PR feedback: Don't require IDistributedCache in DI

Author: MackinnonBuck

src/ModelContextProtocol.AspNetCore/DistributedCacheEventStreamStoreOptionsSetup.cs

@@ -8,7 +8,7 @@ namespace ModelContextProtocol.AspNetCore;
 /// Configures <see cref="DistributedCacheEventStreamStoreOptions"/> by resolving
 /// the <see cref="IDistributedCache"/> from DI when not explicitly set.
 /// </summary>
-internal sealed class DistributedCacheEventStreamStoreOptionsSetup(IDistributedCache cache) : IConfigureOptions<DistributedCacheEventStreamStoreOptions>
+internal sealed class DistributedCacheEventStreamStoreOptionsSetup(IDistributedCache? cache = null) : IConfigureOptions<DistributedCacheEventStreamStoreOptions>
 {
     public void Configure(DistributedCacheEventStreamStoreOptions options)
     {

tests/ModelContextProtocol.AspNetCore.Tests/HttpMcpServerBuilderExtensionsTests.cs

@@ -1,4 +1,6 @@
 using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Caching.Distributed;
+using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 using ModelContextProtocol.AspNetCore.Tests.Utils;
@@ -43,6 +45,22 @@ public void WithDistributedCacheEventStreamStore_ConfigureCallbackIsInvoked()
         Assert.NotNull(capturedOptions);
     }
 
+    [Fact]
+    public void WithDistributedCacheEventStreamStore_WorksWithoutDICache_WhenCacheSetViaCallback()
+    {
+        var explicitCache = new MemoryDistributedCache(Options.Create(new MemoryDistributedCacheOptions()));
+
+        Builder.Services
+            .AddMcpServer()
+            .WithHttpTransport()
+            .WithDistributedCacheEventStreamStore(options => options.Cache = explicitCache);
+
+        using var app = Builder.Build();
+
+        var store = app.Services.GetService<ISseEventStreamStore>();
+        Assert.IsType<DistributedCacheEventStreamStore>(store);
+    }
+
     [Fact]
     public void EventStreamStore_IsPopulatedFromDI_ViaPostConfigure()
     {