feat: add nwc supported extensions info field

packages/ndk/example/nwc/connect_get_info.dart

@@ -14,6 +14,9 @@ void main() async {
   final connection = await ndk.nwc.connect(nwcUri, doGetInfoMethod: true);
 
   print("Connected, permissions: ${connection.permissions}");
+  print(
+    "Supported extensions: ${connection.supportedExtensions.map((extension) => '${extension.identifier} (${extension.name})').join(', ')}",
+  );
 
   if (connection.info != null) {
     print("alias: ${connection.info!.alias}");

packages/ndk/lib/domain_layer/usecases/nwc/consts/nwc_extension.dart

@@ -0,0 +1,47 @@
+/// Optional Nostr Wallet Connect extension specifications.
+///
+/// The identifiers correspond to specification filenames in
+/// https://github.com/nostr-wallet-connect/nwc.
+enum NwcExtension {
+  notifications('02'),
+  holdInvoices('03'),
+  keysend('04'),
+  transactionHistory('05'),
+  metadata('06'),
+  deepLinks('07'),
+  bip321('321');
+
+  /// Identifier advertised by NWC wallet services.
+  final String identifier;
+
+  const NwcExtension(this.identifier);
+
+  /// Returns the extension matching [identifier], or `null` when it is not
+  /// known by this version of NDK.
+  static NwcExtension? fromIdentifier(String identifier) {
+    final normalizedIdentifier = identifier.trim();
+    for (final extension in NwcExtension.values) {
+      if (extension.identifier == normalizedIdentifier) {
+        return extension;
+      }
+    }
+    return null;
+  }
+
+  /// Parses identifiers from NIP-47 fields.
+  ///
+  /// Each input may be a single identifier, as used by `get_info`, or a
+  /// space-separated list, as used by the kind 13194 info event.
+  static Set<NwcExtension> fromIdentifiers(Iterable<String> identifiers) {
+    final extensions = <NwcExtension>{};
+    for (final value in identifiers) {
+      for (final identifier in value.split(RegExp(r'\s+'))) {
+        final extension = fromIdentifier(identifier);
+        if (extension != null) {
+          extensions.add(extension);
+        }
+      }
+    }
+    return extensions;
+  }
+}

packages/ndk/lib/domain_layer/usecases/nwc/nwc.dart

@@ -117,16 +117,15 @@ class Nwc {
       if (encryptions.isNotEmpty) {
         connection.supportedEncryptions = encryptions.first.split(" ");
       }
+      connection.addSupportedExtensions(event.getTags('extensions'));
 
       await _subscribeToNotificationsAndResponses(connection);
 
       if (doGetInfoMethod &&
           (ignoreCapabilitiesCheck ||
               connection.permissions.contains(NwcMethod.GET_INFO.name))) {
         try {
-          await getInfo(connection, timeout: timeout).then((info) {
-            connection.info = info;
-          });
+          await getInfo(connection, timeout: timeout);
         } catch (e) {
           onError?.call("timeout get_info");
         }
@@ -416,11 +415,14 @@ class Nwc {
     NwcConnection connection, {
     Duration? timeout,
   }) async {
-    return _executeRequest<GetInfoResponse>(
+    final info = await _executeRequest<GetInfoResponse>(
       connection,
       GetInfoRequest(),
       timeout: timeout,
     );
+    connection.info = info;
+    connection.supportedExtensions.addAll(info.extensions);
+    return info;
   }
 
   /// Does a `get_balance` request

packages/ndk/lib/domain_layer/usecases/nwc/nwc_connection.dart

@@ -60,6 +60,20 @@ class NwcConnection {
   List<String> supportedVersions = ["0.0"];
   List<String> supportedEncryptions = ["nip04"];
 
+  /// Optional NWC extension specifications advertised by the wallet service.
+  Set<NwcExtension> supportedExtensions = {};
+
+  /// Adds extension identifiers advertised by an info event or `get_info`.
+  /// Unknown identifiers are ignored for forward compatibility.
+  void addSupportedExtensions(Iterable<String> identifiers) {
+    supportedExtensions.addAll(NwcExtension.fromIdentifiers(identifiers));
+  }
+
+  /// Whether the wallet service advertises support for [extension].
+  bool supportsExtension(NwcExtension extension) {
+    return supportedExtensions.contains(extension);
+  }
+
   Set<String> permissions = {};
   final LocalEventSignerFactory eventSignerFactory;
 

packages/ndk/lib/domain_layer/usecases/nwc/responses/get_info_response.dart

@@ -1,6 +1,7 @@
 // ignore_for_file: camel_case_types
 
 import 'package:ndk/domain_layer/usecases/nwc/consts/bitcoin_network.dart';
+import 'package:ndk/domain_layer/usecases/nwc/consts/nwc_extension.dart';
 
 import 'nwc_response.dart';
 
@@ -15,6 +16,9 @@ class GetInfoResponse extends NwcResponse {
   final List<String> methods;
   final List<String> notifications;
 
+  /// Optional NWC extensions supported by this connection.
+  final Set<NwcExtension> extensions;
+
   GetInfoResponse({
     required super.resultType,
     required this.alias,
@@ -25,8 +29,14 @@ class GetInfoResponse extends NwcResponse {
     required this.blockHash,
     required this.methods,
     required this.notifications,
+    this.extensions = const <NwcExtension>{},
   });
 
+  /// Whether the wallet service advertises support for [extension].
+  bool supportsExtension(NwcExtension extension) {
+    return extensions.contains(extension);
+  }
+
   factory GetInfoResponse.deserialize(Map<String, dynamic> input) {
     if (!input.containsKey('result')) {
       throw Exception('Invalid input');
@@ -35,6 +45,7 @@ class GetInfoResponse extends NwcResponse {
     Map<String, dynamic> result = input['result'] as Map<String, dynamic>;
     final methodsList = (result["methods"] as List?) ?? const [];
     final notificationsList = (result["notifications"] as List?) ?? const [];
+    final extensionsList = (result["extensions"] as List?) ?? const [];
 
     List<String> methods =
         methodsList.map((method) => method.toString()).toList();
@@ -53,6 +64,9 @@ class GetInfoResponse extends NwcResponse {
       blockHash: result['block_hash'] as String?,
       methods: methods,
       notifications: notifications,
+      extensions: NwcExtension.fromIdentifiers(
+        extensionsList.map((extension) => extension.toString()),
+      ),
     );
   }
 }

packages/ndk/lib/ndk.dart

@@ -41,6 +41,7 @@ export 'domain_layer/usecases/nwc/responses/lookup_invoice_response.dart';
 export 'domain_layer/usecases/nwc/nwc_connection.dart';
 export 'domain_layer/usecases/nwc/nostr_wallet_connect_uri.dart';
 export 'domain_layer/usecases/nwc/consts/nwc_method.dart';
+export 'domain_layer/usecases/nwc/consts/nwc_extension.dart';
 export 'domain_layer/usecases/nwc/consts/budget_renewal_period.dart';
 export 'domain_layer/entities/blossom_blobs.dart';
 export 'domain_layer/entities/blossom_strategies.dart';

packages/ndk/test/usecases/nwc/nwc_extension_test.dart

@@ -0,0 +1,84 @@
+import 'package:ndk/ndk.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('NwcExtension', () {
+    test('maps the registered NWC extension identifiers', () {
+      expect(NwcExtension.fromIdentifier('02'), NwcExtension.notifications);
+      expect(NwcExtension.fromIdentifier('03'), NwcExtension.holdInvoices);
+      expect(NwcExtension.fromIdentifier('04'), NwcExtension.keysend);
+      expect(
+        NwcExtension.fromIdentifier('05'),
+        NwcExtension.transactionHistory,
+      );
+      expect(
+        NwcExtension.fromIdentifier('06'),
+        NwcExtension.metadata,
+      );
+      expect(NwcExtension.fromIdentifier('07'), NwcExtension.deepLinks);
+      expect(
+        NwcExtension.fromIdentifier('321'),
+        NwcExtension.bip321,
+      );
+    });
+
+    test('parses space-separated values and ignores unknown extensions', () {
+      expect(
+        NwcExtension.fromIdentifiers(['02  03\t321', '999']),
+        {
+          NwcExtension.notifications,
+          NwcExtension.holdInvoices,
+          NwcExtension.bip321,
+        },
+      );
+      expect(NwcExtension.fromIdentifier('999'), isNull);
+    });
+  });
+
+  group('GetInfoResponse extensions', () {
+    test('deserializes and checks supported extensions', () {
+      final response = GetInfoResponse.deserialize({
+        'result_type': 'get_info',
+        'result': {
+          'alias': 'wallet',
+          'network': 'mainnet',
+          'methods': ['pay_invoice'],
+          'extensions': ['02', '05', 'unknown'],
+        },
+      });
+
+      expect(
+        response.extensions,
+        {NwcExtension.notifications, NwcExtension.transactionHistory},
+      );
+      expect(response.supportsExtension(NwcExtension.notifications), isTrue);
+      expect(response.supportsExtension(NwcExtension.holdInvoices), isFalse);
+    });
+
+    test('defaults to no extensions when the optional field is absent', () {
+      final response = GetInfoResponse.deserialize({
+        'result_type': 'get_info',
+        'result': {'alias': 'wallet', 'network': 'mainnet'},
+      });
+
+      expect(response.extensions, isEmpty);
+    });
+  });
+
+  test('NwcConnection can add and check advertised extensions', () {
+    final connection = NwcConnection(
+      NostrWalletConnectUri(
+        walletPubkey: 'wallet-pubkey',
+        relays: ['wss://relay.example.com'],
+        secret: 'secret',
+      ),
+      eventSignerFactory: const Bip340EventSignerFactory(),
+    );
+
+    connection.addSupportedExtensions(['02 04']);
+
+    expect(connection.supportsExtension(NwcExtension.notifications), isTrue);
+    expect(connection.supportsExtension(NwcExtension.keysend), isTrue);
+    expect(connection.supportsExtension(NwcExtension.holdInvoices), isFalse);
+  });
+}