From 771cae8a9a9dd62441644e02f182a46abe348151 Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Tue, 18 Aug 2026 07:40:05 -0400
Subject: [PATCH] Add nopni capability detection when linking a device.

---
 .../linkdevice/LinkDeviceQrScanScreen.kt      | 10 ++++++++
 .../linkdevice/LinkDeviceSettingsState.kt     |  2 +-
 .../linkdevice/LinkDeviceViewModel.kt         | 24 +++++++++++++++----
 app/src/main/res/values/strings.xml           |  2 ++
 4 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceQrScanScreen.kt b/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceQrScanScreen.kt
index 50165564dc..bc28975100 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceQrScanScreen.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceQrScanScreen.kt
@@ -84,6 +84,16 @@ fun LinkDeviceQrScanScreen(
         onDismiss = onQrCodeDismissed
       )
     }
+
+    LinkDeviceSettingsState.QrCodeState.OUTDATED_DEVICE -> {
+      Dialogs.SimpleAlertDialog(
+        title = stringResource(id = R.string.AddLinkDeviceFragment__linking_device_failed),
+        body = stringResource(id = R.string.AddLinkDeviceFragment__the_device_you_are_trying_to_link_is_out_of_date),
+        confirm = stringResource(id = android.R.string.ok),
+        onConfirm = { },
+        onDismiss = onQrCodeDismissed
+      )
+    }
   }
 
   LaunchedEffect(linkDeviceResult) {
diff --git a/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceSettingsState.kt b/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceSettingsState.kt
index db2e75b0ac..5b4728fbb0 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceSettingsState.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceSettingsState.kt
@@ -51,7 +51,7 @@ data class LinkDeviceSettingsState(
   }
 
   enum class QrCodeState {
-    NONE, VALID_WITH_SYNC, VALID_WITHOUT_SYNC, INVALID
+    NONE, VALID_WITH_SYNC, VALID_WITHOUT_SYNC, INVALID, OUTDATED_DEVICE
   }
 
   enum class SyncFailType {
diff --git a/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceViewModel.kt b/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceViewModel.kt
index bc2a1dd6b1..6bc917d0f0 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceViewModel.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/linkdevice/LinkDeviceViewModel.kt
@@ -171,9 +171,15 @@ class LinkDeviceViewModel : ViewModel() {
 
     val uri = Uri.parse(url)
     if (LinkDeviceRepository.isValidQr(uri)) {
+      val capabilities = uri.getCapabilities()
+      val qrCodeState = when {
+        Capability.Numberless !in capabilities && SignalStore.account.pni == null -> QrCodeState.OUTDATED_DEVICE
+        Capability.LinkAndSync in capabilities -> QrCodeState.VALID_WITH_SYNC
+        else -> QrCodeState.VALID_WITHOUT_SYNC
+      }
       _state.update {
         it.copy(
-          qrCodeState = if (uri.supportsLinkAndSync()) QrCodeState.VALID_WITH_SYNC else QrCodeState.VALID_WITHOUT_SYNC,
+          qrCodeState = qrCodeState,
           linkUri = uri
         )
       }
@@ -215,7 +221,7 @@ class LinkDeviceViewModel : ViewModel() {
       Log.i(TAG, "Adding device with sync.")
       addDeviceWithSync(linkUri)
     } else {
-      Log.i(TAG, "Adding device without sync. (uri: ${linkUri.supportsLinkAndSync()})")
+      Log.i(TAG, "Adding device without sync. (backup5: ${Capability.LinkAndSync in linkUri.getCapabilities()})")
       addDeviceWithoutSync(linkUri)
     }
   }
@@ -413,9 +419,17 @@ class LinkDeviceViewModel : ViewModel() {
     LinkedDeviceInactiveCheckJob.enqueue()
   }
 
-  private fun Uri.supportsLinkAndSync(): Boolean {
-    val capabilities = this.getQueryParameter("capabilities")?.split(",")?.toSet() ?: emptySet()
-    return "backup5" in capabilities
+  private fun Uri.getCapabilities(): Set<Capability> {
+    return this.getQueryParameter("capabilities")
+      ?.split(",")
+      ?.mapNotNull { value -> Capability.entries.firstOrNull { it.value == value } }
+      ?.toSet()
+      ?: emptySet()
+  }
+
+  private enum class Capability(val value: String) {
+    LinkAndSync("backup5"),
+    Numberless("nopni")
   }
 
   fun onSyncErrorIgnored() = viewModelScope.launch(Dispatchers.IO) {
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index ec3c3f0680..805270c7a1 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1192,6 +1192,8 @@
     <string name="AddLinkDeviceFragment__this_qr_code_not_valid">This QR code is not valid. Please make sure you are scanning the QR code that is displayed on the device you want to link.</string>
     <!-- Button in dialog to retry linking a device with a qr code -->
     <string name="AddLinkDeviceFragment__retry">Retry</string>
+    <!-- Text shown in a dialog when the device being linked is too out-of-date to be linked to this account -->
+    <string name="AddLinkDeviceFragment__the_device_you_are_trying_to_link_is_out_of_date">The device you\'re trying to link is out of date. Please upgrade and try again.</string>
 
     <!-- LinkDeviceSyncBottomSheet -->
     <!-- Option in bottom sheet to transfer message history -->