diff --git a/mobile/lib/features/agents/agent_creation_draft.dart b/mobile/lib/features/agents/agent_creation_draft.dart
index d1f4a0f3b3..d4110a9783 100644
--- a/mobile/lib/features/agents/agent_creation_draft.dart
+++ b/mobile/lib/features/agents/agent_creation_draft.dart
@@ -6,13 +6,14 @@ import 'package:http/http.dart' as http;
 
 import '../../shared/deeplink/deep_link.dart';
 import '../../shared/hosted/hosted_environment.dart';
+import '../../shared/http/app_http_client.dart';
 import '../../shared/utils/bounded_fetch.dart';
 import 'agent_avatar_picker.dart';
 
 /// Creates the HTTP client that fetches a card's `agent.json`; overridden in
 /// tests.
 final agentCardClientProvider = Provider<http.Client Function()>(
-  (ref) => http.Client.new,
+  (ref) => newAppHttpClient,
 );
 
 /// Largest `agent.json` accepted, far above any real card.
diff --git a/mobile/lib/features/channels/channels_page.dart b/mobile/lib/features/channels/channels_page.dart
index af7875badf..0eea0f29a2 100644
--- a/mobile/lib/features/channels/channels_page.dart
+++ b/mobile/lib/features/channels/channels_page.dart
@@ -4,6 +4,7 @@ import 'package:buzz/shared/widgets/adaptive_conversation_pane.dart';
 import 'channel_unread.dart';
 import '../../shared/widgets/collapsible_section_body.dart';
 import '../../shared/widgets/collapsible_sliver_body.dart';
+import '../../shared/http/app_http_client.dart';
 import '../../shared/me/me_sync.dart';
 import '../../shared/hosted/hosted_relay_auth.dart';
 import '../../shared/hosted/organization_environment.dart';
diff --git a/mobile/lib/features/channels/channels_page/badges.dart b/mobile/lib/features/channels/channels_page/badges.dart
index e2ae974bc7..680ee9a85a 100644
--- a/mobile/lib/features/channels/channels_page/badges.dart
+++ b/mobile/lib/features/channels/channels_page/badges.dart
@@ -46,7 +46,8 @@ class _ErrorView extends HookConsumerWidget {
       }
       return 'Server error (${error.statusCode}). Try again later.';
     }
-    if (error is SocketException) {
+    if (error is SocketException ||
+        urlSessionFailure(error) == TransportFailure.unreachable) {
       return 'Could not reach the relay server.';
     }
     return 'Something went wrong. Check your connection.';
diff --git a/mobile/lib/features/invites/invite_join_provider.dart b/mobile/lib/features/invites/invite_join_provider.dart
index 7b376397c1..49a7b4e6a8 100644
--- a/mobile/lib/features/invites/invite_join_provider.dart
+++ b/mobile/lib/features/invites/invite_join_provider.dart
@@ -1,6 +1,7 @@
 import 'dart:convert';
 
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:nostr/nostr.dart' as nostr;
 import 'package:url_launcher/url_launcher.dart';
@@ -515,7 +516,15 @@ String _friendlyInviteError(Object error) {
   if (message.contains('join_policy_required')) {
     return 'Review this community’s join requirements in your browser, then return to Buzz.';
   }
-  if (message.contains('SocketException') ||
+  final transportFailure = urlSessionFailure(error);
+  if (transportFailure == TransportFailure.insecure) {
+    return 'Secure connection failed. Check your network settings and try again.';
+  }
+  if (transportFailure == TransportFailure.timedOut) {
+    return 'Connection timed out. Check your internet connection and try again.';
+  }
+  if (transportFailure == TransportFailure.unreachable ||
+      message.contains('SocketException') ||
       message.contains('Connection refused') ||
       message.contains('Network is unreachable') ||
       message.contains('No route to host')) {
@@ -526,7 +535,8 @@ String _friendlyInviteError(Object error) {
 
 String _friendlyStarterSetupError(Object error) {
   final message = error.toString();
-  if (message.contains('SocketException') ||
+  if (urlSessionFailure(error) == TransportFailure.unreachable ||
+      message.contains('SocketException') ||
       message.contains('Connection refused') ||
       message.contains('Network is unreachable') ||
       message.contains('No route to host')) {
diff --git a/mobile/lib/features/pairing/pairing_provider.dart b/mobile/lib/features/pairing/pairing_provider.dart
index 435b992d2b..f73f9c9100 100644
--- a/mobile/lib/features/pairing/pairing_provider.dart
+++ b/mobile/lib/features/pairing/pairing_provider.dart
@@ -4,6 +4,7 @@ import 'dart:math' as math;
 
 import 'package:flutter/foundation.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:buzz/shared/http/app_http_client.dart';
 import 'package:nostr/nostr.dart' as nostr;
 
 import '../../shared/auth/auth.dart';
diff --git a/mobile/lib/features/pairing/pairing_provider_helpers.dart b/mobile/lib/features/pairing/pairing_provider_helpers.dart
index 30d11932a5..e2def264e8 100644
--- a/mobile/lib/features/pairing/pairing_provider_helpers.dart
+++ b/mobile/lib/features/pairing/pairing_provider_helpers.dart
@@ -2,7 +2,9 @@ part of 'pairing_provider.dart';
 
 String _friendlyErrorMessage(Object error) {
   final message = error.toString();
-  if (message.contains('SocketException') ||
+  final transportFailure = urlSessionFailure(error);
+  if (transportFailure == TransportFailure.unreachable ||
+      message.contains('SocketException') ||
       message.contains('Connection refused') ||
       message.contains('Network is unreachable') ||
       message.contains('No route to host') ||
@@ -18,12 +20,15 @@ String _friendlyErrorMessage(Object error) {
       message.contains('Null check operator used on a null value')) {
     return 'Pairing stopped because of an internal error. Please try again.';
   }
-  if (message.contains('HandshakeException') ||
+  if (transportFailure == TransportFailure.insecure ||
+      message.contains('HandshakeException') ||
       message.contains('CERTIFICATE_VERIFY_FAILED')) {
     return 'Secure connection failed. Check your network settings '
         'and try again.';
   }
-  if (message.contains('TimeoutException') || message.contains('timed out')) {
+  if (transportFailure == TransportFailure.timedOut ||
+      message.contains('TimeoutException') ||
+      message.contains('timed out')) {
     return 'Connection timed out. Check your internet connection and '
         'try again.';
   }
diff --git a/mobile/lib/shared/community/community_icon_provider.dart b/mobile/lib/shared/community/community_icon_provider.dart
index 9bcf3ecad2..9cce187378 100644
--- a/mobile/lib/shared/community/community_icon_provider.dart
+++ b/mobile/lib/shared/community/community_icon_provider.dart
@@ -3,6 +3,7 @@ import 'dart:convert';
 
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 
 import 'community_icon_cache.dart';
 import 'community_icon_artwork.dart';
@@ -10,12 +11,14 @@ import 'community_icon_artwork.dart';
 const _maximumIconBytes = 256 * 1024;
 const _lookupTimeout = Duration(seconds: 5);
 
-/// Supplies the unauthenticated client for public NIP-11 documents and icons.
-final communityIconHttpClientProvider = Provider<http.Client>((ref) {
-  final client = http.Client();
-  ref.onDispose(client.close);
-  return client;
-});
+/// Supplies the unauthenticated clients for public NIP-11 documents (API
+/// traffic) and icon images (media traffic).
+final communityIconHttpClientProvider =
+    Provider.family<http.Client, HttpTraffic>((ref, traffic) {
+      final client = newAppHttpClient(traffic);
+      ref.onDispose(client.close);
+      return client;
+    });
 
 /// Immediately presents saved artwork while a public metadata refresh runs.
 final communityIconPresentationProvider = Provider.autoDispose
@@ -36,7 +39,7 @@ final communityIconProvider = FutureProvider.autoDispose
       final key = uri.toString();
       final cache = ref.read(communityIconCacheProvider.notifier);
       final saved = ref.read(communityIconCacheProvider)[key];
-      final client = ref.read(communityIconHttpClientProvider);
+      final client = ref.read(communityIconHttpClientProvider(HttpTraffic.api));
       var disposed = false;
       final cancelled = Completer<void>();
       ref.onDispose(() {
@@ -68,7 +71,11 @@ final communityIconProvider = FutureProvider.autoDispose
           final imageUri = Uri.tryParse(icon);
           if (imageUri != null &&
               (imageUri.scheme == 'https' || imageUri.scheme == 'http')) {
-            final image = await _download(client, imageUri, cancelled.future);
+            final image = await _download(
+              ref.read(communityIconHttpClientProvider(HttpTraffic.media)),
+              imageUri,
+              cancelled.future,
+            );
             if (image != null && image.mimeType.startsWith('image/')) {
               artwork = Uri.dataFromBytes(
                 image.bytes,
diff --git a/mobile/lib/shared/hosted/builderlab_account.dart b/mobile/lib/shared/hosted/builderlab_account.dart
index 9bf7f0a029..dd4c10ba6f 100644
--- a/mobile/lib/shared/hosted/builderlab_account.dart
+++ b/mobile/lib/shared/hosted/builderlab_account.dart
@@ -7,6 +7,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 
 import '../storage/secure_storage.dart';
 
@@ -62,7 +63,7 @@ class BuilderlabAccountClient {
     FlutterSecureStorage? storage,
     Uri? accountOrigin,
     this.onSessionChanged,
-  }) : _http = httpClient ?? http.Client(),
+  }) : _http = httpClient ?? newAppHttpClient(),
        _storage = storage ?? defaultStorage,
        accountOrigin = accountOrigin ?? origin;
 
diff --git a/mobile/lib/shared/hosted/hosted_admission.dart b/mobile/lib/shared/hosted/hosted_admission.dart
index 2d30d478a6..aaf46f0ea3 100644
--- a/mobile/lib/shared/hosted/hosted_admission.dart
+++ b/mobile/lib/shared/hosted/hosted_admission.dart
@@ -1,6 +1,7 @@
 import 'dart:convert';
 
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 
 import '../community/community.dart';
 import '../deeplink/deep_link.dart';
@@ -26,7 +27,7 @@ class HostedAdmission {
     Future<bool> Function(HostedJoinPolicy)? confirmPolicy,
     Future<void> Function(Community)? probe,
   }) : _confirmPolicy = confirmPolicy ?? ((_) async => false),
-       _http = client ?? http.Client(),
+       _http = client ?? newAppHttpClient(),
        _probe = probe;
   final HostedRelayAuth relayAuth;
   final BuilderlabAccountClient account;
diff --git a/mobile/lib/shared/hosted/hosted_relay_auth.dart b/mobile/lib/shared/hosted/hosted_relay_auth.dart
index da81f8c550..99fb416204 100644
--- a/mobile/lib/shared/hosted/hosted_relay_auth.dart
+++ b/mobile/lib/shared/hosted/hosted_relay_auth.dart
@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:flutter/foundation.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 
 import '../relay/relay_provider.dart';
 import 'builderlab_account.dart';
@@ -67,11 +68,13 @@ final hostedRelayAuthProvider = Provider<HostedRelayAuth>((ref) {
 });
 
 /// Each transport owns its client lifetime; configuration and auth are shared.
-final hostedHttpClientFactoryProvider = Provider<http.Client Function()>((ref) {
-  final auth = ref.watch(hostedRelayAuthProvider);
-  final config = ref.watch(relayConfigProvider);
-  return () => HostedRelayHttpClient(auth, config);
-});
+final hostedHttpClientFactoryProvider =
+    Provider<http.Client Function({HttpTraffic traffic})>((ref) {
+      final auth = ref.watch(hostedRelayAuthProvider);
+      final config = ref.watch(relayConfigProvider);
+      return ({HttpTraffic traffic = HttpTraffic.api}) =>
+          HostedRelayHttpClient(auth, config, inner: newAppHttpClient(traffic));
+    });
 
 /// The build's one Builderlab session, with a short-lived assertion for the
 /// current relay/key. A public build's hosted communities use [account] when
@@ -91,7 +94,7 @@ class HostedRelayAuth extends ChangeNotifier {
        _discover = discover ?? _fetchRequirement;
 
   static Future<bool> _fetchRequirement(Uri origin) async {
-    final client = http.Client();
+    final client = newAppHttpClient();
     try {
       return await fetchNipFiRequirement(client, origin);
     } finally {
@@ -500,7 +503,7 @@ class HostedRelayHttpClient extends http.BaseClient {
     this.config, {
     http.Client? inner,
     this.canSend,
-  }) : _inner = inner ?? http.Client();
+  }) : _inner = inner ?? newAppHttpClient();
   final HostedRelayAuth auth;
   final RelayConfig config;
   final http.Client _inner;
diff --git a/mobile/lib/shared/hosted/saved_identity_profile.dart b/mobile/lib/shared/hosted/saved_identity_profile.dart
index 8182e6b447..fb730d8c72 100644
--- a/mobile/lib/shared/hosted/saved_identity_profile.dart
+++ b/mobile/lib/shared/hosted/saved_identity_profile.dart
@@ -15,9 +15,10 @@ import '../relay/relay_query_response.dart';
 import '../relay/relay_session.dart';
 import 'device_identity_source.dart';
 import 'hosted_relay_auth.dart';
+import '../http/app_http_client.dart';
 
 final savedIdentityProfileClientProvider = Provider<http.Client Function()>(
-  (ref) => http.Client.new,
+  (ref) => newAppHttpClient,
 );
 
 final _profileQueueProvider = Provider((ref) => _ProfileQueue());
diff --git a/mobile/lib/shared/http/app_http_client.dart b/mobile/lib/shared/http/app_http_client.dart
new file mode 100644
index 0000000000..faf8253769
--- /dev/null
+++ b/mobile/lib/shared/http/app_http_client.dart
@@ -0,0 +1,209 @@
+import 'dart:async';
+import 'dart:io' show Platform;
+
+import 'package:cupertino_http/cupertino_http.dart';
+import 'package:http/http.dart' as http;
+import 'package:objective_c/objective_c.dart';
+import 'package:flutter/foundation.dart' show visibleForTesting;
+
+/// Which app-wide connection pool a request belongs to.
+enum HttpTraffic {
+  /// Relay queries, NIP-11 documents, account and admission calls.
+  api,
+
+  /// Image, video and voice-note downloads and media uploads.
+  media,
+}
+
+final _sessions = <HttpTraffic, http.Client>{};
+
+/// An HTTP client for [traffic]. Callers own it and close it as usual.
+///
+/// On iOS, every client for the same [traffic] shares one `NSURLSession`, so
+/// requests to a host multiplex over one HTTP/2 connection instead of opening
+/// an HTTP/1.1 connection each, and gzip is inflated natively, off the Dart
+/// isolate. Media has its own session, and so its own connection, so image
+/// bytes cannot starve queries queued behind them on a shared connection.
+///
+/// Elsewhere this is `http.Client()`, which also honors `http.runWithClient`.
+http.Client newAppHttpClient([HttpTraffic traffic = HttpTraffic.api]) {
+  if (!Platform.isIOS) return http.Client();
+  return SharedSessionClient(_sessions[traffic] ??= _openUrlSession());
+}
+
+/// Matches the `dart:io` transport apart from the protocol: no HTTP cache and
+/// no cookies.
+http.Client _openUrlSession() {
+  final config = URLSessionConfiguration.ephemeralSessionConfiguration()
+    ..cache = null
+    ..httpShouldSetCookies = false
+    ..httpCookieAcceptPolicy =
+        NSHTTPCookieAcceptPolicy.NSHTTPCookieAcceptPolicyNever;
+  return CupertinoClient.fromSessionConfiguration(config);
+}
+
+/// A caller's handle on an app-wide session. Like closing a `dart:io` client,
+/// [close] cancels the handle's requests still in flight and refuses later
+/// ones, but leaves the session open for other handles. Closing a
+/// `CupertinoClient` while any of its requests run would also throw.
+///
+/// App Transport Security blocks cleartext `URLSession` loads from public
+/// hosts, while saved community icons and remote media may still use
+/// `http://`. Those keep the handle's own `dart:io` client, as before.
+@visibleForTesting
+class SharedSessionClient extends http.BaseClient {
+  SharedSessionClient(this._session, {http.Client Function()? cleartext})
+    : _newCleartext = cleartext ?? http.Client.new;
+
+  final http.Client _session;
+  final http.Client Function() _newCleartext;
+
+  /// One abort trigger per request still running, so [close] can cancel it.
+  /// A request leaves the set once its response body is done, failed or
+  /// cancelled, or once the caller's own abort trigger fires. A body nobody
+  /// listens to stays until then: the session keeps downloading it, so
+  /// callers that drop a response unread must abort it.
+  final _inFlight = <Completer<void>>{};
+  var _closed = false;
+  http.Client? _cleartext;
+
+  @override
+  Future<http.StreamedResponse> send(http.BaseRequest request) async {
+    if (_closed) {
+      throw http.ClientException(
+        'HTTP request failed. Client is already closed.',
+        request.url,
+      );
+    }
+    if (request.url.scheme != 'https') {
+      return (_cleartext ??= _newCleartext()).send(request);
+    }
+    final abort = Completer<void>();
+    void fire() {
+      _inFlight.remove(abort);
+      if (!abort.isCompleted) abort.complete();
+    }
+
+    _inFlight.add(abort);
+    if (request case http.Abortable(:final abortTrigger?)) {
+      abortTrigger.then<void>((_) => fire(), onError: (_) => fire());
+    }
+    final http.StreamedResponse response;
+    try {
+      response = await _session.send(_withAbortTrigger(request, abort.future));
+    } catch (_) {
+      _inFlight.remove(abort);
+      rethrow;
+    }
+    // A controller, not an async* wrapper: async* never listens to the
+    // session's stream when cancelled before its first event, so the
+    // session would keep downloading a body nobody reads.
+    late final StreamSubscription<List<int>> inner;
+    final body = StreamController<List<int>>(sync: true);
+    body
+      ..onListen = () {
+        inner = response.stream.listen(
+          body.add,
+          onError: body.addError,
+          onDone: () {
+            _inFlight.remove(abort);
+            body.close();
+          },
+        );
+      }
+      ..onPause = (() => inner.pause())
+      ..onResume = (() => inner.resume())
+      ..onCancel = () {
+        _inFlight.remove(abort);
+        return inner.cancel();
+      };
+
+    return http.StreamedResponse(
+      http.ByteStream(body.stream),
+      response.statusCode,
+      contentLength: response.contentLength,
+      request: response.request,
+      headers: response.headers,
+      isRedirect: response.isRedirect,
+      persistentConnection: response.persistentConnection,
+      reasonPhrase: response.reasonPhrase,
+    );
+  }
+
+  /// A copy of [request] that the session cancels when [trigger] completes.
+  http.BaseRequest _withAbortTrigger(
+    http.BaseRequest request,
+    Future<void> trigger,
+  ) {
+    if (request is http.Request) {
+      return http.AbortableRequest(
+          request.method,
+          request.url,
+          abortTrigger: trigger,
+        )
+        ..bodyBytes = request.bodyBytes
+        ..headers.addAll(request.headers)
+        ..followRedirects = request.followRedirects
+        ..maxRedirects = request.maxRedirects
+        ..persistentConnection = request.persistentConnection;
+    }
+    // Finalizing first lets a multipart request set its content type.
+    final body = request.finalize();
+    final copy =
+        http.AbortableStreamedRequest(
+            request.method,
+            request.url,
+            abortTrigger: trigger,
+          )
+          ..headers.addAll(request.headers)
+          ..contentLength = request.contentLength
+          ..followRedirects = request.followRedirects
+          ..maxRedirects = request.maxRedirects
+          ..persistentConnection = request.persistentConnection;
+    // addStream keeps backpressure: the body is read only as the session
+    // reads the copy, so upload progress tracks bytes the session has taken
+    // (including its read-ahead buffers), as with plain cupertino_http.
+    unawaited(copy.sink.addStream(body).whenComplete(copy.sink.close));
+    return copy;
+  }
+
+  @override
+  void close() {
+    _closed = true;
+    for (final abort in _inFlight.toList()) {
+      if (!abort.isCompleted) abort.complete();
+    }
+    _inFlight.clear();
+    _cleartext?.close();
+  }
+}
+
+/// How an iOS transport request failed, for user-facing messages. `dart:io`
+/// failures are recognized by their messages instead.
+enum TransportFailure { unreachable, insecure, timedOut }
+
+/// The [TransportFailure] for a `URLSession` error, or null for any other
+/// error.
+TransportFailure? urlSessionFailure(Object error) {
+  if (error is! NSErrorClientException) return null;
+  if (error.error.domain.toDartString() != 'NSURLErrorDomain') return null;
+  return urlErrorFailure(error.error.code);
+}
+
+/// Classifies an `NSURLErrorDomain` code.
+@visibleForTesting
+TransportFailure? urlErrorFailure(int code) => switch (code) {
+  -1001 => TransportFailure.timedOut,
+  // Cannot find host, cannot connect, connection lost, DNS lookup failed,
+  // international roaming off, cellular data not allowed, offline.
+  -1003 ||
+  -1004 ||
+  -1005 ||
+  -1006 ||
+  -1018 ||
+  -1020 ||
+  -1009 => TransportFailure.unreachable,
+  // Secure connection failed and the server certificate errors.
+  >= -1206 && <= -1200 => TransportFailure.insecure,
+  _ => null,
+};
diff --git a/mobile/lib/shared/identity_archives/identity_archives.dart b/mobile/lib/shared/identity_archives/identity_archives.dart
index f1428f6b82..c77bde07e8 100644
--- a/mobile/lib/shared/identity_archives/identity_archives.dart
+++ b/mobile/lib/shared/identity_archives/identity_archives.dart
@@ -5,12 +5,13 @@ import 'dart:isolate';
 import 'package:buzz/shared/crypto/event_signing.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 
 import '../relay/relay.dart';
 import '../me/me_sync.dart';
 
 final relayInformationClientProvider = Provider<http.Client>((ref) {
-  final client = http.Client();
+  final client = newAppHttpClient();
   ref.onDispose(client.close);
   return client;
 });
@@ -21,11 +22,14 @@ final relayInformationClientProvider = Provider<http.Client>((ref) {
 final identityArchivesProvider = FutureProvider<Set<String>>((ref) async {
   final sync = ref.watch(meSyncProvider);
   final client = ref.watch(relayInformationClientProvider);
+  // Completed on every exit, so a dropped, refused or timed-out response
+  // stops downloading on a shared session instead of staying in flight.
+  final abort = Completer<void>();
   try {
     final uri = Uri.parse(sync.community);
     final response = await client
         .send(
-          http.Request('GET', uri)
+          http.AbortableRequest('GET', uri, abortTrigger: abort.future)
             ..headers['Accept'] = 'application/nostr+json',
         )
         .timeout(const Duration(seconds: 3));
@@ -65,6 +69,8 @@ final identityArchivesProvider = FutureProvider<Set<String>>((ref) async {
     return (await _parseArchives(events, authority))..remove(sync.pubkey);
   } catch (_) {
     return {};
+  } finally {
+    if (!abort.isCompleted) abort.complete();
   }
 });
 
diff --git a/mobile/lib/shared/push/dev_push_lease.dart b/mobile/lib/shared/push/dev_push_lease.dart
index f741f22f09..c93fb4c6c4 100644
--- a/mobile/lib/shared/push/dev_push_lease.dart
+++ b/mobile/lib/shared/push/dev_push_lease.dart
@@ -1,8 +1,10 @@
+import 'dart:async';
 import 'dart:convert';
 import 'dart:math';
 
 import 'package:buzz/shared/crypto/event_signing.dart';
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 import 'package:nostr/nostr.dart' as nostr;
 
 import '../crypto/nip44.dart';
@@ -243,10 +245,18 @@ Future<BuzzPushLeaseDescriptor> fetchBuzzPushLeaseDescriptor(
     throw FormatException('Invalid relay HTTP URL: $relayBaseUrl');
   }
   final requestUri = uri.resolve('/');
-  final ownedClient = client ?? http.Client();
+  final ownedClient = client ?? newAppHttpClient();
+  // Closing a client does not stop a request on a shared session.
+  final abort = Completer<void>();
   try {
+    final request = http.AbortableRequest(
+      'GET',
+      requestUri,
+      abortTrigger: abort.future,
+    )..headers['Accept'] = 'application/nostr+json';
     final response = await ownedClient
-        .get(requestUri, headers: const {'Accept': 'application/nostr+json'})
+        .send(request)
+        .then(http.Response.fromStream)
         .timeout(timeout);
     if (response.statusCode != 200) {
       throw StateError(
@@ -259,6 +269,7 @@ Future<BuzzPushLeaseDescriptor> fetchBuzzPushLeaseDescriptor(
     }
     return BuzzPushLeaseDescriptor.fromRelayInformation(decoded);
   } finally {
+    abort.complete();
     if (client == null) ownedClient.close();
   }
 }
diff --git a/mobile/lib/shared/relay/media_image.dart b/mobile/lib/shared/relay/media_image.dart
index 049c5fef0c..9268e825e8 100644
--- a/mobile/lib/shared/relay/media_image.dart
+++ b/mobile/lib/shared/relay/media_image.dart
@@ -7,6 +7,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_hooks/flutter_hooks.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 
 import '../hosted/hosted_relay_auth.dart';
 import '../utils/bounded_fetch.dart';
@@ -17,7 +18,9 @@ import 'media_disk_cache.dart';
 /// so TLS connections are reused across images instead of re-handshaking per
 /// fetch. Override in tests to stub the network.
 final mediaHttpClientProvider = Provider<http.Client>((ref) {
-  final client = ref.watch(hostedHttpClientFactoryProvider)();
+  final client = ref.watch(hostedHttpClientFactoryProvider)(
+    traffic: HttpTraffic.media,
+  );
   ref.onDispose(client.close);
   return client;
 });
diff --git a/mobile/lib/shared/relay/media_upload.dart b/mobile/lib/shared/relay/media_upload.dart
index c814c899d5..e183b8d3f5 100644
--- a/mobile/lib/shared/relay/media_upload.dart
+++ b/mobile/lib/shared/relay/media_upload.dart
@@ -8,6 +8,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 import 'package:image_picker/image_picker.dart';
 import 'package:nostr/nostr.dart' as nostr;
 import 'package:crypto/crypto.dart' as crypto;
@@ -285,7 +286,7 @@ class MediaUploadService {
        _generateVideoPoster = generateVideoPoster ?? _generatePickedVideoPoster,
        _readClipboardImage = readClipboardImage ?? _readPlatformClipboardImage,
        _now = now ?? DateTime.now,
-       _http = httpClient ?? http.Client(),
+       _http = httpClient ?? newAppHttpClient(HttpTraffic.media),
        _ownsHttpClient = httpClient == null;
 
   void dispose() {
diff --git a/mobile/lib/shared/relay/media_upload/platform_bindings.dart b/mobile/lib/shared/relay/media_upload/platform_bindings.dart
index 47e1675510..9c6981f1de 100644
--- a/mobile/lib/shared/relay/media_upload/platform_bindings.dart
+++ b/mobile/lib/shared/relay/media_upload/platform_bindings.dart
@@ -13,7 +13,9 @@ Future<bool> requiresLegacyMediaStoragePermission() async {
 
 final mediaUploadServiceProvider = Provider<MediaUploadService>((ref) {
   final config = ref.watch(relayConfigProvider);
-  final client = ref.watch(hostedHttpClientFactoryProvider)();
+  final client = ref.watch(hostedHttpClientFactoryProvider)(
+    traffic: HttpTraffic.media,
+  );
   ref.onDispose(client.close);
   final picker = ImagePicker();
   final service = MediaUploadService(
diff --git a/mobile/lib/shared/relay/relay_author_provider.dart b/mobile/lib/shared/relay/relay_author_provider.dart
index f35b09bddd..01f35cb85a 100644
--- a/mobile/lib/shared/relay/relay_author_provider.dart
+++ b/mobile/lib/shared/relay/relay_author_provider.dart
@@ -3,9 +3,10 @@ import 'dart:convert';
 
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 
 final relayInformationClientProvider = Provider<http.Client>((ref) {
-  final client = http.Client();
+  final client = newAppHttpClient();
   ref.onDispose(client.close);
   return client;
 });
@@ -24,27 +25,35 @@ final relayAuthorProvider = FutureProvider.autoDispose.family<String?, String>((
     },
   );
   final client = ref.watch(relayInformationClientProvider);
-  final response = await client
-      .send(
-        http.Request('GET', uri)..headers['Accept'] = 'application/nostr+json',
-      )
-      .timeout(const Duration(seconds: 3));
-  final chunks = StreamIterator(
-    response.stream.timeout(const Duration(seconds: 3)),
-  );
+  // Completed on every exit, so a dropped, refused or timed-out response
+  // stops downloading on a shared session instead of staying in flight.
+  final abort = Completer<void>();
   final bytes = <int>[];
   try {
+    final response = await client
+        .send(
+          http.AbortableRequest('GET', uri, abortTrigger: abort.future)
+            ..headers['Accept'] = 'application/nostr+json',
+        )
+        .timeout(const Duration(seconds: 3));
     if (response.statusCode != 200) return null;
-    await (() async {
-      while (await chunks.moveNext()) {
-        if (bytes.length + chunks.current.length > 256 * 1024) {
-          throw const FormatException('Relay information exceeds size limit');
+    final chunks = StreamIterator(
+      response.stream.timeout(const Duration(seconds: 3)),
+    );
+    try {
+      await (() async {
+        while (await chunks.moveNext()) {
+          if (bytes.length + chunks.current.length > 256 * 1024) {
+            throw const FormatException('Relay information exceeds size limit');
+          }
+          bytes.addAll(chunks.current);
         }
-        bytes.addAll(chunks.current);
-      }
-    })().timeout(const Duration(seconds: 3));
+      })().timeout(const Duration(seconds: 3));
+    } finally {
+      await chunks.cancel();
+    }
   } finally {
-    await chunks.cancel();
+    if (!abort.isCompleted) abort.complete();
   }
   final info = jsonDecode(utf8.decode(bytes));
   final author = info is Map ? info['self'] : null;
diff --git a/mobile/lib/shared/relay/relay_client.dart b/mobile/lib/shared/relay/relay_client.dart
index 453e11459e..894aeb2f84 100644
--- a/mobile/lib/shared/relay/relay_client.dart
+++ b/mobile/lib/shared/relay/relay_client.dart
@@ -1,4 +1,5 @@
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 
 /// Lightweight HTTP context for talking to the Buzz relay.
 ///
@@ -12,7 +13,7 @@ class RelayClient {
   final http.Client _http;
 
   RelayClient({required this.baseUrl, http.Client? httpClient})
-    : _http = httpClient ?? http.Client();
+    : _http = httpClient ?? newAppHttpClient(HttpTraffic.media);
 
   /// Shared underlying HTTP client (used by [MediaUploader]).
   http.Client get httpClient => _http;
diff --git a/mobile/lib/shared/relay/relay_http_query_client.dart b/mobile/lib/shared/relay/relay_http_query_client.dart
index 06e8dae730..0feea2261b 100644
--- a/mobile/lib/shared/relay/relay_http_query_client.dart
+++ b/mobile/lib/shared/relay/relay_http_query_client.dart
@@ -3,14 +3,17 @@ import 'dart:io';
 
 import 'package:http/http.dart' as http;
 import 'package:http/io_client.dart';
+import 'package:buzz/shared/http/app_http_client.dart';
 
-/// The default transport. `dart:io` would inflate gzip responses on the
-/// calling isolate, so leave them compressed for the response decoder.
+/// The default transport. On iOS, the app-wide `NSURLSession` inflates gzip
+/// natively, off the Dart isolate. `dart:io` would inflate on the calling
+/// isolate, so leave its responses compressed for the response decoder.
 ///
 /// A non-`dart:io` client supplied through `http.runWithClient`, such as a
 /// `MockClient`, is used as is. An `IOClient` is replaced, not closed, since
 /// it may be shared.
-http.Client _gzipPassthroughClient() {
+http.Client _defaultTransport() {
+  if (Platform.isIOS) return newAppHttpClient();
   final client = http.Client();
   if (client is! IOClient) return client;
   return IOClient(HttpClient()..autoUncompress = false);
@@ -25,7 +28,7 @@ class RelayHttpQueryClient {
     http.Client? client,
     http.Client Function()? clientFactory,
   }) : _injectedClient = client,
-       _clientFactory = clientFactory ?? _gzipPassthroughClient;
+       _clientFactory = clientFactory ?? _defaultTransport;
 
   final http.Client? _injectedClient;
   final http.Client Function() _clientFactory;
@@ -44,12 +47,16 @@ class RelayHttpQueryClient {
         : null;
     generation?.acquire();
     var active = true;
+    // Retiring a generation cannot stop a request on a shared session, so a
+    // timed-out request is aborted rather than left holding bandwidth.
+    final abort = Completer<void>();
     try {
-      final request = http.Request('POST', url)
-        ..followRedirects = false
-        ..headers['Accept-Encoding'] = 'gzip'
-        ..headers.addAll(headers)
-        ..bodyBytes = body;
+      final request =
+          http.AbortableRequest('POST', url, abortTrigger: abort.future)
+            ..followRedirects = false
+            ..headers['Accept-Encoding'] = 'gzip'
+            ..headers.addAll(headers)
+            ..bodyBytes = body;
       final transport = _injectedClient ?? generation!.client;
       final client = decorate?.call(transport, () => active) ?? transport;
       return await client
@@ -57,6 +64,7 @@ class RelayHttpQueryClient {
           .then(http.Response.fromStream)
           .timeout(timeout);
     } on TimeoutException {
+      if (!abort.isCompleted) abort.complete();
       if (identical(_currentGeneration, generation)) {
         _currentGeneration = null;
       }
@@ -76,7 +84,17 @@ class RelayHttpQueryClient {
     required Duration timeout,
     http.Client Function(http.Client, bool Function())? decorate,
   }) async {
-    request.followRedirects = false;
+    // As in [post], a timed-out request on a shared session is aborted.
+    final abort = Completer<void>();
+    final sent =
+        http.AbortableRequest(
+            request.method,
+            request.url,
+            abortTrigger: abort.future,
+          )
+          ..followRedirects = false
+          ..headers.addAll(request.headers)
+          ..bodyBytes = request.bodyBytes;
     final generation = _injectedClient == null
         ? (_currentGeneration ??= _createGeneration())
         : null;
@@ -86,7 +104,7 @@ class RelayHttpQueryClient {
     Future<http.Response> receive() async {
       final transport = _injectedClient ?? generation!.client;
       final client = decorate?.call(transport, () => !finished) ?? transport;
-      final response = await client.send(request);
+      final response = await client.send(sent);
       if (finished) {
         await response.stream.listen(null).cancel();
         throw StateError('Relay request already timed out');
@@ -115,6 +133,7 @@ class RelayHttpQueryClient {
     try {
       return await receive().timeout(timeout);
     } on TimeoutException {
+      if (!abort.isCompleted) abort.complete();
       if (identical(_currentGeneration, generation)) {
         _currentGeneration = null;
       }
@@ -122,6 +141,9 @@ class RelayHttpQueryClient {
       rethrow;
     } finally {
       finished = true;
+      // Cancelling an iterator that never listened leaves the body
+      // downloading on a shared session, so abort on every exit.
+      if (!abort.isCompleted) abort.complete();
       if (iterator != null) await iterator!.cancel();
       generation?.release();
     }
diff --git a/mobile/lib/shared/relay/relay_provider.dart b/mobile/lib/shared/relay/relay_provider.dart
index 692441d211..de0820908e 100644
--- a/mobile/lib/shared/relay/relay_provider.dart
+++ b/mobile/lib/shared/relay/relay_provider.dart
@@ -1,4 +1,5 @@
 import 'package:buzz/shared/crypto/event_signing.dart';
+import 'package:buzz/shared/http/app_http_client.dart';
 import 'package:flutter/foundation.dart' show visibleForTesting;
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:nostr/nostr.dart' as nostr;
@@ -151,7 +152,9 @@ final relayClientProvider = Provider<RelayClient>((ref) {
   final config = ref.watch(relayConfigProvider);
   final client = RelayClient(
     baseUrl: config.baseUrl,
-    httpClient: ref.watch(hostedHttpClientFactoryProvider)(),
+    httpClient: ref.watch(hostedHttpClientFactoryProvider)(
+      traffic: HttpTraffic.media,
+    ),
   );
   ref.onDispose(client.dispose);
   return client;
diff --git a/mobile/lib/shared/relay/relay_session_snapshot.dart b/mobile/lib/shared/relay/relay_session_snapshot.dart
index 138e5c3f31..8434a3bb82 100644
--- a/mobile/lib/shared/relay/relay_session_snapshot.dart
+++ b/mobile/lib/shared/relay/relay_session_snapshot.dart
@@ -53,10 +53,10 @@ extension on RelaySessionNotifier {
     final origin = Uri.parse(config.baseUrl);
     final discovery = http.Request('GET', origin.resolve('/'))
       ..headers['Accept'] = 'application/nostr+json';
-    // The query transport leaves gzip bodies compressed (see
-    // RelayHttpQueryClient), and the relay's CDN gzips both responses. The
-    // inflated size is capped too: the transport cap only sees the
-    // compressed bytes.
+    // The relay's CDN gzips both responses. The inflated size is capped too:
+    // where the query transport leaves gzip bodies compressed (see
+    // RelayHttpQueryClient), the transport cap only sees the compressed
+    // bytes.
     final discovered = await send(discovery, 64 * 1024);
     final info = jsonDecode(
       relayResponseText(
diff --git a/mobile/lib/shared/verified_profiles/verified_profile_discovery_fetch.dart b/mobile/lib/shared/verified_profiles/verified_profile_discovery_fetch.dart
index d0e66d1e08..71bcaa9a8d 100644
--- a/mobile/lib/shared/verified_profiles/verified_profile_discovery_fetch.dart
+++ b/mobile/lib/shared/verified_profiles/verified_profile_discovery_fetch.dart
@@ -1,5 +1,6 @@
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:http/http.dart' as http;
+import 'package:buzz/shared/http/app_http_client.dart';
 
 import '../relay/nip11_document.dart';
 import '../relay/relay.dart';
@@ -11,7 +12,7 @@ typedef VerifiedProfileDiscoveryFetch =
     Future<VerifiedProfileDiscovery> Function();
 
 final verifiedProfileHttpClientProvider = Provider<http.Client>((ref) {
-  final client = http.Client();
+  final client = newAppHttpClient();
   ref.onDispose(client.close);
   return client;
 });
diff --git a/mobile/packages/buzz_secp256k1/pubspec.lock b/mobile/packages/buzz_secp256k1/pubspec.lock
index 13db8441b5..a2b85f9d20 100644
--- a/mobile/packages/buzz_secp256k1/pubspec.lock
+++ b/mobile/packages/buzz_secp256k1/pubspec.lock
@@ -77,10 +77,10 @@ packages:
     dependency: "direct main"
     description:
       name: code_assets
-      sha256: "83ccdaa064c980b5596c35dd64a8d3ecc68620174ab9b90b6343b753aa721687"
+      sha256: bf394f466ba9205f1812a0433b392d6af280f155f56651eda7c18cc32ed493b8
       url: "https://pub.dev"
     source: hosted
-    version: "1.0.0"
+    version: "1.2.1"
   collection:
     dependency: transitive
     description:
@@ -157,10 +157,10 @@ packages:
     dependency: "direct main"
     description:
       name: hooks
-      sha256: "025f060e86d2d4c3c47b56e33caf7f93bf9283340f26d23424ebcfccf34f621e"
+      sha256: eaac480a35ec0814146c2c48d96aaa829e0e44a7662c88ae84c9edf4bc35651f
       url: "https://pub.dev"
     source: hosted
-    version: "1.0.3"
+    version: "2.2.0"
   http:
     dependency: transitive
     description:
@@ -229,10 +229,10 @@ packages:
     dependency: "direct main"
     description:
       name: native_toolchain_c
-      sha256: "6ba77bb18063eebe9de401f5e6437e95e1438af0a87a3a39084fbd37c90df572"
+      sha256: a1c26117c48cebe5677b0cf0e33a980a79a7c5577effc86f52e5a0d309cdcb60
       url: "https://pub.dev"
     source: hosted
-    version: "0.17.6"
+    version: "0.19.3"
   node_preamble:
     dependency: transitive
     description:
@@ -293,10 +293,10 @@ packages:
     dependency: transitive
     description:
       name: record_use
-      sha256: "2551bd8eecfe95d14ae75f6021ad0248be5c27f138c2ec12fcb52b500b3ba1ed"
+      sha256: "1cb8564af8d43b464294411db9217f5ec04891c6f22ee2c32d73ae05e88a6bd2"
       url: "https://pub.dev"
     source: hosted
-    version: "0.6.0"
+    version: "1.1.1"
   shelf:
     dependency: transitive
     description:
diff --git a/mobile/packages/buzz_secp256k1/pubspec.yaml b/mobile/packages/buzz_secp256k1/pubspec.yaml
index c84ad25671..82b8987192 100644
--- a/mobile/packages/buzz_secp256k1/pubspec.yaml
+++ b/mobile/packages/buzz_secp256k1/pubspec.yaml
@@ -9,10 +9,10 @@ environment:
   sdk: ^3.11.4
 
 dependencies:
-  code_assets: ^1.0.0
+  code_assets: ^1.2.0
   ffi: ^2.2.0
-  hooks: ^1.0.2
-  native_toolchain_c: ^0.17.6
+  hooks: ^2.0.0
+  native_toolchain_c: ^0.19.1
 
 dev_dependencies:
   test: ^1.26.0
diff --git a/mobile/pubspec.lock b/mobile/pubspec.lock
index 37404e81a1..298254bbbd 100644
--- a/mobile/pubspec.lock
+++ b/mobile/pubspec.lock
@@ -244,10 +244,10 @@ packages:
     dependency: transitive
     description:
       name: code_assets
-      sha256: "83ccdaa064c980b5596c35dd64a8d3ecc68620174ab9b90b6343b753aa721687"
+      sha256: bf394f466ba9205f1812a0433b392d6af280f155f56651eda7c18cc32ed493b8
       url: "https://pub.dev"
     source: hosted
-    version: "1.0.0"
+    version: "1.2.1"
   collection:
     dependency: transitive
     description:
@@ -312,6 +312,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.0.2"
+  cupertino_http:
+    dependency: "direct main"
+    description:
+      name: cupertino_http
+      sha256: d57188b07349a373bec9a78997a80c00e1de08dab0fe454b3f86c84661ac457c
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.0"
   cupertino_icons:
     dependency: "direct main"
     description:
@@ -659,10 +667,10 @@ packages:
     dependency: transitive
     description:
       name: hooks
-      sha256: e79ed1e8e1929bc6ecb6ec85f0cb519c887aa5b423705ded0d0f2d9226def388
+      sha256: eaac480a35ec0814146c2c48d96aaa829e0e44a7662c88ae84c9edf4bc35651f
       url: "https://pub.dev"
     source: hosted
-    version: "1.0.2"
+    version: "2.2.0"
   hooks_riverpod:
     dependency: "direct main"
     description:
@@ -703,6 +711,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.1.2"
+  http_profile:
+    dependency: transitive
+    description:
+      name: http_profile
+      sha256: "7e679e355b09aaee2ab5010915c932cce3f2d1c11c3b2dc177891687014ffa78"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.1.0"
   image:
     dependency: "direct main"
     description:
@@ -971,10 +987,10 @@ packages:
     dependency: transitive
     description:
       name: native_toolchain_c
-      sha256: "6ba77bb18063eebe9de401f5e6437e95e1438af0a87a3a39084fbd37c90df572"
+      sha256: a1c26117c48cebe5677b0cf0e33a980a79a7c5577effc86f52e5a0d309cdcb60
       url: "https://pub.dev"
     source: hosted
-    version: "0.17.6"
+    version: "0.19.3"
   nm:
     dependency: transitive
     description:
@@ -1000,13 +1016,13 @@ packages:
     source: hosted
     version: "2.0.0"
   objective_c:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: objective_c
-      sha256: "100a1c87616ab6ed41ec263b083c0ef3261ee6cd1dc3b0f35f8ddfa4f996fe52"
+      sha256: b7fb95a6d9a4f009edd63dc5ac69f07420b23a16161c6dd8660290b59c602e8e
       url: "https://pub.dev"
     source: hosted
-    version: "9.3.0"
+    version: "9.5.0"
   open_filex:
     dependency: "direct main"
     description:
@@ -1223,6 +1239,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.6.0"
+  record_use:
+    dependency: transitive
+    description:
+      name: record_use
+      sha256: "1cb8564af8d43b464294411db9217f5ec04891c6f22ee2c32d73ae05e88a6bd2"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.1"
   record_web:
     dependency: transitive
     description:
diff --git a/mobile/pubspec.yaml b/mobile/pubspec.yaml
index cfb45150f6..99811b86a5 100644
--- a/mobile/pubspec.yaml
+++ b/mobile/pubspec.yaml
@@ -18,6 +18,10 @@ dependencies:
   hooks_riverpod: ^3.0.3
   flutter_hooks: ^0.21.3
   http: ^1.4.0
+  # iOS HTTP transport (NSURLSession): HTTP/2 and native gzip. See
+  # lib/shared/http/app_http_client.dart.
+  cupertino_http: ^3.1.0
+  objective_c: ^9.5.0
   crypto: ^3.0.7
   flutter_secure_storage: ^10.0.0
   flutter_svg: ^2.2.4
diff --git a/mobile/test/features/agents/agent_instructions_test.dart b/mobile/test/features/agents/agent_instructions_test.dart
index f7fea7075f..4a6a3df683 100644
--- a/mobile/test/features/agents/agent_instructions_test.dart
+++ b/mobile/test/features/agents/agent_instructions_test.dart
@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:convert';
 import 'package:buzz/shared/relay/relay_author_provider.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
@@ -91,6 +92,34 @@ void main() {
     }
   });
 
+  test('a refused relay information response is aborted', () async {
+    Future<void>? aborted;
+    final container = ProviderContainer(
+      overrides: [
+        relayInformationClientProvider.overrideWithValue(
+          MockClient.streaming((request, _) async {
+            aborted = (request as http.Abortable).abortTrigger;
+            return http.StreamedResponse(
+              StreamController<List<int>>().stream,
+              503,
+            );
+          }),
+        ),
+      ],
+    );
+    addTearDown(container.dispose);
+    final subscription = container.listen(
+      relayAuthorProvider('wss://relay.example'),
+      (_, _) {},
+    );
+    addTearDown(subscription.close);
+    expect(
+      await container.read(relayAuthorProvider('wss://relay.example').future),
+      isNull,
+    );
+    await aborted!.timeout(const Duration(seconds: 1));
+  });
+
   test(
     'instruction sources preserve precedence and do not revive unavailable config',
     () async {
diff --git a/mobile/test/shared/community/community_icon_provider_test.dart b/mobile/test/shared/community/community_icon_provider_test.dart
index aecc3d45d7..2c46a6f52b 100644
--- a/mobile/test/shared/community/community_icon_provider_test.dart
+++ b/mobile/test/shared/community/community_icon_provider_test.dart
@@ -31,7 +31,9 @@ void main() {
     final container = ProviderContainer(
       overrides: [
         savedPrefsProvider.overrideWithValue(prefs),
-        communityIconHttpClientProvider.overrideWithValue(MockClient(handler)),
+        communityIconHttpClientProvider.overrideWith(
+          (ref, _) => MockClient(handler),
+        ),
       ],
     );
     addTearDown(container.dispose);
@@ -246,7 +248,7 @@ void main() {
       final container = ProviderContainer(
         overrides: [
           savedPrefsProvider.overrideWithValue(prefs),
-          communityIconHttpClientProvider.overrideWithValue(client),
+          communityIconHttpClientProvider.overrideWith((ref, _) => client),
         ],
       );
       addTearDown(container.dispose);
@@ -485,7 +487,7 @@ void main() {
         final container = ProviderContainer(
           overrides: [
             savedPrefsProvider.overrideWithValue(prefs),
-            communityIconHttpClientProvider.overrideWithValue(client),
+            communityIconHttpClientProvider.overrideWith((ref, _) => client),
           ],
         );
         addTearDown(container.dispose);
diff --git a/mobile/test/shared/http/app_http_client_test.dart b/mobile/test/shared/http/app_http_client_test.dart
new file mode 100644
index 0000000000..a857852c44
--- /dev/null
+++ b/mobile/test/shared/http/app_http_client_test.dart
@@ -0,0 +1,252 @@
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:buzz/shared/http/app_http_client.dart';
+import 'package:buzz/shared/utils/bounded_fetch.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+
+void main() {
+  test('off iOS, clients come from http.Client()', () {
+    final mock = MockClient((_) async => http.Response('', 200));
+    for (final traffic in HttpTraffic.values) {
+      expect(
+        http.runWithClient(() => newAppHttpClient(traffic), () => mock),
+        same(mock),
+      );
+    }
+  });
+
+  test('closing a shared-session handle leaves the session usable', () async {
+    var sessionClosed = false;
+    final session = _ClosingMock(
+      (_) async => http.Response('ok', 200),
+      onClose: () => sessionClosed = true,
+    );
+    final first = SharedSessionClient(session);
+    final second = SharedSessionClient(session);
+
+    first.close();
+
+    expect(sessionClosed, isFalse);
+    expect((await second.get(Uri.parse('https://relay.example/'))).body, 'ok');
+  });
+
+  test('closing a handle cancels its own in-flight requests only', () async {
+    final session = _AbortRecorder();
+    final first = SharedSessionClient(session);
+    final second = SharedSessionClient(session);
+    unawaited(
+      first
+          .get(Uri.parse('https://relay.example/a'))
+          .then<void>((_) {}, onError: (_) {}),
+    );
+    unawaited(
+      second
+          .get(Uri.parse('https://relay.example/b'))
+          .then<void>((_) {}, onError: (_) {}),
+    );
+    await pumpEventQueue();
+
+    first.close();
+    await pumpEventQueue();
+
+    expect(session.aborted, [Uri.parse('https://relay.example/a')]);
+    await expectLater(
+      first.get(Uri.parse('https://relay.example/c')),
+      throwsA(isA<http.ClientException>()),
+    );
+  });
+
+  test('finished requests hold no abort trigger until close', () async {
+    var fired = 0;
+    var sessionBodyCancelled = false;
+    final client = SharedSessionClient(
+      MockClient.streaming((request, _) async {
+        (request as http.Abortable).abortTrigger?.then((_) => fired++);
+        if (request.url.path == '/video') {
+          final body = StreamController<List<int>>(
+            onCancel: () => sessionBodyCancelled = true,
+          );
+          return http.StreamedResponse(body.stream, 500);
+        }
+        final status = request.url.path == '/missing' ? 404 : 200;
+        return http.StreamedResponse(Stream.value([1]), status);
+      }),
+    );
+    for (var i = 0; i < 3; i++) {
+      await client.get(Uri.parse('https://relay.example/$i'));
+    }
+    // A non-200 body is never read, and boundedGet fires its own trigger.
+    final missing = await boundedGet(
+      client,
+      Uri.parse('https://relay.example/missing'),
+      maxBytes: 10,
+    );
+    expect(missing.statusCode, 404);
+    await pumpEventQueue();
+    // A body cancelled before its first event still cancels the session's
+    // download.
+    final video = await client.send(
+      http.Request('GET', Uri.parse('https://relay.example/video')),
+    );
+    await video.stream.listen(null).cancel();
+    expect(sessionBodyCancelled, isTrue);
+    final ownAborts = fired;
+
+    client.close();
+    await pumpEventQueue();
+
+    expect(fired, ownAborts);
+  });
+
+  test('a request\'s own abort trigger still cancels it', () async {
+    final session = _AbortRecorder();
+    final client = SharedSessionClient(session);
+    final abort = Completer<void>();
+    unawaited(
+      client
+          .send(
+            http.AbortableRequest(
+              'GET',
+              Uri.parse('https://relay.example/a'),
+              abortTrigger: abort.future,
+            ),
+          )
+          .then<void>((_) {}, onError: (_) {}),
+    );
+    await pumpEventQueue();
+
+    abort.complete();
+    await pumpEventQueue();
+
+    expect(session.aborted, [Uri.parse('https://relay.example/a')]);
+  });
+
+  test('requests reach the session with their headers and body', () async {
+    final received =
+        <({String method, Map<String, String> headers, String body})>[];
+    final client = SharedSessionClient(
+      MockClient.streaming((request, body) async {
+        received.add((
+          method: request.method,
+          headers: request.headers,
+          body: utf8.decode(await body.toBytes()),
+        ));
+        return http.StreamedResponse(const Stream.empty(), 200);
+      }),
+    );
+
+    await client.post(
+      Uri.parse('https://relay.example/query'),
+      headers: {'authorization': 'Nostr x'},
+      body: '[]',
+    );
+    final upload = http.MultipartRequest(
+      'PUT',
+      Uri.parse('https://relay.example/upload'),
+    )..fields['name'] = 'value';
+    await client.send(upload);
+
+    expect(received[0].method, 'POST');
+    expect(received[0].headers['authorization'], 'Nostr x');
+    expect(received[0].body, '[]');
+    expect(received[1].method, 'PUT');
+    expect(
+      received[1].headers['content-type'],
+      startsWith('multipart/form-data'),
+    );
+    expect(received[1].body, contains('value'));
+  });
+
+  test(
+    'a streamed body is read only as fast as the session reads it',
+    () async {
+      var produced = 0;
+      Stream<List<int>> chunks() async* {
+        for (var i = 0; i < 100; i++) {
+          produced++;
+          yield [i];
+        }
+      }
+
+      final request = http.StreamedRequest(
+        'PUT',
+        Uri.parse('https://relay.example/upload'),
+      )..contentLength = 100;
+      unawaited(
+        request.sink.addStream(chunks()).whenComplete(request.sink.close),
+      );
+      final client = SharedSessionClient(_AbortRecorder());
+      unawaited(client.send(request).then<void>((_) {}, onError: (_) {}));
+      await pumpEventQueue();
+
+      // Upload progress counts bytes as they are produced, so a copy that
+      // drained the body ahead of the transport would report it sent.
+      expect(produced, lessThan(10));
+      client.close();
+    },
+  );
+
+  test('cleartext requests use the handle\'s own client', () async {
+    final sessionUrls = <Uri>[];
+    final cleartextUrls = <Uri>[];
+    var cleartextClosed = false;
+    final client = SharedSessionClient(
+      MockClient((request) async {
+        sessionUrls.add(request.url);
+        return http.Response('', 200);
+      }),
+      cleartext: () => _ClosingMock((request) async {
+        cleartextUrls.add(request.url);
+        return http.Response('', 200);
+      }, onClose: () => cleartextClosed = true),
+    );
+
+    await client.get(Uri.parse('https://relay.example/a'));
+    await client.get(Uri.parse('http://icons.example/b'));
+    client.close();
+
+    expect(sessionUrls, [Uri.parse('https://relay.example/a')]);
+    expect(cleartextUrls, [Uri.parse('http://icons.example/b')]);
+    expect(cleartextClosed, isTrue);
+  });
+
+  test('URLSession error codes map to user-facing failure kinds', () {
+    expect(urlErrorFailure(-1009), TransportFailure.unreachable);
+    expect(urlErrorFailure(-1004), TransportFailure.unreachable);
+    expect(urlErrorFailure(-1001), TransportFailure.timedOut);
+    expect(urlErrorFailure(-1200), TransportFailure.insecure);
+    expect(urlErrorFailure(-1202), TransportFailure.insecure);
+    expect(urlErrorFailure(-999), isNull);
+    expect(urlSessionFailure(http.ClientException('offline')), isNull);
+  });
+}
+
+class _ClosingMock extends MockClient {
+  _ClosingMock(super.fn, {required this.onClose});
+
+  final void Function() onClose;
+
+  @override
+  void close() {
+    onClose();
+    super.close();
+  }
+}
+
+/// Never responds; records which requests were aborted.
+class _AbortRecorder extends http.BaseClient {
+  final aborted = <Uri>[];
+
+  @override
+  Future<http.StreamedResponse> send(http.BaseRequest request) {
+    final response = Completer<http.StreamedResponse>();
+    (request as http.Abortable).abortTrigger?.then((_) {
+      aborted.add(request.url);
+      response.completeError(http.RequestAbortedException(request.url));
+    });
+    return response.future;
+  }
+}
diff --git a/mobile/test/shared/identity_archives/identity_archives_test.dart b/mobile/test/shared/identity_archives/identity_archives_test.dart
index 230a4c6189..effd4d1e15 100644
--- a/mobile/test/shared/identity_archives/identity_archives_test.dart
+++ b/mobile/test/shared/identity_archives/identity_archives_test.dart
@@ -170,6 +170,31 @@ void main() {
     expect(relay.author, isNull);
   });
 
+  test('a refused metadata response is aborted, not left unread', () async {
+    final owner = nostr.Keys.generate();
+    final relay = _ArchiveRelay(null);
+    Future<void>? aborted;
+    final client = MockClient.streaming((request, _) async {
+      aborted = (request as http.Abortable).abortTrigger;
+      return http.StreamedResponse(StreamController<List<int>>().stream, 503);
+    });
+    final container = ProviderContainer(
+      overrides: [
+        meSyncProvider.overrideWithValue(
+          MeSync(
+            relay,
+            RelayConfig(baseUrl: 'https://relay.test', nsec: owner.nsec),
+          ),
+        ),
+        relayInformationClientProvider.overrideWithValue(client),
+      ],
+    );
+    addTearDown(container.dispose);
+    addTearDown(client.close);
+    expect(await container.read(identityArchivesProvider.future), isEmpty);
+    await aborted!.timeout(const Duration(seconds: 1));
+  });
+
   test(
     'contact keys and unavailable metadata are not archive authority',
     () async {
diff --git a/mobile/test/shared/relay/relay_http_query_client_test.dart b/mobile/test/shared/relay/relay_http_query_client_test.dart
index c3fa2838c1..f57cc6a2be 100644
--- a/mobile/test/shared/relay/relay_http_query_client_test.dart
+++ b/mobile/test/shared/relay/relay_http_query_client_test.dart
@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ -54,4 +55,77 @@ void main() {
       '[]',
     );
   });
+
+  test('a timed-out request is aborted, not left running', () async {
+    final aborted = Completer<void>();
+    final client = RelayHttpQueryClient(
+      client: _HangingClient(onAbort: aborted.complete),
+    );
+
+    await expectLater(
+      client.post(
+        Uri.parse('https://relay.example/query'),
+        headers: const {},
+        body: const [],
+        timeout: const Duration(milliseconds: 10),
+      ),
+      throwsA(isA<TimeoutException>()),
+    );
+    await aborted.future.timeout(const Duration(seconds: 5));
+  });
+
+  test('a timed-out bounded request is aborted, not left running', () async {
+    final aborted = Completer<void>();
+    final client = RelayHttpQueryClient(
+      client: _HangingClient(onAbort: aborted.complete),
+    );
+
+    await expectLater(
+      client.sendBounded(
+        http.Request('GET', Uri.parse('https://relay.example/')),
+        maxBytes: 1024,
+        timeout: const Duration(milliseconds: 10),
+      ),
+      throwsA(isA<TimeoutException>()),
+    );
+    await aborted.future.timeout(const Duration(seconds: 5));
+  });
+
+  test('an oversized bounded response is aborted before it is read', () async {
+    Future<void>? aborted;
+    final client = RelayHttpQueryClient(
+      client: MockClient.streaming((request, _) async {
+        aborted = (request as http.Abortable).abortTrigger;
+        return http.StreamedResponse(
+          StreamController<List<int>>().stream,
+          200,
+          contentLength: 4096,
+        );
+      }),
+    );
+
+    await expectLater(
+      client.sendBounded(
+        http.Request('GET', Uri.parse('https://relay.example/')),
+        maxBytes: 1024,
+        timeout: const Duration(seconds: 5),
+      ),
+      throwsA(isA<FormatException>()),
+    );
+    await aborted!.timeout(const Duration(seconds: 1));
+  });
+}
+
+/// Never responds; reports when the request's abort trigger fires.
+class _HangingClient extends http.BaseClient {
+  _HangingClient({required this.onAbort});
+
+  final void Function() onAbort;
+
+  @override
+  Future<http.StreamedResponse> send(http.BaseRequest request) {
+    final trigger = (request as http.Abortable).abortTrigger;
+    trigger?.then((_) => onAbort());
+    return Completer<http.StreamedResponse>().future;
+  }
 }