diff --git a/lib/core/market/http_marketplace_repository.dart b/lib/core/market/http_marketplace_repository.dart
index 9c0cf2cf..ee4c29d7 100644
--- a/lib/core/market/http_marketplace_repository.dart
+++ b/lib/core/market/http_marketplace_repository.dart
@@ -3,6 +3,7 @@ import 'dart:convert';
 import 'dart:io';
 import 'package:archive/archive.dart';
 import 'package:crypto/crypto.dart';
+import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
 import 'package:path/path.dart' as p;
 import 'package:querya_desktop/core/extensions/extension_support.dart';
@@ -12,6 +13,7 @@ import 'package:querya_desktop/core/extensions/local_extension_registry.dart';
 import 'package:querya_desktop/core/extensions/models/extension_manifest.dart';
 import 'package:querya_desktop/core/extensions/models/extension_type.dart';
 import 'package:querya_desktop/core/security/archive_path_guard.dart';
+import 'marketplace_download_policy.dart';
 import 'marketplace_repository.dart';
 
 /// HTTP implementation of [MarketplaceRepository] connecting to MarketApi backend.
@@ -22,13 +24,46 @@ class HttpMarketplaceRepository implements MarketplaceRepository {
   HttpMarketplaceRepository({
     this.baseUrl = 'http://localhost:8000/api/v1',
     http.Client? client,
-  }) : _client = client ?? http.Client();
+    Iterable<String> extraTrustedDownloadHosts = const [],
+    bool allowLocalhostInDebug = kDebugMode,
+  })  : _client = client ?? http.Client(),
+        _allowLocalhostInDebug = allowLocalhostInDebug,
+        _trustedDownloadHosts = MarketplaceDownloadPolicy.trustedHostsFor(
+          apiBaseUrl: baseUrl,
+          extraTrustedHosts: extraTrustedDownloadHosts,
+        ) {
+    _validateApiBaseUrl();
+  }
 
   final String baseUrl;
   final http.Client _client;
+  final bool _allowLocalhostInDebug;
+  final Set<String> _trustedDownloadHosts;
+
+  void _validateApiBaseUrl() {
+    if (!MarketplaceDownloadPolicy.isAllowedApiBaseUrl(
+      baseUrl,
+      allowLocalhostInDebug: _allowLocalhostInDebug,
+    )) {
+      throw MarketplaceException(
+        'Marketplace API base URL is not allowed: $baseUrl',
+      );
+    }
+  }
+
+  void _validateDownloadUrl(Uri uri) {
+    if (!MarketplaceDownloadPolicy.isAllowedDownloadUrl(
+      uri,
+      trustedHosts: _trustedDownloadHosts,
+      allowLocalhostInDebug: _allowLocalhostInDebug,
+    )) {
+      throw MarketplaceException('Download URL is not allowed: $uri');
+    }
+  }
 
   @override
   Future<List<ExtensionManifest>> getTrending({ExtensionType? type}) async {
+    _validateApiBaseUrl();
     final uri = Uri.parse('$baseUrl/extensions/trending').replace(
       queryParameters: type != null ? {'type': type.value} : null,
     );
@@ -42,6 +77,7 @@ class HttpMarketplaceRepository implements MarketplaceRepository {
 
   @override
   Future<List<ExtensionManifest>> search(String query, {ExtensionType? type}) async {
+    _validateApiBaseUrl();
     final uri = Uri.parse('$baseUrl/extensions/search').replace(
       queryParameters: {
         'q': query.trim(),
@@ -62,6 +98,7 @@ class HttpMarketplaceRepository implements MarketplaceRepository {
     if (uri == null) {
       throw MarketplaceException('Invalid download URL: $url');
     }
+    _validateDownloadUrl(uri);
 
     final request = http.Request('GET', uri);
     final response = await _client.send(request).timeout(const Duration(seconds: 30));
diff --git a/lib/core/market/marketplace_download_policy.dart b/lib/core/market/marketplace_download_policy.dart
new file mode 100644
index 00000000..be5edb04
--- /dev/null
+++ b/lib/core/market/marketplace_download_policy.dart
@@ -0,0 +1,86 @@
+import 'package:flutter/foundation.dart';
+
+import '../theme/theme_remote_install_policy.dart';
+
+/// HTTPS and host allowlist rules for marketplace API and artifact downloads.
+abstract final class MarketplaceDownloadPolicy {
+  /// Hosts permitted for extension archive downloads (API host + extras).
+  static Set<String> trustedHostsFor({
+    required String apiBaseUrl,
+    Iterable<String> extraTrustedHosts = const [],
+  }) {
+    final hosts = <String>{};
+    final apiHost = Uri.tryParse(apiBaseUrl.trim())?.host.toLowerCase();
+    if (apiHost != null && apiHost.isNotEmpty) {
+      hosts.add(apiHost);
+    }
+    for (final host in extraTrustedHosts) {
+      final normalized = host.trim().toLowerCase();
+      if (normalized.isNotEmpty) {
+        hosts.add(normalized);
+      }
+    }
+    return hosts;
+  }
+
+  /// Whether [baseUrl] may be used for MarketApi REST calls.
+  static bool isAllowedApiBaseUrl(
+    String baseUrl, {
+    bool allowLocalhostInDebug = kDebugMode,
+  }) {
+    final uri = Uri.tryParse(baseUrl.trim());
+    if (uri == null || !uri.hasAuthority || uri.host.isEmpty) {
+      return false;
+    }
+
+    if (uri.scheme == 'https') {
+      return ThemeRemoteInstallPolicy.isAllowedUrl(
+        uri,
+        allowLocalhostInDebug: allowLocalhostInDebug,
+      );
+    }
+
+    if (allowLocalhostInDebug && uri.scheme == 'http') {
+      return _isDebugLocalHttpHost(uri.host);
+    }
+
+    return false;
+  }
+
+  /// Whether [uri] may be used to download an extension archive.
+  static bool isAllowedDownloadUrl(
+    Uri uri, {
+    required Set<String> trustedHosts,
+    bool allowLocalhostInDebug = kDebugMode,
+  }) {
+    if (!uri.hasAuthority || uri.host.isEmpty) {
+      return false;
+    }
+
+    final host = uri.host.toLowerCase();
+    if (!trustedHosts.contains(host)) {
+      return false;
+    }
+
+    if (uri.scheme == 'https') {
+      return ThemeRemoteInstallPolicy.isAllowedUrl(
+        uri,
+        allowLocalhostInDebug: allowLocalhostInDebug,
+      );
+    }
+
+    if (allowLocalhostInDebug && uri.scheme == 'http') {
+      return _isDebugLocalHttpHost(host);
+    }
+
+    return false;
+  }
+
+  static bool _isDebugLocalHttpHost(String host) {
+    final probe = Uri.parse('https://$host/');
+    return ThemeRemoteInstallPolicy.isAllowedUrl(
+      probe,
+      allowLocalhostInDebug: true,
+    );
+  }
+}
diff --git a/test/core/market/marketplace_download_policy_test.dart b/test/core/market/marketplace_download_policy_test.dart
new file mode 100644
index 00000000..547e7490
--- /dev/null
+++ b/test/core/market/marketplace_download_policy_test.dart
@@ -0,0 +1,90 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:querya_desktop/core/market/marketplace_download_policy.dart';
+
+void main() {
+  group('MarketplaceDownloadPolicy', () {
+    test('trustedHostsFor includes API host and extras', () {
+      expect(
+        MarketplaceDownloadPolicy.trustedHostsFor(
+          apiBaseUrl: 'https://api.example.com/api/v1',
+          extraTrustedHosts: ['cdn.example.com'],
+        ),
+        {'api.example.com', 'cdn.example.com'},
+      );
+    });
+
+    test('isAllowedApiBaseUrl allows public https API', () {
+      expect(
+        MarketplaceDownloadPolicy.isAllowedApiBaseUrl(
+          'https://api.example.com/api/v1',
+          allowLocalhostInDebug: false,
+        ),
+        isTrue,
+      );
+    });
+
+    test('isAllowedApiBaseUrl rejects cleartext in release mode', () {
+      expect(
+        MarketplaceDownloadPolicy.isAllowedApiBaseUrl(
+          'http://localhost:8000/api/v1',
+          allowLocalhostInDebug: false,
+        ),
+        isFalse,
+      );
+    });
+
+    test('isAllowedApiBaseUrl allows localhost http in debug mode', () {
+      expect(
+        MarketplaceDownloadPolicy.isAllowedApiBaseUrl(
+          'http://localhost:8000/api/v1',
+          allowLocalhostInDebug: true,
+        ),
+        isTrue,
+      );
+    });
+
+    test('isAllowedDownloadUrl rejects untrusted host', () {
+      expect(
+        MarketplaceDownloadPolicy.isAllowedDownloadUrl(
+          Uri.parse('https://evil.example.com/pkg.zip'),
+          trustedHosts: {'api.example.com'},
+          allowLocalhostInDebug: false,
+        ),
+        isFalse,
+      );
+    });
+
+    test('isAllowedDownloadUrl rejects private IPs in release mode', () {
+      expect(
+        MarketplaceDownloadPolicy.isAllowedDownloadUrl(
+          Uri.parse('https://192.168.1.10/pkg.zip'),
+          trustedHosts: {'192.168.1.10'},
+          allowLocalhostInDebug: false,
+        ),
+        isFalse,
+      );
+    });
+
+    test('isAllowedDownloadUrl rejects file scheme', () {
+      expect(
+        MarketplaceDownloadPolicy.isAllowedDownloadUrl(
+          Uri.parse('file:///etc/passwd'),
+          trustedHosts: {'localhost'},
+          allowLocalhostInDebug: true,
+        ),
+        isFalse,
+      );
+    });
+
+    test('isAllowedDownloadUrl allows trusted public https host', () {
+      expect(
+        MarketplaceDownloadPolicy.isAllowedDownloadUrl(
+          Uri.parse('https://cdn.example.com/pkg.zip'),
+          trustedHosts: {'cdn.example.com'},
+          allowLocalhostInDebug: false,
+        ),
+        isTrue,
+      );
+    });
+  });
+}
diff --git a/test/core/market/marketplace_repository_test.dart b/test/core/market/marketplace_repository_test.dart
index e3aeeda1..4e23cfd5 100644
--- a/test/core/market/marketplace_repository_test.dart
+++ b/test/core/market/marketplace_repository_test.dart
@@ -355,6 +355,35 @@ void main() {
         )),
       );
     });
+
+    test('download rejects disallowed URLs when release policy is enforced',
+        () async {
+      final repo = HttpMarketplaceRepository(
+        baseUrl: 'https://cdn.example.com/api/v1',
+        extraTrustedDownloadHosts: ['cdn.example.com'],
+        allowLocalhostInDebug: false,
+        client: MockClient((request) async => http.Response('', 200)),
+      );
+
+      expect(
+        () => repo.download('http://cdn.example.com/test.zip'),
+        throwsA(isA<MarketplaceException>().having(
+          (e) => e.message,
+          'message',
+          contains('Download URL is not allowed'),
+        )),
+      );
+
+      expect(
+        () => repo.download('https://127.0.0.1/test.zip'),
+        throwsA(isA<MarketplaceException>()),
+      );
+
+      expect(
+        () => repo.download('file:///tmp/test.zip'),
+        throwsA(isA<MarketplaceException>()),
+      );
+    });
   });
 }