Build a Praxa backend with .NET

builder.Services.AddHttpClient<PraxaClient>(client =>
{
    client.BaseAddress = new Uri("https://api.praxa.io");
    client.Timeout = TimeSpan.FromSeconds(30);
});

using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json.Serialization;

public sealed record PraxaRun(
    [property: JsonPropertyName("run_id")] string RunId,
    [property: JsonPropertyName("status")] string Status);

public sealed class PraxaClient
{
    private readonly HttpClient _http;
    private readonly string _apiKey;

    public PraxaClient(HttpClient http, IConfiguration configuration)
    {
        _http = http;
        _apiKey = configuration["Praxa:ApiKey"]
            ?? throw new InvalidOperationException("Praxa API key is required");
    }

    public async Task<PraxaRun> SubmitTaskAsync(
        string userId,
        string logicalRequestId,
        string input,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(input) || input.Length > 16_000)
            throw new ArgumentException("Invalid task input", nameof(input));

        var digest = SHA256.HashData(
            Encoding.UTF8.GetBytes(userId + "\0" + logicalRequestId));
        var key = "dotnet:" + Convert.ToHexString(digest).ToLowerInvariant();

        using var request = new HttpRequestMessage(HttpMethod.Post, "/v1/execute");
        request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", _apiKey);
        request.Headers.Add("Idempotency-Key", key);
        request.Content = JsonContent.Create(new
        {
            apiVersion = "v1",
            requestId = key,
            mode = "task",
            task = new { input },
            idempotencyKey = key,
        });

        using var response = await _http.SendAsync(request, cancellationToken);
        response.EnsureSuccessStatusCode();
        return await response.Content.ReadFromJsonAsync<PraxaRun>(
            cancellationToken: cancellationToken)
            ?? throw new InvalidOperationException("Praxa returned no run");
    }
}