diff --git a/mobile/lib/features/channels/channel_detail_page.dart b/mobile/lib/features/channels/channel_detail_page.dart
index 427cc27e34..5d2d525f7a 100644
--- a/mobile/lib/features/channels/channel_detail_page.dart
+++ b/mobile/lib/features/channels/channel_detail_page.dart
@@ -888,6 +888,7 @@ class _ResolvedChannelDetailPage extends HookConsumerWidget {
                       ?assistant.pendingNotice,
                       ComposeBar(
                         channelId: channel.id,
+                        channel: resolvedChannel,
                         focusNode: composerFocusNode,
                         onFocusRestorerChanged: (restoreFocus) =>
                             restoreComposerFocus.value = restoreFocus,
diff --git a/mobile/lib/features/channels/compose_bar/compose_bar_widget.dart b/mobile/lib/features/channels/compose_bar/compose_bar_widget.dart
index 591bcdd2e1..2ad74f2c96 100644
--- a/mobile/lib/features/channels/compose_bar/compose_bar_widget.dart
+++ b/mobile/lib/features/channels/compose_bar/compose_bar_widget.dart
@@ -18,9 +18,14 @@ class ComposeBar extends HookConsumerWidget {
   /// Optional thread IDs for thread-scoped typing indicators.
   final String? threadHeadId;
   final String? rootId;
+
+  /// The destination as the route resolved it. Sends check mentions against
+  /// it, so a DM opened before the channel list reloads can still send them.
+  final Channel? channel;
   const ComposeBar({
     super.key,
     required this.channelId,
+    this.channel,
     this.channelName = '',
     this.hintText,
     this.threadHeadId,
@@ -575,6 +580,7 @@ class ComposeBar extends HookConsumerWidget {
         scan = await _scanNonMemberMentions(
           ref,
           channelId: channelId,
+          routeChannel: channel,
           selectedMentions: selectedMentions,
           currentPubkey: currentPubkey,
         );
diff --git a/mobile/lib/features/channels/compose_bar/helpers.dart b/mobile/lib/features/channels/compose_bar/helpers.dart
index 45c57d2615..6b767ef129 100644
--- a/mobile/lib/features/channels/compose_bar/helpers.dart
+++ b/mobile/lib/features/channels/compose_bar/helpers.dart
@@ -510,10 +510,13 @@ class _NonMemberMentionScan {
 
 /// Resolves which mentioned identities are non-members, and whether this
 /// identity may add them (see [Channel.canAddMembers]). A DM's participant set
-/// is fixed at creation, so nobody outside it can be added.
+/// is fixed at creation, so nobody outside it can be added. [routeChannel],
+/// when given, stands in for the channel list, which may not have a just
+/// opened DM yet.
 Future<_NonMemberMentionScan> _scanNonMemberMentions(
   WidgetRef ref, {
   required String channelId,
+  Channel? routeChannel,
   required List<MentionCandidate> selectedMentions,
   required String? currentPubkey,
 }) async {
@@ -525,9 +528,11 @@ Future<_NonMemberMentionScan> _scanNonMemberMentions(
   );
   if (selectedMentions.isEmpty) return none;
 
-  final channel = (await ref.read(
-    channelsProvider.future,
-  )).firstWhere((candidate) => candidate.id == channelId);
+  final channel =
+      routeChannel ??
+      (await ref.read(
+        channelsProvider.future,
+      )).firstWhere((candidate) => candidate.id == channelId);
 
   // A DM decides who is inside it the way its send does: by current
   // membership, or by the channel metadata when membership is unavailable.
diff --git a/mobile/test/features/channels/compose_bar_test.dart b/mobile/test/features/channels/compose_bar_test.dart
index 9abb9caddb..47d474e149 100644
--- a/mobile/test/features/channels/compose_bar_test.dart
+++ b/mobile/test/features/channels/compose_bar_test.dart
@@ -187,6 +187,8 @@ Widget _buildComposeBar({
   Future<List<ChannelMember>> Function()? loadMembers,
   List<AgentDirectoryEntry> relayAgents = const <AgentDirectoryEntry>[],
   List<Channel> channels = const <Channel>[],
+  bool stallChannels = false,
+  Channel? channel,
   List<ChannelMember> cachedMembers = const <ChannelMember>[],
   String? currentPubkey,
   bool? supportsShowingSystemContextMenu,
@@ -240,7 +242,11 @@ Widget _buildComposeBar({
       if (appLifecycle != null) appLifecycleProvider.overrideWith(appLifecycle),
       savedPrefsProvider.overrideWithValue(_testPrefs),
       channelsProvider.overrideWith(
-        () => _FakeChannelsNotifier(channels, cachedMembers: cachedMembers),
+        () => _FakeChannelsNotifier(
+          channels,
+          cachedMembers: cachedMembers,
+          stall: stallChannels,
+        ),
       ),
     ],
     child: MaterialApp(
@@ -272,6 +278,7 @@ Widget _buildComposeBar({
                 final composeBar = ComposeBar(
                   key: ValueKey(composeBarKey),
                   channelId: 'channel-1',
+                  channel: channel,
                   threadHeadId: threadHeadId,
                   focusNode: focusNode,
                   onFocusRestorerChanged: onFocusRestorerChanged,
@@ -638,17 +645,23 @@ class _FakeChannelsNotifier extends ChannelsNotifier {
   final List<Channel> _channels;
   final List<ChannelMember> _cachedMembers;
 
+  /// Keeps the channel list loading, like a slow full reload.
+  final bool _stall;
+
   _FakeChannelsNotifier(
     this._channels, {
     List<ChannelMember> cachedMembers = const [],
-  }) : _cachedMembers = cachedMembers;
+    bool stall = false,
+  }) : _cachedMembers = cachedMembers,
+       _stall = stall;
 
   @override
   List<ChannelMember> cachedMembersForChannel(String channelId) =>
       channelId == 'channel-1' ? _cachedMembers : const [];
 
   @override
-  Future<List<Channel>> build() async => _channels;
+  Future<List<Channel>> build() =>
+      _stall ? Completer<List<Channel>>().future : Future.value(_channels);
 
   @override
   Future<void> refresh({bool fetchDirectory = false}) async {
@@ -4698,6 +4711,57 @@ void main() {
         expect(sentTags, contains(orderedEquals(['mention', maryJane.pubkey])));
       });
 
+      testWidgets('a DM opened before the channel list loads sends mentions', (
+        tester,
+      ) async {
+        final signer = nostr.Keys.generate();
+        final pat = '1' * 64;
+        List<String>? sentRecipients;
+        List<List<String>>? sentTags;
+        await tester.pumpWidget(
+          _buildComposeBar(
+            uploadService: _testUploadService(signer.nsec),
+            currentPubkey: signer.public,
+            members: [
+              member(signer.public),
+              ChannelMember(
+                pubkey: pat,
+                role: 'member',
+                joinedAt: DateTime.fromMillisecondsSinceEpoch(1000),
+                displayName: 'Pat Peer',
+              ),
+            ],
+            // The route opened the DM from its own metadata and roster while
+            // the full channel list is still loading.
+            stallChannels: true,
+            channel: _makeCurrentChannel(
+              channelType: 'dm',
+              participantPubkeys: [signer.public, pat],
+            ),
+            onSend:
+                (_, recipients, {mediaTags = const <List<String>>[]}) async {
+                  sentRecipients = recipients;
+                  sentTags = mediaTags;
+                },
+          ),
+        );
+        await _expandComposer(tester);
+        await tester.enterText(find.byType(TextField), '@Pat');
+        await tester.pump();
+        await tester.pumpAndSettle();
+        await tester.tap(find.text('Pat Peer'));
+        await tester.pumpAndSettle();
+        await tester.tap(find.byIcon(BuzzIcons.arrowUp));
+        await tester.pumpAndSettle();
+
+        expect(
+          find.text('Message not sent: could not check who is in this channel'),
+          findsNothing,
+        );
+        expect(sentRecipients, contains(pat));
+        expect(sentTags, isNot(contains(orderedEquals(['mention', pat]))));
+      });
+
       testWidgets('a failed member check keeps the draft and Retry sends', (
         tester,
       ) async {