Fix build and code structure improvements. New but essential UI functionality. CI improvements. Documentation improvements. AI module improvements.

docs/router/transports/README.md

@@ -0,0 +1,203 @@
+# Router Transport Plugins
+
+StellaOps Router uses a **plugin-based transport architecture** that enables runtime loading of transport implementations. This allows operators to deploy only the transports they need and swap implementations without recompiling the Gateway.
+
+## Available Transports
+
+| Transport | Plugin Assembly | Use Case | Status |
+|-----------|-----------------|----------|--------|
+| [TCP](./tcp.md) | `StellaOps.Router.Transport.Tcp.dll` | Internal services, same datacenter | Stable |
+| [TLS](./tls.md) | `StellaOps.Router.Transport.Tls.dll` | Cross-datacenter, mTLS | Stable |
+| [UDP](./udp.md) | `StellaOps.Router.Transport.Udp.dll` | Fire-and-forget, broadcast | Stable |
+| [RabbitMQ](./rabbitmq.md) | `StellaOps.Router.Transport.RabbitMq.dll` | Async processing, fan-out | Stable |
+| [InMemory](./inmemory.md) | `StellaOps.Router.Transport.InMemory.dll` | Development, testing | Stable |
+| Valkey | `StellaOps.Messaging.Transport.Valkey.dll` | Distributed, pub/sub | Stable |
+| PostgreSQL | `StellaOps.Messaging.Transport.Postgres.dll` | Transactional, LISTEN/NOTIFY | Stable |
+
+## Plugin Architecture
+
+### Loading Model
+
+Transport plugins are loaded at Gateway startup via `RouterTransportPluginLoader`:
+
+```
+┌─────────────────────────────────────────────────────────────────┐
+│                     Gateway Startup                              │
+│                                                                  │
+│  ┌────────────────────────────────────────────────────────────┐ │
+│  │ RouterTransportPluginLoader                                │ │
+│  │                                                             │ │
+│  │  1. Scan plugins/router/transports/                        │ │
+│  │  2. Load assemblies in isolation (AssemblyLoadContext)     │ │
+│  │  3. Discover IRouterTransportPlugin implementations        │ │
+│  │  4. Register configured transport with DI                  │ │
+│  └────────────────────────────────────────────────────────────┘ │
+│                           │                                      │
+│                           ▼                                      │
+│  ┌────────────────────────────────────────────────────────────┐ │
+│  │ Transport Plugin (e.g., TLS)                               │ │
+│  │                                                             │ │
+│  │  - TransportName: "tls"                                    │ │
+│  │  - DisplayName: "TLS Transport"                            │ │
+│  │  - IsAvailable(): Check dependencies                       │ │
+│  │  - Register(): Wire up ITransportServer/ITransportClient   │ │
+│  └────────────────────────────────────────────────────────────┘ │
+│                                                                  │
+└──────────────────────────────────────────────────────────────────┘
+```
+
+### Directory Structure
+
+```
+plugins/
+└── router/
+    └── transports/
+        ├── StellaOps.Router.Transport.Tcp.dll
+        ├── StellaOps.Router.Transport.Tls.dll
+        ├── StellaOps.Router.Transport.Udp.dll
+        ├── StellaOps.Router.Transport.RabbitMq.dll
+        └── StellaOps.Router.Transport.InMemory.dll
+```
+
+### Configuration
+
+Transport selection and options are configured in `router.yaml` or environment variables:
+
+```yaml
+Router:
+  Transport:
+    Type: tls                     # Which transport plugin to use
+    Tls:                          # Transport-specific options
+      Port: 5101
+      CertificatePath: /certs/server.pfx
+      RequireClientCertificate: true
+    Tcp:
+      Port: 5100
+      MaxConnections: 1000
+```
+
+Environment override:
+```bash
+ROUTER__TRANSPORT__TYPE=tcp
+ROUTER__TRANSPORT__TCP__PORT=5100
+```
+
+## Using Plugins in Gateway
+
+### Programmatic Loading
+
+```csharp
+using StellaOps.Router.Common.Plugins;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Load transport plugins from directory
+var pluginLoader = new RouterTransportPluginLoader(
+    builder.Services.BuildServiceProvider().GetService<ILogger<RouterTransportPluginLoader>>());
+
+var pluginsPath = Path.Combine(AppContext.BaseDirectory, "plugins", "router", "transports");
+pluginLoader.LoadFromDirectory(pluginsPath);
+
+// Register the configured transport (reads Router:Transport:Type from config)
+pluginLoader.RegisterConfiguredTransport(
+    builder.Services,
+    builder.Configuration,
+    RouterTransportMode.Both);  // Register both server and client
+
+var app = builder.Build();
+// ...
+```
+
+### Gateway Integration
+
+The Gateway automatically loads transport plugins during startup. Configure in `router.yaml`:
+
+```yaml
+gateway:
+  name: api-gateway
+  plugins:
+    transports:
+      directory: plugins/router/transports
+      searchPattern: "StellaOps.Router.Transport.*.dll"
+```
+
+## Creating Custom Transports
+
+See the [Transport Plugin Development Guide](./development.md) for creating custom transport implementations.
+
+### Minimal Plugin Example
+
+```csharp
+using StellaOps.Router.Common.Plugins;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace MyCompany.Router.Transport.Custom;
+
+public sealed class CustomTransportPlugin : IRouterTransportPlugin
+{
+    public string TransportName => "custom";
+    public string DisplayName => "Custom Transport";
+
+    public bool IsAvailable(IServiceProvider services) => true;
+
+    public void Register(RouterTransportRegistrationContext context)
+    {
+        var configSection = context.Configuration.GetSection("Router:Transport:Custom");
+
+        context.Services.Configure<CustomTransportOptions>(options =>
+        {
+            configSection.Bind(options);
+        });
+
+        if (context.Mode.HasFlag(RouterTransportMode.Server))
+        {
+            context.Services.AddSingleton<CustomTransportServer>();
+            context.Services.AddSingleton<ITransportServer>(sp =>
+                sp.GetRequiredService<CustomTransportServer>());
+        }
+
+        if (context.Mode.HasFlag(RouterTransportMode.Client))
+        {
+            context.Services.AddSingleton<CustomTransportClient>();
+            context.Services.AddSingleton<ITransportClient>(sp =>
+                sp.GetRequiredService<CustomTransportClient>());
+            context.Services.AddSingleton<IMicroserviceTransport>(sp =>
+                sp.GetRequiredService<CustomTransportClient>());
+        }
+    }
+}
+```
+
+## Transport Selection Guide
+
+| Scenario | Recommended Transport | Configuration |
+|----------|----------------------|---------------|
+| Development/Testing | InMemory | `Type: inmemory` |
+| Same-datacenter | TCP | `Type: tcp` |
+| Cross-datacenter secure | TLS | `Type: tls` with mTLS |
+| High-volume async | RabbitMQ | `Type: rabbitmq` |
+| Broadcast/fire-and-forget | UDP | `Type: udp` |
+| Distributed with replay | Valkey | Via Messaging plugins |
+| Transactional messaging | PostgreSQL | Via Messaging plugins |
+
+## Air-Gap Deployment
+
+For offline/air-gapped deployments:
+
+1. Pre-package transport plugins with your deployment
+2. Configure the plugin directory path
+3. No external network access required
+
+```yaml
+gateway:
+  plugins:
+    transports:
+      directory: /opt/stellaops/plugins/router/transports
+```
+
+## See Also
+
+- [Router Architecture](../ARCHITECTURE.md)
+- [Plugin SDK Guide](../../10_PLUGIN_SDK_GUIDE.md)
+- [Unified Plugin System](../../plugins/README.md)

docs/router/transports/development.md

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+# Transport Plugin Development Guide
+
+This guide explains how to create custom router transport plugins for StellaOps.
+
+## Overview
+
+Router transport plugins implement the `IRouterTransportPlugin` interface to provide custom communication protocols. The plugin system enables:
+
+- Runtime loading of transport implementations
+- Isolation from the Gateway codebase
+- Hot-swappable transports (restart required)
+- Third-party transport extensions
+
+## Prerequisites
+
+- .NET 10 SDK
+- Understanding of async socket programming
+- Familiarity with dependency injection
+
+## Creating a Transport Plugin
+
+### Step 1: Create Project
+
+```bash
+mkdir MyCompany.Router.Transport.Custom
+cd MyCompany.Router.Transport.Custom
+dotnet new classlib -f net10.0
+dotnet add package Microsoft.Extensions.Configuration.Binder
+dotnet add package Microsoft.Extensions.DependencyInjection.Abstractions
+dotnet add package Microsoft.Extensions.Logging.Abstractions
+dotnet add package Microsoft.Extensions.Options
+```
+
+Add project reference to Router.Common:
+
+```xml
+<ItemGroup>
+  <ProjectReference Include="path/to/StellaOps.Router.Common/StellaOps.Router.Common.csproj" />
+</ItemGroup>
+```
+
+### Step 2: Create Options Class
+
+```csharp
+namespace MyCompany.Router.Transport.Custom;
+
+/// <summary>
+/// Configuration options for the custom transport.
+/// </summary>
+public sealed class CustomTransportOptions
+{
+    /// <summary>
+    /// Host address to bind/connect to.
+    /// </summary>
+    public string Host { get; set; } = "0.0.0.0";
+
+    /// <summary>
+    /// Port number.
+    /// </summary>
+    public int Port { get; set; } = 5200;
+
+    /// <summary>
+    /// Connection timeout.
+    /// </summary>
+    public TimeSpan ConnectTimeout { get; set; } = TimeSpan.FromSeconds(30);
+
+    /// <summary>
+    /// Maximum concurrent connections.
+    /// </summary>
+    public int MaxConnections { get; set; } = 1000;
+}
+```
+
+### Step 3: Implement Transport Server
+
+```csharp
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Router.Common.Abstractions;
+
+namespace MyCompany.Router.Transport.Custom;
+
+public sealed class CustomTransportServer : ITransportServer
+{
+    private readonly CustomTransportOptions _options;
+    private readonly ILogger<CustomTransportServer> _logger;
+
+    public CustomTransportServer(
+        IOptions<CustomTransportOptions> options,
+        ILogger<CustomTransportServer> logger)
+    {
+        _options = options.Value;
+        _logger = logger;
+    }
+
+    public async Task StartAsync(CancellationToken cancellationToken)
+    {
+        _logger.LogInformation("Starting custom transport server on {Host}:{Port}",
+            _options.Host, _options.Port);
+
+        // Initialize your transport server (socket, listener, etc.)
+        // ...
+    }
+
+    public async Task StopAsync(CancellationToken cancellationToken)
+    {
+        _logger.LogInformation("Stopping custom transport server");
+
+        // Graceful shutdown
+        // ...
+    }
+
+    public async Task<ITransportConnection> AcceptAsync(CancellationToken cancellationToken)
+    {
+        // Accept incoming connection
+        // Return ITransportConnection implementation
+        throw new NotImplementedException();
+    }
+
+    public void Dispose()
+    {
+        // Cleanup resources
+    }
+}
+```
+
+### Step 4: Implement Transport Client
+
+```csharp
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using StellaOps.Router.Common.Abstractions;
+
+namespace MyCompany.Router.Transport.Custom;
+
+public sealed class CustomTransportClient : ITransportClient, IMicroserviceTransport
+{
+    private readonly CustomTransportOptions _options;
+    private readonly ILogger<CustomTransportClient> _logger;
+
+    public CustomTransportClient(
+        IOptions<CustomTransportOptions> options,
+        ILogger<CustomTransportClient> logger)
+    {
+        _options = options.Value;
+        _logger = logger;
+    }
+
+    public async Task<ITransportConnection> ConnectAsync(
+        string host,
+        int port,
+        CancellationToken cancellationToken)
+    {
+        _logger.LogDebug("Connecting to {Host}:{Port}", host, port);
+
+        // Establish connection
+        // Return ITransportConnection implementation
+        throw new NotImplementedException();
+    }
+
+    public async Task DisconnectAsync(CancellationToken cancellationToken)
+    {
+        // Disconnect from server
+    }
+
+    public void Dispose()
+    {
+        // Cleanup resources
+    }
+}
+```
+
+### Step 5: Implement Connection
+
+```csharp
+using StellaOps.Router.Common.Abstractions;
+
+namespace MyCompany.Router.Transport.Custom;
+
+public sealed class CustomTransportConnection : ITransportConnection
+{
+    public string ConnectionId { get; } = Guid.NewGuid().ToString("N");
+    public bool IsConnected { get; private set; }
+    public EndPoint? RemoteEndPoint { get; private set; }
+
+    public async Task<int> SendAsync(
+        ReadOnlyMemory<byte> data,
+        CancellationToken cancellationToken)
+    {
+        // Send data over transport
+        throw new NotImplementedException();
+    }
+
+    public async Task<int> ReceiveAsync(
+        Memory<byte> buffer,
+        CancellationToken cancellationToken)
+    {
+        // Receive data from transport
+        throw new NotImplementedException();
+    }
+
+    public async Task CloseAsync(CancellationToken cancellationToken)
+    {
+        IsConnected = false;
+        // Close connection
+    }
+
+    public void Dispose()
+    {
+        // Cleanup
+    }
+}
+```
+
+### Step 6: Implement Plugin
+
+```csharp
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using StellaOps.Router.Common.Abstractions;
+using StellaOps.Router.Common.Plugins;
+
+namespace MyCompany.Router.Transport.Custom;
+
+/// <summary>
+/// Plugin implementation for custom transport.
+/// </summary>
+public sealed class CustomTransportPlugin : IRouterTransportPlugin
+{
+    /// <inheritdoc />
+    public string TransportName => "custom";
+
+    /// <inheritdoc />
+    public string DisplayName => "Custom Transport";
+
+    /// <inheritdoc />
+    public bool IsAvailable(IServiceProvider services)
+    {
+        // Check if required dependencies are available
+        // Return false if transport cannot be used in current environment
+        return true;
+    }
+
+    /// <inheritdoc />
+    public void Register(RouterTransportRegistrationContext context)
+    {
+        var services = context.Services;
+        var configuration = context.Configuration;
+
+        // Bind configuration
+        var configSection = context.ConfigurationSection is not null
+            ? configuration.GetSection(context.ConfigurationSection)
+            : configuration.GetSection("Router:Transport:Custom");
+
+        services.AddOptions<CustomTransportOptions>();
+        if (configSection.GetChildren().Any())
+        {
+            services.Configure<CustomTransportOptions>(options =>
+            {
+                configSection.Bind(options);
+            });
+        }
+
+        // Register server if requested
+        if (context.Mode.HasFlag(RouterTransportMode.Server))
+        {
+            services.AddSingleton<CustomTransportServer>();
+            services.AddSingleton<ITransportServer>(sp =>
+                sp.GetRequiredService<CustomTransportServer>());
+        }
+
+        // Register client if requested
+        if (context.Mode.HasFlag(RouterTransportMode.Client))
+        {
+            services.AddSingleton<CustomTransportClient>();
+            services.AddSingleton<ITransportClient>(sp =>
+                sp.GetRequiredService<CustomTransportClient>());
+            services.AddSingleton<IMicroserviceTransport>(sp =>
+                sp.GetRequiredService<CustomTransportClient>());
+        }
+    }
+}
+```
+
+## Building and Packaging
+
+### Build Configuration
+
+Add to your `.csproj`:
+
+```xml
+<PropertyGroup>
+  <TargetFramework>net10.0</TargetFramework>
+  <ImplicitUsings>enable</ImplicitUsings>
+  <Nullable>enable</Nullable>
+  <RootNamespace>MyCompany.Router.Transport.Custom</RootNamespace>
+
+  <!-- Plugin assembly attributes -->
+  <GenerateAssemblyInfo>true</GenerateAssemblyInfo>
+</PropertyGroup>
+
+<!-- Output to plugins directory -->
+<PropertyGroup Condition="'$(Configuration)' == 'Release'">
+  <OutputPath>$(SolutionDir)plugins\router\transports\</OutputPath>
+  <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
+</PropertyGroup>
+```
+
+### Build Commands
+
+```bash
+# Debug build
+dotnet build
+
+# Release build to plugins directory
+dotnet build -c Release
+
+# Publish with all dependencies
+dotnet publish -c Release -o ./publish
+```
+
+## Configuration Schema
+
+Create `plugin.json` manifest:
+
+```json
+{
+  "schemaVersion": "2.0",
+  "id": "mycompany.router.transport.custom",
+  "name": "Custom Transport",
+  "version": "1.0.0",
+  "assembly": {
+    "path": "MyCompany.Router.Transport.Custom.dll",
+    "entryType": "MyCompany.Router.Transport.Custom.CustomTransportPlugin"
+  },
+  "capabilities": ["server", "client", "streaming"],
+  "platforms": ["linux-x64", "win-x64", "osx-arm64"],
+  "enabled": true,
+  "priority": 100
+}
+```
+
+Create `config.yaml` for runtime configuration:
+
+```yaml
+id: mycompany.router.transport.custom
+name: Custom Transport
+enabled: true
+config:
+  host: "0.0.0.0"
+  port: 5200
+  maxConnections: 1000
+  connectTimeout: "00:00:30"
+```
+
+## Testing
+
+### Unit Tests
+
+```csharp
+public class CustomTransportPluginTests
+{
+    [Fact]
+    public void TransportName_ReturnsCustom()
+    {
+        var plugin = new CustomTransportPlugin();
+        Assert.Equal("custom", plugin.TransportName);
+    }
+
+    [Fact]
+    public void Register_AddsServerServices()
+    {
+        var plugin = new CustomTransportPlugin();
+        var services = new ServiceCollection();
+        var config = new ConfigurationBuilder().Build();
+
+        var context = new RouterTransportRegistrationContext(
+            services, config, RouterTransportMode.Server);
+
+        plugin.Register(context);
+
+        var provider = services.BuildServiceProvider();
+        Assert.NotNull(provider.GetService<ITransportServer>());
+    }
+}
+```
+
+### Integration Tests
+
+```csharp
+public class CustomTransportIntegrationTests
+{
+    [Fact]
+    public async Task Server_AcceptsConnections()
+    {
+        var services = new ServiceCollection();
+        services.AddLogging();
+        services.Configure<CustomTransportOptions>(opts =>
+        {
+            opts.Port = 15200;  // Test port
+        });
+        services.AddSingleton<CustomTransportServer>();
+
+        var provider = services.BuildServiceProvider();
+        var server = provider.GetRequiredService<CustomTransportServer>();
+
+        await server.StartAsync(CancellationToken.None);
+
+        // Connect client and verify
+        // ...
+
+        await server.StopAsync(CancellationToken.None);
+    }
+}
+```
+
+## Best Practices
+
+### Error Handling
+
+```csharp
+public async Task<ITransportConnection> ConnectAsync(
+    string host,
+    int port,
+    CancellationToken cancellationToken)
+{
+    try
+    {
+        // Attempt connection
+        return await ConnectInternalAsync(host, port, cancellationToken);
+    }
+    catch (SocketException ex) when (ex.SocketErrorCode == SocketError.ConnectionRefused)
+    {
+        _logger.LogWarning("Connection refused to {Host}:{Port}", host, port);
+        throw new TransportConnectionException($"Connection refused to {host}:{port}", ex);
+    }
+    catch (OperationCanceledException)
+    {
+        _logger.LogDebug("Connection attempt cancelled");
+        throw;
+    }
+    catch (Exception ex)
+    {
+        _logger.LogError(ex, "Failed to connect to {Host}:{Port}", host, port);
+        throw new TransportConnectionException($"Failed to connect to {host}:{port}", ex);
+    }
+}
+```
+
+### Resource Management
+
+```csharp
+public sealed class CustomTransportServer : ITransportServer, IAsyncDisposable
+{
+    private readonly SemaphoreSlim _connectionLock = new(1, 1);
+    private readonly List<ITransportConnection> _connections = [];
+    private bool _disposed;
+
+    public async ValueTask DisposeAsync()
+    {
+        if (_disposed) return;
+        _disposed = true;
+
+        await _connectionLock.WaitAsync();
+        try
+        {
+            foreach (var conn in _connections)
+            {
+                await conn.CloseAsync(CancellationToken.None);
+                conn.Dispose();
+            }
+            _connections.Clear();
+        }
+        finally
+        {
+            _connectionLock.Release();
+            _connectionLock.Dispose();
+        }
+    }
+}
+```
+
+### Logging
+
+```csharp
+// Use structured logging
+_logger.LogInformation(
+    "Connection established {ConnectionId} from {RemoteEndPoint}",
+    connection.ConnectionId,
+    connection.RemoteEndPoint);
+
+// Include correlation IDs
+using (_logger.BeginScope(new Dictionary<string, object>
+{
+    ["ConnectionId"] = connectionId,
+    ["TraceId"] = Activity.Current?.TraceId.ToString() ?? "N/A"
+}))
+{
+    await ProcessConnectionAsync(connection, cancellationToken);
+}
+```
+
+## Deployment
+
+### Copy to Plugins Directory
+
+```bash
+cp ./publish/*.dll /opt/stellaops/plugins/router/transports/
+```
+
+### Verify Plugin Loading
+
+```bash
+# Check logs for plugin discovery
+grep "Loaded router transport plugin" /var/log/stellaops/gateway.log
+```
+
+### Configuration
+
+```yaml
+# router.yaml
+Router:
+  Transport:
+    Type: custom
+    Custom:
+      Host: "0.0.0.0"
+      Port: 5200
+```
+
+## See Also
+
+- [Transport Overview](./README.md)
+- [Plugin SDK Guide](../../10_PLUGIN_SDK_GUIDE.md)
+- [IRouterTransportPlugin API](../../../src/Router/__Libraries/StellaOps.Router.Common/Plugins/IRouterTransportPlugin.cs)

docs/router/transports/inmemory.md

@@ -0,0 +1,233 @@
+# InMemory Transport
+
+The InMemory transport provides zero-latency, in-process communication for development, testing, and scenarios where services run in the same process.
+
+## Overview
+
+| Property | Value |
+|----------|-------|
+| Plugin Assembly | `StellaOps.Router.Transport.InMemory.dll` |
+| Transport Name | `inmemory` |
+| Latency | Sub-microsecond |
+| Use Case | Development, testing, embedded scenarios |
+
+## Configuration
+
+### router.yaml
+
+```yaml
+Router:
+  Transport:
+    Type: inmemory
+    InMemory:
+      MaxPendingMessages: 10000
+      MessageTimeout: "00:01:00"
+```
+
+### microservice.yaml
+
+```yaml
+routers:
+  - host: localhost
+    port: 0               # Port ignored for InMemory
+    transportType: InMemory
+    priority: 1
+```
+
+### Environment Variables
+
+```bash
+ROUTER__TRANSPORT__TYPE=inmemory
+```
+
+## Options Reference
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `MaxPendingMessages` | int | `10000` | Maximum queued messages before backpressure |
+| `MessageTimeout` | TimeSpan | `00:01:00` | Timeout for pending messages |
+| `PreserveMessageOrder` | bool | `true` | Guarantee message ordering |
+
+## Architecture
+
+The InMemory transport uses a shared `InMemoryConnectionRegistry` singleton that enables direct in-process communication:
+
+```
+┌─────────────────────────────────────────────────────────────────┐
+│                        Single Process                            │
+│                                                                  │
+│  ┌─────────────────────────────────────────────────────────────┐│
+│  │                InMemoryConnectionRegistry                   ││
+│  │                     (Singleton)                             ││
+│  │                                                              ││
+│  │  ┌────────────────┐      ┌─────────────────────────────┐   ││
+│  │  │ Service A      │      │ Service B                   │   ││
+│  │  │ (InMemoryClient│◄────►│ (InMemoryServer)            │   ││
+│  │  │  endpoints)    │      │                              │   ││
+│  │  └────────────────┘      └─────────────────────────────┘   ││
+│  │                                                              ││
+│  │  Messages passed directly via                               ││
+│  │  ConcurrentQueue<T> - no serialization                      ││
+│  └──────────────────────────────────────────────────────────────┘│
+│                                                                  │
+└──────────────────────────────────────────────────────────────────┘
+```
+
+## Use Cases
+
+### Development
+
+Run Gateway and microservices in the same process:
+
+```csharp
+var builder = WebApplication.CreateBuilder(args);
+
+// Register InMemory transport (shared between gateway and services)
+builder.Services.AddInMemoryTransport();
+
+// Add gateway
+builder.Services.AddRouterGateway(builder.Configuration);
+
+// Add microservice in same process
+builder.Services.AddStellaMicroservice(options =>
+{
+    options.ServiceName = "order-service";
+    options.Version = "1.0.0";
+});
+
+var app = builder.Build();
+app.UseRouterGateway();
+app.Run();
+```
+
+### Integration Testing
+
+```csharp
+public class OrderServiceTests : IClassFixture<WebApplicationFactory<Program>>
+{
+    private readonly WebApplicationFactory<Program> _factory;
+
+    public OrderServiceTests(WebApplicationFactory<Program> factory)
+    {
+        _factory = factory.WithWebHostBuilder(builder =>
+        {
+            builder.ConfigureServices(services =>
+            {
+                // Use InMemory transport for tests
+                services.Configure<RouterOptions>(opts =>
+                    opts.Transport.Type = "inmemory");
+            });
+        });
+    }
+
+    [Fact]
+    public async Task CreateOrder_ReturnsOrderId()
+    {
+        var client = _factory.CreateClient();
+        var response = await client.PostAsJsonAsync("/orders", new
+        {
+            CustomerId = "CUST-001",
+            Amount = 99.99m
+        });
+
+        response.EnsureSuccessStatusCode();
+        var result = await response.Content.ReadFromJsonAsync<OrderResponse>();
+        Assert.NotNull(result?.OrderId);
+    }
+}
+```
+
+### Embedded Scenarios
+
+For single-binary deployments:
+
+```csharp
+// All services compiled into one executable
+var host = Host.CreateDefaultBuilder(args)
+    .ConfigureServices(services =>
+    {
+        services.AddInMemoryTransport();
+
+        // Register all microservice handlers
+        services.AddScoped<CreateOrderEndpoint>();
+        services.AddScoped<GetOrderEndpoint>();
+        services.AddScoped<CreateInvoiceEndpoint>();
+    })
+    .Build();
+```
+
+## Performance Characteristics
+
+| Metric | Typical Value |
+|--------|---------------|
+| Latency (p50) | < 0.1ms |
+| Latency (p99) | < 0.5ms |
+| Throughput | 500,000+ rps |
+| Memory overhead | Minimal |
+
+*Zero serialization, direct object passing*
+
+## Limitations
+
+1. **Single process only**: Cannot communicate across process boundaries
+2. **No persistence**: Messages lost on process termination
+3. **No distribution**: Cannot scale to multiple nodes
+4. **Shared memory**: Large messages consume process memory
+
+## When to Use InMemory
+
+| Scenario | Use InMemory? |
+|----------|---------------|
+| Local development | Yes |
+| Unit testing | Yes |
+| Integration testing | Yes |
+| Single-binary deployment | Yes |
+| Multi-node deployment | No - use TCP/TLS |
+| Production load testing | No - use production transport |
+
+## Transitioning to Production
+
+When moving from development to production:
+
+```yaml
+# Development (appsettings.Development.json)
+Router:
+  Transport:
+    Type: inmemory
+
+# Production (appsettings.Production.json)
+Router:
+  Transport:
+    Type: tls
+    Tls:
+      Port: 5101
+      CertificatePath: /certs/server.pfx
+```
+
+No code changes required - just configuration.
+
+## Troubleshooting
+
+### Messages Not Being Delivered
+
+1. Verify both client and server use InMemory transport
+2. Check `InMemoryConnectionRegistry` is registered as singleton
+3. Ensure services are registered in same DI container
+
+### Memory Growing
+
+1. Check `MaxPendingMessages` limit
+2. Verify consumers are processing messages
+3. Monitor for message timeout (messages queued too long)
+
+### Order Not Preserved
+
+1. Set `PreserveMessageOrder: true`
+2. Ensure single consumer per endpoint
+3. Don't use parallel processing in handlers
+
+## See Also
+
+- [TCP Transport](./tcp.md) - For multi-process development
+- [Transport Overview](./README.md)
+- [Testing Guide](../../19_TEST_SUITE_OVERVIEW.md)

docs/router/transports/rabbitmq.md

@@ -0,0 +1,241 @@
+# RabbitMQ Transport
+
+The RabbitMQ transport provides durable, asynchronous message delivery using AMQP 0.9.1 protocol. Ideal for high-volume async processing, fan-out patterns, and scenarios requiring message persistence.
+
+## Overview
+
+| Property | Value |
+|----------|-------|
+| Plugin Assembly | `StellaOps.Router.Transport.RabbitMq.dll` |
+| Transport Name | `rabbitmq` |
+| Protocol | AMQP 0.9.1 (RabbitMQ.Client 7.x) |
+| Security | TLS, SASL authentication |
+| Use Case | Async processing, fan-out, durable messaging |
+
+## Configuration
+
+### router.yaml
+
+```yaml
+Router:
+  Transport:
+    Type: rabbitmq
+    RabbitMq:
+      HostName: rabbitmq.internal
+      Port: 5672
+      VirtualHost: /stellaops
+      UserName: stellaops
+      Password: ${RABBITMQ_PASSWORD:-}
+      Ssl:
+        Enabled: true
+        ServerName: rabbitmq.internal
+        CertPath: /certs/client.pfx
+      Exchange:
+        Name: stellaops.router
+        Type: topic
+        Durable: true
+      Queue:
+        Durable: true
+        AutoDelete: false
+        PrefetchCount: 100
+```
+
+### microservice.yaml
+
+```yaml
+routers:
+  - host: rabbitmq.internal
+    port: 5672
+    transportType: RabbitMq
+    priority: 1
+    rabbitmq:
+      virtualHost: /stellaops
+      exchange: stellaops.router
+      routingKeyPrefix: orders
+```
+
+### Environment Variables
+
+```bash
+ROUTER__TRANSPORT__TYPE=rabbitmq
+ROUTER__TRANSPORT__RABBITMQ__HOSTNAME=rabbitmq.internal
+ROUTER__TRANSPORT__RABBITMQ__PORT=5672
+ROUTER__TRANSPORT__RABBITMQ__USERNAME=stellaops
+ROUTER__TRANSPORT__RABBITMQ__PASSWORD=secret
+```
+
+## Options Reference
+
+### Connection Options
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `HostName` | string | `localhost` | RabbitMQ server hostname |
+| `Port` | int | `5672` | AMQP port (5671 for TLS) |
+| `VirtualHost` | string | `/` | RabbitMQ virtual host |
+| `UserName` | string | `guest` | Authentication username |
+| `Password` | string | `guest` | Authentication password |
+| `ConnectionTimeout` | TimeSpan | `00:00:30` | Connection timeout |
+| `RequestedHeartbeat` | TimeSpan | `00:01:00` | Heartbeat interval |
+
+### SSL Options
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `Ssl:Enabled` | bool | `false` | Enable TLS |
+| `Ssl:ServerName` | string | - | Expected server certificate name |
+| `Ssl:CertPath` | string | - | Client certificate path |
+| `Ssl:CertPassphrase` | string | - | Client certificate password |
+| `Ssl:Version` | SslProtocols | `Tls13` | TLS version |
+
+### Exchange Options
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `Exchange:Name` | string | `stellaops.router` | Exchange name |
+| `Exchange:Type` | string | `topic` | Exchange type (direct, topic, fanout, headers) |
+| `Exchange:Durable` | bool | `true` | Survive broker restart |
+| `Exchange:AutoDelete` | bool | `false` | Delete when unused |
+
+### Queue Options
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `Queue:Durable` | bool | `true` | Persist messages to disk |
+| `Queue:AutoDelete` | bool | `false` | Delete when all consumers disconnect |
+| `Queue:Exclusive` | bool | `false` | Single-consumer queue |
+| `Queue:PrefetchCount` | int | `100` | Prefetch limit per consumer |
+
+## Message Flow
+
+```
+┌───────────────┐         ┌─────────────────────────────────────────────┐
+│   Gateway     │         │               RabbitMQ Broker                │
+│               │         │                                              │
+│ ─────────────►│  AMQP   │  ┌───────────────┐    ┌──────────────────┐ │
+│  Publish      │────────►│  │   Exchange    │───►│  Service Queue   │ │
+│               │         │  │ (topic/fanout)│    │  (orders.*)      │ │
+└───────────────┘         │  └───────────────┘    └────────┬─────────┘ │
+                          │                                 │          │
+                          └─────────────────────────────────│──────────┘
+                                                            │
+                                                            ▼
+                          ┌───────────────────────────────────────────┐
+                          │              Microservices                  │
+                          │  ┌─────────────┐  ┌─────────────────────┐ │
+                          │  │ OrderCreate │  │ OrderNotification   │ │
+                          │  │ Consumer    │  │ Consumer            │ │
+                          │  └─────────────┘  └─────────────────────┘ │
+                          └───────────────────────────────────────────┘
+```
+
+## Routing Patterns
+
+### Topic Routing
+
+```yaml
+Exchange:
+  Type: topic
+
+# Microservice A binds to: orders.create.#
+# Microservice B binds to: orders.*.notify
+# Gateway publishes to: orders.create.premium → matches A only
+# Gateway publishes to: orders.cancel.notify → matches B only
+```
+
+### Fan-Out Pattern
+
+```yaml
+Exchange:
+  Type: fanout
+
+# All bound queues receive every message
+# Good for broadcasting events to all services
+```
+
+### Direct Routing
+
+```yaml
+Exchange:
+  Type: direct
+
+# Exact routing key match required
+# Gateway publishes to: order-service
+# Only queue bound with key "order-service" receives
+```
+
+## Performance Characteristics
+
+| Metric | Typical Value |
+|--------|---------------|
+| Latency (p50) | < 5ms |
+| Latency (p99) | < 20ms |
+| Throughput | 50,000+ mps |
+| Memory per connection | ~16KB |
+
+*Persistent messages with acknowledgments on dedicated broker*
+
+## High Availability
+
+### Clustered RabbitMQ
+
+```yaml
+RabbitMq:
+  Endpoints:
+    - Host: rabbit1.internal
+      Port: 5672
+    - Host: rabbit2.internal
+      Port: 5672
+    - Host: rabbit3.internal
+      Port: 5672
+  Queue:
+    Arguments:
+      x-ha-policy: all        # Mirror to all nodes
+      x-queue-type: quorum    # Quorum queue (RabbitMQ 3.8+)
+```
+
+### Dead Letter Handling
+
+```yaml
+Queue:
+  Arguments:
+    x-dead-letter-exchange: stellaops.dlx
+    x-dead-letter-routing-key: failed
+    x-message-ttl: 3600000    # 1 hour TTL
+```
+
+## Troubleshooting
+
+### Connection Refused
+
+```
+Error: Failed to connect to rabbitmq.internal:5672
+```
+
+1. Verify RabbitMQ is running: `rabbitmqctl status`
+2. Check firewall allows AMQP port
+3. Verify virtual host exists: `rabbitmqctl list_vhosts`
+4. Confirm user has permissions: `rabbitmqctl list_user_permissions stellaops`
+
+### Authentication Failed
+
+```
+Error: ACCESS_REFUSED - Login was refused
+```
+
+1. Check username/password are correct
+2. Verify user exists: `rabbitmqctl list_users`
+3. Grant permissions: `rabbitmqctl set_permissions -p /stellaops stellaops ".*" ".*" ".*"`
+
+### Messages Not Being Consumed
+
+1. Check queue exists: `rabbitmqctl list_queues`
+2. Verify binding: `rabbitmqctl list_bindings -p /stellaops`
+3. Check consumer is connected: `rabbitmqctl list_consumers`
+4. Monitor unacked messages: `rabbitmqctl list_queues messages_unacknowledged`
+
+## See Also
+
+- [RabbitMQ Documentation](https://www.rabbitmq.com/documentation.html)
+- [Transport Overview](./README.md)
+- [Messaging Transports](../../messaging/)

docs/router/transports/tcp.md

@@ -0,0 +1,135 @@
+# TCP Transport
+
+The TCP transport provides high-performance binary communication for internal microservices within the same datacenter or trusted network.
+
+## Overview
+
+| Property | Value |
+|----------|-------|
+| Plugin Assembly | `StellaOps.Router.Transport.Tcp.dll` |
+| Transport Name | `tcp` |
+| Default Port | 5100 |
+| Security | Network isolation (no encryption) |
+| Use Case | Internal services, low-latency communication |
+
+## Configuration
+
+### router.yaml
+
+```yaml
+Router:
+  Transport:
+    Type: tcp
+    Tcp:
+      Host: "0.0.0.0"
+      Port: 5100
+      MaxConnections: 1000
+      ReceiveBufferSize: 65536
+      SendBufferSize: 65536
+      KeepAlive: true
+      NoDelay: true
+```
+
+### microservice.yaml
+
+```yaml
+routers:
+  - host: gateway.internal
+    port: 5100
+    transportType: Tcp
+    priority: 1
+```
+
+### Environment Variables
+
+```bash
+ROUTER__TRANSPORT__TYPE=tcp
+ROUTER__TRANSPORT__TCP__HOST=0.0.0.0
+ROUTER__TRANSPORT__TCP__PORT=5100
+ROUTER__TRANSPORT__TCP__MAXCONNECTIONS=1000
+```
+
+## Options Reference
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `Host` | string | `0.0.0.0` | Bind address for server |
+| `Port` | int | `5100` | TCP port number |
+| `MaxConnections` | int | `1000` | Maximum concurrent connections |
+| `ReceiveBufferSize` | int | `65536` | Socket receive buffer size in bytes |
+| `SendBufferSize` | int | `65536` | Socket send buffer size in bytes |
+| `KeepAlive` | bool | `true` | Enable TCP keep-alive probes |
+| `NoDelay` | bool | `true` | Disable Nagle's algorithm (lower latency) |
+| `ConnectTimeout` | TimeSpan | `00:00:30` | Connection timeout |
+| `ReadTimeout` | TimeSpan | `00:02:00` | Socket read timeout |
+| `WriteTimeout` | TimeSpan | `00:02:00` | Socket write timeout |
+
+## Performance Characteristics
+
+| Metric | Typical Value |
+|--------|---------------|
+| Latency (p50) | < 1ms |
+| Latency (p99) | < 5ms |
+| Throughput | 100,000+ rps |
+| Memory per connection | ~2KB |
+
+*Benchmarks on 10Gbps network with small payloads (<1KB)*
+
+## Security Considerations
+
+TCP transport does **not** provide encryption. Use only in:
+- Private networks with proper network segmentation
+- Same-datacenter deployments with firewalled traffic
+- Container orchestration networks (Kubernetes pod network)
+
+For encrypted communication, use [TLS transport](./tls.md).
+
+## Framing Protocol
+
+The TCP transport uses the standard Router binary framing protocol:
+
+```
+┌────────────────────────────────────────────────────────────────┐
+│                        Frame Header (24 bytes)                  │
+├────────────┬────────────┬────────────┬────────────┬────────────┤
+│ Magic (4)  │ Version(2) │ Type (2)   │ Flags (4)  │ Length (8) │
+├────────────┴────────────┴────────────┴────────────┴────────────┤
+│ Correlation ID (4)                                              │
+├─────────────────────────────────────────────────────────────────┤
+│                        Frame Payload (variable)                 │
+└─────────────────────────────────────────────────────────────────┘
+```
+
+## Troubleshooting
+
+### Connection Refused
+
+```
+Error: Connection refused to gateway.internal:5100
+```
+
+1. Verify Gateway is running and listening on port 5100
+2. Check firewall rules allow traffic on port 5100
+3. Verify DNS resolution of hostname
+
+### Connection Timeout
+
+```
+Error: Connection to gateway.internal:5100 timed out
+```
+
+1. Increase `ConnectTimeout` value
+2. Check network connectivity between services
+3. Verify no network segmentation blocking traffic
+
+### Performance Issues
+
+1. Enable `NoDelay: true` for latency-sensitive workloads
+2. Tune buffer sizes based on payload sizes
+3. Monitor connection pool exhaustion
+
+## See Also
+
+- [TLS Transport](./tls.md) - Encrypted variant
+- [Transport Overview](./README.md)
+- [Router Architecture](../ARCHITECTURE.md)

docs/router/transports/tls.md

@@ -0,0 +1,223 @@
+# TLS Transport
+
+The TLS transport provides encrypted communication with optional mutual TLS (mTLS) authentication for secure cross-datacenter and external service communication.
+
+## Overview
+
+| Property | Value |
+|----------|-------|
+| Plugin Assembly | `StellaOps.Router.Transport.Tls.dll` |
+| Transport Name | `tls` |
+| Default Port | 5101 |
+| Security | TLS 1.3, optional mTLS |
+| Use Case | Cross-datacenter, external services, compliance-required environments |
+
+## Configuration
+
+### router.yaml (Gateway/Server)
+
+```yaml
+Router:
+  Transport:
+    Type: tls
+    Tls:
+      Host: "0.0.0.0"
+      Port: 5101
+      CertificatePath: /certs/server.pfx
+      CertificatePassword: ${TLS_CERT_PASSWORD:-}
+      RequireClientCertificate: true      # Enable mTLS
+      AllowedClientCertificates:
+        - /certs/trusted/client1.cer
+        - /certs/trusted/client2.cer
+      TlsProtocols: Tls13                 # TLS 1.3 only
+      CheckCertificateRevocation: true
+```
+
+### microservice.yaml (Client)
+
+```yaml
+routers:
+  - host: gateway.external.company.com
+    port: 5101
+    transportType: Tls
+    priority: 1
+    tls:
+      clientCertificatePath: /certs/client.pfx
+      clientCertificatePassword: ${CLIENT_CERT_PASSWORD:-}
+      validateServerCertificate: true
+      serverCertificateThumbprints:
+        - "A1B2C3D4E5F6..."
+```
+
+### Environment Variables
+
+```bash
+ROUTER__TRANSPORT__TYPE=tls
+ROUTER__TRANSPORT__TLS__PORT=5101
+ROUTER__TRANSPORT__TLS__CERTIFICATEPATH=/certs/server.pfx
+ROUTER__TRANSPORT__TLS__CERTIFICATEPASSWORD=secret
+ROUTER__TRANSPORT__TLS__REQUIRECLIENTCERTIFICATE=true
+```
+
+## Options Reference
+
+### Server Options
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `Host` | string | `0.0.0.0` | Bind address |
+| `Port` | int | `5101` | TLS port number |
+| `CertificatePath` | string | - | Path to server certificate (PFX/P12) |
+| `CertificatePassword` | string | - | Password for certificate file |
+| `RequireClientCertificate` | bool | `false` | Enable mutual TLS |
+| `AllowedClientCertificates` | string[] | - | Paths to trusted client certs |
+| `TlsProtocols` | TlsProtocols | `Tls12,Tls13` | Allowed TLS versions |
+| `CheckCertificateRevocation` | bool | `true` | Check CRL/OCSP |
+| `CipherSuites` | string[] | - | Allowed cipher suites (TLS 1.3) |
+
+### Client Options
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `ClientCertificatePath` | string | - | Path to client certificate (PFX/P12) |
+| `ClientCertificatePassword` | string | - | Password for client certificate |
+| `ValidateServerCertificate` | bool | `true` | Validate server certificate |
+| `ServerCertificateThumbprints` | string[] | - | Pinned server cert thumbprints |
+| `AllowUntrustedCertificates` | bool | `false` | Allow self-signed certs (dev only) |
+
+## Mutual TLS (mTLS)
+
+For zero-trust environments, enable mutual TLS authentication:
+
+```
+┌──────────────────┐                    ┌──────────────────┐
+│   Microservice   │                    │     Gateway      │
+│                  │                    │                  │
+│  Client Cert     │◄───── TLS ────────►│  Server Cert     │
+│  (identity)      │    Handshake       │  (identity)      │
+│                  │                    │                  │
+│  Validates:      │                    │  Validates:      │
+│  - Server cert   │                    │  - Client cert   │
+│  - Thumbprint    │                    │  - Allowlist     │
+└──────────────────┘                    └──────────────────┘
+```
+
+### Certificate Requirements
+
+**Server Certificate:**
+- Extended Key Usage: `Server Authentication (1.3.6.1.5.5.7.3.1)`
+- Subject Alternative Name: Include all DNS names clients will connect to
+
+**Client Certificate:**
+- Extended Key Usage: `Client Authentication (1.3.6.1.5.5.7.3.2)`
+- Common Name or SAN identifying the service
+
+## Performance Characteristics
+
+| Metric | Typical Value |
+|--------|---------------|
+| Latency (p50) | < 2ms |
+| Latency (p99) | < 10ms |
+| Throughput | 80,000+ rps |
+| Memory per connection | ~8KB |
+
+*TLS 1.3 with session resumption on 10Gbps network*
+
+## Certificate Management
+
+### Generating Certificates
+
+```bash
+# Generate CA
+openssl genrsa -out ca.key 4096
+openssl req -new -x509 -days 3650 -key ca.key -out ca.crt \
+  -subj "/CN=StellaOps Internal CA"
+
+# Generate server certificate
+openssl genrsa -out server.key 2048
+openssl req -new -key server.key -out server.csr \
+  -subj "/CN=gateway.internal" \
+  -addext "subjectAltName=DNS:gateway.internal,DNS:localhost"
+openssl x509 -req -days 365 -in server.csr -CA ca.crt -CAkey ca.key \
+  -CAcreateserial -out server.crt \
+  -extfile <(echo "subjectAltName=DNS:gateway.internal,DNS:localhost")
+
+# Package as PFX
+openssl pkcs12 -export -out server.pfx -inkey server.key -in server.crt \
+  -certfile ca.crt -passout pass:changeit
+```
+
+### Certificate Rotation
+
+1. Generate new certificate before expiry
+2. Update `CertificatePath` in configuration
+3. Restart Gateway (no connection interruption with graceful shutdown)
+4. Update client thumbprint pins if using certificate pinning
+
+## Air-Gap Deployment
+
+For offline environments:
+
+1. Pre-provision all certificates
+2. Disable CRL/OCSP checks: `CheckCertificateRevocation: false`
+3. Use certificate pinning instead of chain validation
+
+```yaml
+Router:
+  Transport:
+    Type: tls
+    Tls:
+      CheckCertificateRevocation: false
+      AllowedClientCertificates:
+        - /certs/trusted/client1.cer
+```
+
+## Troubleshooting
+
+### Certificate Validation Failed
+
+```
+Error: The remote certificate is invalid according to the validation procedure
+```
+
+1. Verify certificate is not expired: `openssl x509 -in cert.pem -noout -dates`
+2. Check certificate chain is complete
+3. Verify CA is trusted by the system or explicitly configured
+
+### mTLS Handshake Failed
+
+```
+Error: The client certificate is not provided
+```
+
+1. Ensure client certificate is configured with correct path
+2. Verify certificate has Client Authentication EKU
+3. Check certificate is in Gateway's allowlist
+
+### TLS Protocol Mismatch
+
+```
+Error: A call to SSPI failed, TLS version mismatch
+```
+
+1. Ensure both sides support compatible TLS versions
+2. Update `TlsProtocols` to include common version
+3. TLS 1.3 recommended for new deployments
+
+## Compliance
+
+The TLS transport supports compliance requirements:
+
+| Standard | Configuration |
+|----------|---------------|
+| PCI-DSS | TLS 1.2+, strong ciphers, certificate validation |
+| HIPAA | TLS 1.2+, mTLS for service-to-service |
+| FedRAMP | TLS 1.3, FIPS-validated crypto modules |
+
+For FIPS mode, ensure .NET is configured for FIPS compliance and use FIPS-approved cipher suites.
+
+## See Also
+
+- [TCP Transport](./tcp.md) - Unencrypted variant for internal use
+- [Transport Overview](./README.md)
+- [Security Hardening Guide](../../17_SECURITY_HARDENING_GUIDE.md)

docs/router/transports/udp.md

@@ -0,0 +1,173 @@
+# UDP Transport
+
+The UDP transport provides connectionless, fire-and-forget messaging suitable for broadcast notifications and scenarios where delivery guarantees are not critical.
+
+## Overview
+
+| Property | Value |
+|----------|-------|
+| Plugin Assembly | `StellaOps.Router.Transport.Udp.dll` |
+| Transport Name | `udp` |
+| Default Port | 5102 |
+| Security | Network isolation (no encryption) |
+| Use Case | Broadcast, metrics, fire-and-forget events |
+
+## Configuration
+
+### router.yaml
+
+```yaml
+Router:
+  Transport:
+    Type: udp
+    Udp:
+      Host: "0.0.0.0"
+      Port: 5102
+      ReceiveBufferSize: 65536
+      SendBufferSize: 65536
+      MulticastGroup: null         # Optional multicast group
+      MulticastTtl: 1
+      EnableBroadcast: false
+```
+
+### microservice.yaml
+
+```yaml
+routers:
+  - host: gateway.internal
+    port: 5102
+    transportType: Udp
+    priority: 1
+```
+
+### Environment Variables
+
+```bash
+ROUTER__TRANSPORT__TYPE=udp
+ROUTER__TRANSPORT__UDP__HOST=0.0.0.0
+ROUTER__TRANSPORT__UDP__PORT=5102
+```
+
+## Options Reference
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `Host` | string | `0.0.0.0` | Bind address |
+| `Port` | int | `5102` | UDP port number |
+| `ReceiveBufferSize` | int | `65536` | Socket receive buffer size |
+| `SendBufferSize` | int | `65536` | Socket send buffer size |
+| `MulticastGroup` | string | `null` | Multicast group address (e.g., `239.1.2.3`) |
+| `MulticastTtl` | int | `1` | Multicast time-to-live |
+| `EnableBroadcast` | bool | `false` | Allow broadcast to `255.255.255.255` |
+| `MaxDatagramSize` | int | `65507` | Maximum UDP datagram size |
+
+## Use Cases
+
+### Fire-and-Forget Events
+
+For events where acknowledgment is not required:
+
+```csharp
+[StellaEndpoint("POST", "/events/metrics", FireAndForget = true)]
+public sealed class MetricsEndpoint : IStellaEndpoint<MetricsBatch, EmptyResponse>
+{
+    public Task<EmptyResponse> HandleAsync(MetricsBatch request, CancellationToken ct)
+    {
+        // Process metrics - no response expected
+        return Task.FromResult(new EmptyResponse());
+    }
+}
+```
+
+### Multicast Broadcasting
+
+For broadcasting to multiple listeners:
+
+```yaml
+Router:
+  Transport:
+    Type: udp
+    Udp:
+      MulticastGroup: "239.0.1.1"
+      MulticastTtl: 2
+```
+
+Services join the multicast group to receive broadcasts:
+
+```csharp
+// All services with this config receive broadcasts
+routers:
+  - host: "239.0.1.1"
+    port: 5102
+    transportType: Udp
+```
+
+## Performance Characteristics
+
+| Metric | Typical Value |
+|--------|---------------|
+| Latency (p50) | < 0.5ms |
+| Latency (p99) | < 2ms |
+| Throughput | 150,000+ pps |
+| Memory per socket | ~1KB |
+
+*Note: No delivery guarantees; packets may be lost under load*
+
+## Limitations
+
+1. **No delivery guarantees**: Packets may be dropped
+2. **No ordering guarantees**: Packets may arrive out of order
+3. **Size limits**: Maximum datagram size ~65KB (64KB practical limit)
+4. **No acknowledgments**: Sender doesn't know if message was received
+5. **No fragmentation handling**: Large messages must fit in single datagram
+
+## When to Use UDP
+
+**Good fit:**
+- Real-time metrics and telemetry
+- Service discovery announcements
+- Health check broadcasts
+- Low-latency gaming or streaming metadata
+
+**Not recommended:**
+- Transaction processing
+- Data that must not be lost
+- Large payloads (use TCP/TLS instead)
+
+## Security Considerations
+
+UDP transport does **not** provide encryption or authentication. Consider:
+
+- Network segmentation
+- Firewall rules to restrict UDP traffic
+- Application-level message signing if integrity is needed
+- DTLS wrapper for encrypted UDP (not built-in)
+
+## Troubleshooting
+
+### Messages Not Received
+
+1. Check firewall allows UDP traffic on the configured port
+2. Verify receiver is bound to correct address/port
+3. Check for buffer overflow (increase `ReceiveBufferSize`)
+4. Monitor for packet loss with network tools
+
+### Multicast Not Working
+
+1. Verify multicast routing is enabled on network
+2. Check `MulticastTtl` is sufficient for network topology
+3. Ensure IGMP snooping is properly configured
+4. Verify all receivers joined the multicast group
+
+### High Packet Loss
+
+1. Reduce message rate
+2. Increase buffer sizes
+3. Check for network congestion
+4. Consider switching to TCP for reliable delivery
+
+## See Also
+
+- [TCP Transport](./tcp.md) - Reliable delivery
+- [Transport Overview](./README.md)
+- [Router Architecture](../ARCHITECTURE.md)