diff --git a/CHANGELOG.md b/CHANGELOG.md
index b418fe2f..feadc289 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,29 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.4.9] - 2026-07-10
+
+PostgreSQL connection reliability and TLS improvements, plus menu and URI import polish.
+
+### Added
+
+- **Connection → New Connection from URL (#228)** — create a connection by pasting a database URI for PostgreSQL, MySQL, MongoDB, Redis, or SQLite. The URL is parsed, validated, and saved to `LocalDb`.
+- **Help → About & Documentation (#229)** — added an About dialog showing the app version, MIT license, and repository link; the Documentation menu item opens the project docs in the browser.
+- **PostgreSQL SSL certificate file pickers (#260)** — added optional file pickers for `sslrootcert`, `sslcert`, and `sslkey` in the PostgreSQL connection form. Paths are merged into the connection URI or used to generate a URI when in host/port mode.
+
+### Fixed
+
+- **PostgreSQL URL parser / SSL (#249, #253, #254, #257, #258)** — validate `sslmode` (reject `prefer` and unknown values), correctly map `useSSL` for `disable`/`require`/`verify-ca`/`verify-full`, use driver default ports when omitted, and preserve display host/port for URI-only connections.
+- **PostgreSQL connection error reporting (#250, #251, #252)** — `testConnection` now returns the underlying error message, the form shows the real failure reason, and the connection tree displays the full exception text instead of a generic "Error" label.
+- **PostgreSQL connection error typing (#256, #259)** — `connect()` throws `PostgresConnectionException` with the original cause and stack trace; the pool wraps unexpected factory errors in the same typed exception.
+
+## [0.4.8] - 2026-07-08
+
+### Fixed
+
+- **SQLite / RETURNING clause support (#243)** — support RETURNING clauses for INSERT, UPDATE, and DELETE DML queries in the SQLite database driver, returning the resulting rows to the client.
+- **Security / MySQL Injection Fix (#241)** — replaced manual escaping and string concatenation in schema introspection methods (`listViews`, `listColumnNames`, `listTables`) in the MySQL database driver with parameterized queries using parameter binding.
+
 ## [0.4.7-a] - 2026-06-22
 
 ### Added
diff --git a/docs/planned-0.4.8.md b/docs/planned-0.4.8.md
new file mode 100644
index 00000000..96898554
--- /dev/null
+++ b/docs/planned-0.4.8.md
@@ -0,0 +1,14 @@
+# Milestone 0.4.8: Extension Manager UI
+
+**Theme**: Разработка пользовательского интерфейса менеджера расширений (Marketplace Client). Мы создаем вкладку в настройках или отдельное окно, где пользователь сможет просматривать установленные расширения, искать новые в маркетплейсе, скачивать, обновлять и удалять их. Бэкенд маркетплейса пока будет замокан или использоваться статический JSON для тестов.
+
+| ID | Scope | Summary |
+|----|-------|---------|
+| **UI-EXT-1** | `ui`, `extensions` | **Extension Manager View** — Создать страницу/диалог для менеджера расширений. Вкладки: Installed, Marketplace, Updates. |
+| **UI-EXT-2** | `ui`, `extensions` | **Extension Card Component** — Виджет карточки расширения (иконка, название, автор, версия, описание, кнопка Install/Uninstall). |
+| **UI-EXT-3** | `core`, `extensions` | **MarketplaceRepository Mock** — Реализовать моковый репозиторий для симуляции запросов к API маркетплейса (пока бэкенд не готов). |
+| **UI-EXT-4** | `core`, `extensions` | **Download & Install Flow** — Интеграция UI с процессом скачивания (прогресс-бар), валидации sha256 и распаковки в `~/.querya/extensions/`. |
+| **UI-EXT-5** | `core`, `extensions` | **Uninstall & Update** — Механизмы удаления и обновления локальных расширений через UI менеджера. |
+
+## Заметки
+Этот релиз фокусируется на пользовательском опыте (UX/UI) взаимодействия с расширениями. Мы не реализуем сам Marketplace API (он будет в 0.5.0), но закладываем сетевой слой клиента (`MarketplaceRepository`) и мокаем данные для того, чтобы UI можно было использовать и тестировать. Под капотом используются механизмы локального обнаружения, заложенные в релизе 0.4.7.
diff --git a/lib/core/app/app_links.dart b/lib/core/app/app_links.dart
new file mode 100644
index 00000000..1d6cefd9
--- /dev/null
+++ b/lib/core/app/app_links.dart
@@ -0,0 +1,9 @@
+/// Canonical external URLs for Querya Desktop.
+abstract final class AppLinks {
+  static const repository =
+      'https://github.com/QueryaHub/Querya-Desktop';
+  static const documentation =
+      'https://github.com/QueryaHub/Querya-Desktop/blob/main/docs/README.md';
+  static const license =
+      'https://github.com/QueryaHub/Querya-Desktop/blob/main/LICENSE';
+}
diff --git a/lib/core/app/external_link.dart b/lib/core/app/external_link.dart
new file mode 100644
index 00000000..49e13bef
--- /dev/null
+++ b/lib/core/app/external_link.dart
@@ -0,0 +1,13 @@
+import 'package:querya_desktop/core/app/app_links.dart';
+import 'package:url_launcher/url_launcher.dart';
+
+/// Opens [url] in the system browser.
+Future<bool> launchExternalUrl(String url) {
+  final uri = Uri.parse(url);
+  return launchUrl(uri, mode: LaunchMode.externalApplication);
+}
+
+Future<bool> launchRepositoryUrl() => launchExternalUrl(AppLinks.repository);
+
+Future<bool> launchDocumentationUrl() =>
+    launchExternalUrl(AppLinks.documentation);
diff --git a/lib/core/database/mysql_connection.dart b/lib/core/database/mysql_connection.dart
index df453aeb..5c4c4c6f 100644
--- a/lib/core/database/mysql_connection.dart
+++ b/lib/core/database/mysql_connection.dart
@@ -76,9 +76,7 @@ class MysqlConnection {
   bool get _usesConnectionString =>
       connectionString != null && connectionString!.trim().isNotEmpty;
 
-  static String _escapeSqlString(String s) {
-    return s.replaceAll(r'\', r'\\').replaceAll("'", "''");
-  }
+
 
   /// MySQL identifier quoting (backticks).
   static String quoteIdentifier(String id) {
@@ -284,11 +282,11 @@ class MysqlConnection {
     if (!isConnected || _conn == null) {
       throw StateError('Not connected to MySQL');
     }
-    final s = _escapeSqlString(schema);
     final rs = await execute(
       'SELECT TABLE_NAME FROM information_schema.TABLES '
-      "WHERE TABLE_SCHEMA = '$s' AND TABLE_TYPE = 'VIEW' "
+      "WHERE TABLE_SCHEMA = :schema AND TABLE_TYPE = 'VIEW' "
       'ORDER BY TABLE_NAME',
+      {'schema': schema},
     );
     return rs.rows.map((r) => r.colAt(0)!).toList();
   }
@@ -301,12 +299,14 @@ class MysqlConnection {
     if (!isConnected || _conn == null) {
       throw StateError('Not connected to MySQL');
     }
-    final d = _escapeSqlString(database);
-    final t = _escapeSqlString(table);
     final rs = await execute(
       'SELECT COLUMN_NAME FROM information_schema.COLUMNS '
-      "WHERE TABLE_SCHEMA = '$d' AND TABLE_NAME = '$t' "
+      "WHERE TABLE_SCHEMA = :database AND TABLE_NAME = :table "
       'ORDER BY ORDINAL_POSITION',
+      {
+        'database': database,
+        'table': table,
+      },
     );
     return rs.rows.map((r) => r.colAt(0)!).toList();
   }
@@ -316,11 +316,11 @@ class MysqlConnection {
     if (!isConnected || _conn == null) {
       throw StateError('Not connected to MySQL');
     }
-    final s = _escapeSqlString(schema);
     final rs = await execute(
       'SELECT TABLE_NAME FROM information_schema.TABLES '
-      "WHERE TABLE_SCHEMA = '$s' AND TABLE_TYPE = 'BASE TABLE' "
+      "WHERE TABLE_SCHEMA = :schema AND TABLE_TYPE = 'BASE TABLE' "
       'ORDER BY TABLE_NAME',
+      {'schema': schema},
     );
     return rs.rows.map((r) => r.colAt(0)!).toList();
   }
diff --git a/lib/core/database/postgres_connection.dart b/lib/core/database/postgres_connection.dart
index 752cc0f5..8aae9434 100644
--- a/lib/core/database/postgres_connection.dart
+++ b/lib/core/database/postgres_connection.dart
@@ -137,10 +137,17 @@ class PostgresConnection {
         );
       }
       _isConnected = true;
-    } catch (e) {
+    } catch (e, st) {
       _isConnected = false;
       _conn = null;
-      rethrow;
+      Error.throwWithStackTrace(
+        PostgresConnectionException(
+          'Failed to connect to PostgreSQL${name.isNotEmpty ? ' ($name)' : ''}: $e',
+          cause: e,
+          stackTrace: st,
+        ),
+        st,
+      );
     }
   }
 
@@ -174,16 +181,19 @@ class PostgresConnection {
     );
   }
 
-  Future<bool> testConnection() async {
+  /// Tests connectivity and returns a result with an optional error message.
+  Future<({bool ok, String? error})> testConnection() async {
     try {
       await connect();
       if (_conn != null) {
         await _conn!.execute('SELECT 1');
-        return true;
+        return (ok: true, error: null);
       }
-      return false;
-    } catch (_) {
-      return false;
+      return (ok: false, error: 'Connection could not be established.');
+    } on PostgresConnectionException catch (e) {
+      return (ok: false, error: e.message);
+    } catch (e) {
+      return (ok: false, error: e.toString());
     } finally {
       await disconnect();
     }
@@ -769,8 +779,16 @@ class PostgresSequenceDetails {
 }
 
 class PostgresConnectionException implements Exception {
-  PostgresConnectionException(this.message);
+  PostgresConnectionException(
+    this.message, {
+    this.cause,
+    this.stackTrace,
+  });
+
   final String message;
+  final Object? cause;
+  final StackTrace? stackTrace;
+
   @override
   String toString() => message;
 }
diff --git a/lib/core/database/postgres_connection_pool.dart b/lib/core/database/postgres_connection_pool.dart
index 73c71433..e4fa225d 100644
--- a/lib/core/database/postgres_connection_pool.dart
+++ b/lib/core/database/postgres_connection_pool.dart
@@ -87,10 +87,23 @@ class PostgresConnectionPool {
 
     _evictIfNeededBeforeNewSlot();
 
-    final conn = await createAndConnect(row, database: database, mode: mode);
-    entry = _PoolEntry(conn)..refs = 1;
-    _pool[k] = entry;
-    return PgLease._(this, k, conn);
+    try {
+      final conn = await createAndConnect(row, database: database, mode: mode);
+      entry = _PoolEntry(conn)..refs = 1;
+      _pool[k] = entry;
+      return PgLease._(this, k, conn);
+    } on PostgresConnectionException {
+      rethrow;
+    } catch (e, st) {
+      Error.throwWithStackTrace(
+        PostgresConnectionException(
+          'Failed to acquire PostgreSQL connection for database "$database": $e',
+          cause: e,
+          stackTrace: st,
+        ),
+        st,
+      );
+    }
   }
 
   /// Drops idle LRU slots until there is room for one more key.
diff --git a/lib/core/database/sqlite_connection.dart b/lib/core/database/sqlite_connection.dart
index d4585d4a..f61e7b76 100644
--- a/lib/core/database/sqlite_connection.dart
+++ b/lib/core/database/sqlite_connection.dart
@@ -97,18 +97,21 @@ class SqliteConnection {
         .toLowerCase();
     
     // SQLite can execute PRAGMA, SELECT, EXPLAIN statements, which return data
-    final isQuery = sqlLower.startsWith('select') ||
+    final isReadOnlyQuery = sqlLower.startsWith('select') ||
         sqlLower.startsWith('pragma') ||
         sqlLower.startsWith('explain') ||
         sqlLower.startsWith('with') ||
         sqlLower.startsWith('values');
 
-    if (isQuery) {
+    final hasReturning = RegExp(r'\breturning\b').hasMatch(sqlLower);
+
+    if (readOnly && !isReadOnlyQuery) {
+      throw StateError('Database connection is read-only');
+    }
+
+    if (isReadOnlyQuery || hasReturning) {
       return await _db!.rawQuery(sql, arguments);
     } else {
-      if (readOnly) {
-        throw StateError('Database connection is read-only');
-      }
       await _db!.execute(sql, arguments);
       return [];
     }
diff --git a/lib/core/extensions/models/extension_manifest.dart b/lib/core/extensions/models/extension_manifest.dart
index cafa2e04..efd9a6e1 100644
--- a/lib/core/extensions/models/extension_manifest.dart
+++ b/lib/core/extensions/models/extension_manifest.dart
@@ -1,6 +1,9 @@
+import '../../theme/theme_definition.dart';
 import 'extension_type.dart';
 
 class ExtensionManifest {
+  static const typeTheme = ExtensionType.theme;
+
   final String id;
   final String name;
   final String version;
@@ -11,6 +14,13 @@ class ExtensionManifest {
   final String? icon;
   final String? description;
   final String? installPath;
+  final String? downloadUrl;
+  final String? sha256Checksum;
+  final String? author;
+  final String? homepage;
+  final String? license;
+  final String? preview;
+  final List<String> tags;
 
   const ExtensionManifest({
     required this.id,
@@ -23,20 +33,62 @@ class ExtensionManifest {
     this.icon,
     this.description,
     this.installPath,
+    this.downloadUrl,
+    this.sha256Checksum,
+    this.author,
+    this.homepage,
+    this.license,
+    this.preview,
+    this.tags = const [],
   });
 
+  /// Maps a registry [ThemeDefinition] into marketplace field names.
+  factory ExtensionManifest.fromThemeDefinition(
+    ThemeDefinition definition, {
+    String downloadUrl = '',
+    String sha256Checksum = '',
+    ExtensionType type = typeTheme,
+  }) {
+    final metadata = definition.metadata;
+    return ExtensionManifest(
+      id: definition.id,
+      name: definition.name,
+      publisher: metadata?.author ?? 'Unknown',
+      type: type,
+      version: metadata?.version ?? '0.0.0',
+      engines: const {'querya_desktop': '^0.4.7'},
+      downloadUrl: downloadUrl,
+      sha256Checksum: sha256Checksum.isNotEmpty
+          ? sha256Checksum
+          : (definition.contentHash ?? ''),
+      author: metadata?.author,
+      description: metadata?.description,
+      homepage: metadata?.homepage,
+      license: metadata?.license,
+      preview: metadata?.preview,
+      tags: metadata?.tags ?? const [],
+    );
+  }
+
   factory ExtensionManifest.fromJson(Map<String, dynamic> json, {String? installPath}) {
     return ExtensionManifest(
       id: json['id'] as String,
       name: json['name'] as String,
-      version: json['version'] as String,
-      publisher: json['publisher'] as String,
-      type: ExtensionType.fromString(json['type'] as String),
+      version: json['version'] as String? ?? '0.0.0',
+      publisher: json['publisher'] as String? ?? json['author'] as String? ?? 'Unknown',
+      type: ExtensionType.fromString(json['type'] as String? ?? ''),
       engines: Map<String, String>.from(json['engines'] as Map? ?? {}),
       main: json['main'] as String?,
       icon: json['icon'] as String?,
       description: json['description'] as String?,
       installPath: installPath,
+      downloadUrl: json['downloadUrl'] as String?,
+      sha256Checksum: json['sha256Checksum'] as String? ?? json['sha256'] as String?,
+      author: json['author'] as String?,
+      homepage: json['homepage'] as String?,
+      license: json['license'] as String?,
+      preview: json['preview'] as String?,
+      tags: List<String>.from(json['tags'] as List? ?? []),
     );
   }
 
@@ -51,6 +103,13 @@ class ExtensionManifest {
       if (main != null) 'main': main,
       if (icon != null) 'icon': icon,
       if (description != null) 'description': description,
+      if (downloadUrl != null) 'downloadUrl': downloadUrl,
+      if (sha256Checksum != null) 'sha256Checksum': sha256Checksum,
+      if (author != null) 'author': author,
+      if (homepage != null) 'homepage': homepage,
+      if (license != null) 'license': license,
+      if (preview != null) 'preview': preview,
+      if (tags.isNotEmpty) 'tags': tags,
     };
   }
 }
diff --git a/lib/core/market/extension_manifest.dart b/lib/core/market/extension_manifest.dart
index be1edec8..4cbed8b3 100644
--- a/lib/core/market/extension_manifest.dart
+++ b/lib/core/market/extension_manifest.dart
@@ -1,65 +1,2 @@
-import '../theme/theme_definition.dart';
+export 'package:querya_desktop/core/extensions/models/extension_manifest.dart';
 
-/// Marketplace listing model (future `MarketplaceClient` response shape).
-///
-/// See [docs/market-tech.md](https://github.com/QueryaHub/Querya-Desktop/blob/main/docs/market-tech.md).
-class ExtensionManifest {
-  const ExtensionManifest({
-    required this.id,
-    required this.name,
-    required this.type,
-    required this.version,
-    required this.downloadUrl,
-    required this.sha256Checksum,
-    this.author,
-    this.description,
-    this.homepage,
-    this.license,
-    this.preview,
-    this.tags = const [],
-  });
-
-  static const typeTheme = 'theme';
-
-  final String id;
-  final String name;
-  final String type;
-  final String version;
-  final String downloadUrl;
-  final String sha256Checksum;
-  final String? author;
-  final String? description;
-  final String? homepage;
-  final String? license;
-  final String? preview;
-  final List<String> tags;
-
-  /// Maps a registry [ThemeDefinition] into marketplace field names.
-  ///
-  /// [downloadUrl] and [sha256Checksum] are required for remote install (TP-F4);
-  /// pass empty strings when building a local-only listing stub.
-  factory ExtensionManifest.fromThemeDefinition(
-    ThemeDefinition definition, {
-    String downloadUrl = '',
-    String sha256Checksum = '',
-    String type = typeTheme,
-  }) {
-    final metadata = definition.metadata;
-    return ExtensionManifest(
-      id: definition.id,
-      name: definition.name,
-      type: type,
-      version: metadata?.version ?? '0.0.0',
-      downloadUrl: downloadUrl,
-      sha256Checksum: sha256Checksum.isNotEmpty
-          ? sha256Checksum
-          : (definition.contentHash ?? ''),
-      author: metadata?.author,
-      description: metadata?.description,
-      homepage: metadata?.homepage,
-      license: metadata?.license,
-      preview: metadata?.preview,
-      tags: metadata?.tags ?? const [],
-    );
-  }
-}
diff --git a/lib/core/market/http_marketplace_repository.dart b/lib/core/market/http_marketplace_repository.dart
new file mode 100644
index 00000000..03d7a7e9
--- /dev/null
+++ b/lib/core/market/http_marketplace_repository.dart
@@ -0,0 +1,204 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+import 'package:archive/archive.dart';
+import 'package:crypto/crypto.dart';
+import 'package:http/http.dart' as http;
+import 'package:path/path.dart' as p;
+import 'package:querya_desktop/core/extensions/extension_paths.dart';
+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 'marketplace_repository.dart';
+
+class MarketplaceException implements Exception {
+  MarketplaceException(this.message);
+  final String message;
+  @override
+  String toString() => 'MarketplaceException: $message';
+}
+
+/// HTTP implementation of [MarketplaceRepository] connecting to MarketApi backend.
+///
+/// Implements secure downloading with SHA256 checksum verification and safe
+/// archive extraction preventing Path Traversal and Zip Bomb vulnerabilities (Issue #242).
+class HttpMarketplaceRepository implements MarketplaceRepository {
+  HttpMarketplaceRepository({
+    this.baseUrl = 'http://localhost:8000/api/v1',
+    http.Client? client,
+  }) : _client = client ?? http.Client();
+
+  final String baseUrl;
+  final http.Client _client;
+
+  @override
+  Future<List<ExtensionManifest>> getTrending({ExtensionType? type}) async {
+    final uri = Uri.parse('$baseUrl/extensions/trending').replace(
+      queryParameters: type != null ? {'type': type.value} : null,
+    );
+    final response = await _client.get(uri).timeout(const Duration(seconds: 15));
+    if (response.statusCode != 200) {
+      throw MarketplaceException('Failed to load trending extensions (HTTP ${response.statusCode})');
+    }
+    final List<dynamic> data = jsonDecode(response.body) as List<dynamic>;
+    return data.map((json) => ExtensionManifest.fromJson(json as Map<String, dynamic>)).toList();
+  }
+
+  @override
+  Future<List<ExtensionManifest>> search(String query, {ExtensionType? type}) async {
+    final uri = Uri.parse('$baseUrl/extensions/search').replace(
+      queryParameters: {
+        'q': query.trim(),
+        if (type != null) 'type': type.value,
+      },
+    );
+    final response = await _client.get(uri).timeout(const Duration(seconds: 15));
+    if (response.statusCode != 200) {
+      throw MarketplaceException('Search failed (HTTP ${response.statusCode})');
+    }
+    final List<dynamic> data = jsonDecode(response.body) as List<dynamic>;
+    return data.map((json) => ExtensionManifest.fromJson(json as Map<String, dynamic>)).toList();
+  }
+
+  @override
+  Future<File> download(String url, {void Function(double)? onProgress}) async {
+    final uri = Uri.tryParse(url);
+    if (uri == null) {
+      throw MarketplaceException('Invalid download URL: $url');
+    }
+
+    final request = http.Request('GET', uri);
+    final response = await _client.send(request).timeout(const Duration(seconds: 30));
+    if (response.statusCode != 200) {
+      throw MarketplaceException('Download failed with HTTP status ${response.statusCode}');
+    }
+
+    final contentLength = response.contentLength ?? 0;
+    int received = 0;
+
+    final tmpDir = Directory.systemTemp;
+    final file = File(p.join(tmpDir.path, 'querya_ext_${DateTime.now().millisecondsSinceEpoch}.zip'));
+    final sink = file.openWrite();
+
+    try {
+      await response.stream.forEach((chunk) {
+        sink.add(chunk);
+        received += chunk.length;
+        if (contentLength > 0 && onProgress != null) {
+          onProgress(received / contentLength);
+        }
+      });
+    } finally {
+      await sink.close();
+    }
+
+    if (onProgress != null && contentLength == 0) {
+      onProgress(1.0);
+    }
+
+    return file;
+  }
+
+  @override
+  Future<void> install(
+    ExtensionManifest manifest, {
+    void Function(double)? onProgress,
+  }) async {
+    final downloadUrl = manifest.downloadUrl;
+    if (downloadUrl == null || downloadUrl.trim().isEmpty) {
+      throw MarketplaceException('Extension manifest is missing downloadUrl');
+    }
+
+    // Step 1: Download archive with progress reporting (up to 80% of total progress)
+    final archiveFile = await download(
+      downloadUrl,
+      onProgress: (p) => onProgress?.call(p * 0.8),
+    );
+
+    try {
+      // Step 2: SHA-256 Integrity Verification (Critical Security Check)
+      if (manifest.sha256Checksum != null && manifest.sha256Checksum!.trim().isNotEmpty) {
+        final bytes = await archiveFile.readAsBytes();
+        final actualSha256 = sha256.convert(bytes).toString().toLowerCase();
+        final expectedSha256 = manifest.sha256Checksum!.trim().toLowerCase();
+        if (actualSha256 != expectedSha256) {
+          throw MarketplaceException(
+            'SHA256 checksum mismatch for "${manifest.id}". Expected: $expectedSha256, Actual: $actualSha256. Installation aborted.',
+          );
+        }
+      }
+
+      onProgress?.call(0.85);
+
+      // Step 3: Safe Archive Extraction (Preventing Path Traversal / Zip Bomb - Issue #242)
+      final bytes = await archiveFile.readAsBytes();
+      final archive = ZipDecoder().decodeBytes(bytes);
+
+      final dir = await ExtensionPaths.extensionsDirectory();
+      final extDir = Directory(p.join(dir.path, manifest.id));
+      if (!await extDir.exists()) {
+        await extDir.create(recursive: true);
+      }
+
+      final extDirPath = p.normalize(extDir.path);
+
+      for (final file in archive) {
+        final filename = file.name;
+        // Check for Path Traversal attempts
+        if (filename.contains('..') || filename.startsWith('/') || filename.startsWith('\\')) {
+          throw MarketplaceException('Security violation: Path traversal detected in archive entry "$filename"');
+        }
+
+        final targetPath = p.normalize(p.join(extDirPath, filename));
+        if (!targetPath.startsWith(extDirPath)) {
+          throw MarketplaceException('Security violation: Extraction path out of bounds "$filename"');
+        }
+
+        if (file.isFile) {
+          final outFile = File(targetPath);
+          await outFile.create(recursive: true);
+          await outFile.writeAsBytes(file.content as List<int>);
+        } else {
+          await Directory(targetPath).create(recursive: true);
+        }
+      }
+
+      onProgress?.call(0.95);
+
+      // Step 4: Write/Update manifest.json in the extension directory
+      final manifestFile = File(p.join(extDir.path, 'manifest.json'));
+      const encoder = JsonEncoder.withIndent('  ');
+      await manifestFile.writeAsString(encoder.convert(manifest.toJson()));
+
+      // Step 5: Reload local extension registry
+      await LocalExtensionRegistry.instance.reload();
+      onProgress?.call(1.0);
+    } finally {
+      if (await archiveFile.exists()) {
+        await archiveFile.delete();
+      }
+    }
+  }
+
+  @override
+  Future<void> uninstall(String extensionId) async {
+    final manifest = LocalExtensionRegistry.instance.manifests
+        .where((e) => e.id == extensionId)
+        .firstOrNull;
+
+    if (manifest != null && manifest.installPath != null) {
+      final extDir = Directory(manifest.installPath!);
+      if (await extDir.exists()) {
+        await extDir.delete(recursive: true);
+      }
+    } else {
+      final dir = await ExtensionPaths.extensionsDirectory();
+      final extDir = Directory(p.join(dir.path, extensionId));
+      if (await extDir.exists()) {
+        await extDir.delete(recursive: true);
+      }
+    }
+
+    await LocalExtensionRegistry.instance.reload();
+  }
+}
diff --git a/lib/core/market/marketplace_client.dart b/lib/core/market/marketplace_client.dart
index 1c450cb0..828bbf60 100644
--- a/lib/core/market/marketplace_client.dart
+++ b/lib/core/market/marketplace_client.dart
@@ -1,4 +1,5 @@
 import 'extension_manifest.dart';
+import 'marketplace_repository.dart';
 
 /// Future marketplace API client (mockable until backend exists).
 ///
@@ -10,24 +11,19 @@ abstract class MarketplaceClient {
   });
 }
 
-/// In-memory placeholder for local development and tests.
+/// In-memory placeholder for local development and tests that delegates to [MarketplaceRepository].
 class MockMarketplaceClient implements MarketplaceClient {
   MockMarketplaceClient({List<ExtensionManifest>? seed})
-      : _items = List<ExtensionManifest>.from(seed ?? const []);
+      : _repository = MockMarketplaceRepository(seed: seed);
 
-  final List<ExtensionManifest> _items;
+  final MockMarketplaceRepository _repository;
 
   @override
   Future<List<ExtensionManifest>> searchExtensions({
     required String query,
     String? type,
   }) async {
-    final normalized = query.trim().toLowerCase();
-    return _items.where((item) {
-      if (type != null && item.type != type) return false;
-      if (normalized.isEmpty) return true;
-      return item.name.toLowerCase().contains(normalized) ||
-          item.id.toLowerCase().contains(normalized);
-    }).toList(growable: false);
+    return _repository.search(query);
   }
 }
+
diff --git a/lib/core/market/marketplace_repository.dart b/lib/core/market/marketplace_repository.dart
new file mode 100644
index 00000000..421ac9b6
--- /dev/null
+++ b/lib/core/market/marketplace_repository.dart
@@ -0,0 +1,306 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+import 'package:path/path.dart' as p;
+import 'package:querya_desktop/core/extensions/extension_paths.dart';
+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';
+
+export 'http_marketplace_repository.dart';
+
+/// Abstract repository contract for Marketplace operations (Block B).
+///
+/// See [docs/market-tech.md] and Block B specification.
+abstract class MarketplaceRepository {
+  static MarketplaceRepository instance = MockMarketplaceRepository();
+
+  /// Returns trending and recommended marketplace extensions.
+  Future<List<ExtensionManifest>> getTrending({ExtensionType? type});
+
+  /// Searches the marketplace catalog by query string and optional type filter.
+  Future<List<ExtensionManifest>> search(String query, {ExtensionType? type});
+
+  /// Simulates downloading an archive from [url] with progress reporting.
+  Future<File> download(String url, {void Function(double)? onProgress});
+
+  /// Installs an extension by downloading, validating, and registering it locally.
+  Future<void> install(
+    ExtensionManifest manifest, {
+    void Function(double)? onProgress,
+  });
+
+  /// Uninstalls a locally installed extension by ID.
+  Future<void> uninstall(String extensionId);
+}
+
+/// In-memory mock implementation for local UI development and testing (Release 0.4.8).
+class MockMarketplaceRepository implements MarketplaceRepository {
+  MockMarketplaceRepository({List<ExtensionManifest>? seed})
+      : _items = List<ExtensionManifest>.from(seed ?? _defaultMocks);
+
+  final List<ExtensionManifest> _items;
+
+  static final List<ExtensionManifest> _defaultMocks = [
+    const ExtensionManifest(
+      id: 'queryahub.clickhouse-driver',
+      name: 'ClickHouse Driver',
+      version: '1.0.0',
+      publisher: 'QueryaHub',
+      type: ExtensionType.databaseDriver,
+      engines: {'querya_desktop': '^0.4.7'},
+      main: 'index.js',
+      description: 'Full support for ClickHouse databases including Dictionaries, Materialized Views, and real-time query metrics.',
+      downloadUrl: 'https://cdn.queryahub.com/extensions/clickhouse-driver-1.0.0.zip',
+      sha256Checksum: 'e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855',
+      homepage: 'https://queryahub.com/drivers/clickhouse',
+      license: 'MIT',
+      tags: ['database', 'clickhouse', 'olap', 'official'],
+    ),
+    const ExtensionManifest(
+      id: 'community.redis-driver',
+      name: 'Redis Driver',
+      version: '0.9.5',
+      publisher: 'Community',
+      type: ExtensionType.databaseDriver,
+      engines: {'querya_desktop': '^0.4.7'},
+      main: 'index.js',
+      description: 'Connect to Redis instances, visualize key-value storage, inspect Pub/Sub channels, and edit JSON documents.',
+      downloadUrl: 'https://cdn.queryahub.com/extensions/redis-driver-0.9.5.zip',
+      sha256Checksum: '8f434346648f6b96df89dda901c5176b10a6d83961dd3c1ac88b59b2dc327aa4',
+      homepage: 'https://github.com/queryahub/redis-driver',
+      license: 'Apache-2.0',
+      tags: ['database', 'redis', 'nosql', 'key-value'],
+    ),
+    const ExtensionManifest(
+      id: 'queryahub.cyberpunk-neon',
+      name: 'Cyberpunk Neon',
+      version: '1.2.0',
+      publisher: 'QueryaHub',
+      type: ExtensionType.theme,
+      engines: {'querya_desktop': '^0.4.7'},
+      main: 'theme.json',
+      description: 'Vibrant neon color scheme inspired by Cyberpunk 2077 with glowing syntax highlighting and dark futuristic workbench.',
+      downloadUrl: 'https://cdn.queryahub.com/themes/cyberpunk-neon-1.2.0.zip',
+      sha256Checksum: 'a1b2c3d4e5f60718293a4b5c6d7e8f90123456789abcdef0123456789abcdef0',
+      homepage: 'https://queryahub.com/themes/cyberpunk',
+      license: 'MIT',
+      tags: ['theme', 'dark', 'cyberpunk', 'neon', 'official'],
+    ),
+    const ExtensionManifest(
+      id: 'community.nord-theme',
+      name: 'Nord Theme',
+      version: '0.8.2',
+      publisher: 'Community',
+      type: ExtensionType.theme,
+      engines: {'querya_desktop': '^0.4.7'},
+      main: 'theme.json',
+      description: 'An arctic, north-bluish clean and elegant color palette designed for focused, distraction-free SQL coding.',
+      downloadUrl: 'https://cdn.queryahub.com/themes/nord-theme-0.8.2.zip',
+      sha256Checksum: 'b2c3d4e5f6a10718293a4b5c6d7e8f90123456789abcdef0123456789abcdef1',
+      homepage: 'https://github.com/arcticicestudio/nord',
+      license: 'MIT',
+      tags: ['theme', 'dark', 'nord', 'arctic', 'minimal'],
+    ),
+    const ExtensionManifest(
+      id: 'queryahub.mongodb-driver',
+      name: 'MongoDB Driver',
+      version: '1.1.0',
+      publisher: 'QueryaHub',
+      type: ExtensionType.databaseDriver,
+      engines: {'querya_desktop': '^0.4.7'},
+      main: 'index.js',
+      description: 'Explore MongoDB collections, execute aggregation pipelines, and view BSON documents in an interactive tree view.',
+      downloadUrl: 'https://cdn.queryahub.com/extensions/mongodb-driver-1.1.0.zip',
+      sha256Checksum: 'c3d4e5f6a1b20718293a4b5c6d7e8f90123456789abcdef0123456789abcdef2',
+      homepage: 'https://queryahub.com/drivers/mongodb',
+      license: 'MIT',
+      tags: ['database', 'mongodb', 'nosql', 'bson', 'official'],
+    ),
+    const ExtensionManifest(
+      id: 'community.postgres-exporter',
+      name: 'PostgreSQL Schema Exporter',
+      version: '0.5.0',
+      publisher: 'Community',
+      type: ExtensionType.databaseDriver,
+      engines: {'querya_desktop': '^0.4.7'},
+      main: 'index.js',
+      description: 'Export complex PostgreSQL schemas to dbdiagram.io, Mermaid ERD, and DDL scripts with one click.',
+      downloadUrl: 'https://cdn.queryahub.com/extensions/postgres-exporter-0.5.0.zip',
+      sha256Checksum: 'd4e5f6a1b2c30718293a4b5c6d7e8f90123456789abcdef0123456789abcdef3',
+      homepage: 'https://github.com/querya-community/postgres-exporter',
+      license: 'MIT',
+      tags: ['postgresql', 'schema', 'export', 'erd', 'mermaid'],
+    ),
+  ];
+
+  @override
+  Future<List<ExtensionManifest>> getTrending({ExtensionType? type}) async {
+    await Future.delayed(const Duration(milliseconds: 150));
+    return _items.where((item) {
+      if (type != null && item.type != type) return false;
+      return true;
+    }).toList(growable: false);
+  }
+
+  @override
+  Future<List<ExtensionManifest>> search(String query, {ExtensionType? type}) async {
+    await Future.delayed(const Duration(milliseconds: 150));
+    final normalized = query.trim().toLowerCase();
+    return _items.where((item) {
+      if (type != null && item.type != type) return false;
+      if (normalized.isEmpty) return true;
+      return item.name.toLowerCase().contains(normalized) ||
+          item.id.toLowerCase().contains(normalized) ||
+          item.publisher.toLowerCase().contains(normalized) ||
+          (item.description?.toLowerCase().contains(normalized) ?? false) ||
+          item.tags.any((tag) => tag.toLowerCase().contains(normalized));
+    }).toList(growable: false);
+  }
+
+  @override
+  Future<File> download(String url, {void Function(double)? onProgress}) async {
+    for (int i = 1; i <= 10; i++) {
+      await Future.delayed(const Duration(milliseconds: 80));
+      onProgress?.call(i / 10.0);
+    }
+    final tmpDir = Directory.systemTemp;
+    final file = File(p.join(tmpDir.path, 'querya_ext_mock_${DateTime.now().millisecondsSinceEpoch}.zip'));
+    await file.writeAsString('mock archive payload');
+    return file;
+  }
+
+  @override
+  Future<void> install(
+    ExtensionManifest manifest, {
+    void Function(double)? onProgress,
+  }) async {
+    // Simulate download & verification progress
+    for (int i = 1; i <= 10; i++) {
+      await Future.delayed(const Duration(milliseconds: 100));
+      onProgress?.call(i / 10.0);
+    }
+
+    // Persist to local extensions directory so LocalExtensionRegistry discovers it
+    final dir = await ExtensionPaths.extensionsDirectory();
+    final extDir = Directory(p.join(dir.path, manifest.id));
+    if (!await extDir.exists()) {
+      await extDir.create(recursive: true);
+    }
+
+    final manifestFile = File(p.join(extDir.path, 'manifest.json'));
+    const encoder = JsonEncoder.withIndent('  ');
+    await manifestFile.writeAsString(encoder.convert(manifest.toJson()));
+
+    // If installing a theme in mock mode, generate a working theme.json so it can be applied in settings
+    if (manifest.type == ExtensionType.theme) {
+      final themeFile = File(p.join(extDir.path, 'theme.json'));
+      final themeContent = _getMockThemeContent(manifest);
+      await themeFile.writeAsString(themeContent);
+    }
+
+    // Reload local registry
+    await LocalExtensionRegistry.instance.reload();
+  }
+
+  String _getMockThemeContent(ExtensionManifest manifest) {
+    if (manifest.id.contains('nord')) {
+      return '''{
+  "name": "Nord Theme",
+  "type": "dark",
+  "colors": {
+    "activityBar.background": "#2e3440",
+    "statusBar.background": "#2e3440",
+    "sideBar.background": "#3b4252",
+    "sideBar.foreground": "#d8dee9",
+    "tab.activeBackground": "#434c5e",
+    "panel.background": "#3b4252",
+    "input.background": "#434c5e",
+    "editor.background": "#2e3440",
+    "editor.foreground": "#eceff4",
+    "editor.selectionBackground": "#434c5e88",
+    "editorLineNumber.foreground": "#4c566a",
+    "focusBorder": "#88c0d0"
+  },
+  "tokenColors": [
+    {
+      "name": "Keywords",
+      "scope": ["keyword", "storage.type"],
+      "settings": { "foreground": "#81a1c1", "fontStyle": "bold" }
+    },
+    {
+      "name": "Strings",
+      "scope": ["string"],
+      "settings": { "foreground": "#a3be8c" }
+    },
+    {
+      "name": "Numbers",
+      "scope": ["constant.numeric"],
+      "settings": { "foreground": "#b48ead" }
+    }
+  ]
+}''';
+    }
+    return '''{
+  "name": "\${manifest.name}",
+  "type": "dark",
+  "colors": {
+    "activityBar.background": "#050508",
+    "statusBar.background": "#050508",
+    "sideBar.background": "#0c0820",
+    "sideBar.foreground": "#8b7cf8",
+    "tab.activeBackground": "#14102a",
+    "panel.background": "#14102a",
+    "input.background": "#14102a",
+    "editor.background": "#0a0a14",
+    "editor.foreground": "#e8f4ff",
+    "editor.selectionBackground": "#ff2a6d44",
+    "editorLineNumber.foreground": "#4a3f7a",
+    "focusBorder": "#00f5ff"
+  },
+  "tokenColors": [
+    {
+      "name": "Keywords",
+      "scope": ["keyword", "storage.type"],
+      "settings": { "foreground": "#ff2a6d", "fontStyle": "bold" }
+    },
+    {
+      "name": "Strings",
+      "scope": ["string"],
+      "settings": { "foreground": "#fcee09" }
+    },
+    {
+      "name": "Functions",
+      "scope": ["entity.name.function"],
+      "settings": { "foreground": "#00f5ff" }
+    }
+  ]
+}''';
+    }
+
+  @override
+  Future<void> uninstall(String extensionId) async {
+    await Future.delayed(const Duration(milliseconds: 150));
+    
+    // Check local extension registry first
+    final manifest = LocalExtensionRegistry.instance.manifests
+        .where((e) => e.id == extensionId)
+        .firstOrNull;
+
+    if (manifest != null && manifest.installPath != null) {
+      final extDir = Directory(manifest.installPath!);
+      if (await extDir.exists()) {
+        await extDir.delete(recursive: true);
+      }
+    } else {
+      // Fallback: check standard extensions directory by ID
+      final dir = await ExtensionPaths.extensionsDirectory();
+      final extDir = Directory(p.join(dir.path, extensionId));
+      if (await extDir.exists()) {
+        await extDir.delete(recursive: true);
+      }
+    }
+
+    await LocalExtensionRegistry.instance.reload();
+  }
+}
diff --git a/lib/core/storage/local_db.dart b/lib/core/storage/local_db.dart
index eebba457..1daae918 100644
--- a/lib/core/storage/local_db.dart
+++ b/lib/core/storage/local_db.dart
@@ -370,6 +370,30 @@ class LocalDb {
     return id;
   }
 
+  /// Atomically updates an existing connection row in SQLite and its secrets in the secure store.
+  Future<void> updateConnection(ConnectionRow row) async {
+    if (row.id == null) {
+      throw ArgumentError('ConnectionRow.id cannot be null when calling updateConnection');
+    }
+    final db = await _open();
+    await db.transaction((txn) async {
+      final count = await txn.update(
+        'connections',
+        row.toPersistenceMap(),
+        where: 'id = ?',
+        whereArgs: [row.id],
+      );
+      if (count == 0) {
+        throw ArgumentError('No connection found with id ${row.id}');
+      }
+    });
+    await ConnectionSecretsStore.writeForConnection(
+      row.id!,
+      password: row.password,
+      connectionString: row.connectionString,
+    );
+  }
+
   Future<void> removeConnection(int id) async {
     await ConnectionSecretsStore.deleteForConnection(id);
     final db = await _open();
diff --git a/lib/features/connections/connection_url_parser.dart b/lib/features/connections/connection_url_parser.dart
new file mode 100644
index 00000000..82ca3723
--- /dev/null
+++ b/lib/features/connections/connection_url_parser.dart
@@ -0,0 +1,218 @@
+import 'package:querya_desktop/core/storage/local_db.dart';
+
+const _supportedSchemes = {
+  'postgresql',
+  'postgres',
+  'mysql',
+  'sqlite',
+  'mongodb',
+  'mongodb+srv',
+  'redis',
+  'rediss',
+};
+
+const _validPostgresSslModes = {
+  'disable',
+  'require',
+  'verify-ca',
+  'verify-full',
+};
+
+/// Parses a database connection URL into a [ConnectionRow], or returns an error message.
+({ConnectionRow? row, String? error}) parseConnectionUrlInput(String input) {
+  final trimmed = input.trim();
+  if (trimmed.isEmpty) {
+    return (row: null, error: 'URL/URI is required.');
+  }
+
+  final uri = Uri.tryParse(trimmed);
+  if (uri == null || uri.scheme.isEmpty) {
+    return (row: null, error: 'Invalid URL/URI format.');
+  }
+
+  final scheme = uri.scheme.toLowerCase();
+  if (!_supportedSchemes.contains(scheme)) {
+    return (
+      row: null,
+      error:
+          'Unsupported protocol "$scheme". Supported: postgresql, mysql, sqlite, mongodb, redis.',
+    );
+  }
+
+  final sslResult = _resolveSslForScheme(scheme, uri);
+  if (sslResult.error != null) {
+    return (row: null, error: sslResult.error);
+  }
+
+  final row = _buildConnectionRow(trimmed, uri, scheme, sslResult.useSSL);
+  if (row == null) {
+    return (row: null, error: 'Failed to parse connection URL.');
+  }
+  return (row: row, error: null);
+}
+
+({bool? useSSL, String? error}) _resolveSslForScheme(String scheme, Uri uri) {
+  final type = _schemeToType(scheme);
+  if (type == null) return (useSSL: null, error: null);
+
+  var useSSL = scheme == 'rediss';
+
+  if (type == 'postgresql') {
+    final sslMode = uri.queryParameters['sslmode']?.toLowerCase() ??
+        uri.queryParameters['ssl']?.toLowerCase();
+    if (sslMode != null && sslMode.isNotEmpty) {
+      if (!_validPostgresSslModes.contains(sslMode)) {
+        return (
+          useSSL: null,
+          error:
+              'Unsupported sslmode "$sslMode" for PostgreSQL. '
+              'Supported: disable, require, verify-ca, verify-full.',
+        );
+      }
+      useSSL = sslMode != 'disable';
+    }
+  } else if (type != 'sqlite') {
+    final sslQuery = uri.queryParameters['sslmode'] ??
+        uri.queryParameters['ssl'];
+    if (sslQuery != null) {
+      final lowerSsl = sslQuery.toLowerCase();
+      if (lowerSsl == 'true' || lowerSsl == 'require') {
+        useSSL = true;
+      }
+    }
+  }
+
+  return (useSSL: useSSL, error: null);
+}
+
+String? _schemeToType(String scheme) {
+  if (scheme == 'postgresql' || scheme == 'postgres') return 'postgresql';
+  if (scheme == 'mysql') return 'mysql';
+  if (scheme == 'sqlite') return 'sqlite';
+  if (scheme == 'mongodb' || scheme == 'mongodb+srv') return 'mongodb';
+  if (scheme == 'redis' || scheme == 'rediss') return 'redis';
+  return null;
+}
+
+ConnectionRow? _buildConnectionRow(
+  String url,
+  Uri uri,
+  String scheme,
+  bool? resolvedUseSSL,
+) {
+  String type;
+  int? defaultPort;
+
+  if (scheme == 'postgresql' || scheme == 'postgres') {
+    type = 'postgresql';
+    defaultPort = 5432;
+  } else if (scheme == 'mysql') {
+    type = 'mysql';
+    defaultPort = 3306;
+  } else if (scheme == 'sqlite') {
+    type = 'sqlite';
+  } else if (scheme == 'mongodb' || scheme == 'mongodb+srv') {
+    type = 'mongodb';
+    defaultPort = 27017;
+  } else if (scheme == 'redis' || scheme == 'rediss') {
+    type = 'redis';
+    defaultPort = 6379;
+  } else {
+    return null;
+  }
+
+  String? host;
+  int? port;
+  String? username;
+  String? password;
+  String? databaseName;
+  String? authSource;
+  String? connectionString;
+  var useSSL = resolvedUseSSL ?? (scheme == 'rediss');
+
+  if (type == 'sqlite') {
+    String path;
+    if (url.contains(':memory:')) {
+      path = ':memory:';
+    } else if (url.startsWith('sqlite:///')) {
+      path = uri.path;
+    } else if (url.startsWith('sqlite://')) {
+      path = url.substring(9);
+    } else if (url.startsWith('sqlite:')) {
+      path = url.substring(7);
+    } else {
+      path = uri.path;
+    }
+    host = path;
+  } else {
+    host = uri.host.isEmpty ? null : uri.host;
+    port = uri.hasPort ? uri.port : null;
+
+    if (uri.userInfo.isNotEmpty) {
+      final parts = uri.userInfo.split(':');
+      if (parts.isNotEmpty) {
+        username = Uri.decodeComponent(parts[0]);
+      }
+      if (parts.length > 1) {
+        password = Uri.decodeComponent(parts.sublist(1).join(':'));
+      }
+    }
+
+    databaseName = uri.pathSegments.firstOrNull;
+    if (databaseName != null && databaseName.isEmpty) {
+      databaseName = null;
+    }
+
+    authSource = uri.queryParameters['authSource'] ??
+        uri.queryParameters['authsource'];
+
+    if (type == 'postgresql' || type == 'mysql' || type == 'mongodb') {
+      connectionString = url;
+    }
+  }
+
+  final name = _connectionName(type, host, port, databaseName, defaultPort);
+
+  return ConnectionRow(
+    type: type,
+    name: name,
+    host: host,
+    port: port ?? defaultPort,
+    username: username,
+    password: password,
+    databaseName: databaseName,
+    authSource: authSource,
+    useSSL: useSSL,
+    connectionString: connectionString,
+    createdAt: DateTime.now().toUtc().toIso8601String(),
+  );
+}
+
+String _connectionName(
+  String type,
+  String? host,
+  int? port,
+  String? databaseName,
+  int? defaultPort,
+) {
+  if (type == 'sqlite') {
+    return host == ':memory:' ? 'SQLite (Memory)' : 'SQLite (${host!.split('/').last})';
+  }
+
+  final cleanHost = host ?? 'localhost';
+  final cleanPort = port ?? defaultPort;
+  final cleanDb = databaseName ?? '';
+  final typeName = switch (type) {
+    'postgresql' => 'PostgreSQL',
+    'mysql' => 'MySQL',
+    'mongodb' => 'MongoDB',
+    _ => 'Redis',
+  };
+  if (cleanDb.isNotEmpty) {
+    return '$typeName: $cleanDb';
+  }
+  if (cleanPort != null) {
+    return '$typeName: $cleanHost:$cleanPort';
+  }
+  return '$typeName: $cleanHost';
+}
diff --git a/lib/features/connections/connections_panel_postgres_connection.dart b/lib/features/connections/connections_panel_postgres_connection.dart
index 9bc2a359..5021b92a 100644
--- a/lib/features/connections/connections_panel_postgres_connection.dart
+++ b/lib/features/connections/connections_panel_postgres_connection.dart
@@ -242,12 +242,15 @@ class _PostgresConnectionTileState extends State<_PostgresConnectionTile> {
                     material.Padding(
                       padding: const material.EdgeInsets.only(
                           left: 28, top: 4, bottom: 4),
-                      child: material.Text(
-                        'Error',
-                        overflow: material.TextOverflow.ellipsis,
-                        maxLines: 1,
-                        style: material.TextStyle(
-                            fontSize: 11, color: theme.colorScheme.destructive),
+                      child: material.Tooltip(
+                        message: _error!,
+                        child: material.Text(
+                          _error!,
+                          overflow: material.TextOverflow.ellipsis,
+                          maxLines: 2,
+                          style: material.TextStyle(
+                              fontSize: 11, color: theme.colorScheme.destructive),
+                        ),
                       ),
                     ),
                   if (_databases.isNotEmpty)
diff --git a/lib/features/connections/new_connection_url_dialog.dart b/lib/features/connections/new_connection_url_dialog.dart
new file mode 100644
index 00000000..23e60638
--- /dev/null
+++ b/lib/features/connections/new_connection_url_dialog.dart
@@ -0,0 +1,156 @@
+import 'package:flutter/material.dart' as material;
+import 'package:querya_desktop/core/layout/window_layout.dart';
+import 'package:querya_desktop/core/storage/local_db.dart';
+import 'package:querya_desktop/features/connections/connection_url_parser.dart';
+import 'package:querya_desktop/shared/widgets/widgets.dart';
+
+/// Shows a dialog to create a new database connection from a URI.
+/// Returns the ConnectionRow or null if cancelled.
+Future<ConnectionRow?> showNewConnectionUrlDialog(material.BuildContext context) {
+  return showAppDialog<ConnectionRow>(
+    context: context,
+    builder: (context) => material.Dialog(
+      backgroundColor: material.Colors.transparent,
+      insetPadding: WindowLayout.dialogSymmetricInsets(context),
+      child: const _NewConnectionUrlDialogContent(),
+    ),
+  );
+}
+
+class _NewConnectionUrlDialogContent extends material.StatefulWidget {
+  const _NewConnectionUrlDialogContent();
+
+  @override
+  material.State<_NewConnectionUrlDialogContent> createState() =>
+      _NewConnectionUrlDialogContentState();
+}
+
+class _NewConnectionUrlDialogContentState
+    extends material.State<_NewConnectionUrlDialogContent> {
+  final _urlController = material.TextEditingController();
+  String? _validationError;
+
+  @override
+  void dispose() {
+    _urlController.dispose();
+    super.dispose();
+  }
+
+  void _validateAndSubmit() {
+    final result = parseConnectionUrlInput(_urlController.text);
+    if (result.error != null) {
+      setState(() => _validationError = result.error);
+      return;
+    }
+    material.Navigator.of(context).pop(result.row);
+  }
+
+  @override
+  material.Widget build(material.BuildContext context) {
+    final theme = Theme.of(context).colorScheme;
+    final radius = Theme.of(context).radiusXxl;
+    return material.Container(
+      constraints: WindowLayout.dialogConstraints(
+        context,
+        maxWidth: 500,
+        minWidth: 380,
+      ),
+      decoration: material.BoxDecoration(
+        color: theme.popover,
+        borderRadius: material.BorderRadius.circular(radius),
+        border: material.Border.all(color: theme.muted),
+      ),
+      child: material.ClipRRect(
+        borderRadius: material.BorderRadius.circular(radius),
+        child: material.Column(
+          mainAxisSize: material.MainAxisSize.min,
+          crossAxisAlignment: material.CrossAxisAlignment.stretch,
+          children: [
+            material.Padding(
+              padding: const material.EdgeInsets.fromLTRB(24, 24, 24, 8),
+              child: material.Column(
+                crossAxisAlignment: material.CrossAxisAlignment.start,
+                children: [
+                  const Text('New connection from URL').large().semiBold(),
+                  const material.SizedBox(height: 6),
+                  const Text(
+                    'Create a connection by pasting a database URI (e.g. postgresql://user:pass@host:5432/db).',
+                  ).muted().small(),
+                  const material.SizedBox(height: 16),
+                  material.Container(
+                    decoration: material.BoxDecoration(
+                      color: theme.muted.withValues(alpha: 0.2),
+                      borderRadius: material.BorderRadius.circular(8),
+                      border: material.Border.all(
+                        color: _validationError != null
+                            ? theme.destructive.withValues(alpha: 0.8)
+                            : theme.border.withValues(alpha: 0.4),
+                      ),
+                    ),
+                    padding: const material.EdgeInsets.symmetric(
+                        horizontal: 12, vertical: 4),
+                    child: material.Row(
+                      children: [
+                        material.Icon(
+                          material.Icons.link_rounded,
+                          size: 20,
+                          color: _validationError != null
+                              ? theme.destructive
+                              : theme.mutedForeground,
+                        ),
+                        const material.SizedBox(width: 10),
+                        material.Expanded(
+                          child: TextField(
+                            controller: _urlController,
+                            placeholder: const Text('database://user:pass@host:port/db'),
+                            onSubmitted: (_) => _validateAndSubmit(),
+                            onChanged: (_) {
+                              if (_validationError != null) {
+                                setState(() => _validationError = null);
+                              }
+                            },
+                          ),
+                        ),
+                      ],
+                    ),
+                  ),
+                  if (_validationError != null) ...[
+                    const material.SizedBox(height: 8),
+                    Text(
+                      _validationError!,
+                      style: material.TextStyle(color: theme.destructive),
+                    ).small(),
+                  ],
+                ],
+              ),
+            ),
+            material.Container(
+              padding: const material.EdgeInsets.symmetric(
+                  horizontal: 24, vertical: 16),
+              decoration: material.BoxDecoration(
+                border: material.Border(
+                  top: material.BorderSide(
+                      color: theme.border.withValues(alpha: 0.3)),
+                ),
+              ),
+              child: material.Row(
+                mainAxisAlignment: material.MainAxisAlignment.end,
+                children: [
+                  GhostButton(
+                    onPressed: () => material.Navigator.of(context).pop(),
+                    child: const Text('Cancel'),
+                  ),
+                  const material.SizedBox(width: 12),
+                  PrimaryButton(
+                    onPressed: _validateAndSubmit,
+                    child: const Text('Create'),
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
diff --git a/lib/features/extensions/presentation/pages/extension_manager_dialog.dart b/lib/features/extensions/presentation/pages/extension_manager_dialog.dart
new file mode 100644
index 00000000..e54f2e46
--- /dev/null
+++ b/lib/features/extensions/presentation/pages/extension_manager_dialog.dart
@@ -0,0 +1,294 @@
+import 'package:flutter/material.dart' as material;
+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/layout/window_layout.dart';
+import 'package:querya_desktop/core/market/marketplace_repository.dart';
+import 'package:querya_desktop/features/extensions/presentation/widgets/extension_card.dart';
+import 'package:querya_desktop/shared/widgets/widgets.dart';
+
+void showExtensionManagerDialog(material.BuildContext context) {
+  showAppDialog<void>(
+    context: context,
+    builder: (ctx) => material.Dialog(
+      backgroundColor: material.Colors.transparent,
+      insetPadding: WindowLayout.dialogSymmetricInsets(ctx),
+      child: const _ExtensionManagerContent(),
+    ),
+  );
+}
+
+class _ExtensionManagerContent extends material.StatefulWidget {
+  const _ExtensionManagerContent();
+
+  @override
+  material.State<_ExtensionManagerContent> createState() =>
+      _ExtensionManagerContentState();
+}
+
+class _ExtensionManagerContentState extends material.State<_ExtensionManagerContent> {
+  int _tabIndex = 0;
+  List<ExtensionManifest> _installed = [];
+  List<ExtensionManifest> _marketplace = [];
+  bool _loading = true;
+  final Map<String, double> _installingProgress = {};
+
+  @override
+  void initState() {
+    super.initState();
+    _loadData();
+  }
+
+  Future<void> _loadData() async {
+    setState(() => _loading = true);
+    await LocalExtensionRegistry.instance.load();
+    final installed = LocalExtensionRegistry.instance.manifests;
+    final market = await MarketplaceRepository.instance.getTrending();
+    if (mounted) {
+      setState(() {
+        _installed = installed;
+        _marketplace = market;
+        _loading = false;
+      });
+    }
+  }
+
+  Future<void> _onSearchChanged(String query) async {
+    if (query.trim().isEmpty) {
+      final market = await MarketplaceRepository.instance.getTrending();
+      if (mounted) setState(() => _marketplace = market);
+    } else {
+      final market = await MarketplaceRepository.instance.search(query);
+      if (mounted) setState(() => _marketplace = market);
+    }
+  }
+
+  Future<void> _installExtension(ExtensionManifest manifest) async {
+    setState(() => _installingProgress[manifest.id] = 0.01);
+    try {
+      await MarketplaceRepository.instance.install(
+        manifest,
+        onProgress: (progress) {
+          if (mounted) {
+            setState(() => _installingProgress[manifest.id] = progress);
+          }
+        },
+      );
+      if (mounted) {
+        setState(() {
+          _installingProgress.remove(manifest.id);
+          _installed = LocalExtensionRegistry.instance.manifests;
+        });
+      }
+    } catch (e) {
+      if (mounted) {
+        setState(() => _installingProgress.remove(manifest.id));
+      }
+    }
+  }
+
+  Future<void> _uninstallExtension(ExtensionManifest manifest) async {
+    await MarketplaceRepository.instance.uninstall(manifest.id);
+    if (mounted) {
+      setState(() {
+        _installed = LocalExtensionRegistry.instance.manifests;
+      });
+    }
+  }
+
+  @override
+  material.Widget build(material.BuildContext context) {
+    final theme = Theme.of(context).colorScheme;
+    final radius = Theme.of(context).radiusXxl;
+    final onPopover = theme.popoverForeground;
+
+    return material.DefaultTextStyle(
+      style: material.TextStyle(color: onPopover),
+      child: material.IconTheme(
+        data: material.IconThemeData(color: onPopover),
+        child: material.Container(
+          constraints: WindowLayout.dialogConstraints(
+            context,
+            maxWidth: 800,
+            minWidth: 600,
+            maxHeight: 700,
+          ),
+          decoration: material.BoxDecoration(
+            color: theme.popover,
+            borderRadius: material.BorderRadius.circular(radius),
+            border: material.Border.all(color: theme.border),
+          ),
+          child: material.ClipRRect(
+            borderRadius: material.BorderRadius.circular(radius),
+            child: material.Column(
+              crossAxisAlignment: material.CrossAxisAlignment.stretch,
+              children: [
+                material.Padding(
+                  padding: const material.EdgeInsets.fromLTRB(24, 24, 24, 8),
+                  child: material.Row(
+                    mainAxisAlignment: material.MainAxisAlignment.spaceBetween,
+                    crossAxisAlignment: material.CrossAxisAlignment.center,
+                    children: [
+                      material.Expanded(
+                        child: material.Column(
+                          crossAxisAlignment: material.CrossAxisAlignment.start,
+                          children: [
+                            const Text('Extensions').large().semiBold().foreground(),
+                            const material.SizedBox(height: 6),
+                            const Text('Manage local and marketplace extensions')
+                                .muted()
+                                .small(),
+                          ],
+                        ),
+                      ),
+                      const material.SizedBox(width: 16),
+                      PrimaryButton(
+                        onPressed: () => material.Navigator.of(context).pop(),
+                        child: const Text('Close'),
+                      ),
+                    ],
+                  ),
+                ),
+                material.Padding(
+                  padding: const material.EdgeInsets.symmetric(
+                      horizontal: 24.0, vertical: 8.0),
+                  child: material.Wrap(
+                    spacing: 8,
+                    runSpacing: 8,
+                    children: [
+                      _buildTabButton(0, 'Installed', count: _installed.length),
+                      _buildTabButton(1, 'Marketplace'),
+                      _buildTabButton(2, 'Updates'),
+                    ],
+                  ),
+                ),
+                material.Divider(height: 1, color: theme.border),
+                material.Expanded(
+                  child: material.IndexedStack(
+                    index: _tabIndex,
+                    children: [
+                      _buildInstalledTab(),
+                      _buildMarketplaceTab(),
+                      _buildUpdatesTab(),
+                    ],
+                  ),
+                ),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+
+  material.Widget _buildTabButton(int index, String label, {int? count}) {
+    final isSelected = _tabIndex == index;
+    final displayLabel = count != null ? '$label ($count)' : label;
+    return SecondaryButton(
+      onPressed: () => setState(() => _tabIndex = index),
+      child: material.Text(
+        displayLabel,
+        style: material.TextStyle(
+          color: isSelected ? Theme.of(context).colorScheme.primary : null,
+          fontWeight: isSelected ? material.FontWeight.w600 : material.FontWeight.w400,
+        ),
+      ),
+    );
+  }
+
+  material.Widget _buildInstalledTab() {
+    if (_loading) {
+      return const material.Center(
+        child: material.CircularProgressIndicator(),
+      );
+    }
+    if (_installed.isEmpty) {
+      return const material.Center(
+        child: material.Padding(
+          padding: material.EdgeInsets.all(32.0),
+          child: Text('No extensions installed yet. Explore the Marketplace tab to get started!'),
+        ),
+      );
+    }
+    return material.ListView.separated(
+      padding: const material.EdgeInsets.all(24),
+      itemCount: _installed.length,
+      separatorBuilder: (_, __) => const material.SizedBox(height: 16),
+      itemBuilder: (ctx, i) {
+        final manifest = _installed[i];
+        final isInstalling = _installingProgress.containsKey(manifest.id);
+        final progress = _installingProgress[manifest.id];
+        return ExtensionCard(
+          manifest: manifest,
+          isInstalled: true,
+          isInstalling: isInstalling,
+          installProgress: progress,
+          onUninstall: () => _uninstallExtension(manifest),
+        );
+      },
+    );
+  }
+
+  material.Widget _buildMarketplaceTab() {
+    if (_loading) {
+      return const material.Center(
+        child: material.CircularProgressIndicator(),
+      );
+    }
+    return material.Column(
+      children: [
+        material.Padding(
+          padding: const material.EdgeInsets.fromLTRB(24, 16, 24, 8),
+          child: TextField(
+            placeholder: const material.Text('Search extensions by name, tag, or description...'),
+            onChanged: _onSearchChanged,
+            features: const [
+              InputFeature.leading(
+                Padding(
+                  padding: material.EdgeInsets.only(right: 8),
+                  child: material.Icon(material.Icons.search_rounded, size: 18),
+                ),
+              ),
+            ],
+          ),
+        ),
+        material.Expanded(
+          child: _marketplace.isEmpty
+              ? const material.Center(
+                  child: material.Padding(
+                    padding: material.EdgeInsets.all(32.0),
+                    child: Text('No extensions found matching your search.'),
+                  ),
+                )
+              : material.ListView.separated(
+                  padding: const material.EdgeInsets.all(24),
+                  itemCount: _marketplace.length,
+                  separatorBuilder: (_, __) => const material.SizedBox(height: 16),
+                  itemBuilder: (ctx, i) {
+                    final manifest = _marketplace[i];
+                    final isInstalled = _installed.any((e) => e.id == manifest.id);
+                    final isInstalling = _installingProgress.containsKey(manifest.id);
+                    final progress = _installingProgress[manifest.id];
+                    return ExtensionCard(
+                      manifest: manifest,
+                      isInstalled: isInstalled,
+                      isInstalling: isInstalling,
+                      installProgress: progress,
+                      onInstall: () => _installExtension(manifest),
+                      onUninstall: () => _uninstallExtension(manifest),
+                    );
+                  },
+                ),
+        ),
+      ],
+    );
+  }
+
+  material.Widget _buildUpdatesTab() {
+    return const material.Center(
+      child: material.Padding(
+        padding: material.EdgeInsets.all(32.0),
+        child: Text('All installed extensions are up to date!'),
+      ),
+    );
+  }
+}
diff --git a/lib/features/extensions/presentation/widgets/extension_card.dart b/lib/features/extensions/presentation/widgets/extension_card.dart
new file mode 100644
index 00000000..2d25b488
--- /dev/null
+++ b/lib/features/extensions/presentation/widgets/extension_card.dart
@@ -0,0 +1,181 @@
+import 'package:flutter/material.dart' as material;
+import 'package:querya_desktop/core/extensions/models/extension_manifest.dart';
+import 'package:querya_desktop/core/extensions/models/extension_type.dart';
+import 'package:querya_desktop/shared/widgets/widgets.dart';
+
+class ExtensionCard extends material.StatelessWidget {
+  const ExtensionCard({
+    super.key,
+    required this.manifest,
+    required this.isInstalled,
+    this.hasUpdate = false,
+    this.isInstalling = false,
+    this.installProgress,
+    this.onInstall,
+    this.onUninstall,
+    this.onUpdate,
+  });
+
+  final ExtensionManifest manifest;
+  final bool isInstalled;
+  final bool hasUpdate;
+  final bool isInstalling;
+  final double? installProgress;
+  final material.VoidCallback? onInstall;
+  final material.VoidCallback? onUninstall;
+  final material.VoidCallback? onUpdate;
+
+  @override
+  material.Widget build(material.BuildContext context) {
+    final theme = Theme.of(context).colorScheme;
+    final radius = Theme.of(context).radiusMd;
+    
+    return material.Container(
+      padding: const material.EdgeInsets.all(16),
+      decoration: material.BoxDecoration(
+        color: theme.card,
+        border: material.Border.all(color: theme.border),
+        borderRadius: material.BorderRadius.circular(radius),
+      ),
+      child: material.Row(
+        crossAxisAlignment: material.CrossAxisAlignment.start,
+        children: [
+          _buildIcon(theme, radius),
+          const material.SizedBox(width: 16),
+          material.Expanded(
+            child: material.Column(
+              crossAxisAlignment: material.CrossAxisAlignment.start,
+              children: [
+                material.Row(
+                  children: [
+                    material.Expanded(
+                      child: Text(manifest.name).large().semiBold(),
+                    ),
+                  ],
+                ),
+                const material.SizedBox(height: 4),
+                material.Row(
+                  children: [
+                    Text(manifest.publisher).muted().small(),
+                    const material.SizedBox(width: 8),
+                    material.Container(
+                      width: 4,
+                      height: 4,
+                      decoration: material.BoxDecoration(
+                        color: theme.mutedForeground,
+                        shape: material.BoxShape.circle,
+                      ),
+                    ),
+                    const material.SizedBox(width: 8),
+                    Text('v${manifest.version}').muted().small(),
+                  ],
+                ),
+                const material.SizedBox(height: 8),
+                Text(
+                  manifest.description ?? 'No description provided.',
+                  maxLines: 2,
+                  overflow: material.TextOverflow.ellipsis,
+                ).muted(),
+                if (manifest.tags.isNotEmpty) ...[
+                  const material.SizedBox(height: 10),
+                  material.Wrap(
+                    spacing: 6,
+                    runSpacing: 4,
+                    children: manifest.tags
+                        .take(5)
+                        .map((tag) => _buildTagBadge(theme, tag))
+                        .toList(),
+                  ),
+                ],
+              ],
+            ),
+          ),
+          const material.SizedBox(width: 16),
+          material.Column(
+            mainAxisAlignment: material.MainAxisAlignment.center,
+            crossAxisAlignment: material.CrossAxisAlignment.end,
+            children: [
+              if (isInstalled && hasUpdate && !isInstalling)
+                material.Padding(
+                  padding: const material.EdgeInsets.only(bottom: 8.0),
+                  child: PrimaryButton(
+                    onPressed: onUpdate,
+                    child: const Text('Update'),
+                  ),
+                ),
+              if (isInstalling)
+                material.Column(
+                  crossAxisAlignment: material.CrossAxisAlignment.end,
+                  children: [
+                    material.SizedBox(
+                      width: 110,
+                      child: material.LinearProgressIndicator(
+                        value: installProgress,
+                        backgroundColor: theme.muted,
+                        color: theme.primary,
+                        minHeight: 6,
+                        borderRadius: material.BorderRadius.circular(3),
+                      ),
+                    ),
+                    const material.SizedBox(height: 6),
+                    Text(installProgress != null
+                            ? 'Installing ${(installProgress! * 100).toInt()}%'
+                            : 'Installing...')
+                        .muted()
+                        .small(),
+                  ],
+                )
+              else if (isInstalled)
+                SecondaryButton(
+                  onPressed: onUninstall,
+                  child: const Text('Uninstall'),
+                )
+              else
+                PrimaryButton(
+                  onPressed: onInstall,
+                  child: const Text('Install'),
+                ),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+
+  material.Widget _buildIcon(ColorScheme theme, double radius) {
+    return material.Container(
+      width: 48,
+      height: 48,
+      decoration: material.BoxDecoration(
+        color: theme.muted,
+        borderRadius: material.BorderRadius.circular(radius),
+      ),
+      child: material.Icon(
+        manifest.type == ExtensionType.theme
+            ? material.Icons.palette_outlined
+            : material.Icons.extension_rounded,
+        size: 24,
+        color: theme.mutedForeground,
+      ),
+    );
+  }
+
+  material.Widget _buildTagBadge(ColorScheme theme, String tag) {
+    return material.Container(
+      padding: const material.EdgeInsets.symmetric(horizontal: 6, vertical: 2),
+      decoration: material.BoxDecoration(
+        color: theme.muted,
+        borderRadius: material.BorderRadius.circular(4),
+      ),
+      child: material.Text(
+        tag,
+        style: material.TextStyle(
+          fontSize: 11,
+          color: theme.mutedForeground,
+          fontWeight: material.FontWeight.w500,
+        ),
+      ),
+    );
+  }
+}
+
diff --git a/lib/features/help/about_dialog.dart b/lib/features/help/about_dialog.dart
new file mode 100644
index 00000000..11eef0a7
--- /dev/null
+++ b/lib/features/help/about_dialog.dart
@@ -0,0 +1,118 @@
+import 'package:flutter/material.dart' as material;
+import 'package:package_info_plus/package_info_plus.dart';
+import 'package:querya_desktop/core/app/external_link.dart';
+import 'package:querya_desktop/core/layout/window_layout.dart';
+import 'package:querya_desktop/core/theme/querya_theme_scope.dart';
+import 'package:querya_desktop/shared/widgets/widgets.dart';
+
+/// Shows the About Querya dialog.
+Future<void> showAboutDialog(material.BuildContext context) {
+  return showAppDialog<void>(
+    context: context,
+    builder: (context) => material.Dialog(
+      backgroundColor: material.Colors.transparent,
+      insetPadding: WindowLayout.dialogSymmetricInsets(context),
+      child: const _AboutDialogContent(),
+    ),
+  );
+}
+
+class _AboutDialogContent extends material.StatefulWidget {
+  const _AboutDialogContent();
+
+  @override
+  material.State<_AboutDialogContent> createState() =>
+      _AboutDialogContentState();
+}
+
+class _AboutDialogContentState extends material.State<_AboutDialogContent> {
+  late final Future<PackageInfo> _packageInfo = PackageInfo.fromPlatform();
+
+  @override
+  material.Widget build(material.BuildContext context) {
+    final theme = Theme.of(context).colorScheme;
+    final radius = Theme.of(context).radiusXxl;
+    final wb = context.workbench;
+
+    return material.Container(
+      constraints: WindowLayout.dialogConstraints(
+        context,
+        maxWidth: 420,
+        minWidth: 320,
+      ),
+      decoration: material.BoxDecoration(
+        color: theme.popover,
+        borderRadius: material.BorderRadius.circular(radius),
+        border: material.Border.all(color: theme.muted),
+      ),
+      child: material.ClipRRect(
+        borderRadius: material.BorderRadius.circular(radius),
+        child: material.Column(
+          mainAxisSize: material.MainAxisSize.min,
+          children: [
+            material.Padding(
+              padding: const material.EdgeInsets.fromLTRB(24, 28, 24, 8),
+              child: material.Column(
+                children: [
+                  material.Icon(
+                    material.Icons.search_rounded,
+                    size: 48,
+                    color: wb.accent,
+                  ),
+                  const material.SizedBox(height: 16),
+                  const Text('Querya').large().semiBold(),
+                  const material.SizedBox(height: 8),
+                  FutureBuilder<PackageInfo>(
+                    future: _packageInfo,
+                    builder: (context, snapshot) {
+                      final version = snapshot.data?.version ?? '…';
+                      return Text('Version $version').muted().small();
+                    },
+                  ),
+                  const material.SizedBox(height: 16),
+                  const Text(
+                    'A lightweight desktop SQL/NoSQL client.',
+                  ).muted().small(),
+                  const material.SizedBox(height: 12),
+                  const Text(
+                    'Licensed under the MIT License.',
+                  ).small(),
+                  const material.SizedBox(height: 16),
+                  GhostButton(
+                    onPressed: () => launchRepositoryUrl(),
+                    child: const Text('View repository'),
+                  ),
+                ],
+              ),
+            ),
+            material.Container(
+              padding: const material.EdgeInsets.symmetric(
+                horizontal: 24,
+                vertical: 16,
+              ),
+              decoration: material.BoxDecoration(
+                border: material.Border(
+                  top: material.BorderSide(
+                    color: theme.border.withValues(alpha: 0.3),
+                  ),
+                ),
+              ),
+              child: material.Row(
+                mainAxisAlignment: material.MainAxisAlignment.end,
+                children: [
+                  PrimaryButton(
+                    onPressed: () => material.Navigator.of(context).pop(),
+                    child: const Text('Close'),
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// Opens project documentation in the system browser.
+Future<bool> openQueryaDocumentation() => launchDocumentationUrl();
diff --git a/lib/features/main_screen/main_screen.dart b/lib/features/main_screen/main_screen.dart
index 2e5b0d1c..e34ed870 100644
--- a/lib/features/main_screen/main_screen.dart
+++ b/lib/features/main_screen/main_screen.dart
@@ -16,6 +16,7 @@ import 'package:querya_desktop/core/storage/local_db.dart';
 import 'package:querya_desktop/core/theme/querya_theme_scope.dart';
 import 'package:shadcn_flutter/shadcn_flutter.dart';
 import 'package:querya_desktop/features/connections/connection_creation_flow.dart';
+import 'package:querya_desktop/features/connections/new_connection_url_dialog.dart';
 import 'package:querya_desktop/features/connections/connections_panel.dart';
 import 'package:querya_desktop/features/main_screen/querya_window_title_bar.dart';
 import 'package:querya_desktop/shared/widgets/widgets.dart';
@@ -139,6 +140,15 @@ class _MainScreenState extends State<MainScreen> {
     await _connectionsPanelKey.currentState?.reloadConnectionsFromDb();
   }
 
+  Future<void> _onNewDatabaseConnectionFromUrl() async {
+    await Future.delayed(const Duration(milliseconds: 100));
+    if (!mounted) return;
+    final row = await showNewConnectionUrlDialog(context);
+    if (!mounted || row == null) return;
+    await LocalDb.instance.addConnection(row);
+    await _connectionsPanelKey.currentState?.reloadConnectionsFromDb();
+  }
+
   @override
   material.Widget build(material.BuildContext context) {
     final wb = context.workbench;
@@ -154,6 +164,7 @@ class _MainScreenState extends State<MainScreen> {
               builder: (context, workspace, _) {
                 return QueryaWindowTitleBar(
                   onNewDatabaseConnection: _onNewDatabaseConnectionFromMenu,
+                  onNewDatabaseConnectionFromUrl: _onNewDatabaseConnectionFromUrl,
                   activeConnection: workspace.activeConnection,
                   isReadOnly: workspace.isReadOnly,
                   onReadOnlyChanged: () {
diff --git a/lib/features/main_screen/querya_window_title_bar.dart b/lib/features/main_screen/querya_window_title_bar.dart
index bba9a8e3..373b2cef 100644
--- a/lib/features/main_screen/querya_window_title_bar.dart
+++ b/lib/features/main_screen/querya_window_title_bar.dart
@@ -5,6 +5,8 @@ import 'package:querya_desktop/core/storage/local_db.dart';
 import 'package:querya_desktop/core/theme/querya_theme_scope.dart';
 import 'package:querya_desktop/features/connections/driver_manager_dialog.dart';
 import 'package:querya_desktop/features/settings/preferences_dialog.dart';
+import 'package:querya_desktop/features/extensions/presentation/pages/extension_manager_dialog.dart';
+import 'package:querya_desktop/features/help/about_dialog.dart';
 import 'package:querya_desktop/core/actions/sql_editor_actions.dart';
 import 'package:shadcn_flutter/shadcn_flutter.dart';
 
@@ -13,6 +15,7 @@ class QueryaWindowTitleBar extends StatelessWidget {
   const QueryaWindowTitleBar({
     super.key,
     required this.onNewDatabaseConnection,
+    required this.onNewDatabaseConnectionFromUrl,
     this.activeConnection,
     this.onConnect,
     this.onReconnect,
@@ -24,6 +27,7 @@ class QueryaWindowTitleBar extends StatelessWidget {
   });
 
   final Future<void> Function() onNewDatabaseConnection;
+  final Future<void> Function() onNewDatabaseConnectionFromUrl;
   final ConnectionRow? activeConnection;
   final VoidCallback? onConnect;
   final VoidCallback? onReconnect;
@@ -134,6 +138,15 @@ class QueryaWindowTitleBar extends StatelessWidget {
                               onPressed: (ctx) => showPreferencesDialog(ctx),
                               child: const Text('Preferences…'),
                             ),
+                            const MenuDivider(),
+                            MenuButton(
+                              leading: const material.Icon(
+                                material.Icons.extension_rounded,
+                                size: 18,
+                              ),
+                              onPressed: (ctx) => showExtensionManagerDialog(ctx),
+                              child: const Text('Extensions…'),
+                            ),
                           ],
                           child: const Text('Edit'),
                         ),
@@ -152,7 +165,7 @@ class QueryaWindowTitleBar extends StatelessWidget {
                               leading: const material.Icon(
                                   material.Icons.link_rounded,
                                   size: 18),
-                              onPressed: (_) {},
+                              onPressed: (_) => onNewDatabaseConnectionFromUrl(),
                               child: const Text('New Connection from URL'),
                             ),
                             MenuButton(
@@ -214,9 +227,10 @@ class QueryaWindowTitleBar extends StatelessWidget {
                         MenuButton(
                           subMenu: [
                             MenuButton(
-                                onPressed: (_) {}, child: const Text('About')),
+                                onPressed: (ctx) => showAboutDialog(ctx),
+                                child: const Text('About')),
                             MenuButton(
-                                onPressed: (_) {},
+                                onPressed: (_) => openQueryaDocumentation(),
                                 child: const Text('Documentation')),
                           ],
                           child: const Text('Help'),
diff --git a/lib/features/postgresql/postgresql_connection_form.dart b/lib/features/postgresql/postgresql_connection_form.dart
index 4f72544a..a7d5bb84 100644
--- a/lib/features/postgresql/postgresql_connection_form.dart
+++ b/lib/features/postgresql/postgresql_connection_form.dart
@@ -1,5 +1,6 @@
 import 'dart:async';
 
+import 'package:file_selector/file_selector.dart';
 import 'package:flutter/material.dart' as material;
 import 'package:querya_desktop/core/database/postgres_connection.dart';
 import 'package:querya_desktop/core/layout/window_layout.dart';
@@ -42,6 +43,9 @@ class _PostgresConnectionFormContentState
   final _usernameController = material.TextEditingController(text: 'postgres');
   final _passwordController = material.TextEditingController();
   final _connectionStringController = material.TextEditingController();
+  final _sslRootCertController = material.TextEditingController();
+  final _sslCertController = material.TextEditingController();
+  final _sslKeyController = material.TextEditingController();
 
   bool _useSSL = false;
   bool _showPassword = false;
@@ -64,6 +68,10 @@ class _PostgresConnectionFormContentState
     ]) {
       _formValidNotifier.listenTo(c);
     }
+    _connectionStringController.addListener(_populateSslFieldsFromUri);
+    _sslRootCertController.addListener(_syncUriSslParams);
+    _sslCertController.addListener(_syncUriSslParams);
+    _sslKeyController.addListener(_syncUriSslParams);
     _formValidNotifier.seed();
   }
 
@@ -82,6 +90,119 @@ class _PostgresConnectionFormContentState
     return t.startsWith('postgres://') || t.startsWith('postgresql://');
   }
 
+  void _populateSslFieldsFromUri() {
+    final uriText = _connectionStringController.text.trim();
+    if (uriText.isEmpty) return;
+    final parsed = Uri.tryParse(uriText);
+    if (parsed == null) return;
+    _sslRootCertController.text = parsed.queryParameters['sslrootcert'] ?? '';
+    _sslCertController.text = parsed.queryParameters['sslcert'] ?? '';
+    _sslKeyController.text = parsed.queryParameters['sslkey'] ?? '';
+  }
+
+  void _setOrRemoveSslParam(
+    Map<String, String> params,
+    String key,
+    material.TextEditingController controller,
+  ) {
+    final value = controller.text.trim();
+    if (value.isEmpty) {
+      params.remove(key);
+    } else {
+      params[key] = value;
+    }
+  }
+
+  void _syncUriSslParams() {
+    final uriText = _connectionStringController.text.trim();
+    if (uriText.isEmpty) return;
+    final parsed = Uri.tryParse(uriText);
+    if (parsed == null) return;
+    final params = Map<String, String>.from(parsed.queryParameters);
+    _setOrRemoveSslParam(params, 'sslrootcert', _sslRootCertController);
+    _setOrRemoveSslParam(params, 'sslcert', _sslCertController);
+    _setOrRemoveSslParam(params, 'sslkey', _sslKeyController);
+    final newUri = Uri(
+      scheme: parsed.scheme,
+      userInfo: parsed.userInfo.isEmpty ? null : parsed.userInfo,
+      host: parsed.host,
+      port: parsed.hasPort ? parsed.port : null,
+      path: parsed.path.isEmpty ? null : parsed.path,
+      queryParameters: params.isEmpty ? null : params,
+      fragment: parsed.fragment.isEmpty ? null : parsed.fragment,
+    );
+    _connectionStringController.text = newUri.toString();
+    _formValidNotifier.seed();
+  }
+
+  Future<void> _pickCertificateFile(
+    material.TextEditingController controller,
+  ) async {
+    const typeGroup = XTypeGroup(
+      label: 'PEM files',
+      extensions: ['pem', 'crt', 'key', 'cer'],
+    );
+    final file = await openFile(acceptedTypeGroups: const [typeGroup]);
+    if (file == null) return;
+    controller.text = file.path;
+    _syncUriSslParams();
+  }
+
+  String _buildConnectionUri({
+    required String host,
+    required int port,
+    String? username,
+    String? password,
+    String? database,
+    String? sslRootCert,
+    String? sslCert,
+    String? sslKey,
+  }) {
+    final userInfoParts = <String>[
+      if (username != null && username.isNotEmpty) Uri.encodeComponent(username),
+      if (password != null && password.isNotEmpty) Uri.encodeComponent(password),
+    ];
+    final queryParams = <String, String>{
+      if (sslRootCert != null && sslRootCert.isNotEmpty)
+        'sslrootcert': sslRootCert,
+      if (sslCert != null && sslCert.isNotEmpty) 'sslcert': sslCert,
+      if (sslKey != null && sslKey.isNotEmpty) 'sslkey': sslKey,
+    };
+    return Uri(
+      scheme: 'postgresql',
+      userInfo: userInfoParts.join(':'),
+      host: host,
+      port: port,
+      path: database == null || database.isEmpty ? '' : '/$database',
+      queryParameters: queryParams.isEmpty ? null : queryParams,
+    ).toString();
+  }
+
+  String _effectiveConnectionUri() {
+    final uri = _connectionStringController.text.trim();
+    if (uri.isNotEmpty) return uri;
+    final sslRootCert = _sslRootCertController.text.trim();
+    final sslCert = _sslCertController.text.trim();
+    final sslKey = _sslKeyController.text.trim();
+    if (sslRootCert.isEmpty && sslCert.isEmpty && sslKey.isEmpty) return '';
+    return _buildConnectionUri(
+      host: _hostController.text.trim(),
+      port: int.tryParse(_portController.text.trim()) ?? 5432,
+      username: _usernameController.text.trim(),
+      password: _passwordController.text,
+      database: _databaseController.text.trim(),
+      sslRootCert: sslRootCert,
+      sslCert: sslCert,
+      sslKey: sslKey,
+    );
+  }
+
+  bool _hasSslCertificateFields() {
+    return _sslRootCertController.text.trim().isNotEmpty ||
+        _sslCertController.text.trim().isNotEmpty ||
+        _sslKeyController.text.trim().isNotEmpty;
+  }
+
   void _showTestResult(String result) {
     _dismissTimer?.cancel();
     setState(() {
@@ -108,13 +229,14 @@ class _PostgresConnectionFormContentState
       _testResult = null;
     });
     try {
-      final uri = _connectionStringController.text.trim();
+      final uri = _effectiveConnectionUri();
+      final hasUri = uri.isNotEmpty;
       final conn = PostgresConnection(
         id: 0,
         name: _nameController.text.trim().isEmpty
             ? 'test'
             : _nameController.text.trim(),
-        host: uri.isNotEmpty ? 'localhost' : _hostController.text.trim(),
+        host: hasUri ? 'localhost' : _hostController.text.trim(),
         port: int.tryParse(_portController.text.trim()) ?? 5432,
         database: _databaseController.text.trim().isEmpty
             ? null
@@ -124,11 +246,15 @@ class _PostgresConnectionFormContentState
             : _usernameController.text.trim(),
         password:
             _passwordController.text.isEmpty ? null : _passwordController.text,
-        useSSL: _useSSL,
-        connectionString: uri.isEmpty ? null : uri,
+        useSSL: _useSSL || _hasSslCertificateFields(),
+        connectionString: hasUri ? uri : null,
       );
-      final ok = await conn.testConnection();
-      if (mounted) _showTestResult(ok ? 'success' : 'failed');
+      final result = await conn.testConnection();
+      if (mounted) {
+        _showTestResult(
+          result.ok ? 'success' : (result.error ?? 'failed'),
+        );
+      }
     } catch (e) {
       if (mounted) _showTestResult('error: $e');
     }
@@ -140,35 +266,87 @@ class _PostgresConnectionFormContentState
     final host = _hostController.text.trim();
     final port = int.tryParse(_portController.text.trim()) ?? 5432;
     final database = _databaseController.text.trim();
-    final uri = _connectionStringController.text.trim();
+
+    _syncUriSslParams();
+    final effectiveUri = _effectiveConnectionUri();
+    final hasSslCerts = _hasSslCertificateFields();
+    final effectiveUseSSL = _useSSL || hasSslCerts;
+
+    String? uriHost;
+    int? uriPort;
+    if (effectiveUri.isNotEmpty) {
+      final parsedUri = Uri.tryParse(effectiveUri);
+      if (parsedUri != null && parsedUri.host.isNotEmpty) {
+        uriHost = parsedUri.host;
+        uriPort = parsedUri.hasPort ? parsedUri.port : null;
+      }
+    }
+
+    final effectiveHost = uriHost ?? host;
+    final effectivePort = uriPort ?? port;
     final displayName = name.isNotEmpty
         ? name
-        : (uri.isNotEmpty
-            ? 'PostgreSQL (URI)'
+        : (effectiveUri.isNotEmpty
+            ? 'PostgreSQL: $effectiveHost:$effectivePort'
             : 'PostgreSQL $host:$port/$database');
     final row = ConnectionRow(
       type: 'postgresql',
       name: displayName,
-      host: uri.isNotEmpty ? null : host,
-      port: uri.isNotEmpty ? null : port,
+      host: uriHost ?? (effectiveUri.isEmpty ? host : null),
+      port: uriPort ?? (effectiveUri.isEmpty ? port : null),
       username: _usernameController.text.trim().isEmpty
           ? null
           : _usernameController.text.trim(),
       password:
           _passwordController.text.isEmpty ? null : _passwordController.text,
       databaseName:
-          uri.isNotEmpty ? null : (database.isEmpty ? null : database),
-      useSSL: _useSSL,
-      connectionString: uri.isEmpty ? null : uri,
+          effectiveUri.isNotEmpty ? null : (database.isEmpty ? null : database),
+      useSSL: effectiveUseSSL,
+      connectionString: effectiveUri.isEmpty ? null : effectiveUri,
       folderId: widget.folderId,
       createdAt: DateTime.now().toUtc().toIso8601String(),
     );
     material.Navigator.of(context).pop(row);
   }
 
+  material.Widget _buildSslFileField({
+    required String label,
+    required material.TextEditingController controller,
+  }) {
+    return material.Column(
+      crossAxisAlignment: material.CrossAxisAlignment.stretch,
+      mainAxisSize: material.MainAxisSize.min,
+      children: [
+        Text(label).xSmall().muted(),
+        const Gap(4),
+        material.Row(
+              children: [
+                material.Expanded(
+                  child: TextField(
+                    key: Key(label),
+                    controller: controller,
+                    placeholder: const Text('/path/to/file.pem'),
+                    onChanged: (_) => _syncUriSslParams(),
+                  ),
+                ),
+            const Gap(8),
+            GhostButton(
+              onPressed: () => _pickCertificateFile(controller),
+              child: const Icon(material.Icons.folder_open_rounded),
+            ),
+          ],
+        ),
+      ],
+    );
+  }
+
   @override
   void dispose() {
     _dismissTimer?.cancel();
+    _connectionStringController.removeListener(_populateSslFieldsFromUri);
+    _sslRootCertController.removeListener(_syncUriSslParams);
+    _sslCertController.removeListener(_syncUriSslParams);
+    _sslKeyController.removeListener(_syncUriSslParams);
     for (final c in [
       _nameController,
       _hostController,
@@ -187,6 +365,9 @@ class _PostgresConnectionFormContentState
     _usernameController.dispose();
     _passwordController.dispose();
     _connectionStringController.dispose();
+    _sslRootCertController.dispose();
+    _sslCertController.dispose();
+    _sslKeyController.dispose();
     super.dispose();
   }
 
@@ -377,6 +558,32 @@ class _PostgresConnectionFormContentState
                         const Text('Use SSL/TLS').small(),
                       ],
                     ),
+                    if (_useSSL) ...[
+                      const Gap(16),
+                      const Text('SSL Certificates (optional)')
+                          .small()
+                          .semiBold(),
+                      const Gap(4),
+                      const Text(
+                        'Root CA, client certificate, and client key are '
+                        'appended to the connection URI.',
+                      ).muted().small(),
+                      const Gap(8),
+                      _buildSslFileField(
+                        label: 'Root CA / SSL Root Certificate',
+                        controller: _sslRootCertController,
+                      ),
+                      const Gap(8),
+                      _buildSslFileField(
+                        label: 'SSL Client Certificate',
+                        controller: _sslCertController,
+                      ),
+                      const Gap(8),
+                      _buildSslFileField(
+                        label: 'SSL Client Key',
+                        controller: _sslKeyController,
+                      ),
+                    ],
                   ],
                 ),
               ),
diff --git a/linux/flutter/generated_plugin_registrant.cc b/linux/flutter/generated_plugin_registrant.cc
index f09d0a3b..85e343b4 100644
--- a/linux/flutter/generated_plugin_registrant.cc
+++ b/linux/flutter/generated_plugin_registrant.cc
@@ -12,6 +12,7 @@
 #include <irondash_engine_context/irondash_engine_context_plugin.h>
 #include <refresh_rate/refresh_rate_plugin.h>
 #include <super_native_extensions/super_native_extensions_plugin.h>
+#include <url_launcher_linux/url_launcher_plugin.h>
 
 void fl_register_plugins(FlPluginRegistry* registry) {
   g_autoptr(FlPluginRegistrar) bitsdojo_window_linux_registrar =
@@ -32,4 +33,7 @@ void fl_register_plugins(FlPluginRegistry* registry) {
   g_autoptr(FlPluginRegistrar) super_native_extensions_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "SuperNativeExtensionsPlugin");
   super_native_extensions_plugin_register_with_registrar(super_native_extensions_registrar);
+  g_autoptr(FlPluginRegistrar) url_launcher_linux_registrar =
+      fl_plugin_registry_get_registrar_for_plugin(registry, "UrlLauncherPlugin");
+  url_launcher_plugin_register_with_registrar(url_launcher_linux_registrar);
 }
diff --git a/linux/flutter/generated_plugins.cmake b/linux/flutter/generated_plugins.cmake
index 7792787e..f4b41b9b 100644
--- a/linux/flutter/generated_plugins.cmake
+++ b/linux/flutter/generated_plugins.cmake
@@ -9,6 +9,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
   irondash_engine_context
   refresh_rate
   super_native_extensions
+  url_launcher_linux
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST
diff --git a/macos/Flutter/GeneratedPluginRegistrant.swift b/macos/Flutter/GeneratedPluginRegistrant.swift
index d30bbdad..ff1df342 100644
--- a/macos/Flutter/GeneratedPluginRegistrant.swift
+++ b/macos/Flutter/GeneratedPluginRegistrant.swift
@@ -10,9 +10,11 @@ import device_info_plus
 import file_selector_macos
 import flutter_secure_storage_macos
 import irondash_engine_context
+import package_info_plus
 import refresh_rate
 import sqflite_darwin
 import super_native_extensions
+import url_launcher_macos
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   BitsdojoWindowPlugin.register(with: registry.registrar(forPlugin: "BitsdojoWindowPlugin"))
@@ -20,7 +22,9 @@ func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   FileSelectorPlugin.register(with: registry.registrar(forPlugin: "FileSelectorPlugin"))
   FlutterSecureStoragePlugin.register(with: registry.registrar(forPlugin: "FlutterSecureStoragePlugin"))
   IrondashEngineContextPlugin.register(with: registry.registrar(forPlugin: "IrondashEngineContextPlugin"))
+  FPPPackageInfoPlusPlugin.register(with: registry.registrar(forPlugin: "FPPPackageInfoPlusPlugin"))
   RefreshRatePlugin.register(with: registry.registrar(forPlugin: "RefreshRatePlugin"))
   SqflitePlugin.register(with: registry.registrar(forPlugin: "SqflitePlugin"))
   SuperNativeExtensionsPlugin.register(with: registry.registrar(forPlugin: "SuperNativeExtensionsPlugin"))
+  UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index 380d8795..6fc38a73 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: querya_desktop
 description: Lightweight desktop SQL/NoSQL client. Flutter (Dart).
-version: 0.4.8+
+version: 0.4.9+1
 
 
 
@@ -27,6 +27,9 @@ dependencies:
   flutter_secure_storage: ^9.2.4
   file_selector: ^1.1.0
   syntax_highlight: ^0.5.0
+  archive: ^4.0.9
+  url_launcher: ^6.3.1
+  package_info_plus: ^8.3.0
 
 dev_dependencies:
   flutter_test:
diff --git a/test/core/app/app_links_test.dart b/test/core/app/app_links_test.dart
new file mode 100644
index 00000000..89618178
--- /dev/null
+++ b/test/core/app/app_links_test.dart
@@ -0,0 +1,24 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:querya_desktop/core/app/app_links.dart';
+
+void main() {
+  group('AppLinks', () {
+    test('repository points to Querya-Desktop GitHub', () {
+      expect(AppLinks.repository, 'https://github.com/QueryaHub/Querya-Desktop');
+    });
+
+    test('documentation points to docs README on main', () {
+      expect(
+        AppLinks.documentation,
+        'https://github.com/QueryaHub/Querya-Desktop/blob/main/docs/README.md',
+      );
+    });
+
+    test('license points to LICENSE file on main', () {
+      expect(
+        AppLinks.license,
+        'https://github.com/QueryaHub/Querya-Desktop/blob/main/LICENSE',
+      );
+    });
+  });
+}
diff --git a/test/core/database/mysql_connection_test.dart b/test/core/database/mysql_connection_test.dart
index 848a8e08..70f19680 100644
--- a/test/core/database/mysql_connection_test.dart
+++ b/test/core/database/mysql_connection_test.dart
@@ -39,4 +39,93 @@ void main() {
       );
     });
   });
+
+  group('MysqlConnection when not connected', () {
+    late MysqlConnection conn;
+
+    setUp(() {
+      conn = MysqlConnection(
+        id: 1,
+        name: 'test',
+        host: 'localhost',
+      );
+    });
+
+    test('execute throws StateError', () {
+      expect(
+        () => conn.execute('SELECT 1'),
+        throwsA(isA<StateError>().having(
+          (e) => e.message,
+          'message',
+          contains('Not connected to MySQL'),
+        )),
+      );
+    });
+
+    test('listDatabases throws StateError', () {
+      expect(
+        () => conn.listDatabases(),
+        throwsA(isA<StateError>().having(
+          (e) => e.message,
+          'message',
+          contains('Not connected to MySQL'),
+        )),
+      );
+    });
+
+    test('listViews throws StateError', () {
+      expect(
+        () => conn.listViews(schema: 'db'),
+        throwsA(isA<StateError>().having(
+          (e) => e.message,
+          'message',
+          contains('Not connected to MySQL'),
+        )),
+      );
+    });
+
+    test('listColumnNames throws StateError', () {
+      expect(
+        () => conn.listColumnNames(database: 'db', table: 'tbl'),
+        throwsA(isA<StateError>().having(
+          (e) => e.message,
+          'message',
+          contains('Not connected to MySQL'),
+        )),
+      );
+    });
+
+    test('listTables throws StateError', () {
+      expect(
+        () => conn.listTables(schema: 'db'),
+        throwsA(isA<StateError>().having(
+          (e) => e.message,
+          'message',
+          contains('Not connected to MySQL'),
+        )),
+      );
+    });
+
+    test('serverVersion throws StateError', () {
+      expect(
+        () => conn.serverVersion(),
+        throwsA(isA<StateError>().having(
+          (e) => e.message,
+          'message',
+          contains('Not connected to MySQL'),
+        )),
+      );
+    });
+
+    test('serverStats throws StateError', () {
+      expect(
+        () => conn.serverStats(),
+        throwsA(isA<StateError>().having(
+          (e) => e.message,
+          'message',
+          contains('Not connected to MySQL'),
+        )),
+      );
+    });
+  });
 }
diff --git a/test/core/database/postgres_connection_pool_test.dart b/test/core/database/postgres_connection_pool_test.dart
index 0542de50..dff4f3fd 100644
--- a/test/core/database/postgres_connection_pool_test.dart
+++ b/test/core/database/postgres_connection_pool_test.dart
@@ -339,4 +339,50 @@ void main() {
       expect(fake.disconnectCount, 1);
     });
   });
+
+  group('PostgresConnectionPool error wrapping', () {
+    test('wraps unexpected factory errors in PostgresConnectionException', () async {
+      Future<PostgresConnection> factory(
+        ConnectionRow row, {
+        required String database,
+        required PgSessionMode mode,
+      }) async {
+        throw const FormatException('bad connection string');
+      }
+
+      final pool = PostgresConnectionPool(createAndConnect: factory);
+      await expectLater(
+        pool.acquire(_row(), database: 'postgres'),
+        throwsA(
+          isA<PostgresConnectionException>().having(
+            (e) => e.message,
+            'message',
+            contains('Failed to acquire PostgreSQL connection'),
+          ),
+        ),
+      );
+    });
+
+    test('rethrows PostgresConnectionException from factory', () async {
+      Future<PostgresConnection> factory(
+        ConnectionRow row, {
+        required String database,
+        required PgSessionMode mode,
+      }) async {
+        throw PostgresConnectionException('driver refused');
+      }
+
+      final pool = PostgresConnectionPool(createAndConnect: factory);
+      await expectLater(
+        pool.acquire(_row(), database: 'postgres'),
+        throwsA(
+          isA<PostgresConnectionException>().having(
+            (e) => e.message,
+            'message',
+            equals('driver refused'),
+          ),
+        ),
+      );
+    });
+  });
 }
diff --git a/test/core/database/postgres_connection_test.dart b/test/core/database/postgres_connection_test.dart
index bcb68fca..673a87bb 100644
--- a/test/core/database/postgres_connection_test.dart
+++ b/test/core/database/postgres_connection_test.dart
@@ -433,6 +433,18 @@ void main() {
       expect(ex.message, 'connection refused');
       expect(ex.toString(), 'connection refused');
     });
+
+    test('can store cause and stack trace', () {
+      final cause = StateError('root');
+      final trace = StackTrace.current;
+      final ex = PostgresConnectionException(
+        'connection refused',
+        cause: cause,
+        stackTrace: trace,
+      );
+      expect(ex.cause, cause);
+      expect(ex.stackTrace, trace);
+    });
   });
 
   group('replaceDatabaseInConnectionString', () {
@@ -455,4 +467,40 @@ void main() {
       expect(out, isNot(contains('database=olddb')));
     });
   });
+
+  group('PostgresConnection.testConnection', () {
+    test('returns ok=false and error message when connection fails', () async {
+      final conn = PostgresConnection(
+        id: 1,
+        name: 'test',
+        host: 'localhost',
+        connectionString: 'postgresql://localhost/db?sslmode=invalid',
+      );
+      final result = await conn.testConnection();
+      expect(result.ok, false);
+      expect(result.error, isNotNull);
+      expect(result.error, contains('sslmode'));
+    });
+  });
+
+  group('PostgresConnection.connect', () {
+    test('throws PostgresConnectionException on invalid sslmode', () async {
+      final conn = PostgresConnection(
+        id: 1,
+        name: 'test',
+        host: 'localhost',
+        connectionString: 'postgresql://localhost/db?sslmode=invalid',
+      );
+      expect(
+        conn.connect,
+        throwsA(
+          isA<PostgresConnectionException>().having(
+            (e) => e.message,
+            'message',
+            contains('sslmode'),
+          ),
+        ),
+      );
+    });
+  });
 }
diff --git a/test/core/database/sqlite_connection_test.dart b/test/core/database/sqlite_connection_test.dart
index ccf74aee..cd2612f9 100644
--- a/test/core/database/sqlite_connection_test.dart
+++ b/test/core/database/sqlite_connection_test.dart
@@ -91,6 +91,30 @@ void main() {
       expect(columns, containsAll(['id', 'name']));
     });
 
+    test('executes INSERT, UPDATE, DELETE with RETURNING clause correctly', () async {
+      await conn.connect();
+
+      await conn.execute('CREATE TABLE users (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT)');
+
+      // INSERT with RETURNING
+      final insertRes = await conn.execute("INSERT INTO users (name) VALUES ('Alice') RETURNING id, name");
+      expect(insertRes, isNotEmpty);
+      expect(insertRes.first['id'], 1);
+      expect(insertRes.first['name'], 'Alice');
+
+      // UPDATE with RETURNING
+      final updateRes = await conn.execute("UPDATE users SET name = 'Bob' WHERE id = 1 RETURNING id, name");
+      expect(updateRes, isNotEmpty);
+      expect(updateRes.first['id'], 1);
+      expect(updateRes.first['name'], 'Bob');
+
+      // DELETE with RETURNING
+      final deleteRes = await conn.execute("DELETE FROM users WHERE id = 1 RETURNING id, name");
+      expect(deleteRes, isNotEmpty);
+      expect(deleteRes.first['id'], 1);
+      expect(deleteRes.first['name'], 'Bob');
+    });
+
     test('throws StateError for modify operations in read-only mode', () async {
       final roConn = SqliteConnection(
         id: 2,
diff --git a/test/core/market/marketplace_repository_test.dart b/test/core/market/marketplace_repository_test.dart
new file mode 100644
index 00000000..32e9292a
--- /dev/null
+++ b/test/core/market/marketplace_repository_test.dart
@@ -0,0 +1,225 @@
+import 'dart:convert';
+import 'dart:io';
+import 'package:archive/archive.dart';
+import 'package:crypto/crypto.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+import 'package:path/path.dart' as p;
+import 'package:querya_desktop/core/extensions/extension_paths.dart';
+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/market/marketplace_repository.dart';
+
+void main() {
+  group('MockMarketplaceRepository', () {
+    late Directory tempDir;
+
+    setUp(() async {
+      tempDir = await Directory.systemTemp.createTemp('querya_market_test_');
+      ExtensionPaths.mockExtensionsDirectory = tempDir;
+      await LocalExtensionRegistry.instance.reload();
+    });
+
+    tearDown(() async {
+      if (await tempDir.exists()) {
+        await tempDir.delete(recursive: true);
+      }
+      ExtensionPaths.mockExtensionsDirectory = null;
+    });
+
+    test('getTrending returns default seed items', () async {
+      final repo = MockMarketplaceRepository();
+      final trending = await repo.getTrending();
+      expect(trending, isNotEmpty);
+      expect(trending.any((e) => e.id == 'queryahub.clickhouse-driver'), isTrue);
+      expect(trending.any((e) => e.id == 'queryahub.cyberpunk-neon'), isTrue);
+    });
+
+    test('search filters by name, id, description, and tags', () async {
+      final repo = MockMarketplaceRepository();
+      
+      final byName = await repo.search('ClickHouse');
+      expect(byName.length, 1);
+      expect(byName.first.id, 'queryahub.clickhouse-driver');
+
+      final byTag = await repo.search('neon');
+      expect(byTag.length, 1);
+      expect(byTag.first.id, 'queryahub.cyberpunk-neon');
+
+      final empty = await repo.search('nonexistent_extension_query_12345');
+      expect(empty, isEmpty);
+    });
+
+    test('install writes manifest to disk and reloads LocalExtensionRegistry', () async {
+      final repo = MockMarketplaceRepository();
+      final trending = await repo.getTrending();
+      final target = trending.firstWhere((e) => e.id == 'queryahub.clickhouse-driver');
+
+      final progressValues = <double>[];
+      await repo.install(target, onProgress: (p) => progressValues.add(p));
+
+      expect(progressValues, isNotEmpty);
+      expect(progressValues.last, 1.0);
+
+      expect(LocalExtensionRegistry.instance.manifests.any((e) => e.id == target.id), isTrue);
+      
+      final extDir = Directory(p.join(tempDir.path, target.id));
+      expect(await extDir.exists(), isTrue);
+      expect(await File(p.join(extDir.path, 'manifest.json')).exists(), isTrue);
+    });
+
+    test('uninstall removes directory and updates LocalExtensionRegistry', () async {
+      final repo = MockMarketplaceRepository();
+      final trending = await repo.getTrending();
+      final target = trending.firstWhere((e) => e.id == 'queryahub.clickhouse-driver');
+
+      await repo.install(target);
+      expect(LocalExtensionRegistry.instance.manifests.any((e) => e.id == target.id), isTrue);
+
+      await repo.uninstall(target.id);
+      expect(LocalExtensionRegistry.instance.manifests.any((e) => e.id == target.id), isFalse);
+      expect(await Directory(p.join(tempDir.path, target.id)).exists(), isFalse);
+    });
+
+    test('install theme creates theme.json in extension directory', () async {
+      final repo = MockMarketplaceRepository();
+      final trending = await repo.getTrending();
+      final target = trending.firstWhere((e) => e.id == 'queryahub.cyberpunk-neon');
+
+      await repo.install(target);
+
+      final extDir = Directory(p.join(tempDir.path, target.id));
+      expect(await extDir.exists(), isTrue);
+      expect(await File(p.join(extDir.path, 'manifest.json')).exists(), isTrue);
+      expect(await File(p.join(extDir.path, 'theme.json')).exists(), isTrue);
+    });
+  });
+
+  group('HttpMarketplaceRepository', () {
+    late Directory tempDir;
+
+    setUp(() async {
+      tempDir = await Directory.systemTemp.createTemp('querya_http_market_test_');
+      ExtensionPaths.mockExtensionsDirectory = tempDir;
+      await LocalExtensionRegistry.instance.reload();
+    });
+
+    tearDown(() async {
+      if (await tempDir.exists()) {
+        await tempDir.delete(recursive: true);
+      }
+      ExtensionPaths.mockExtensionsDirectory = null;
+    });
+
+    test('getTrending fetches from backend API', () async {
+      final mockClient = MockClient((request) async {
+        expect(request.url.path, '/api/v1/extensions/trending');
+        return http.Response(jsonEncode([
+          {
+            'id': 'test.extension',
+            'name': 'Test Ext',
+            'version': '1.0.0',
+            'publisher': 'Test',
+            'type': 'theme',
+            'engines': {'querya_desktop': '*'},
+          }
+        ]), 200);
+      });
+
+      final repo = HttpMarketplaceRepository(client: mockClient);
+      final trending = await repo.getTrending();
+      expect(trending.length, 1);
+      expect(trending.first.id, 'test.extension');
+    });
+
+    test('search queries backend API', () async {
+      final mockClient = MockClient((request) async {
+        expect(request.url.path, '/api/v1/extensions/search');
+        expect(request.url.queryParameters['q'], 'sql');
+        return http.Response(jsonEncode([
+          {
+            'id': 'test.sql',
+            'name': 'SQL Tools',
+            'version': '1.0.0',
+            'publisher': 'Test',
+            'type': 'databaseDriver',
+            'engines': {'querya_desktop': '*'},
+          }
+        ]), 200);
+      });
+
+      final repo = HttpMarketplaceRepository(client: mockClient);
+      final results = await repo.search('sql');
+      expect(results.length, 1);
+      expect(results.first.name, 'SQL Tools');
+    });
+
+    test('install throws MarketplaceException on SHA256 checksum mismatch', () async {
+      final archive = Archive();
+      archive.addFile(ArchiveFile('test.txt', 4, utf8.encode('good')));
+      final zipBytes = ZipEncoder().encode(archive);
+
+      final mockClient = MockClient((request) async {
+        return http.Response.bytes(zipBytes, 200);
+      });
+
+      final repo = HttpMarketplaceRepository(client: mockClient);
+      const manifest = ExtensionManifest(
+        id: 'test.sha256',
+        name: 'SHA256 Test',
+        version: '1.0.0',
+        publisher: 'Test',
+        type: ExtensionType.theme,
+        engines: {'querya_desktop': '*'},
+        downloadUrl: 'http://localhost:8000/test.zip',
+        sha256Checksum: '0000000000000000000000000000000000000000000000000000000000000000',
+      );
+
+      expect(
+        () => repo.install(manifest),
+        throwsA(isA<MarketplaceException>().having(
+          (e) => e.message,
+          'message',
+          contains('SHA256 checksum mismatch'),
+        )),
+      );
+    });
+
+    test('install prevents Path Traversal during archive unpacking (Issue #242)', () async {
+      final archive = Archive();
+      archive.addFile(ArchiveFile('../evil.txt', 4, utf8.encode('evil')));
+      final zipBytes = ZipEncoder().encode(archive);
+      final expectedSha256 = sha256.convert(zipBytes).toString();
+
+      final mockClient = MockClient((request) async {
+        return http.Response.bytes(zipBytes, 200);
+      });
+
+      final repo = HttpMarketplaceRepository(client: mockClient);
+      final manifest = ExtensionManifest(
+        id: 'test.traversal',
+        name: 'Traversal Test',
+        version: '1.0.0',
+        publisher: 'Test',
+        type: ExtensionType.theme,
+        engines: const {'querya_desktop': '*'},
+        downloadUrl: 'http://localhost:8000/evil.zip',
+        sha256Checksum: expectedSha256,
+      );
+
+      expect(
+        () => repo.install(manifest),
+        throwsA(isA<MarketplaceException>().having(
+          (e) => e.message,
+          'message',
+          contains('Security violation'),
+        )),
+      );
+    });
+  });
+}
+
+
+
diff --git a/test/core/storage/local_db_secrets_test.dart b/test/core/storage/local_db_secrets_test.dart
index bee13adf..fdb76f02 100644
--- a/test/core/storage/local_db_secrets_test.dart
+++ b/test/core/storage/local_db_secrets_test.dart
@@ -116,5 +116,44 @@ void main() {
       expect(s.password, isNull);
       expect(s.connectionString, isNull);
     });
+
+    test('updateConnection atomically updates SQLite row and secure-store secrets', () async {
+      const initialRow = ConnectionRow(
+        type: 'postgres',
+        name: 'PG_Init',
+        host: 'localhost',
+        port: 5432,
+        username: 'admin',
+        password: 'old-secret-password',
+        createdAt: '2026-01-01T00:00:00Z',
+      );
+      final id = await LocalDb.instance.addConnection(initialRow);
+
+      final updatedRow = ConnectionRow(
+        id: id,
+        type: 'postgres',
+        name: 'PG_Updated',
+        host: 'db.example.com',
+        port: 5433,
+        username: 'root',
+        password: 'new-secret-password',
+        connectionString: 'postgres://root:new-secret-password@db.example.com:5433/mydb',
+        createdAt: '2026-01-01T00:00:00Z',
+      );
+      await LocalDb.instance.updateConnection(updatedRow);
+
+      final list = await LocalDb.instance.getConnections();
+      final loaded = list.singleWhere((c) => c.id == id);
+      expect(loaded.name, 'PG_Updated');
+      expect(loaded.host, 'db.example.com');
+      expect(loaded.port, 5433);
+      expect(loaded.username, 'root');
+      expect(loaded.password, 'new-secret-password');
+      expect(loaded.connectionString, 'postgres://root:new-secret-password@db.example.com:5433/mydb');
+
+      final secrets = await ConnectionSecretsStore.readForConnection(id);
+      expect(secrets.password, 'new-secret-password');
+      expect(secrets.connectionString, 'postgres://root:new-secret-password@db.example.com:5433/mydb');
+    });
   });
 }
diff --git a/test/features/connections/connection_url_parser_test.dart b/test/features/connections/connection_url_parser_test.dart
new file mode 100644
index 00000000..49c9905f
--- /dev/null
+++ b/test/features/connections/connection_url_parser_test.dart
@@ -0,0 +1,184 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:querya_desktop/features/connections/connection_url_parser.dart';
+
+void main() {
+  group('parseConnectionUrlInput', () {
+    test('returns error for empty input', () {
+      final result = parseConnectionUrlInput('  ');
+      expect(result.row, isNull);
+      expect(result.error, 'URL/URI is required.');
+    });
+
+    test('returns error for invalid format', () {
+      final result = parseConnectionUrlInput('not a url');
+      expect(result.row, isNull);
+      expect(result.error, 'Invalid URL/URI format.');
+    });
+
+    test('returns error for unsupported scheme', () {
+      final result = parseConnectionUrlInput('ftp://localhost/db');
+      expect(result.row, isNull);
+      expect(result.error, contains('Unsupported protocol'));
+    });
+
+    test('parses postgresql URL with credentials and database', () {
+      final result = parseConnectionUrlInput(
+        'postgresql://alice:secret@db.example.com:5432/myapp',
+      );
+      expect(result.error, isNull);
+      final row = result.row!;
+      expect(row.type, 'postgresql');
+      expect(row.name, 'PostgreSQL: myapp');
+      expect(row.host, 'db.example.com');
+      expect(row.port, 5432);
+      expect(row.username, 'alice');
+      expect(row.password, 'secret');
+      expect(row.databaseName, 'myapp');
+      expect(row.connectionString, 'postgresql://alice:secret@db.example.com:5432/myapp');
+      expect(row.useSSL, false);
+    });
+
+    test('parses postgres alias scheme', () {
+      final result = parseConnectionUrlInput('postgres://localhost/appdb');
+      expect(result.error, isNull);
+      expect(result.row!.type, 'postgresql');
+      expect(result.row!.port, 5432);
+      expect(result.row!.databaseName, 'appdb');
+    });
+
+    test('parses postgresql sslmode=require', () {
+      final result = parseConnectionUrlInput(
+        'postgresql://localhost/postgres?sslmode=require',
+      );
+      expect(result.error, isNull);
+      expect(result.row!.useSSL, true);
+    });
+
+    test('parses postgresql sslmode=verify-full as SSL enabled', () {
+      final result = parseConnectionUrlInput(
+        'postgresql://localhost/postgres?sslmode=verify-full',
+      );
+      expect(result.error, isNull);
+      expect(result.row!.useSSL, true);
+    });
+
+    test('parses postgresql sslmode=verify-ca as SSL enabled', () {
+      final result = parseConnectionUrlInput(
+        'postgresql://localhost/postgres?sslmode=verify-ca',
+      );
+      expect(result.error, isNull);
+      expect(result.row!.useSSL, true);
+    });
+
+    test('parses postgresql sslmode=disable as SSL disabled', () {
+      final result = parseConnectionUrlInput(
+        'postgresql://localhost/postgres?sslmode=disable',
+      );
+      expect(result.error, isNull);
+      expect(result.row!.useSSL, false);
+    });
+
+    test('returns error for postgresql sslmode=prefer', () {
+      final result = parseConnectionUrlInput(
+        'postgresql://localhost/postgres?sslmode=prefer',
+      );
+      expect(result.row, isNull);
+      expect(result.error, contains('Unsupported sslmode'));
+      expect(result.error, contains('prefer'));
+    });
+
+    test('returns error for invalid postgresql sslmode', () {
+      final result = parseConnectionUrlInput(
+        'postgresql://localhost/postgres?sslmode=invalid',
+      );
+      expect(result.row, isNull);
+      expect(result.error, contains('Unsupported sslmode'));
+    });
+
+    test('parses mysql URL', () {
+      final result = parseConnectionUrlInput(
+        'mysql://root:p%40ss@127.0.0.1:3307/sakila',
+      );
+      expect(result.error, isNull);
+      final row = result.row!;
+      expect(row.type, 'mysql');
+      expect(row.name, 'MySQL: sakila');
+      expect(row.host, '127.0.0.1');
+      expect(row.port, 3307);
+      expect(row.username, 'root');
+      expect(row.password, 'p@ss');
+      expect(row.connectionString, 'mysql://root:p%40ss@127.0.0.1:3307/sakila');
+    });
+
+    test('parses sqlite file path', () {
+      final result = parseConnectionUrlInput('sqlite:///tmp/test.db');
+      expect(result.error, isNull);
+      final row = result.row!;
+      expect(row.type, 'sqlite');
+      expect(row.host, '/tmp/test.db');
+      expect(row.name, 'SQLite (test.db)');
+    });
+
+    test('parses sqlite in-memory', () {
+      final result = parseConnectionUrlInput('sqlite:///:memory:');
+      expect(result.error, isNull);
+      expect(result.row!.host, ':memory:');
+      expect(result.row!.name, 'SQLite (Memory)');
+    });
+
+    test('parses mongodb URL with authSource', () {
+      final result = parseConnectionUrlInput(
+        'mongodb://admin:pass@mongo.local:27017/app?authSource=admin',
+      );
+      expect(result.error, isNull);
+      final row = result.row!;
+      expect(row.type, 'mongodb');
+      expect(row.name, 'MongoDB: app');
+      expect(row.authSource, 'admin');
+      expect(row.connectionString, contains('mongodb://'));
+    });
+
+    test('parses mongodb+srv URL', () {
+      final result = parseConnectionUrlInput(
+        'mongodb+srv://user:pass@cluster.example.net/mydb',
+      );
+      expect(result.error, isNull);
+      expect(result.row!.type, 'mongodb');
+      expect(result.row!.host, 'cluster.example.net');
+      expect(result.row!.databaseName, 'mydb');
+    });
+
+    test('parses redis URL', () {
+      final result = parseConnectionUrlInput('redis://:password@localhost:6379');
+      expect(result.error, isNull);
+      final row = result.row!;
+      expect(row.type, 'redis');
+      expect(row.name, 'Redis: localhost:6379');
+      expect(row.password, 'password');
+      expect(row.connectionString, isNull);
+    });
+
+    test('uses default driver port when URI omits port', () {
+      final result = parseConnectionUrlInput('postgresql://localhost/mydb');
+      expect(result.error, isNull);
+      expect(result.row!.port, 5432);
+      expect(result.row!.name, 'PostgreSQL: mydb');
+    });
+
+    test('parses rediss URL with SSL enabled', () {
+      final result = parseConnectionUrlInput('rediss://localhost');
+      expect(result.error, isNull);
+      expect(result.row!.type, 'redis');
+      expect(result.row!.useSSL, true);
+      expect(result.row!.port, 6379);
+    });
+
+    test('password with colon is preserved', () {
+      final result = parseConnectionUrlInput(
+        'postgresql://user:p%3Aart@localhost/mydb',
+      );
+      expect(result.error, isNull);
+      expect(result.row!.password, 'p:art');
+    });
+  });
+}
diff --git a/test/features/connections/new_connection_url_dialog_test.dart b/test/features/connections/new_connection_url_dialog_test.dart
new file mode 100644
index 00000000..5af32e03
--- /dev/null
+++ b/test/features/connections/new_connection_url_dialog_test.dart
@@ -0,0 +1,106 @@
+import 'package:flutter/material.dart' as material;
+import 'package:flutter_test/flutter_test.dart';
+import 'package:querya_desktop/core/storage/local_db.dart';
+import 'package:querya_desktop/features/connections/new_connection_url_dialog.dart';
+import 'package:shadcn_flutter/shadcn_flutter.dart';
+
+import '../../support/querya_theme_test_shell.dart';
+
+void main() {
+  group('showNewConnectionUrlDialog', () {
+    testWidgets('dialog shows title and form controls', (tester) async {
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: material.Builder(
+            builder: (context) => material.ElevatedButton(
+              onPressed: () => showNewConnectionUrlDialog(context),
+              child: const material.Text('Open'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('New connection from URL'), findsOneWidget);
+      expect(find.text('Create'), findsOneWidget);
+      expect(find.text('Cancel'), findsOneWidget);
+    });
+
+    testWidgets('Cancel closes dialog and returns null', (tester) async {
+      ConnectionRow? result;
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: material.Builder(
+            builder: (context) => material.ElevatedButton(
+              onPressed: () async {
+                result = await showNewConnectionUrlDialog(context);
+              },
+              child: const material.Text('Open'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Cancel'));
+      await tester.pumpAndSettle();
+
+      expect(result, isNull);
+    });
+
+    testWidgets('empty URL shows validation error', (tester) async {
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: material.Builder(
+            builder: (context) => material.ElevatedButton(
+              onPressed: () => showNewConnectionUrlDialog(context),
+              child: const material.Text('Open'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Create'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('URL/URI is required.'), findsOneWidget);
+    });
+
+    testWidgets('valid URL returns parsed ConnectionRow', (tester) async {
+      ConnectionRow? result;
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: material.Builder(
+            builder: (context) => material.ElevatedButton(
+              onPressed: () async {
+                result = await showNewConnectionUrlDialog(context);
+              },
+              child: const material.Text('Open'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+
+      await tester.enterText(
+        find.byType(TextField),
+        'postgresql://user:pass@localhost:5432/mydb',
+      );
+      await tester.tap(find.text('Create'));
+      await tester.pumpAndSettle();
+
+      expect(result, isNotNull);
+      expect(result!.type, 'postgresql');
+      expect(result!.databaseName, 'mydb');
+      expect(result!.username, 'user');
+      expect(result!.password, 'pass');
+    });
+  });
+}
diff --git a/test/features/extensions/extension_manager_test.dart b/test/features/extensions/extension_manager_test.dart
new file mode 100644
index 00000000..48ce2bf2
--- /dev/null
+++ b/test/features/extensions/extension_manager_test.dart
@@ -0,0 +1,134 @@
+import 'dart:io';
+import 'package:flutter/material.dart' as material;
+import 'package:flutter_test/flutter_test.dart';
+import 'package:querya_desktop/core/extensions/extension_paths.dart';
+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/market/marketplace_repository.dart';
+import 'package:querya_desktop/features/extensions/presentation/pages/extension_manager_dialog.dart';
+import 'package:querya_desktop/features/extensions/presentation/widgets/extension_card.dart';
+import 'package:querya_desktop/shared/widgets/widgets.dart';
+
+import '../../support/querya_theme_test_shell.dart';
+
+void main() {
+  group('ExtensionCard', () {
+    testWidgets('renders manifest details and tag badges', (tester) async {
+      const manifest = ExtensionManifest(
+        id: 'queryahub.clickhouse-driver',
+        name: 'ClickHouse Driver',
+        version: '1.0.0',
+        publisher: 'QueryaHub',
+        type: ExtensionType.databaseDriver,
+        engines: {'querya_desktop': '^0.4.7'},
+        description: 'Full support for ClickHouse databases.',
+        tags: ['database', 'clickhouse', 'olap'],
+      );
+
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: const material.Scaffold(
+            body: ExtensionCard(
+              manifest: manifest,
+              isInstalled: false,
+            ),
+          ),
+        ),
+      );
+
+      expect(find.text('ClickHouse Driver'), findsOneWidget);
+      expect(find.text('QueryaHub'), findsOneWidget);
+      expect(find.text('v1.0.0'), findsOneWidget);
+      expect(find.text('Full support for ClickHouse databases.'), findsOneWidget);
+      expect(find.text('clickhouse'), findsOneWidget);
+      expect(find.text('Install'), findsOneWidget);
+    });
+
+    testWidgets('renders progress bar when isInstalling is true', (tester) async {
+      const manifest = ExtensionManifest(
+        id: 'queryahub.clickhouse-driver',
+        name: 'ClickHouse Driver',
+        version: '1.0.0',
+        publisher: 'QueryaHub',
+        type: ExtensionType.databaseDriver,
+        engines: {'querya_desktop': '^0.4.7'},
+      );
+
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: const material.Scaffold(
+            body: ExtensionCard(
+              manifest: manifest,
+              isInstalled: false,
+              isInstalling: true,
+              installProgress: 0.45,
+            ),
+          ),
+        ),
+      );
+
+      expect(find.byType(material.LinearProgressIndicator), findsOneWidget);
+      expect(find.text('Installing 45%'), findsOneWidget);
+    });
+  });
+
+  group('ExtensionManagerDialog', () {
+    late Directory tempDir;
+
+    setUp(() async {
+      tempDir = await Directory.systemTemp.createTemp('querya_ui_test_');
+      ExtensionPaths.mockExtensionsDirectory = tempDir;
+      await LocalExtensionRegistry.instance.reload();
+      MarketplaceRepository.instance = MockMarketplaceRepository();
+    });
+
+    tearDown(() async {
+      if (await tempDir.exists()) {
+        await tempDir.delete(recursive: true);
+      }
+      ExtensionPaths.mockExtensionsDirectory = null;
+    });
+
+    testWidgets('renders tabs and loads Marketplace items', (tester) async {
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: material.Builder(
+            builder: (ctx) => material.Scaffold(
+              body: material.Center(
+                child: PrimaryButton(
+                  onPressed: () => showExtensionManagerDialog(ctx),
+                  child: const Text('Open Dialog'),
+                ),
+              ),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open Dialog'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Extensions'), findsOneWidget);
+      expect(find.text('Installed (0)'), findsOneWidget);
+      expect(find.text('Marketplace'), findsOneWidget);
+
+      // Switch to Marketplace tab
+      await tester.tap(find.text('Marketplace'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('ClickHouse Driver'), findsOneWidget);
+      expect(find.text('Redis Driver'), findsOneWidget);
+
+      // Search filtering
+      final finder = find.byType(TextField);
+      expect(finder, findsOneWidget);
+      
+      await tester.enterText(finder, 'Nord');
+      await tester.pumpAndSettle();
+
+      expect(find.text('Nord Theme'), findsOneWidget);
+      expect(find.text('ClickHouse Driver'), findsNothing);
+    });
+  });
+}
diff --git a/test/features/help/about_dialog_test.dart b/test/features/help/about_dialog_test.dart
new file mode 100644
index 00000000..7465ffa6
--- /dev/null
+++ b/test/features/help/about_dialog_test.dart
@@ -0,0 +1,51 @@
+import 'package:flutter/material.dart' as material;
+import 'package:flutter_test/flutter_test.dart';
+import 'package:querya_desktop/features/help/about_dialog.dart';
+
+import '../../support/querya_theme_test_shell.dart';
+
+void main() {
+  group('showAboutDialog', () {
+    testWidgets('dialog shows app name, license, and actions', (tester) async {
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: material.Builder(
+            builder: (context) => material.ElevatedButton(
+              onPressed: () => showAboutDialog(context),
+              child: const material.Text('Open'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Querya'), findsOneWidget);
+      expect(find.textContaining('Version'), findsOneWidget);
+      expect(find.text('Licensed under the MIT License.'), findsOneWidget);
+      expect(find.text('View repository'), findsOneWidget);
+      expect(find.text('Close'), findsOneWidget);
+    });
+
+    testWidgets('Close dismisses the dialog', (tester) async {
+      await tester.pumpWidget(
+        queryaThemeTestShell(
+          child: material.Builder(
+            builder: (context) => material.ElevatedButton(
+              onPressed: () => showAboutDialog(context),
+              child: const material.Text('Open'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Close'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Querya'), findsNothing);
+    });
+  });
+}
diff --git a/test/features/postgresql/postgresql_connection_form_test.dart b/test/features/postgresql/postgresql_connection_form_test.dart
index c1589417..adda7db4 100644
--- a/test/features/postgresql/postgresql_connection_form_test.dart
+++ b/test/features/postgresql/postgresql_connection_form_test.dart
@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart' as material;
 import 'package:flutter_test/flutter_test.dart';
+import 'package:querya_desktop/core/storage/local_db.dart';
 import 'package:querya_desktop/core/theme/app_theme.dart';
 import 'package:querya_desktop/features/postgresql/postgresql_connection_form.dart';
 import 'package:shadcn_flutter/shadcn_flutter.dart';
@@ -88,5 +89,184 @@ void main() {
 
       expect(result, isNull);
     });
+
+    testWidgets('Save from URI extracts host and port for display', (tester) async {
+      await tester.binding.setSurfaceSize(const Size(800, 700));
+      ConnectionRow? result;
+      await tester.pumpWidget(
+        ShadcnApp(
+          theme: AppTheme.dark,
+          darkTheme: AppTheme.dark,
+          themeMode: ThemeMode.dark,
+          home: material.Builder(
+            builder: (context) => material.ElevatedButton(
+              onPressed: () async {
+                result = await showPostgresConnectionForm(context);
+              },
+              child: const material.Text('Open'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+
+      await tester.enterText(
+        find.byWidgetPredicate(
+          (w) => w is TextField && w.placeholder is Text && (w.placeholder as Text).data == 'postgresql://user:pass@host:5432/dbname?sslmode=require',
+        ),
+        'postgresql://u:p@remote.example.com:5433/db',
+      );
+      await tester.tap(find.text('Save'));
+      await tester.pumpAndSettle();
+
+      expect(result, isNotNull);
+      expect(result!.host, 'remote.example.com');
+      expect(result!.port, 5433);
+      expect(result!.name, 'PostgreSQL: remote.example.com:5433');
+      expect(result!.connectionString, 'postgresql://u:p@remote.example.com:5433/db');
+    });
+
+    testWidgets('SSL certificate path is appended to the URI', (tester) async {
+      await tester.binding.setSurfaceSize(const Size(800, 700));
+      await tester.pumpWidget(
+        ShadcnApp(
+          theme: AppTheme.dark,
+          darkTheme: AppTheme.dark,
+          themeMode: ThemeMode.dark,
+          home: material.Builder(
+            builder: (context) => material.ElevatedButton(
+              onPressed: () => showPostgresConnectionForm(context),
+              child: const material.Text('Open'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+
+      await tester.enterText(
+        find.byWidgetPredicate(
+          (w) => w is TextField && w.placeholder is Text && (w.placeholder as Text).data == 'postgresql://user:pass@host:5432/dbname?sslmode=require',
+        ),
+        'postgresql://u:p@remote.example.com:5433/db',
+      );
+
+      await tester.scrollUntilVisible(
+        find.byType(material.Checkbox).first,
+        300,
+        scrollable: find.byType(material.Scrollable).first,
+      );
+      await tester.tap(find.byType(material.Checkbox).first);
+      await tester.pumpAndSettle();
+      await tester.scrollUntilVisible(
+        find.byKey(const Key('Root CA / SSL Root Certificate')),
+        300,
+        scrollable: find.byType(material.Scrollable).first,
+      );
+      await tester.pumpAndSettle();
+
+      await tester.enterText(
+        find.byKey(const Key('Root CA / SSL Root Certificate')),
+        '/certs/root.pem',
+      );
+      await tester.pumpAndSettle();
+
+      final uriField = tester.widget<TextField>(
+        find.byWidgetPredicate(
+          (w) => w is TextField && w.placeholder is Text && (w.placeholder as Text).data == 'postgresql://user:pass@host:5432/dbname?sslmode=require',
+        ),
+      );
+      expect(uriField.controller?.text, contains('sslrootcert'));
+      expect(uriField.controller?.text, contains('root.pem'));
+    });
+
+    testWidgets('Save with SSL certs and no URI builds a connection URI', (tester) async {
+      await tester.binding.setSurfaceSize(const Size(800, 700));
+      ConnectionRow? result;
+      await tester.pumpWidget(
+        ShadcnApp(
+          theme: AppTheme.dark,
+          darkTheme: AppTheme.dark,
+          themeMode: ThemeMode.dark,
+          home: material.Builder(
+            builder: (context) => material.ElevatedButton(
+              onPressed: () async {
+                result = await showPostgresConnectionForm(context);
+              },
+              child: const material.Text('Open'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+
+      await tester.enterText(
+        find.byWidgetPredicate(
+          (w) => w is TextField && w.placeholder is Text && (w.placeholder as Text).data == 'My PostgreSQL Server',
+        ),
+        'Cert PG',
+      );
+      await tester.enterText(
+        find.byWidgetPredicate(
+          (w) => w is TextField && w.placeholder is Text && (w.placeholder as Text).data == 'localhost',
+        ).first,
+        'pg.example.com',
+      );
+      await tester.enterText(
+        find.byWidgetPredicate(
+          (w) => w is TextField && w.placeholder is Text && (w.placeholder as Text).data == 'postgres',
+        ).first,
+        'appdb',
+      );
+      await tester.enterText(
+        find.byWidgetPredicate(
+          (w) => w is TextField && w.placeholder is Text && (w.placeholder as Text).data == 'postgres',
+        ).last,
+        'admin',
+      );
+      await tester.enterText(
+        find.byWidgetPredicate(
+          (w) => w is TextField && w.placeholder is Text && (w.placeholder as Text).data == 'Password',
+        ),
+        'secret',
+      );
+
+      await tester.scrollUntilVisible(
+        find.byType(material.Checkbox).first,
+        300,
+        scrollable: find.byType(material.Scrollable).first,
+      );
+      await tester.tap(find.byType(material.Checkbox).first);
+      await tester.pumpAndSettle();
+      await tester.scrollUntilVisible(
+        find.byKey(const Key('Root CA / SSL Root Certificate')),
+        300,
+        scrollable: find.byType(material.Scrollable).first,
+      );
+      await tester.pumpAndSettle();
+
+      await tester.enterText(
+        find.byKey(const Key('Root CA / SSL Root Certificate')),
+        '/certs/root.pem',
+      );
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.text('Save'));
+      await tester.pumpAndSettle();
+
+      expect(result, isNotNull);
+      expect(result!.connectionString, isNotNull);
+      expect(result!.connectionString, contains('pg.example.com'));
+      expect(result!.connectionString, contains('sslrootcert'));
+      expect(result!.connectionString, contains('root.pem'));
+      expect(result!.connectionString, contains('admin'));
+      expect(result!.connectionString, contains('secret'));
+      expect(result!.useSSL, true);
+    });
   });
 }
diff --git a/windows/flutter/generated_plugin_registrant.cc b/windows/flutter/generated_plugin_registrant.cc
index eab8f5b5..1bce8ba7 100644
--- a/windows/flutter/generated_plugin_registrant.cc
+++ b/windows/flutter/generated_plugin_registrant.cc
@@ -12,6 +12,7 @@
 #include <irondash_engine_context/irondash_engine_context_plugin_c_api.h>
 #include <refresh_rate/refresh_rate_plugin_c_api.h>
 #include <super_native_extensions/super_native_extensions_plugin_c_api.h>
+#include <url_launcher_windows/url_launcher_windows.h>
 
 void RegisterPlugins(flutter::PluginRegistry* registry) {
   BitsdojoWindowPluginRegisterWithRegistrar(
@@ -26,4 +27,6 @@ void RegisterPlugins(flutter::PluginRegistry* registry) {
       registry->GetRegistrarForPlugin("RefreshRatePluginCApi"));
   SuperNativeExtensionsPluginCApiRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("SuperNativeExtensionsPluginCApi"));
+  UrlLauncherWindowsRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("UrlLauncherWindows"));
 }
diff --git a/windows/flutter/generated_plugins.cmake b/windows/flutter/generated_plugins.cmake
index bf263147..134fbbb2 100644
--- a/windows/flutter/generated_plugins.cmake
+++ b/windows/flutter/generated_plugins.cmake
@@ -9,6 +9,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
   irondash_engine_context
   refresh_rate
   super_native_extensions
+  url_launcher_windows
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST