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src/__Libraries/StellaOps.DependencyInjection/Validation/OptionsValidationHostedService.cs

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+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Options;
+
+namespace StellaOps.DependencyInjection.Validation;
+
+/// <summary>
+/// A hosted service that validates options at application startup.
+/// This ensures configuration errors are detected early rather than at first use.
+/// </summary>
+/// <typeparam name="TOptions">The options type to validate.</typeparam>
+internal sealed class OptionsValidationHostedService<TOptions> : IHostedService
+    where TOptions : class
+{
+    private readonly IOptions<TOptions> _options;
+
+    public OptionsValidationHostedService(IOptions<TOptions> options)
+    {
+        _options = options;
+    }
+
+    public Task StartAsync(CancellationToken cancellationToken)
+    {
+        // Accessing .Value triggers validation if IValidateOptions<TOptions> is registered
+        _ = _options.Value;
+        return Task.CompletedTask;
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+}