diff --git a/GenHub/GenHub.Tests/GenHub.Tests.Core/Features/Manifest/ManifestDiscoveryServiceTests.cs b/GenHub/GenHub.Tests/GenHub.Tests.Core/Features/Manifest/ManifestDiscoveryServiceTests.cs
index 6cf445c5d..81b6c547b 100644
--- a/GenHub/GenHub.Tests/GenHub.Tests.Core/Features/Manifest/ManifestDiscoveryServiceTests.cs
+++ b/GenHub/GenHub.Tests/GenHub.Tests.Core/Features/Manifest/ManifestDiscoveryServiceTests.cs
@@ -4,6 +4,7 @@
 using GenHub.Features.Manifest;
 using Microsoft.Extensions.Logging;
 using Moq;
+using System.Text.Json;
 using ContentType = GenHub.Core.Models.Enums.ContentType;
 
 namespace GenHub.Tests.Features.Manifest;
@@ -11,7 +12,7 @@ namespace GenHub.Tests.Features.Manifest;
 /// <summary>
 /// Unit tests for the <see cref="ManifestDiscoveryService"/> class.
 /// </summary>
-public class ManifestDiscoveryServiceTests
+public class ManifestDiscoveryServiceTests : IDisposable
 {
     /// <summary>
     /// Mock logger for the manifest discovery service.
@@ -28,6 +29,11 @@ public class ManifestDiscoveryServiceTests
     /// </summary>
     private readonly ManifestDiscoveryService _discoveryService;
 
+    /// <summary>
+    /// Temporary directory used for filesystem discovery tests.
+    /// </summary>
+    private readonly string _tempDirectory;
+
     /// <summary>
     /// Initializes a new instance of the <see cref="ManifestDiscoveryServiceTests"/> class.
     /// </summary>
@@ -36,6 +42,7 @@ public ManifestDiscoveryServiceTests()
         _loggerMock = new Mock<ILogger<ManifestDiscoveryService>>();
         _cacheMock = new Mock<IManifestCache>();
         _discoveryService = new ManifestDiscoveryService(_loggerMock.Object, _cacheMock.Object);
+        _tempDirectory = Directory.CreateTempSubdirectory("GenHub.ManifestDiscoveryTests.").FullName;
     }
 
     /// <summary>
@@ -84,6 +91,58 @@ public void GetCompatibleManifests_FiltersCorrectly()
         Assert.Single(zeroHourCompatible);
     }
 
+    /// <summary>
+    /// Tests that manifest discovery finds JSON manifests in nested directories and ignores non-JSON files.
+    /// </summary>
+    /// <returns>A <see cref="Task"/> representing the asynchronous test operation.</returns>
+    [Fact]
+    public async Task DiscoverManifestsAsync_DiscoversNestedJsonManifest_AndIgnoresNonJsonFile()
+    {
+        // Arrange
+        const string nestedManifestId = "1.0.genhub.mod.nested";
+        const string ignoredManifestId = "1.0.genhub.mod.ignored";
+        var nestedDirectory = Path.Combine(_tempDirectory, "content", "manifests");
+        Directory.CreateDirectory(nestedDirectory);
+        await File.WriteAllTextAsync(
+            Path.Combine(nestedDirectory, "nested.json"),
+            SerializeManifest(nestedManifestId));
+        await File.WriteAllTextAsync(
+            Path.Combine(_tempDirectory, "ignored.txt"),
+            SerializeManifest(ignoredManifestId));
+
+        // Act
+        var manifests = await _discoveryService.DiscoverManifestsAsync([_tempDirectory]);
+
+        // Assert
+        Assert.Single(manifests);
+        Assert.Contains(nestedManifestId, manifests);
+        Assert.DoesNotContain(ignoredManifestId, manifests);
+    }
+
+    /// <summary>
+    /// Tests that a malformed JSON file does not prevent other nested manifests from being discovered.
+    /// </summary>
+    /// <returns>A <see cref="Task"/> representing the asynchronous test operation.</returns>
+    [Fact]
+    public async Task DiscoverManifestsAsync_WithMalformedJson_ContinuesDiscoveringNestedManifest()
+    {
+        // Arrange
+        const string nestedManifestId = "1.0.genhub.mod.valid";
+        var nestedDirectory = Path.Combine(_tempDirectory, "content", "manifests");
+        Directory.CreateDirectory(nestedDirectory);
+        await File.WriteAllTextAsync(
+            Path.Combine(nestedDirectory, "valid.json"),
+            SerializeManifest(nestedManifestId));
+        await File.WriteAllTextAsync(Path.Combine(_tempDirectory, "malformed.json"), "{ invalid json");
+
+        // Act
+        var manifests = await _discoveryService.DiscoverManifestsAsync([_tempDirectory]);
+
+        // Assert
+        var manifest = Assert.Single(manifests);
+        Assert.Equal(nestedManifestId, manifest.Key);
+    }
+
     /// <summary>
     /// Tests that ValidateDependencies returns false when a required dependency is missing.
     /// </summary>
@@ -156,4 +215,27 @@ public void ValidateDependencies_ReturnsTrue_WhenNoDependencies()
         // Assert
         Assert.True(result);
     }
-}
\ No newline at end of file
+
+    /// <summary>
+    /// Deletes temporary files created by filesystem discovery tests.
+    /// </summary>
+    public void Dispose()
+    {
+        try
+        {
+            if (Directory.Exists(_tempDirectory))
+            {
+                Directory.Delete(_tempDirectory, true);
+            }
+        }
+        catch (Exception ex) when (ex is IOException or UnauthorizedAccessException)
+        {
+            // Best-effort cleanup should not fail an otherwise successful test.
+        }
+    }
+
+    private static string SerializeManifest(string id)
+    {
+        return JsonSerializer.Serialize(new ContentManifest { Id = ManifestId.Create(id) });
+    }
+}
diff --git a/GenHub/GenHub/Features/Manifest/ManifestDiscoveryService.cs b/GenHub/GenHub/Features/Manifest/ManifestDiscoveryService.cs
index 6f9350c32..9691169ba 100644
--- a/GenHub/GenHub/Features/Manifest/ManifestDiscoveryService.cs
+++ b/GenHub/GenHub/Features/Manifest/ManifestDiscoveryService.cs
@@ -61,7 +61,7 @@ public async Task<Dictionary<string, ContentManifest>> DiscoverManifestsAsync(
         foreach (var directory in searchDirectories.Where(Directory.Exists))
         {
             logger.LogInformation("Scanning directory for manifests: {Directory}", directory);
-            var manifestFiles = Directory.EnumerateFiles(directory, "FileTypes.JsonFilePattern", SearchOption.AllDirectories);
+            var manifestFiles = Directory.EnumerateFiles(directory, FileTypes.JsonFilePattern, SearchOption.AllDirectories);
             foreach (var manifestFile in manifestFiles)
             {
                 try
@@ -242,4 +242,4 @@ private async Task DiscoverEmbeddedManifestsAsync(CancellationToken cancellation
             }
         }
     }
-}
\ No newline at end of file
+}