = null,
         modifier = Modifier
           .padding(top = 20.dp)
@@ -83,7 +100,6 @@ fun ChangeNumberScreen(
         text = stringResource(id = R.string.AccountSettingsFragment__change_phone_number),
         style = MaterialTheme.typography.headlineMedium,
         textAlign = TextAlign.Center,
-        fontWeight = FontWeight.Bold,
         modifier = Modifier.padding(top = 24.dp)
       )
 

app/src/main/java/org/thoughtcrime/securesms/components/settings/app/changenumber/ChangeNumberPostRegistrationWaitSheet.kt

@@ -0,0 +1,151 @@
+/*
+ * Copyright 2026 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.components.settings.app.changenumber
+
+import android.os.Bundle
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.pluralStringResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+import androidx.fragment.app.FragmentManager
+import org.signal.core.ui.BottomSheetUtil
+import org.signal.core.ui.compose.BottomSheets
+import org.signal.core.ui.compose.Buttons
+import org.signal.core.ui.compose.ComposeBottomSheetDialogFragment
+import org.signal.core.ui.compose.DayNightPreviews
+import org.signal.core.ui.compose.Previews
+import org.signal.core.ui.compose.horizontalGutters
+import org.thoughtcrime.securesms.R
+import kotlin.math.ceil
+
+/**
+ * Sheet shown when the user attempts to change their phone number before the
+ * post-registration waiting period has elapsed.
+ */
+class ChangeNumberPostRegistrationWaitSheet : ComposeBottomSheetDialogFragment() {
+
+  companion object {
+    private const val ARG_REMAINING_SECONDS = "arg.remaining_seconds"
+
+    @JvmStatic
+    fun show(fragmentManager: FragmentManager, remainingSeconds: Long) {
+      ChangeNumberPostRegistrationWaitSheet().apply {
+        arguments = Bundle().apply {
+          putLong(ARG_REMAINING_SECONDS, remainingSeconds)
+        }
+      }.show(fragmentManager, BottomSheetUtil.STANDARD_BOTTOM_SHEET_FRAGMENT_TAG)
+    }
+  }
+
+  private val remainingSeconds: Long
+    get() = requireArguments().getLong(ARG_REMAINING_SECONDS)
+
+  @Composable
+  override fun SheetContent() {
+    SheetContent(
+      remainingSeconds = remainingSeconds,
+      onDismiss = { dismissAllowingStateLoss() }
+    )
+  }
+}
+
+@Composable
+private fun SheetContent(
+  remainingSeconds: Long,
+  onDismiss: () -> Unit
+) {
+  Column(
+    horizontalAlignment = Alignment.CenterHorizontally,
+    modifier = Modifier
+      .fillMaxWidth()
+      .horizontalGutters(gutterSize = 36.dp)
+  ) {
+    BottomSheets.Handle()
+
+    Image(
+      painter = painterResource(R.drawable.change_number_error),
+      contentDescription = null,
+      modifier = Modifier
+        .padding(top = 26.dp)
+    )
+
+    Text(
+      text = stringResource(R.string.ChangeNumberPostRegistrationWaitSheet__title),
+      style = MaterialTheme.typography.titleLarge,
+      textAlign = TextAlign.Center,
+      color = MaterialTheme.colorScheme.onPrimaryContainer,
+      modifier = Modifier.padding(top = 16.dp)
+    )
+
+    Text(
+      text = stringResource(R.string.ChangeNumberPostRegistrationWaitSheet__body),
+      style = MaterialTheme.typography.bodyLarge,
+      textAlign = TextAlign.Center,
+      color = MaterialTheme.colorScheme.onSurfaceVariant,
+      modifier = Modifier.padding(top = 12.dp)
+    )
+
+    Text(
+      text = formatTryAgainIn(remainingSeconds),
+      style = MaterialTheme.typography.bodyLarge,
+      textAlign = TextAlign.Center,
+      color = MaterialTheme.colorScheme.onSurfaceVariant,
+      modifier = Modifier.padding(top = 16.dp)
+    )
+
+    Buttons.LargeTonal(
+      onClick = onDismiss,
+      modifier = Modifier
+        .fillMaxWidth()
+        .padding(top = 32.dp, bottom = 24.dp, start = 12.dp, end = 12.dp)
+    ) {
+      Text(stringResource(R.string.ChangeNumberPostRegistrationWaitSheet__ok))
+    }
+  }
+}
+
+@DayNightPreviews
+@Composable
+private fun SheetContentMinutesPreview() {
+  Previews.BottomSheetContentPreview {
+    SheetContent(
+      remainingSeconds = 25 * 60,
+      onDismiss = {}
+    )
+  }
+}
+
+@DayNightPreviews
+@Composable
+private fun SheetContentHoursPreview() {
+  Previews.BottomSheetContentPreview {
+    SheetContent(
+      remainingSeconds = 2 * 60 * 60,
+      onDismiss = {}
+    )
+  }
+}
+
+@Composable
+private fun formatTryAgainIn(remainingSeconds: Long): String {
+  val minutes = ceil(remainingSeconds / 60.0).toInt().coerceAtLeast(1)
+  return if (minutes >= 60) {
+    val hours = ceil(minutes / 60.0).toInt()
+    pluralStringResource(R.plurals.ChangeNumberPostRegistrationWaitSheet__try_again_in_hours, hours, hours)
+  } else {
+    pluralStringResource(R.plurals.ChangeNumberPostRegistrationWaitSheet__try_again_in_minutes, minutes, minutes)
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/keyvalue/AccountValues.kt

@@ -434,7 +434,7 @@ class AccountValues internal constructor(store: KeyValueStore, context: Context)
   val isRegistered: Boolean
     get() = getBoolean(KEY_IS_REGISTERED, false)
 
-  fun setRegistered(registered: Boolean) {
+  fun setRegistered(registered: Boolean, isAciChanged: Boolean = false) {
     Log.i(TAG, "Setting push registered: $registered", Throwable())
 
     val previous = isRegistered
@@ -451,7 +451,7 @@ class AccountValues internal constructor(store: KeyValueStore, context: Context)
       clearLocalCredentials()
     }
 
-    if (!previous && registered) {
+    if (registered && (!previous || isAciChanged)) {
       registeredAtTimestamp = System.currentTimeMillis()
     } else if (!registered) {
       registeredAtTimestamp = -1

app/src/main/java/org/thoughtcrime/securesms/registration/data/RegistrationRepository.kt

@@ -184,6 +184,7 @@ object RegistrationRepository {
     val aci: ACI = ACI.parseOrThrow(data.aci)
     val pni: PNI = PNI.parseOrThrow(data.pni)
     val hasPin: Boolean = data.hasPin
+    val isAciChanged: Boolean = SignalStore.account.aci != aci
 
     SignalStore.account.setAci(aci)
     SignalStore.account.setPni(pni)
@@ -232,7 +233,7 @@ object RegistrationRepository {
     }
 
     SignalStore.account.setServicePassword(data.servicePassword)
-    SignalStore.account.setRegistered(true)
+    SignalStore.account.setRegistered(registered = true, isAciChanged = isAciChanged)
     TextSecurePreferences.setPromptedPushRegistration(context, true)
     TextSecurePreferences.setUnauthorizedReceived(context, false)
     NotificationManagerCompat.from(context).cancel(NotificationIds.UNREGISTERED_NOTIFICATION_ID)

app/src/main/java/org/thoughtcrime/securesms/util/RemoteConfig.kt

@@ -1411,6 +1411,15 @@ object RemoteConfig {
     hotSwappable = true
   )
 
+  /** Seconds after registration during which change-number is blocked. */
+  @JvmStatic
+  @get:JvmName("changeNumberPostRegistrationWaitingPeriodSeconds")
+  val changeNumberPostRegistrationWaitingPeriodSeconds: Long by remoteLong(
+    key = "global.changeNumber.postRegistrationWaitingPeriodSeconds",
+    defaultValue = 3600,
+    hotSwappable = true
+  )
+
   /**
    * A ratio between 0 and 1, where 0 means that a session is never archived due
    * to a lack of PQ, and 1 means that a session is always archived due to a