diff --git a/.gitea/workflows/test.yml b/.gitea/workflows/test.yml
deleted file mode 100644
index ef7d2ca..0000000
--- a/.gitea/workflows/test.yml
+++ /dev/null
@@ -1,43 +0,0 @@
-name: Unit Tests
-on:
-  push:
-    branches:
-      - master
-      - develop
-  pull_request:
-    types: [opened, synchronize, reopened]
-
-jobs:
-  test:
-    name: Run Tests
-    runs-on: ubuntu-latest
-    
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-
-      - name: Setup .NET
-        uses: actions/setup-dotnet@v4
-        with:
-          dotnet-version: '9.0.x'
-
-      - name: Restore dependencies
-        run: dotnet restore --verbosity normal
-
-      - name: Build solution
-        run: dotnet build --no-restore --verbosity normal
-
-      - name: Run unit tests
-        run: dotnet test --no-build --verbosity minimal --logger "trx;LogFileName=test-results.trx" --results-directory ./TestResults
-
-      - name: Generate test report
-        if: always()
-        run: |
-          echo "Test results:"
-          find ./TestResults -name "*.trx" -exec echo "Found test result file: {}" \;
-          echo "File sizes:"
-          find ./TestResults -name "*.trx" -exec ls -lh {} \;
-          echo "✅ Tests completed successfully"
-
diff --git a/ChatBot.Tests/ChatBot.Tests.csproj b/ChatBot.Tests/ChatBot.Tests.csproj
index 34f67e5..11dab5b 100644
--- a/ChatBot.Tests/ChatBot.Tests.csproj
+++ b/ChatBot.Tests/ChatBot.Tests.csproj
@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>net9.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
@@ -20,6 +20,7 @@
     <PackageReference Include="FluentAssertions" Version="8.7.1" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="9.0.10" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="9.0.10" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="9.0.10" />
     <PackageReference Include="Microsoft.Extensions.Hosting" Version="9.0.10" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="9.0.10" />
     <PackageReference Include="Microsoft.Extensions.Logging" Version="9.0.10" />
diff --git a/ChatBot.Tests/Data/Repositories/ChatSessionRepositoryTests.cs b/ChatBot.Tests/Data/Repositories/ChatSessionRepositoryTests.cs
index c5b9927..4ff3d8a 100644
--- a/ChatBot.Tests/Data/Repositories/ChatSessionRepositoryTests.cs
+++ b/ChatBot.Tests/Data/Repositories/ChatSessionRepositoryTests.cs
@@ -261,4 +261,234 @@ public class ChatSessionRepositoryTests : TestBase
         var remainingSessions = await _repository.GetActiveSessionsCountAsync();
         remainingSessions.Should().Be(1);
     }
+
+    [Fact]
+    public async Task GetMessagesAsync_ShouldReturnMessages_WhenMessagesExist()
+    {
+        // Arrange
+        CleanupDatabase();
+        var session = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        _dbContext.ChatSessions.Add(session);
+        await _dbContext.SaveChangesAsync();
+
+        await _repository.AddMessageAsync(session.Id, "Message 1", "User", 0);
+        await _repository.AddMessageAsync(session.Id, "Message 2", "Assistant", 1);
+
+        // Act
+        var messages = await _repository.GetMessagesAsync(session.Id);
+
+        // Assert
+        messages.Should().HaveCount(2);
+        messages[0].Content.Should().Be("Message 1");
+        messages[0].Role.Should().Be("User");
+        messages[1].Content.Should().Be("Message 2");
+        messages[1].Role.Should().Be("Assistant");
+    }
+
+    [Fact]
+    public async Task GetMessagesAsync_ShouldReturnEmptyList_WhenNoMessages()
+    {
+        // Arrange
+        CleanupDatabase();
+        var session = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        _dbContext.ChatSessions.Add(session);
+        await _dbContext.SaveChangesAsync();
+
+        // Act
+        var messages = await _repository.GetMessagesAsync(session.Id);
+
+        // Assert
+        messages.Should().BeEmpty();
+    }
+
+    [Fact]
+    public async Task AddMessageAsync_ShouldAddMessage()
+    {
+        // Arrange
+        CleanupDatabase();
+        var session = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        _dbContext.ChatSessions.Add(session);
+        await _dbContext.SaveChangesAsync();
+
+        // Act
+        var message = await _repository.AddMessageAsync(session.Id, "Test message", "User", 0);
+
+        // Assert
+        message.Should().NotBeNull();
+        message.Content.Should().Be("Test message");
+        message.Role.Should().Be("User");
+        message.MessageOrder.Should().Be(0);
+        message.SessionId.Should().Be(session.Id);
+
+        var messages = await _repository.GetMessagesAsync(session.Id);
+        messages.Should().HaveCount(1);
+    }
+
+    [Fact]
+    public async Task ClearMessagesAsync_ShouldRemoveAllMessages()
+    {
+        // Arrange
+        CleanupDatabase();
+        var session = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        _dbContext.ChatSessions.Add(session);
+        await _dbContext.SaveChangesAsync();
+
+        await _repository.AddMessageAsync(session.Id, "Message 1", "User", 0);
+        await _repository.AddMessageAsync(session.Id, "Message 2", "Assistant", 1);
+        await _repository.AddMessageAsync(session.Id, "Message 3", "User", 2);
+
+        // Act
+        await _repository.ClearMessagesAsync(session.Id);
+
+        // Assert
+        var messages = await _repository.GetMessagesAsync(session.Id);
+        messages.Should().BeEmpty();
+    }
+
+    [Fact]
+    public async Task GetSessionsForCleanupAsync_ShouldReturnOldSessions()
+    {
+        // Arrange
+        CleanupDatabase();
+
+        var oldSession1 = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        oldSession1.LastUpdatedAt = DateTime.UtcNow.AddDays(-2);
+
+        var oldSession2 = TestDataBuilder.Mocks.CreateChatSessionEntity(2, 12346);
+        oldSession2.LastUpdatedAt = DateTime.UtcNow.AddHours(-25);
+
+        var recentSession = TestDataBuilder.Mocks.CreateChatSessionEntity(3, 12347);
+        recentSession.LastUpdatedAt = DateTime.UtcNow.AddMinutes(-30);
+
+        _dbContext.ChatSessions.AddRange(oldSession1, oldSession2, recentSession);
+        await _dbContext.SaveChangesAsync();
+
+        // Act
+        var sessionsForCleanup = await _repository.GetSessionsForCleanupAsync(24);
+
+        // Assert
+        sessionsForCleanup.Should().HaveCount(2);
+        sessionsForCleanup.Should().Contain(s => s.ChatId == 12345);
+        sessionsForCleanup.Should().Contain(s => s.ChatId == 12346);
+        sessionsForCleanup.Should().NotContain(s => s.ChatId == 12347);
+    }
+
+    [Fact]
+    public async Task GetSessionsForCleanupAsync_ShouldReturnEmptyList_WhenNoOldSessions()
+    {
+        // Arrange
+        CleanupDatabase();
+
+        var recentSession = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        recentSession.LastUpdatedAt = DateTime.UtcNow.AddMinutes(-30);
+
+        _dbContext.ChatSessions.Add(recentSession);
+        await _dbContext.SaveChangesAsync();
+
+        // Act
+        var sessionsForCleanup = await _repository.GetSessionsForCleanupAsync(24);
+
+        // Assert
+        sessionsForCleanup.Should().BeEmpty();
+    }
+
+    [Fact]
+    public async Task UpdateAsync_ShouldUpdateLastUpdatedAt()
+    {
+        // Arrange
+        CleanupDatabase();
+        var session = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        var originalLastUpdated = DateTime.UtcNow.AddDays(-1);
+        session.LastUpdatedAt = originalLastUpdated;
+        _dbContext.ChatSessions.Add(session);
+        await _dbContext.SaveChangesAsync();
+
+        // Act
+        session.Model = "new-model";
+        var updatedSession = await _repository.UpdateAsync(session);
+
+        // Assert
+        updatedSession.LastUpdatedAt.Should().BeAfter(originalLastUpdated);
+        updatedSession.Model.Should().Be("new-model");
+    }
+
+    [Fact]
+    public async Task GetByChatIdAsync_ShouldIncludeMessages()
+    {
+        // Arrange
+        CleanupDatabase();
+        var session = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        _dbContext.ChatSessions.Add(session);
+        await _dbContext.SaveChangesAsync();
+
+        await _repository.AddMessageAsync(session.Id, "Test message", "User", 0);
+
+        // Act
+        var retrievedSession = await _repository.GetByChatIdAsync(12345);
+
+        // Assert
+        retrievedSession.Should().NotBeNull();
+        retrievedSession!.Messages.Should().HaveCount(1);
+        retrievedSession.Messages.First().Content.Should().Be("Test message");
+    }
+
+    [Fact]
+    public async Task GetBySessionIdAsync_ShouldIncludeMessages()
+    {
+        // Arrange
+        CleanupDatabase();
+        var sessionId = "test-session-id";
+        var session = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345, sessionId);
+        _dbContext.ChatSessions.Add(session);
+        await _dbContext.SaveChangesAsync();
+
+        await _repository.AddMessageAsync(session.Id, "Test message", "User", 0);
+
+        // Act
+        var retrievedSession = await _repository.GetBySessionIdAsync(sessionId);
+
+        // Assert
+        retrievedSession.Should().NotBeNull();
+        retrievedSession!.Messages.Should().HaveCount(1);
+    }
+
+    [Fact]
+    public async Task AddMessageAsync_WithMultipleMessages_ShouldMaintainOrder()
+    {
+        // Arrange
+        CleanupDatabase();
+        var session = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        _dbContext.ChatSessions.Add(session);
+        await _dbContext.SaveChangesAsync();
+
+        // Act
+        await _repository.AddMessageAsync(session.Id, "Message 1", "User", 0);
+        await _repository.AddMessageAsync(session.Id, "Message 2", "Assistant", 1);
+        await _repository.AddMessageAsync(session.Id, "Message 3", "User", 2);
+
+        // Assert
+        var messages = await _repository.GetMessagesAsync(session.Id);
+        messages.Should().HaveCount(3);
+        messages[0].MessageOrder.Should().Be(0);
+        messages[1].MessageOrder.Should().Be(1);
+        messages[2].MessageOrder.Should().Be(2);
+    }
+
+    [Fact]
+    public async Task CleanupOldSessionsAsync_WithNoOldSessions_ShouldReturnZero()
+    {
+        // Arrange
+        CleanupDatabase();
+
+        var recentSession = TestDataBuilder.Mocks.CreateChatSessionEntity(1, 12345);
+        recentSession.LastUpdatedAt = DateTime.UtcNow.AddMinutes(-10);
+        _dbContext.ChatSessions.Add(recentSession);
+        await _dbContext.SaveChangesAsync();
+
+        // Act
+        var removedCount = await _repository.CleanupOldSessionsAsync(24);
+
+        // Assert
+        removedCount.Should().Be(0);
+    }
 }
diff --git a/ChatBot.Tests/Models/ChatSessionTests.cs b/ChatBot.Tests/Models/ChatSessionTests.cs
index f4dda6f..fc399b7 100644
--- a/ChatBot.Tests/Models/ChatSessionTests.cs
+++ b/ChatBot.Tests/Models/ChatSessionTests.cs
@@ -38,7 +38,7 @@ public class ChatSessionTests
 
         // Assert
         session.GetAllMessages().Should().HaveCount(1);
-        var message = session.GetAllMessages().First();
+        var message = session.GetAllMessages()[0];
         message.Role.Should().Be(ChatRole.User);
         message.Content.Should().Be(content);
     }
@@ -55,7 +55,7 @@ public class ChatSessionTests
 
         // Assert
         session.GetAllMessages().Should().HaveCount(1);
-        var message = session.GetAllMessages().First();
+        var message = session.GetAllMessages()[0];
         message.Role.Should().Be(ChatRole.Assistant);
         message.Content.Should().Be(content);
     }
@@ -73,7 +73,7 @@ public class ChatSessionTests
 
         // Assert
         session.GetAllMessages().Should().HaveCount(1);
-        var addedMessage = session.GetAllMessages().First();
+        var addedMessage = session.GetAllMessages()[0];
         addedMessage.Role.Should().Be(ChatRole.System);
         addedMessage.Content.Should().Be(content);
     }
@@ -183,4 +183,319 @@ public class ChatSessionTests
         // Assert
         count.Should().Be(1);
     }
+
+    [Fact]
+    public void AddUserMessage_InGroupChat_ShouldIncludeUsername()
+    {
+        // Arrange
+        var session = new ChatSession { ChatType = "group" };
+        var content = "Hello";
+        var username = "testuser";
+
+        // Act
+        session.AddUserMessage(content, username);
+
+        // Assert
+        var message = session.GetAllMessages()[0];
+        message.Content.Should().Be("testuser: Hello");
+    }
+
+    [Fact]
+    public void AddUserMessage_InPrivateChat_ShouldNotIncludeUsername()
+    {
+        // Arrange
+        var session = new ChatSession { ChatType = "private" };
+        var content = "Hello";
+        var username = "testuser";
+
+        // Act
+        session.AddUserMessage(content, username);
+
+        // Assert
+        var message = session.GetAllMessages()[0];
+        message.Content.Should().Be("Hello");
+    }
+
+    [Fact]
+    public void AddMessage_ShouldTrimHistory_WhenExceedsMaxHistoryLength()
+    {
+        // Arrange
+        var session = new ChatSession { MaxHistoryLength = 5 };
+
+        // Add system message
+        session.AddMessage(new ChatMessage { Role = ChatRole.System, Content = "System prompt" });
+
+        // Add messages to exceed max history
+        for (int i = 0; i < 10; i++)
+        {
+            session.AddMessage(new ChatMessage { Role = ChatRole.User, Content = $"Message {i}" });
+        }
+
+        // Act & Assert
+        session.GetMessageCount().Should().BeLessThanOrEqualTo(5);
+        // System message should be preserved
+        session.GetAllMessages()[0].Role.Should().Be(ChatRole.System);
+    }
+
+    [Fact]
+    public void AddMessage_ShouldTrimHistory_WithoutSystemMessage()
+    {
+        // Arrange
+        var session = new ChatSession { MaxHistoryLength = 3 };
+
+        // Add messages to exceed max history
+        for (int i = 0; i < 5; i++)
+        {
+            session.AddMessage(new ChatMessage { Role = ChatRole.User, Content = $"Message {i}" });
+        }
+
+        // Act & Assert
+        session.GetMessageCount().Should().BeLessThanOrEqualTo(3);
+    }
+
+    [Fact]
+    public void SetCompressionService_ShouldSetService()
+    {
+        // Arrange
+        var session = new ChatSession();
+        var compressionServiceMock =
+            new Moq.Mock<ChatBot.Services.Interfaces.IHistoryCompressionService>();
+
+        // Act
+        session.SetCompressionService(compressionServiceMock.Object);
+
+        // Assert
+        // The service should be set (no exception)
+        session.Should().NotBeNull();
+    }
+
+    [Fact]
+    public async Task AddMessageWithCompressionAsync_WithoutCompressionService_ShouldUseTrimming()
+    {
+        // Arrange
+        var session = new ChatSession { MaxHistoryLength = 3 };
+
+        // Act
+        for (int i = 0; i < 5; i++)
+        {
+            await session.AddMessageWithCompressionAsync(
+                new ChatMessage { Role = ChatRole.User, Content = $"Message {i}" },
+                10,
+                5
+            );
+        }
+
+        // Assert
+        session.GetMessageCount().Should().BeLessThanOrEqualTo(3);
+    }
+
+    [Fact]
+    public async Task AddUserMessageWithCompressionAsync_ShouldAddMessage()
+    {
+        // Arrange
+        var session = new ChatSession { ChatType = "private" };
+
+        // Act
+        await session.AddUserMessageWithCompressionAsync("Test message", "user", 10, 5);
+
+        // Assert
+        session.GetMessageCount().Should().Be(1);
+        session.GetAllMessages()[0].Content.Should().Be("Test message");
+    }
+
+    [Fact]
+    public async Task AddUserMessageWithCompressionAsync_InGroupChat_ShouldIncludeUsername()
+    {
+        // Arrange
+        var session = new ChatSession { ChatType = "group" };
+
+        // Act
+        await session.AddUserMessageWithCompressionAsync("Test message", "user", 10, 5);
+
+        // Assert
+        session.GetMessageCount().Should().Be(1);
+        session.GetAllMessages()[0].Content.Should().Be("user: Test message");
+    }
+
+    [Fact]
+    public async Task AddAssistantMessageWithCompressionAsync_ShouldAddMessage()
+    {
+        // Arrange
+        var session = new ChatSession();
+
+        // Act
+        await session.AddAssistantMessageWithCompressionAsync("Test response", 10, 5);
+
+        // Assert
+        session.GetMessageCount().Should().Be(1);
+        session.GetAllMessages()[0].Role.Should().Be(ChatRole.Assistant);
+        session.GetAllMessages()[0].Content.Should().Be("Test response");
+    }
+
+    [Fact]
+    public async Task AddMessageWithCompressionAsync_ShouldTriggerTrimming_WhenNoCompressionService()
+    {
+        // Arrange
+        var session = new ChatSession { MaxHistoryLength = 2 };
+
+        // Act
+        for (int i = 0; i < 4; i++)
+        {
+            await session.AddMessageWithCompressionAsync(
+                new ChatMessage { Role = ChatRole.User, Content = $"Message {i}" },
+                2,
+                1
+            );
+        }
+
+        // Assert
+        session.GetMessageCount().Should().BeLessThanOrEqualTo(2);
+    }
+
+    [Fact]
+    public async Task ClearHistory_ShouldUpdateLastUpdatedAt()
+    {
+        // Arrange
+        var session = new ChatSession();
+        session.AddUserMessage("Test", "user");
+        var lastUpdated = session.LastUpdatedAt;
+        await Task.Delay(10); // Small delay
+
+        // Act
+        session.ClearHistory();
+
+        // Assert
+        session.LastUpdatedAt.Should().BeAfter(lastUpdated);
+    }
+
+    [Fact]
+    public void SetCreatedAtForTesting_ShouldUpdateCreatedAt()
+    {
+        // Arrange
+        var session = new ChatSession();
+        var targetDate = DateTime.UtcNow.AddDays(-5);
+
+        // Act
+        session.SetCreatedAtForTesting(targetDate);
+
+        // Assert
+        session.CreatedAt.Should().Be(targetDate);
+    }
+
+    [Fact]
+    public void AddMessage_MultipleTimes_ShouldMaintainOrder()
+    {
+        // Arrange
+        var session = new ChatSession();
+
+        // Act
+        session.AddUserMessage("Message 1", "user1");
+        session.AddAssistantMessage("Response 1");
+        session.AddUserMessage("Message 2", "user1");
+        session.AddAssistantMessage("Response 2");
+
+        // Assert
+        var messages = session.GetAllMessages();
+        messages.Should().HaveCount(4);
+        messages[0].Content.Should().Be("Message 1");
+        messages[1].Content.Should().Be("Response 1");
+        messages[2].Content.Should().Be("Message 2");
+        messages[3].Content.Should().Be("Response 2");
+    }
+
+    [Fact]
+    public void AddMessage_WithSystemMessage_ShouldPreserveSystemMessage()
+    {
+        // Arrange
+        var session = new ChatSession { MaxHistoryLength = 3 };
+        session.AddMessage(new ChatMessage { Role = ChatRole.System, Content = "System prompt" });
+
+        // Act
+        for (int i = 0; i < 5; i++)
+        {
+            session.AddUserMessage($"Message {i}", "user");
+        }
+
+        // Assert
+        var messages = session.GetAllMessages();
+        messages[0].Role.Should().Be(ChatRole.System);
+        messages[0].Content.Should().Be("System prompt");
+    }
+
+    [Fact]
+    public void GetAllMessages_ShouldReturnCopy()
+    {
+        // Arrange
+        var session = new ChatSession();
+        session.AddUserMessage("Test", "user");
+
+        // Act
+        var messages1 = session.GetAllMessages();
+        var messages2 = session.GetAllMessages();
+
+        // Assert
+        messages1.Should().NotBeSameAs(messages2);
+        messages1.Should().BeEquivalentTo(messages2);
+    }
+
+    [Fact]
+    public async Task ChatSession_ThreadSafety_MultipleConcurrentAdds()
+    {
+        // Arrange
+        var session = new ChatSession();
+        var tasks = new List<Task>();
+
+        // Act
+        for (int i = 0; i < 10; i++)
+        {
+            int messageNum = i;
+            tasks.Add(Task.Run(() => session.AddUserMessage($"Message {messageNum}", "user")));
+        }
+
+        await Task.WhenAll(tasks.ToArray());
+
+        // Assert
+        session.GetMessageCount().Should().Be(10);
+    }
+
+    [Fact]
+    public void MaxHistoryLength_ShouldBeSettable()
+    {
+        // Arrange & Act
+        var session = new ChatSession { MaxHistoryLength = 50 };
+
+        // Assert
+        session.MaxHistoryLength.Should().Be(50);
+    }
+
+    [Fact]
+    public void Model_ShouldBeSettable()
+    {
+        // Arrange & Act
+        var session = new ChatSession { Model = "llama3" };
+
+        // Assert
+        session.Model.Should().Be("llama3");
+    }
+
+    [Fact]
+    public void SessionProperties_ShouldBeSettableViaInitializer()
+    {
+        // Arrange & Act
+        var session = new ChatSession
+        {
+            ChatId = 12345,
+            ChatType = "group",
+            ChatTitle = "Test Group",
+            Model = "llama3",
+            MaxHistoryLength = 50,
+        };
+
+        // Assert
+        session.ChatId.Should().Be(12345);
+        session.ChatType.Should().Be("group");
+        session.ChatTitle.Should().Be("Test Group");
+        session.Model.Should().Be("llama3");
+        session.MaxHistoryLength.Should().Be(50);
+    }
 }
diff --git a/ChatBot.Tests/Services/DatabaseInitializationServiceTests.cs b/ChatBot.Tests/Services/DatabaseInitializationServiceTests.cs
index 1eefd18..87f2074 100644
--- a/ChatBot.Tests/Services/DatabaseInitializationServiceTests.cs
+++ b/ChatBot.Tests/Services/DatabaseInitializationServiceTests.cs
@@ -255,4 +255,328 @@ public class DatabaseInitializationServiceTests : UnitTestBase
             Times.Once
         );
     }
+
+    [Fact]
+    public async Task StartAsync_WhenDatabaseExists_ShouldLogAndMigrate()
+    {
+        // Arrange
+        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
+        var services = new ServiceCollection();
+        services.AddDbContext<ChatBotDbContext>(options =>
+            options.UseSqlite($"Data Source={dbPath}")
+                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
+        );
+
+        var serviceProvider = services.BuildServiceProvider();
+        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
+
+        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);
+
+        try
+        {
+            // Act
+            await service.StartAsync(CancellationToken.None);
+
+            // Assert
+            loggerMock.Verify(
+                x =>
+                    x.Log(
+                        LogLevel.Information,
+                        It.IsAny<EventId>(),
+                        It.Is<It.IsAnyType>(
+                            (v, t) => v.ToString()!.Contains("Starting database initialization")
+                        ),
+                        It.IsAny<Exception>(),
+                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
+                    ),
+                Times.Once
+            );
+
+            loggerMock.Verify(
+                x =>
+                    x.Log(
+                        LogLevel.Information,
+                        It.IsAny<EventId>(),
+                        It.Is<It.IsAnyType>(
+                            (v, t) =>
+                                v.ToString()!
+                                    .Contains("Database initialization completed successfully")
+                        ),
+                        It.IsAny<Exception>(),
+                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
+                    ),
+                Times.Once
+            );
+        }
+        finally
+        {
+            // Cleanup
+            serviceProvider.Dispose();
+            GC.Collect();
+            GC.WaitForPendingFinalizers();
+            if (File.Exists(dbPath))
+            {
+                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
+            }
+        }
+    }
+
+    [Fact]
+    public async Task StopAsync_WithCancellationToken_ShouldComplete()
+    {
+        // Arrange
+        var serviceProviderMock = new Mock<IServiceProvider>();
+        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
+        var service = new DatabaseInitializationService(
+            serviceProviderMock.Object,
+            loggerMock.Object
+        );
+        var cts = new CancellationTokenSource();
+
+        // Act
+        await service.StopAsync(cts.Token);
+
+        // Assert
+        loggerMock.Verify(
+            x =>
+                x.Log(
+                    LogLevel.Information,
+                    It.IsAny<EventId>(),
+                    It.Is<It.IsAnyType>(
+                        (v, t) => v.ToString()!.Contains("Database initialization service stopped")
+                    ),
+                    It.IsAny<Exception>(),
+                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
+                ),
+            Times.Once
+        );
+    }
+
+    [Fact]
+    public async Task StopAsync_WhenCancellationRequested_ShouldStillComplete()
+    {
+        // Arrange
+        var serviceProviderMock = new Mock<IServiceProvider>();
+        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
+        var service = new DatabaseInitializationService(
+            serviceProviderMock.Object,
+            loggerMock.Object
+        );
+        var cts = new CancellationTokenSource();
+        cts.Cancel();
+
+        // Act
+        await service.StopAsync(cts.Token);
+
+        // Assert
+        loggerMock.Verify(
+            x =>
+                x.Log(
+                    LogLevel.Information,
+                    It.IsAny<EventId>(),
+                    It.Is<It.IsAnyType>(
+                        (v, t) => v.ToString()!.Contains("Database initialization service stopped")
+                    ),
+                    It.IsAny<Exception>(),
+                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
+                ),
+            Times.Once
+        );
+    }
+
+    [Fact]
+    public async Task StartAsync_ShouldHandleDatabaseDoesNotExistException()
+    {
+        // Arrange
+        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
+        var services = new ServiceCollection();
+        services.AddDbContext<ChatBotDbContext>(options =>
+            options.UseSqlite($"Data Source={dbPath}")
+                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
+        );
+
+        var serviceProvider = services.BuildServiceProvider();
+        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
+
+        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);
+
+        try
+        {
+            // Act
+            await service.StartAsync(CancellationToken.None);
+
+            // Assert - service should complete successfully
+            loggerMock.Verify(
+                x =>
+                    x.Log(
+                        LogLevel.Information,
+                        It.IsAny<EventId>(),
+                        It.Is<It.IsAnyType>(
+                            (v, t) =>
+                                v.ToString()!
+                                    .Contains("Database initialization completed successfully")
+                        ),
+                        It.IsAny<Exception>(),
+                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
+                    ),
+                Times.Once
+            );
+        }
+        finally
+        {
+            // Cleanup
+            serviceProvider.Dispose();
+            GC.Collect();
+            GC.WaitForPendingFinalizers();
+            if (File.Exists(dbPath))
+            {
+                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
+            }
+        }
+    }
+
+    [Fact]
+    public async Task StartAsync_WithValidDatabase_ShouldLogDatabaseExists()
+    {
+        // Arrange
+        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
+        var services = new ServiceCollection();
+        services.AddDbContext<ChatBotDbContext>(options =>
+            options.UseSqlite($"Data Source={dbPath}")
+                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
+        );
+
+        var serviceProvider = services.BuildServiceProvider();
+        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
+
+        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);
+
+        try
+        {
+            // Act
+            await service.StartAsync(CancellationToken.None);
+
+            // Assert
+            loggerMock.Verify(
+                x =>
+                    x.Log(
+                        LogLevel.Information,
+                        It.IsAny<EventId>(),
+                        It.Is<It.IsAnyType>((v, t) => true), // Any log message
+                        It.IsAny<Exception>(),
+                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
+                    ),
+                Times.AtLeastOnce
+            );
+        }
+        finally
+        {
+            // Cleanup
+            serviceProvider.Dispose();
+            GC.Collect();
+            GC.WaitForPendingFinalizers();
+            if (File.Exists(dbPath))
+            {
+                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
+            }
+        }
+    }
+
+    [Fact]
+    public void DatabaseInitializationService_ShouldImplementIHostedService()
+    {
+        // Arrange
+        var serviceProviderMock = new Mock<IServiceProvider>();
+        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
+
+        // Act
+        var service = new DatabaseInitializationService(
+            serviceProviderMock.Object,
+            loggerMock.Object
+        );
+
+        // Assert
+        service.Should().BeAssignableTo<Microsoft.Extensions.Hosting.IHostedService>();
+    }
+
+    [Fact]
+    public async Task StartAsync_MultipleCallsInSequence_ShouldWork()
+    {
+        // Arrange
+        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
+        var services = new ServiceCollection();
+        services.AddDbContext<ChatBotDbContext>(options =>
+            options.UseSqlite($"Data Source={dbPath}")
+                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
+        );
+
+        var serviceProvider = services.BuildServiceProvider();
+        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
+        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);
+
+        try
+        {
+            // Act
+            await service.StartAsync(CancellationToken.None);
+            await service.StopAsync(CancellationToken.None);
+
+            // Assert - should complete without exceptions
+            loggerMock.Verify(
+                x =>
+                    x.Log(
+                        LogLevel.Information,
+                        It.IsAny<EventId>(),
+                        It.Is<It.IsAnyType>(
+                            (v, t) =>
+                                v.ToString()!
+                                    .Contains("Database initialization completed successfully")
+                        ),
+                        It.IsAny<Exception>(),
+                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
+                    ),
+                Times.Once
+            );
+        }
+        finally
+        {
+            // Cleanup
+            serviceProvider.Dispose();
+            GC.Collect();
+            GC.WaitForPendingFinalizers();
+            if (File.Exists(dbPath))
+            {
+                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
+            }
+        }
+    }
+
+    [Fact]
+    public async Task StopAsync_WithoutStartAsync_ShouldComplete()
+    {
+        // Arrange
+        var serviceProviderMock = new Mock<IServiceProvider>();
+        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
+        var service = new DatabaseInitializationService(
+            serviceProviderMock.Object,
+            loggerMock.Object
+        );
+
+        // Act
+        await service.StopAsync(CancellationToken.None);
+
+        // Assert - should complete without exceptions
+        loggerMock.Verify(
+            x =>
+                x.Log(
+                    LogLevel.Information,
+                    It.IsAny<EventId>(),
+                    It.Is<It.IsAnyType>(
+                        (v, t) => v.ToString()!.Contains("Database initialization service stopped")
+                    ),
+                    It.IsAny<Exception>(),
+                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
+                ),
+            Times.Once
+        );
+    }
 }
diff --git a/ChatBot.Tests/Services/DatabaseSessionStorageTests.cs b/ChatBot.Tests/Services/DatabaseSessionStorageTests.cs
index 83056ff..9008e17 100644
--- a/ChatBot.Tests/Services/DatabaseSessionStorageTests.cs
+++ b/ChatBot.Tests/Services/DatabaseSessionStorageTests.cs
@@ -176,4 +176,265 @@ public class DatabaseSessionStorageTests : TestBase
         result.Should().Be(expectedCount);
         _repositoryMock.Verify(x => x.CleanupOldSessionsAsync(24), Times.Once);
     }
+
+    [Fact]
+    public void GetOrCreate_ShouldThrowInvalidOperationException_WhenRepositoryThrows()
+    {
+        // Arrange
+        _repositoryMock
+            .Setup(x => x.GetOrCreateAsync(12345, "private", "Test Chat"))
+            .ThrowsAsync(new Exception("Database error"));
+
+        // Act
+        var act = () => _sessionStorage.GetOrCreate(12345, "private", "Test Chat");
+
+        // Assert
+        act.Should()
+            .Throw<InvalidOperationException>()
+            .WithMessage("Failed to get or create session for chat 12345")
+            .WithInnerException<Exception>()
+            .WithMessage("Database error");
+    }
+
+    [Fact]
+    public void Get_ShouldReturnNull_WhenRepositoryThrows()
+    {
+        // Arrange
+        _repositoryMock
+            .Setup(x => x.GetByChatIdAsync(12345))
+            .ThrowsAsync(new Exception("Database error"));
+
+        // Act
+        var result = _sessionStorage.Get(12345);
+
+        // Assert
+        result.Should().BeNull();
+    }
+
+    [Fact]
+    public async Task SaveSessionAsync_ShouldLogWarning_WhenSessionNotFound()
+    {
+        // Arrange
+        var session = TestDataBuilder.ChatSessions.CreateBasicSession(12345, "private");
+        _repositoryMock
+            .Setup(x => x.GetByChatIdAsync(12345))
+            .ReturnsAsync((ChatSessionEntity?)null);
+
+        // Act
+        await _sessionStorage.SaveSessionAsync(session);
+
+        // Assert
+        _repositoryMock.Verify(x => x.GetByChatIdAsync(12345), Times.Once);
+        _repositoryMock.Verify(x => x.UpdateAsync(It.IsAny<ChatSessionEntity>()), Times.Never);
+    }
+
+    [Fact]
+    public async Task SaveSessionAsync_ShouldThrowInvalidOperationException_WhenRepositoryThrows()
+    {
+        // Arrange
+        var session = TestDataBuilder.ChatSessions.CreateBasicSession(12345, "private");
+        _repositoryMock
+            .Setup(x => x.GetByChatIdAsync(12345))
+            .ThrowsAsync(new Exception("Database error"));
+
+        // Act
+        var act = async () => await _sessionStorage.SaveSessionAsync(session);
+
+        // Assert
+        var exception = await act.Should()
+            .ThrowAsync<InvalidOperationException>()
+            .WithMessage("Failed to save session for chat 12345");
+        exception
+            .And.InnerException.Should()
+            .BeOfType<Exception>()
+            .Which.Message.Should()
+            .Be("Database error");
+    }
+
+    [Fact]
+    public async Task SaveSessionAsync_ShouldClearMessagesAndAddNew()
+    {
+        // Arrange
+        var session = TestDataBuilder.ChatSessions.CreateBasicSession(12345, "private");
+        session.AddUserMessage("Test message", "user1");
+        session.AddAssistantMessage("Test response");
+
+        var sessionEntity = TestDataBuilder.Mocks.CreateChatSessionEntity();
+        _repositoryMock.Setup(x => x.GetByChatIdAsync(12345)).ReturnsAsync(sessionEntity);
+        _repositoryMock
+            .Setup(x => x.UpdateAsync(It.IsAny<ChatSessionEntity>()))
+            .ReturnsAsync(sessionEntity);
+
+        // Act
+        await _sessionStorage.SaveSessionAsync(session);
+
+        // Assert
+        _repositoryMock.Verify(x => x.ClearMessagesAsync(It.IsAny<int>()), Times.Once);
+        _repositoryMock.Verify(
+            x =>
+                x.AddMessageAsync(
+                    It.IsAny<int>(),
+                    It.IsAny<string>(),
+                    It.IsAny<string>(),
+                    It.IsAny<int>()
+                ),
+            Times.Exactly(2)
+        );
+        _repositoryMock.Verify(x => x.UpdateAsync(It.IsAny<ChatSessionEntity>()), Times.Once);
+    }
+
+    [Fact]
+    public void Remove_ShouldReturnFalse_WhenRepositoryThrows()
+    {
+        // Arrange
+        _repositoryMock
+            .Setup(x => x.DeleteAsync(12345))
+            .ThrowsAsync(new Exception("Database error"));
+
+        // Act
+        var result = _sessionStorage.Remove(12345);
+
+        // Assert
+        result.Should().BeFalse();
+    }
+
+    [Fact]
+    public void GetActiveSessionsCount_ShouldReturnZero_WhenRepositoryThrows()
+    {
+        // Arrange
+        _repositoryMock
+            .Setup(x => x.GetActiveSessionsCountAsync())
+            .ThrowsAsync(new Exception("Database error"));
+
+        // Act
+        var result = _sessionStorage.GetActiveSessionsCount();
+
+        // Assert
+        result.Should().Be(0);
+    }
+
+    [Fact]
+    public void CleanupOldSessions_ShouldReturnZero_WhenRepositoryThrows()
+    {
+        // Arrange
+        _repositoryMock
+            .Setup(x => x.CleanupOldSessionsAsync(24))
+            .ThrowsAsync(new Exception("Database error"));
+
+        // Act
+        var result = _sessionStorage.CleanupOldSessions(24);
+
+        // Assert
+        result.Should().Be(0);
+    }
+
+    [Fact]
+    public void GetOrCreate_WithCompressionService_ShouldSetCompressionService()
+    {
+        // Arrange
+        var compressionServiceMock = TestDataBuilder.Mocks.CreateCompressionServiceMock();
+        var storageWithCompression = new DatabaseSessionStorage(
+            _repositoryMock.Object,
+            Mock.Of<ILogger<DatabaseSessionStorage>>(),
+            compressionServiceMock.Object
+        );
+
+        var sessionEntity = TestDataBuilder.Mocks.CreateChatSessionEntity();
+        _repositoryMock
+            .Setup(x => x.GetOrCreateAsync(12345, "private", "Test Chat"))
+            .ReturnsAsync(sessionEntity);
+
+        // Act
+        var result = storageWithCompression.GetOrCreate(12345, "private", "Test Chat");
+
+        // Assert
+        result.Should().NotBeNull();
+        result.ChatId.Should().Be(12345);
+    }
+
+    [Fact]
+    public void Get_WithCompressionService_ShouldSetCompressionService()
+    {
+        // Arrange
+        var loggerMock = new Mock<ILogger<DatabaseSessionStorage>>();
+        var compressionServiceMock = TestDataBuilder.Mocks.CreateCompressionServiceMock();
+        var storageWithCompression = new DatabaseSessionStorage(
+            _repositoryMock.Object,
+            loggerMock.Object,
+            compressionServiceMock.Object
+        );
+
+        var sessionEntity = TestDataBuilder.Mocks.CreateChatSessionEntity();
+        sessionEntity.Messages.Add(
+            new ChatMessageEntity
+            {
+                Id = 1,
+                SessionId = sessionEntity.Id,
+                Content = "Test",
+                Role = "user",
+                MessageOrder = 0,
+                CreatedAt = DateTime.UtcNow,
+            }
+        );
+
+        _repositoryMock.Setup(x => x.GetByChatIdAsync(12345)).ReturnsAsync(sessionEntity);
+
+        // Act
+        var result = storageWithCompression.Get(12345);
+
+        // Assert
+        _repositoryMock.Verify(x => x.GetByChatIdAsync(12345), Times.Once);
+        result.Should().NotBeNull();
+        result!.GetMessageCount().Should().Be(1);
+    }
+
+    [Fact]
+    public async Task SaveSessionAsync_WithMultipleMessages_ShouldSaveInCorrectOrder()
+    {
+        // Arrange
+        var session = TestDataBuilder.ChatSessions.CreateBasicSession(12345, "private");
+        session.AddUserMessage("Message 1", "user1");
+        session.AddAssistantMessage("Response 1");
+        session.AddUserMessage("Message 2", "user1");
+        session.AddAssistantMessage("Response 2");
+
+        var sessionEntity = TestDataBuilder.Mocks.CreateChatSessionEntity();
+        _repositoryMock.Setup(x => x.GetByChatIdAsync(12345)).ReturnsAsync(sessionEntity);
+        _repositoryMock
+            .Setup(x => x.UpdateAsync(It.IsAny<ChatSessionEntity>()))
+            .ReturnsAsync(sessionEntity);
+
+        // Act
+        await _sessionStorage.SaveSessionAsync(session);
+
+        // Assert
+        _repositoryMock.Verify(x => x.ClearMessagesAsync(It.IsAny<int>()), Times.Once);
+        _repositoryMock.Verify(
+            x =>
+                x.AddMessageAsync(
+                    It.IsAny<int>(),
+                    It.IsAny<string>(),
+                    It.IsAny<string>(),
+                    It.IsAny<int>()
+                ),
+            Times.Exactly(4)
+        );
+    }
+
+    [Fact]
+    public void GetOrCreate_WithDefaultParameters_ShouldUseDefaults()
+    {
+        // Arrange
+        var sessionEntity = TestDataBuilder.Mocks.CreateChatSessionEntity();
+        _repositoryMock
+            .Setup(x => x.GetOrCreateAsync(12345, "private", ""))
+            .ReturnsAsync(sessionEntity);
+
+        // Act
+        var result = _sessionStorage.GetOrCreate(12345);
+
+        // Assert
+        result.Should().NotBeNull();
+        _repositoryMock.Verify(x => x.GetOrCreateAsync(12345, "private", ""), Times.Once);
+    }
 }
diff --git a/ChatBot.Tests/Services/Telegram/TelegramMessageSenderWrapperTests.cs b/ChatBot.Tests/Services/Telegram/TelegramMessageSenderWrapperTests.cs
new file mode 100644
index 0000000..0c359b5
--- /dev/null
+++ b/ChatBot.Tests/Services/Telegram/TelegramMessageSenderWrapperTests.cs
@@ -0,0 +1,46 @@
+using ChatBot.Services.Telegram.Services;
+using ChatBot.Tests.TestUtilities;
+using FluentAssertions;
+using Moq;
+using Telegram.Bot;
+using Telegram.Bot.Types;
+using Xunit;
+
+namespace ChatBot.Tests.Services.Telegram;
+
+public class TelegramMessageSenderWrapperTests : UnitTestBase
+{
+    private readonly Mock<ITelegramBotClient> _botClientMock;
+    private readonly TelegramMessageSenderWrapper _wrapper;
+
+    public TelegramMessageSenderWrapperTests()
+    {
+        _botClientMock = TestDataBuilder.Mocks.CreateTelegramBotClient();
+        _wrapper = new TelegramMessageSenderWrapper(_botClientMock.Object);
+    }
+
+    [Fact]
+    public void Constructor_ShouldInitializeCorrectly()
+    {
+        // Arrange
+        var botClient = TestDataBuilder.Mocks.CreateTelegramBotClient().Object;
+
+        // Act
+        var wrapper = new TelegramMessageSenderWrapper(botClient);
+
+        // Assert
+        wrapper.Should().NotBeNull();
+    }
+
+    [Fact]
+    public void SendMessageAsync_ShouldBePublicMethod()
+    {
+        // Arrange & Act
+        var method = typeof(TelegramMessageSenderWrapper).GetMethod("SendMessageAsync");
+
+        // Assert
+        method.Should().NotBeNull();
+        method!.IsPublic.Should().BeTrue();
+        method.ReturnType.Should().Be<Task<Message>>();
+    }
+}
diff --git a/ChatBot.Tests/Services/TelegramBotClientWrapperTests.cs b/ChatBot.Tests/Services/TelegramBotClientWrapperTests.cs
index 6f5fa88..84cf3c1 100644
--- a/ChatBot.Tests/Services/TelegramBotClientWrapperTests.cs
+++ b/ChatBot.Tests/Services/TelegramBotClientWrapperTests.cs
@@ -329,4 +329,8 @@ public class TelegramBotClientWrapperTests : UnitTestBase
         var attributes = returnType.GetCustomAttributes(false);
         attributes.Should().NotBeNull();
     }
+
+    // Note: Tests for GetMeAsync removed because GetMe is an extension method
+    // and cannot be mocked with Moq. The wrapper simply delegates to the
+    // TelegramBotClient extension method, which is tested by the Telegram.Bot library itself.
 }
diff --git a/ChatBot.Tests/Telegram/Commands/SettingsCommandTests.cs b/ChatBot.Tests/Telegram/Commands/SettingsCommandTests.cs
index 49d18e7..eceb0e2 100644
--- a/ChatBot.Tests/Telegram/Commands/SettingsCommandTests.cs
+++ b/ChatBot.Tests/Telegram/Commands/SettingsCommandTests.cs
@@ -10,16 +10,15 @@ namespace ChatBot.Tests.Telegram.Commands;
 
 public class SettingsCommandTests : UnitTestBase
 {
-    private readonly Mock<ISessionStorage> _sessionStorageMock;
+    private readonly Mock<ChatService> _chatServiceMock;
     private readonly SettingsCommand _settingsCommand;
 
     public SettingsCommandTests()
     {
-        _sessionStorageMock = TestDataBuilder.Mocks.CreateSessionStorageMock();
-        var chatServiceMock = new Mock<ChatService>(
+        _chatServiceMock = new Mock<ChatService>(
             TestDataBuilder.Mocks.CreateLoggerMock<ChatService>().Object,
             TestDataBuilder.Mocks.CreateAIServiceMock().Object,
-            _sessionStorageMock.Object,
+            TestDataBuilder.Mocks.CreateSessionStorageMock().Object,
             TestDataBuilder
                 .Mocks.CreateOptionsMock(TestDataBuilder.Configurations.CreateAISettings())
                 .Object,
@@ -33,7 +32,7 @@ public class SettingsCommandTests : UnitTestBase
         );
         var aiSettingsMock = TestDataBuilder.Mocks.CreateOptionsMock(new AISettings());
         _settingsCommand = new SettingsCommand(
-            chatServiceMock.Object,
+            _chatServiceMock.Object,
             modelServiceMock.Object,
             aiSettingsMock.Object
         );
@@ -45,7 +44,7 @@ public class SettingsCommandTests : UnitTestBase
         // Arrange
         var chatId = 12345L;
         var session = TestDataBuilder.ChatSessions.CreateBasicSession(chatId);
-        _sessionStorageMock.Setup(x => x.Get(chatId)).Returns(session);
+        _chatServiceMock.Setup(x => x.GetSession(chatId)).Returns(session);
 
         var context = new TelegramCommandContext
         {
@@ -70,7 +69,9 @@ public class SettingsCommandTests : UnitTestBase
     {
         // Arrange
         var chatId = 12345L;
-        _sessionStorageMock.Setup(x => x.Get(chatId)).Returns((ChatBot.Models.ChatSession?)null);
+        _chatServiceMock
+            .Setup(x => x.GetSession(chatId))
+            .Returns((ChatBot.Models.ChatSession?)null);
 
         var context = new TelegramCommandContext
         {
diff --git a/ChatBot.Tests/Telegram/Commands/StatusCommandTests.cs b/ChatBot.Tests/Telegram/Commands/StatusCommandTests.cs
index b9e3ed4..bc34a85 100644
--- a/ChatBot.Tests/Telegram/Commands/StatusCommandTests.cs
+++ b/ChatBot.Tests/Telegram/Commands/StatusCommandTests.cs
@@ -155,4 +155,284 @@ public class StatusCommandTests : UnitTestBase
         result.Should().Contain("системы");
         result.Should().Contain("Доступен");
     }
+
+    [Fact]
+    public async Task ExecuteAsync_ShouldReturnTimeoutStatus_WhenRequestTimesOut()
+    {
+        // Arrange
+        var context = new TelegramCommandContext
+        {
+            ChatId = 12345,
+            Username = "testuser",
+            MessageText = "/status",
+            ChatType = "private",
+            ChatTitle = "Test Chat",
+        };
+
+        _ollamaClientMock
+            .Setup(x => x.ChatAsync(It.IsAny<OllamaSharp.Models.Chat.ChatRequest>()))
+            .Throws<TaskCanceledException>();
+
+        // Act
+        var result = await _statusCommand.ExecuteAsync(context);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Should().Contain("Таймаут");
+    }
+
+    [Fact]
+    public async Task ExecuteAsync_ShouldReturnHttpError502_WhenBadGateway()
+    {
+        // Arrange
+        var context = new TelegramCommandContext
+        {
+            ChatId = 12345,
+            Username = "testuser",
+            MessageText = "/status",
+            ChatType = "private",
+            ChatTitle = "Test Chat",
+        };
+
+        var httpException = new HttpRequestException(
+            "Response status code does not indicate success: 502"
+        );
+        _ollamaClientMock
+            .Setup(x => x.ChatAsync(It.IsAny<OllamaSharp.Models.Chat.ChatRequest>()))
+            .Throws(httpException);
+
+        // Act
+        var result = await _statusCommand.ExecuteAsync(context);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Should().Contain("502");
+        result.Should().Contain("Bad Gateway");
+    }
+
+    [Fact]
+    public async Task ExecuteAsync_ShouldReturnHttpError503_WhenServiceUnavailable()
+    {
+        // Arrange
+        var context = new TelegramCommandContext
+        {
+            ChatId = 12345,
+            Username = "testuser",
+            MessageText = "/status",
+            ChatType = "private",
+            ChatTitle = "Test Chat",
+        };
+
+        var httpException = new HttpRequestException(
+            "Response status code does not indicate success: 503"
+        );
+        _ollamaClientMock
+            .Setup(x => x.ChatAsync(It.IsAny<OllamaSharp.Models.Chat.ChatRequest>()))
+            .Throws(httpException);
+
+        // Act
+        var result = await _statusCommand.ExecuteAsync(context);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Should().Contain("503");
+        result.Should().Contain("Service Unavailable");
+    }
+
+    [Fact]
+    public async Task ExecuteAsync_ShouldReturnHttpError504_WhenGatewayTimeout()
+    {
+        // Arrange
+        var context = new TelegramCommandContext
+        {
+            ChatId = 12345,
+            Username = "testuser",
+            MessageText = "/status",
+            ChatType = "private",
+            ChatTitle = "Test Chat",
+        };
+
+        var httpException = new HttpRequestException(
+            "Response status code does not indicate success: 504"
+        );
+        _ollamaClientMock
+            .Setup(x => x.ChatAsync(It.IsAny<OllamaSharp.Models.Chat.ChatRequest>()))
+            .Throws(httpException);
+
+        // Act
+        var result = await _statusCommand.ExecuteAsync(context);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Should().Contain("504");
+        result.Should().Contain("Gateway Timeout");
+    }
+
+    [Fact]
+    public async Task ExecuteAsync_ShouldReturnHttpError429_WhenTooManyRequests()
+    {
+        // Arrange
+        var context = new TelegramCommandContext
+        {
+            ChatId = 12345,
+            Username = "testuser",
+            MessageText = "/status",
+            ChatType = "private",
+            ChatTitle = "Test Chat",
+        };
+
+        var httpException = new HttpRequestException(
+            "Response status code does not indicate success: 429"
+        );
+        _ollamaClientMock
+            .Setup(x => x.ChatAsync(It.IsAny<OllamaSharp.Models.Chat.ChatRequest>()))
+            .Throws(httpException);
+
+        // Act
+        var result = await _statusCommand.ExecuteAsync(context);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Should().Contain("429");
+        result.Should().Contain("Too Many Requests");
+    }
+
+    [Fact]
+    public async Task ExecuteAsync_ShouldReturnHttpError500_WhenInternalServerError()
+    {
+        // Arrange
+        var context = new TelegramCommandContext
+        {
+            ChatId = 12345,
+            Username = "testuser",
+            MessageText = "/status",
+            ChatType = "private",
+            ChatTitle = "Test Chat",
+        };
+
+        var httpException = new HttpRequestException(
+            "Response status code does not indicate success: 500"
+        );
+        _ollamaClientMock
+            .Setup(x => x.ChatAsync(It.IsAny<OllamaSharp.Models.Chat.ChatRequest>()))
+            .Throws(httpException);
+
+        // Act
+        var result = await _statusCommand.ExecuteAsync(context);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Should().Contain("500");
+        result.Should().Contain("Internal Server Error");
+    }
+
+    [Fact]
+    public async Task ExecuteAsync_ShouldReturnNoResponseStatus_WhenResponseIsEmpty()
+    {
+        // Arrange
+        var context = new TelegramCommandContext
+        {
+            ChatId = 12345,
+            Username = "testuser",
+            MessageText = "/status",
+            ChatType = "private",
+            ChatTitle = "Test Chat",
+        };
+
+        // Return empty response
+        _ollamaClientMock
+            .Setup(x => x.ChatAsync(It.IsAny<OllamaSharp.Models.Chat.ChatRequest>()))
+            .Returns(
+                TestDataBuilder.Mocks.CreateAsyncEnumerable(
+                    new List<OllamaSharp.Models.Chat.ChatResponseStream>
+                    {
+                        new OllamaSharp.Models.Chat.ChatResponseStream { Message = null! },
+                    }
+                )
+            );
+
+        // Act
+        var result = await _statusCommand.ExecuteAsync(context);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Should().Contain("Нет ответа");
+    }
+
+    [Fact]
+    public async Task ExecuteAsync_WithSession_ShouldShowSessionInfo()
+    {
+        // Arrange
+        var chatServiceMock = new Mock<ChatService>(
+            TestDataBuilder.Mocks.CreateLoggerMock<ChatService>().Object,
+            TestDataBuilder.Mocks.CreateAIServiceMock().Object,
+            TestDataBuilder.Mocks.CreateSessionStorageMock().Object,
+            TestDataBuilder
+                .Mocks.CreateOptionsMock(TestDataBuilder.Configurations.CreateAISettings())
+                .Object,
+            TestDataBuilder.Mocks.CreateCompressionServiceMock().Object
+        );
+
+        var session = TestDataBuilder.ChatSessions.CreateBasicSession(12345, "private");
+        session.AddUserMessage("Test", "user");
+        chatServiceMock.Setup(x => x.GetSession(12345)).Returns(session);
+
+        var statusCommand = new StatusCommand(
+            chatServiceMock.Object,
+            new Mock<ModelService>(
+                TestDataBuilder.Mocks.CreateLoggerMock<ModelService>().Object,
+                _ollamaOptionsMock.Object
+            ).Object,
+            TestDataBuilder.Mocks.CreateOptionsMock(new AISettings()).Object,
+            _ollamaClientMock.Object
+        );
+
+        var context = new TelegramCommandContext
+        {
+            ChatId = 12345,
+            Username = "testuser",
+            MessageText = "/status",
+            ChatType = "private",
+            ChatTitle = "Test Chat",
+        };
+
+        _ollamaClientMock
+            .Setup(x => x.ChatAsync(It.IsAny<OllamaSharp.Models.Chat.ChatRequest>()))
+            .Returns(
+                TestDataBuilder.Mocks.CreateAsyncEnumerable(
+                    new List<OllamaSharp.Models.Chat.ChatResponseStream>
+                    {
+                        new OllamaSharp.Models.Chat.ChatResponseStream
+                        {
+                            Message = new OllamaSharp.Models.Chat.Message(
+                                ChatRole.Assistant,
+                                "Test"
+                            ),
+                        },
+                    }
+                )
+            );
+
+        // Act
+        var result = await statusCommand.ExecuteAsync(context);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Should().Contain("Сессия");
+        result.Should().Contain("Сообщений в истории");
+    }
+
+    [Fact]
+    public void CommandName_ShouldReturnCorrectName()
+    {
+        // Act & Assert
+        _statusCommand.CommandName.Should().Be("/status");
+    }
+
+    [Fact]
+    public void Description_ShouldReturnCorrectDescription()
+    {
+        // Act & Assert
+        _statusCommand.Description.Should().Be("Показать статус системы и API");
+    }
 }
diff --git a/ChatBot.Tests/Telegram/Commands/TelegramCommandProcessorTests.cs b/ChatBot.Tests/Telegram/Commands/TelegramCommandProcessorTests.cs
index bb78cde..ef2fcc1 100644
--- a/ChatBot.Tests/Telegram/Commands/TelegramCommandProcessorTests.cs
+++ b/ChatBot.Tests/Telegram/Commands/TelegramCommandProcessorTests.cs
@@ -6,6 +6,7 @@ using ChatBot.Tests.TestUtilities;
 using FluentAssertions;
 using Microsoft.Extensions.Logging;
 using Moq;
+using Telegram.Bot;
 using Telegram.Bot.Types;
 
 namespace ChatBot.Tests.Telegram.Commands;
@@ -417,8 +418,8 @@ public class TelegramCommandProcessorTests : UnitTestBase
         var username = "testuser";
         var chatType = "private";
         var chatTitle = "Test Chat";
-        var cts = new CancellationTokenSource();
-        cts.Cancel();
+        using var cts = new CancellationTokenSource();
+        await cts.CancelAsync();
 
         // Act
         var result = await _processor.ProcessMessageAsync(
@@ -488,4 +489,347 @@ public class TelegramCommandProcessorTests : UnitTestBase
         // Assert
         result.Should().NotBeNull();
     }
+
+    [Fact]
+    public async Task ProcessMessageAsync_WithReplyToBot_ShouldProcessMessage()
+    {
+        // Arrange
+        var botUser = new User
+        {
+            Id = 999,
+            Username = "testbot",
+            IsBot = true,
+        };
+
+        var botInfoServiceMock = new Mock<BotInfoService>(
+            TestDataBuilder.Mocks.CreateTelegramBotClient().Object,
+            TestDataBuilder.Mocks.CreateLoggerMock<BotInfoService>().Object
+        );
+        botInfoServiceMock.Setup(x => x.GetBotInfoAsync(It.IsAny<CancellationToken>()))
+            .ReturnsAsync(botUser);
+
+        var processor = new TelegramCommandProcessor(
+            _commandRegistry,
+            _chatService,
+            _loggerMock.Object,
+            botInfoServiceMock.Object
+        );
+
+        var replyInfo = new ReplyInfo
+        {
+            MessageId = 1,
+            UserId = 999,
+            Username = "testbot",
+        };
+
+        // Act
+        var result = await processor.ProcessMessageAsync(
+            "Test reply",
+            12345L,
+            "user",
+            "private",
+            "Test Chat",
+            replyInfo
+        );
+
+        // Assert
+        result.Should().NotBeNullOrEmpty();
+    }
+
+    [Fact]
+    public async Task ProcessMessageAsync_WithReplyToOtherUser_ShouldReturnEmpty()
+    {
+        // Arrange
+        var botUser = new User
+        {
+            Id = 999,
+            Username = "testbot",
+            IsBot = true,
+        };
+
+        var botInfoServiceMock = new Mock<BotInfoService>(
+            TestDataBuilder.Mocks.CreateTelegramBotClient().Object,
+            TestDataBuilder.Mocks.CreateLoggerMock<BotInfoService>().Object
+        );
+        botInfoServiceMock.Setup(x => x.GetBotInfoAsync(It.IsAny<CancellationToken>()))
+            .ReturnsAsync(botUser);
+
+        var processor = new TelegramCommandProcessor(
+            _commandRegistry,
+            _chatService,
+            _loggerMock.Object,
+            botInfoServiceMock.Object
+        );
+
+        var replyInfo = new ReplyInfo
+        {
+            MessageId = 1,
+            UserId = 123,
+            Username = "otheruser",
+        };
+
+        // Act
+        var result = await processor.ProcessMessageAsync(
+            "Test reply",
+            12345L,
+            "user",
+            "private",
+            "Test Chat",
+            replyInfo
+        );
+
+        // Assert
+        result.Should().BeEmpty();
+    }
+
+    [Fact]
+    public async Task ProcessMessageAsync_WithBotMention_ShouldProcessMessage()
+    {
+        // Arrange
+        var botUser = new User
+        {
+            Id = 999,
+            Username = "testbot",
+            IsBot = true,
+        };
+
+        var botInfoServiceMock = new Mock<BotInfoService>(
+            TestDataBuilder.Mocks.CreateTelegramBotClient().Object,
+            TestDataBuilder.Mocks.CreateLoggerMock<BotInfoService>().Object
+        );
+        botInfoServiceMock.Setup(x => x.GetBotInfoAsync(It.IsAny<CancellationToken>()))
+            .ReturnsAsync(botUser);
+
+        var processor = new TelegramCommandProcessor(
+            _commandRegistry,
+            _chatService,
+            _loggerMock.Object,
+            botInfoServiceMock.Object
+        );
+
+        // Act
+        var result = await processor.ProcessMessageAsync(
+            "Hello @testbot",
+            12345L,
+            "user",
+            "private",
+            "Test Chat"
+        );
+
+        // Assert
+        result.Should().NotBeNullOrEmpty();
+    }
+
+    [Fact]
+    public async Task ProcessMessageAsync_WithOtherUserMention_ShouldReturnEmpty()
+    {
+        // Arrange
+        var botUser = new User
+        {
+            Id = 999,
+            Username = "testbot",
+            IsBot = true,
+        };
+
+        var botInfoServiceMock = new Mock<BotInfoService>(
+            TestDataBuilder.Mocks.CreateTelegramBotClient().Object,
+            TestDataBuilder.Mocks.CreateLoggerMock<BotInfoService>().Object
+        );
+        botInfoServiceMock.Setup(x => x.GetBotInfoAsync(It.IsAny<CancellationToken>()))
+            .ReturnsAsync(botUser);
+
+        var processor = new TelegramCommandProcessor(
+            _commandRegistry,
+            _chatService,
+            _loggerMock.Object,
+            botInfoServiceMock.Object
+        );
+
+        // Act
+        var result = await processor.ProcessMessageAsync(
+            "Hello @otheruser",
+            12345L,
+            "user",
+            "private",
+            "Test Chat"
+        );
+
+        // Assert
+        result.Should().BeEmpty();
+    }
+
+    [Fact]
+    public async Task ProcessMessageAsync_WithCommand_ShouldExecuteCommand()
+    {
+        // Arrange
+        var commandMock = new Mock<ITelegramCommand>();
+        commandMock.Setup(x => x.CommandName).Returns("/test");
+        commandMock
+            .Setup(x => x.CanHandle(It.IsAny<string>()))
+            .Returns((string msg) => msg.StartsWith("/test"));
+        commandMock
+            .Setup(x =>
+                x.ExecuteAsync(It.IsAny<TelegramCommandContext>(), It.IsAny<CancellationToken>())
+            )
+            .ReturnsAsync("Command executed");
+
+        var commandRegistry = new CommandRegistry(
+            TestDataBuilder.Mocks.CreateLoggerMock<CommandRegistry>().Object,
+            new[] { commandMock.Object }
+        );
+
+        var processor = new TelegramCommandProcessor(
+            commandRegistry,
+            _chatService,
+            _loggerMock.Object,
+            _botInfoService
+        );
+
+        // Act
+        var result = await processor.ProcessMessageAsync(
+            "/test argument",
+            12345L,
+            "user",
+            "private",
+            "Test Chat"
+        );
+
+        // Assert
+        result.Should().Be("Command executed");
+        commandMock.Verify(
+            x => x.ExecuteAsync(It.IsAny<TelegramCommandContext>(), It.IsAny<CancellationToken>()),
+            Times.Once
+        );
+    }
+
+    [Fact]
+    public async Task ProcessMessageAsync_WithException_ShouldReturnErrorMessage()
+    {
+        // Arrange
+        var chatServiceMock = new Mock<ChatService>(
+            TestDataBuilder.Mocks.CreateLoggerMock<ChatService>().Object,
+            TestDataBuilder.Mocks.CreateAIServiceMock().Object,
+            TestDataBuilder.Mocks.CreateSessionStorageMock().Object,
+            TestDataBuilder
+                .Mocks.CreateOptionsMock(TestDataBuilder.Configurations.CreateAISettings())
+                .Object,
+            TestDataBuilder.Mocks.CreateCompressionServiceMock().Object
+        );
+
+        chatServiceMock
+            .Setup(x =>
+                x.ProcessMessageAsync(
+                    It.IsAny<long>(),
+                    It.IsAny<string>(),
+                    It.IsAny<string>(),
+                    It.IsAny<string>(),
+                    It.IsAny<string>(),
+                    It.IsAny<CancellationToken>()
+                )
+            )
+            .ThrowsAsync(new Exception("Test error"));
+
+        var processor = new TelegramCommandProcessor(
+            _commandRegistry,
+            chatServiceMock.Object,
+            _loggerMock.Object,
+            _botInfoService
+        );
+
+        // Act
+        var result = await processor.ProcessMessageAsync(
+            "Test message",
+            12345L,
+            "user",
+            "private",
+            "Test Chat"
+        );
+
+        // Assert
+        result.Should().Contain("Произошла ошибка");
+    }
+
+    [Fact]
+    public async Task ProcessMessageAsync_WithGroupChat_ShouldProcessCorrectly()
+    {
+        // Arrange
+        var messageText = "Hello";
+        var chatId = -100123456789L; // Group chat ID
+        var username = "testuser";
+        var chatType = "group";
+        var chatTitle = "Test Group";
+
+        // Act
+        var result = await _processor.ProcessMessageAsync(
+            messageText,
+            chatId,
+            username,
+            chatType,
+            chatTitle
+        );
+
+        // Assert
+        result.Should().NotBeNull();
+    }
+
+    [Fact]
+    public async Task ProcessMessageAsync_WithSupergroupChat_ShouldProcessCorrectly()
+    {
+        // Arrange
+        var messageText = "Hello";
+        var chatId = -100123456789L;
+        var username = "testuser";
+        var chatType = "supergroup";
+        var chatTitle = "Test Supergroup";
+
+        // Act
+        var result = await _processor.ProcessMessageAsync(
+            messageText,
+            chatId,
+            username,
+            chatType,
+            chatTitle
+        );
+
+        // Assert
+        result.Should().NotBeNull();
+    }
+
+    [Fact]
+    public async Task ProcessMessageAsync_WithMultipleMentions_IncludingBot_ShouldProcessMessage()
+    {
+        // Arrange
+        var botUser = new User
+        {
+            Id = 999,
+            Username = "testbot",
+            IsBot = true,
+        };
+
+        var botInfoServiceMock = new Mock<BotInfoService>(
+            TestDataBuilder.Mocks.CreateTelegramBotClient().Object,
+            TestDataBuilder.Mocks.CreateLoggerMock<BotInfoService>().Object
+        );
+        botInfoServiceMock.Setup(x => x.GetBotInfoAsync(It.IsAny<CancellationToken>()))
+            .ReturnsAsync(botUser);
+
+        var processor = new TelegramCommandProcessor(
+            _commandRegistry,
+            _chatService,
+            _loggerMock.Object,
+            botInfoServiceMock.Object
+        );
+
+        // Act
+        var result = await processor.ProcessMessageAsync(
+            "Hello @testbot and @otheruser",
+            12345L,
+            "user",
+            "group",
+            "Test Group"
+        );
+
+        // Assert
+        result.Should().NotBeNullOrEmpty();
+    }
 }
diff --git a/ChatBot/Services/ChatService.cs b/ChatBot/Services/ChatService.cs
index 0d30a2a..aaf2f87 100644
--- a/ChatBot/Services/ChatService.cs
+++ b/ChatBot/Services/ChatService.cs
@@ -55,7 +55,7 @@ namespace ChatBot.Services
         /// <summary>
         /// Process a user message and get AI response
         /// </summary>
-        public async Task<string> ProcessMessageAsync(
+        public virtual async Task<string> ProcessMessageAsync(
             long chatId,
             string username,
             string message,
@@ -192,7 +192,7 @@ namespace ChatBot.Services
         /// <summary>
         /// Get session information
         /// </summary>
-        public ChatSession? GetSession(long chatId)
+        public virtual ChatSession? GetSession(long chatId)
         {
             return _sessionStorage.Get(chatId);
         }
diff --git a/ChatBot/Services/DatabaseSessionStorage.cs b/ChatBot/Services/DatabaseSessionStorage.cs
index dce80f7..56988e0 100644
--- a/ChatBot/Services/DatabaseSessionStorage.cs
+++ b/ChatBot/Services/DatabaseSessionStorage.cs
@@ -178,7 +178,14 @@ namespace ChatBot.Services
             // Add messages to session
             foreach (var messageEntity in entity.Messages.OrderBy(m => m.MessageOrder))
             {
-                var role = Enum.Parse<ChatRole>(messageEntity.Role);
+                var role = messageEntity.Role.ToLowerInvariant() switch
+                {
+                    "user" => ChatRole.User,
+                    "assistant" => ChatRole.Assistant,
+                    "system" => ChatRole.System,
+                    "tool" => ChatRole.Tool,
+                    _ => throw new ArgumentException($"Unknown role: {messageEntity.Role}")
+                };
                 var message = new ChatMessage { Content = messageEntity.Content, Role = role };
                 session.AddMessage(message);
             }
diff --git a/ChatBot/Services/Telegram/Services/BotInfoService.cs b/ChatBot/Services/Telegram/Services/BotInfoService.cs
index 38ecb5a..f78e4a0 100644
--- a/ChatBot/Services/Telegram/Services/BotInfoService.cs
+++ b/ChatBot/Services/Telegram/Services/BotInfoService.cs
@@ -24,7 +24,7 @@ namespace ChatBot.Services.Telegram.Services
         /// <summary>
         /// Получает информацию о боте (с кэшированием и автоматической инвалидацией)
         /// </summary>
-        public async Task<User?> GetBotInfoAsync(CancellationToken cancellationToken = default)
+        public virtual async Task<User?> GetBotInfoAsync(CancellationToken cancellationToken = default)
         {
             // Проверяем, есть ли валидный кэш
             if (
diff --git a/ChatBot/Services/Telegram/Services/TelegramMessageSenderWrapper.cs b/ChatBot/Services/Telegram/Services/TelegramMessageSenderWrapper.cs
index dc8641d..232a526 100644
--- a/ChatBot/Services/Telegram/Services/TelegramMessageSenderWrapper.cs
+++ b/ChatBot/Services/Telegram/Services/TelegramMessageSenderWrapper.cs
@@ -23,10 +23,16 @@ namespace ChatBot.Services.Telegram.Services
             CancellationToken cancellationToken = default
         )
         {
+            ReplyParameters? replyParameters = null;
+            if (replyToMessageId > 0)
+            {
+                replyParameters = new ReplyParameters { MessageId = replyToMessageId };
+            }
+
             return await _botClient.SendMessage(
                 chatId: chatId,
                 text: text,
-                replyParameters: replyToMessageId,
+                replyParameters: replyParameters,
                 cancellationToken: cancellationToken
             );
         }