fix: address remaining PR review feedback

- ignore local test output artifact to prevent noisy diffs
- cache chat captcha unavailable response payload
- add tests for partial captcha configuration guard paths

Author: BenjaminMichaelis

.gitignore

@@ -33,6 +33,7 @@ TestResults/
 
 # Old or generated files to not commit
 build_output.txt
+test_output.txt
 wwwroot/sitemap.xml
 wwwroot/Chapters
 EssentialCSharp.Web/wwwroot/Chapters

EssentialCSharp.Web.Tests/CaptchaValidationServiceTests.cs

@@ -24,6 +24,40 @@ public async Task ValidateAsync_MissingConfig_RejectsWithoutVerification()
         await Assert.That(captchaService.CallCount).IsEqualTo(0);
     }
 
+    [Test]
+    public async Task ValidateAsync_MissingSiteKey_RejectsWithoutVerification()
+    {
+        StubCaptchaService captchaService = new((_, _, _) => throw new InvalidOperationException("Verifier should not be called."));
+        using ServiceProvider serviceProvider = CreateServiceProvider(
+            new CaptchaOptions { SecretKey = "secret", SiteKey = string.Empty },
+            captchaService);
+
+        ICaptchaValidationService validationService = serviceProvider.GetRequiredService<ICaptchaValidationService>();
+
+        CaptchaValidationResult result = await validationService.ValidateAsync("token", "127.0.0.1");
+
+        await Assert.That(result.Outcome).IsEqualTo(CaptchaValidationOutcome.Disabled);
+        await Assert.That(result.ShouldProceed).IsFalse();
+        await Assert.That(captchaService.CallCount).IsEqualTo(0);
+    }
+
+    [Test]
+    public async Task ValidateAsync_MissingSecretKey_RejectsWithoutVerification()
+    {
+        StubCaptchaService captchaService = new((_, _, _) => throw new InvalidOperationException("Verifier should not be called."));
+        using ServiceProvider serviceProvider = CreateServiceProvider(
+            new CaptchaOptions { SecretKey = string.Empty, SiteKey = "sitekey" },
+            captchaService);
+
+        ICaptchaValidationService validationService = serviceProvider.GetRequiredService<ICaptchaValidationService>();
+
+        CaptchaValidationResult result = await validationService.ValidateAsync("token", "127.0.0.1");
+
+        await Assert.That(result.Outcome).IsEqualTo(CaptchaValidationOutcome.Disabled);
+        await Assert.That(result.ShouldProceed).IsFalse();
+        await Assert.That(captchaService.CallCount).IsEqualTo(0);
+    }
+
     [Test]
     public async Task ValidateAsync_MissingToken_ReturnsMissingToken()
     {

EssentialCSharp.Web/Controllers/ChatController.cs

@@ -344,8 +344,11 @@ private async Task HandleCaptchaValidationFailureAsync(CaptchaValidationResult c
         }
     }
 
-    private static object CaptchaUnavailableResponseBody =>
-        new { error = "Human verification is temporarily unavailable. Please try again later.", errorCode = "captcha_unavailable" };
+    private static readonly object CaptchaUnavailableResponseBody = new
+    {
+        error = "Human verification is temporarily unavailable. Please try again later.",
+        errorCode = "captcha_unavailable"
+    };
 
     private void LogCaptchaUnavailable(CaptchaValidationOutcome outcome)
     {