feat: initialize KwisatzHaderach .NET web application

src/backend/KwisatzHaderach/Configuration/AIOptions.cs

@@ -0,0 +1,6 @@
+namespace KwisatzHaderach.Configuration;
+
+public record AIOptions
+{
+    public required string Host { get; init; }
+}

src/backend/KwisatzHaderach/Controllers/PromptController.cs

@@ -0,0 +1,71 @@
+using KwisatzHaderach.Infrastructure.Api;
+using KwisatzHaderach.Models;
+using Microsoft.AspNetCore.Mvc;
+using System.Runtime.CompilerServices;
+using System.Text.Json;
+
+namespace KwisatzHaderach.Controllers;
+
+[ApiController]
+[Route("[controller]")]
+public class PromptController : ControllerBase
+{
+    public record StreamChunk(string? Content);
+
+    [HttpPost("ask")]
+    public async IAsyncEnumerable<StreamChunk> GetPromptResponseAsync([FromBody] PromptRequest req,
+                                                                       ILLMClient llmClient,
+                                                                       [EnumeratorCancellation] CancellationToken cancellationToken)
+    {
+
+        var jsonSerializerOptions = new JsonSerializerOptions { PropertyNameCaseInsensitive = true };
+        HttpResponseMessage? llmResponse = null;
+
+        StreamChunk? errorChunk = null;
+        Exception? capturedException = null;
+        try
+        {
+            llmResponse = await llmClient.GetPromptResponseAsync(req, cancellationToken);
+            llmResponse.EnsureSuccessStatusCode();
+        }
+        catch (OperationCanceledException opEx)
+        {
+            capturedException = opEx;
+        }
+        catch (Exception ex)
+        {
+            errorChunk = new($"[ERROR] Error reading LLM response: {ex.Message}");
+            capturedException = ex;
+        }
+
+        if (capturedException != null || llmResponse == null)
+        {
+            if (errorChunk != null)
+            {
+                yield return errorChunk;
+            }
+            yield break;
+        }
+
+
+        using (llmResponse)
+        {
+            await using var responseStream = await llmResponse.Content.ReadAsStreamAsync(cancellationToken);
+
+            using var reader = new StreamReader(responseStream);
+
+            // Read the stream chunk by chunk until the server closes the connection.
+            char[] buffer = new char[1024]; // Read in chunks of 1KB
+            int bytesRead;
+            while ((bytesRead = await reader.ReadAsync(buffer, 0, buffer.Length)) > 0)
+            {
+                // Get the string content that was just read.
+                string textChunk = new string(buffer, 0, bytesRead);
+                // Wrap the raw string into the StreamChunk object that the React client expects.
+                yield return new StreamChunk(textChunk);
+            }
+        }
+
+        yield break;
+    }
+}

src/backend/KwisatzHaderach/Infrastructure/Api/ILLMClient.cs

@@ -0,0 +1,10 @@
+using KwisatzHaderach.Models;
+using Refit;
+
+namespace KwisatzHaderach.Infrastructure.Api;
+
+public interface ILLMClient
+{
+    [Post("/ask-stream")]
+    Task<HttpResponseMessage> GetPromptResponseAsync([Body]PromptRequest req, CancellationToken cancellationToken);
+}

src/backend/KwisatzHaderach/KwisatzHaderach.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net9.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="9.0.9" />
+    <PackageReference Include="Refit.HttpClientFactory" Version="8.0.0" />
+  </ItemGroup>
+
+</Project>

src/backend/KwisatzHaderach/Models/PromptRequest.cs

@@ -0,0 +1,7 @@
+using System.Text.Json.Serialization;
+
+namespace KwisatzHaderach.Models;
+
+public record PromptRequest(
+    [property: JsonPropertyName("question")]string Question
+);

src/backend/KwisatzHaderach/Program.cs

@@ -0,0 +1,38 @@
+using KwisatzHaderach.Configuration;
+using KwisatzHaderach.Infrastructure.Api;
+using Microsoft.Extensions.Options;
+using Refit;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Add services to the container.
+
+builder.Services.AddControllers();
+builder.Services.AddOpenApi();
+
+builder.Services.Configure<AIOptions>(
+    builder.Configuration.GetSection("AI")
+);
+
+builder.Services.AddRefitClient<ILLMClient>()
+    .ConfigureHttpClient((provider, client) =>
+    {
+        IOptions<AIOptions> aiOptions = provider.GetRequiredService<IOptions<AIOptions>>();
+        client.BaseAddress = new(aiOptions.Value.Host);
+    });
+
+var app = builder.Build();
+
+// Configure the HTTP request pipeline.
+if (app.Environment.IsDevelopment())
+{
+    app.MapOpenApi();
+}
+
+app.UseHttpsRedirection();
+
+app.UseAuthorization();
+
+app.MapControllers();
+
+app.Run();

src/backend/KwisatzHaderach/Properties/launchSettings.json

@@ -0,0 +1,23 @@
+{
+  "$schema": "https://json.schemastore.org/launchsettings.json",
+  "profiles": {
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": false,
+      "applicationUrl": "http://localhost:5187",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": false,
+      "applicationUrl": "https://localhost:7056;http://localhost:5187",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

src/backend/KwisatzHaderach/appsettings.Development.json

@@ -0,0 +1,11 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AI": {
+    "Host": "http://127.0.0.1:8000"
+  }
+}

src/backend/KwisatzHaderach/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}