feat: Add configurable STDIO and HTTP transport support for MCP server

[Meir017]

Summary

Implements configurable transport modes for the MCP (Model Context Protocol) server, supporting both STDIO (standard input/output) and HTTP transports. This allows the server to work seamlessly with different MCP client types.

Changes

Core Implementation

• ✅ Dual Transport Support: STDIO and HTTP transport modes
• ✅ Unified Architecture: Uses WebApplicationBuilder with NoOpServer for STDIO mode
• ✅ Configuration-Driven: Supports appsettings.json, environment variables, and command-line arguments
• ✅ Smart Defaults: STDIO as default (ideal for MCP servers), easily overrideable

Key Files

• src/LoggerUsage.Mcp/Program.cs - Conditional transport registration with NoOpServer
• src/LoggerUsage.Mcp/TransportOptions.cs - Transport configuration model with XML docs
• src/LoggerUsage.Mcp/appsettings.json - STDIO default configuration
• src/LoggerUsage.Mcp/appsettings.Development.json - STDIO for development
• est/LoggerUsage.Mcp.Tests/TransportConfigurationTests.cs - Comprehensive tests (6 methods, 10 test cases)

Features

1. STDIO Transport (Default)

   • Uses standard input/output streams
   • Ideal for VS Code, command-line tools, and MCP clients that spawn processes
   • Lower latency than HTTP
   • No network overhead

2. HTTP Transport

   • Traditional HTTP+SSE endpoints
   • Supports remote connections
   • Multiple concurrent clients
   • Web-based integrations

3. Configuration Options
   \\�ash

   Via command-line

   dotnet run --project src/LoggerUsage.Mcp -- --Transport:Mode=Http

   Via environment variable

   export Transport__Mode=Stdio

   Via appsettings.json

   { "Transport": { "Mode": "Stdio" } }
   \\

4. Validation

   • Throws InvalidOperationException if configuration fails
   • Clear error messages for invalid transport modes

Technical Details

Architecture

Uses a unified WebApplicationBuilder with conditional configuration:

• STDIO Mode: Registers NoOpServer to avoid Kestrel overhead, adds WithStdioServerTransport()
• HTTP Mode: Uses default Kestrel server, adds WithHttpTransport() and MapMcp() middleware

NoOpServer Implementation

Custom IServer implementation that satisfies ASP.NET Core hosting requirements without starting an HTTP listener:
\\csharp
internal class NoOpServer : IServer
{
public IFeatureCollection Features { get; } = new FeatureCollection();
public void Dispose() { }
public Task StartAsync(...) => Task.CompletedTask;
public Task StopAsync(...) => Task.CompletedTask;
}
\\

Testing

• ✅ 6 Transport Configuration Tests - All passing (10 test cases total)
  • Default STDIO behavior
  • Explicit HTTP/STDIO configuration
  • Invalid mode exception handling
  • Case-insensitive parsing (6 variations)
  • Configuration priority (command-line overrides)
• ⚠️ 4 Integration Tests - Need refactoring for NoOpServer pattern (tracked separately)

Commits

• \23f42ee\ - Planning and specification
• \