Mercados-Web/src/Mercados.Worker/Program.cs

using System.Text;
using Mercados.Infrastructure;
using Mercados.Infrastructure.DataFetchers;
using Mercados.Infrastructure.Persistence;
using Mercados.Infrastructure.Persistence.Repositories;
using Mercados.Worker;
using Polly;
using Polly.Extensions.Http;
using Mercados.Infrastructure.Services;

IHost host = Host.CreateDefaultBuilder(args)
    .ConfigureServices((hostContext, services) =>
    {
        IConfiguration configuration = hostContext.Configuration;

        // El resto del código no cambia. IConfiguration recogerá automáticamente
        // las variables de entorno que cargamos correctamente.
        services.AddSingleton<IDbConnectionFactory, SqlConnectionFactory>();
        services.AddScoped<ICotizacionGanadoRepository, CotizacionGanadoRepository>();
        services.AddScoped<ICotizacionGranoRepository, CotizacionGranoRepository>();
        services.AddScoped<ICotizacionBolsaRepository, CotizacionBolsaRepository>();
        services.AddScoped<IFuenteDatoRepository, FuenteDatoRepository>();
        services.AddScoped<INotificationService, EmailNotificationService>();

        services.AddScoped<IDataFetcher, MercadoAgroFetcher>();
        services.AddScoped<IDataFetcher, BcrDataFetcher>();
        services.AddScoped<IDataFetcher, FinnhubDataFetcher>();
        services.AddScoped<IDataFetcher, YahooFinanceDataFetcher>();

        services.AddHttpClient("MercadoAgroFetcher").AddPolicyHandler(GetRetryPolicy());
        services.AddHttpClient("BcrDataFetcher").AddPolicyHandler(GetRetryPolicy());
        services.AddHttpClient("FinnhubDataFetcher").AddPolicyHandler(GetRetryPolicy());

        // Servicio de caché en memoria de .NET
        services.AddMemoryCache();
        // Registramos nuestro nuevo servicio de feriados
        services.AddScoped<IHolidayService, FinnhubHolidayService>();
        services.AddScoped<IDataFetcher, HolidayDataFetcher>();
        services.AddScoped<IMercadoFeriadoRepository, MercadoFeriadoRepository>();

        services.AddHostedService<DataFetchingService>();
    })
    .Build();

static IAsyncPolicy<HttpResponseMessage> GetRetryPolicy()
{
    return HttpPolicyExtensions
        .HandleTransientHttpError()
        .OrResult(msg => msg.StatusCode == System.Net.HttpStatusCode.RequestTimeout)
        .WaitAndRetryAsync(3, retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)),
            onRetry: (outcome, timespan, retryAttempt, context) =>
            {
                Console.WriteLine($"[Polly] Reintentando petición... Intento {retryAttempt}. Esperando {timespan.TotalSeconds}s. Causa: {outcome.Exception?.Message ?? outcome.Result.ReasonPhrase}");
            });
}

await host.RunAsync();