Fully stabilize now-stable protocol properties (#1686)

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

src/ModelContextProtocol.Core/Protocol/ClientCapabilities.cs

@@ -1,4 +1,3 @@
-using System.ComponentModel;
 using System.Text.Json.Serialization;
 using ModelContextProtocol.Client;
 using ModelContextProtocol.Server;
@@ -83,15 +82,6 @@ public sealed class ClientCapabilities
     /// interoperability. Clients advertise extension support via this field during the initialization handshake.
     /// </para>
     /// </remarks>
-    [JsonIgnore]
-    public IDictionary<string, object>? Extensions
-    {
-        get => ExtensionsCore;
-        set => ExtensionsCore = value;
-    }
-
-    // See ExperimentalInternalPropertyTests.cs before modifying this property.
-    [JsonInclude]
     [JsonPropertyName("extensions")]
-    internal IDictionary<string, object>? ExtensionsCore { get; set; }
+    public IDictionary<string, object>? Extensions { get; set; }
 }

src/ModelContextProtocol.Core/Protocol/RequestParams.cs

@@ -35,17 +35,8 @@ public abstract class RequestParams
     /// the value is the client's response to that input request.
     /// </para>
     /// </remarks>
-    [JsonIgnore]
-    public IDictionary<string, InputResponse>? InputResponses
-    {
-        get => InputResponsesCore;
-        set => InputResponsesCore = value;
-    }
-
-    // See ExperimentalInternalPropertyTests.cs before modifying this property.
-    [JsonInclude]
     [JsonPropertyName("inputResponses")]
-    internal IDictionary<string, InputResponse>? InputResponsesCore { get; set; }
+    public IDictionary<string, InputResponse>? InputResponses { get; set; }
 
     /// <summary>
     /// Gets or sets opaque request state echoed back from a previous <see cref="InputRequiredResult"/>.
@@ -57,17 +48,8 @@ public abstract class RequestParams
     /// exact value without modification.
     /// </para>
     /// </remarks>
-    [JsonIgnore]
-    public string? RequestState
-    {
-        get => RequestStateCore;
-        set => RequestStateCore = value;
-    }
-
-    // See ExperimentalInternalPropertyTests.cs before modifying this property.
-    [JsonInclude]
     [JsonPropertyName("requestState")]
-    internal string? RequestStateCore { get; set; }
+    public string? RequestState { get; set; }
 
     /// <summary>
     /// Gets the opaque token that will be attached to any subsequent progress notifications.

src/ModelContextProtocol.Core/Protocol/ServerCapabilities.cs

@@ -1,4 +1,3 @@
-using System.ComponentModel;
 using System.Text.Json.Serialization;
 using ModelContextProtocol.Server;
 
@@ -81,15 +80,6 @@ public sealed class ServerCapabilities
     /// interoperability. Servers advertise extension support via this field during the initialization handshake.
     /// </para>
     /// </remarks>
-    [JsonIgnore]
-    public IDictionary<string, object>? Extensions
-    {
-        get => ExtensionsCore;
-        set => ExtensionsCore = value;
-    }
-
-    // See ExperimentalInternalPropertyTests.cs before modifying this property.
-    [JsonInclude]
     [JsonPropertyName("extensions")]
-    internal IDictionary<string, object>? ExtensionsCore { get; set; }
+    public IDictionary<string, object>? Extensions { get; set; }
 }

tests/ModelContextProtocol.Tests/ExperimentalPropertySerializationTests.cs

@@ -1,120 +0,0 @@
-using System.Text.Json;
-using System.Text.Json.Nodes;
-using System.Text.Json.Serialization;
-using ModelContextProtocol.Protocol;
-
-namespace ModelContextProtocol.Tests;
-
-/// <summary>
-/// Validates that the internal property pattern used for experimental properties
-/// produces the expected serialization behavior for SDK consumers using source generators.
-/// </summary>
-/// <remarks>
-/// <para>
-/// Experimental properties (e.g. <see cref="ServerCapabilities.Extensions"/>, <see cref="ClientCapabilities.Extensions"/>)
-/// use an internal <c>*Core</c> property for serialization. A consumer's source-generated
-/// <see cref="JsonSerializerContext"/> cannot see internal members, so experimental data is
-/// silently dropped unless the consumer chains the SDK's resolver into their options.
-/// </para>
-/// <para>
-/// These tests depend on <see cref="ServerCapabilities.Extensions"/> and <see cref="ClientCapabilities.Extensions"/>
-/// being experimental. When those APIs stabilize, update these tests to reference whatever
-/// experimental properties exist at that time, or remove them entirely if no experimental
-/// APIs remain.
-/// </para>
-/// </remarks>
-public class ExperimentalPropertySerializationTests
-{
-    [Fact]
-    public void ExperimentalProperties_Dropped_WithConsumerContextOnly()
-    {
-        var options = new JsonSerializerOptions
-        {
-            TypeInfoResolverChain = { ConsumerJsonContext.Default }
-        };
-
-        var capabilities = new ServerCapabilities
-        {
-            Tools = new ToolsCapability(),
-            Extensions = new Dictionary<string, object> { ["io.test"] = new JsonObject { ["enabled"] = true } }
-        };
-
-        string json = JsonSerializer.Serialize(capabilities, options);
-        Assert.DoesNotContain("\"extensions\"", json);
-        Assert.Contains("\"tools\"", json);
-    }
-
-    [Fact]
-    public void ExperimentalProperties_IgnoredOnDeserialize_WithConsumerContextOnly()
-    {
-        string json = JsonSerializer.Serialize(
-            new ServerCapabilities
-            {
-                Tools = new ToolsCapability(),
-                Extensions = new Dictionary<string, object> { ["io.test"] = new JsonObject { ["enabled"] = true } }
-            },
-            McpJsonUtilities.DefaultOptions);
-        Assert.Contains("\"extensions\"", json);
-
-        var options = new JsonSerializerOptions
-        {
-            TypeInfoResolverChain = { ConsumerJsonContext.Default }
-        };
-        var deserialized = JsonSerializer.Deserialize<ServerCapabilities>(json, options)!;
-        Assert.NotNull(deserialized.Tools);
-        Assert.Null(deserialized.Extensions);
-    }
-
-    [Fact]
-    public void ExperimentalProperties_RoundTrip_WhenSdkResolverIsChained()
-    {
-        var options = new JsonSerializerOptions
-        {
-            TypeInfoResolverChain =
-            {
-                McpJsonUtilities.DefaultOptions.TypeInfoResolver!,
-                ConsumerJsonContext.Default,
-            }
-        };
-
-        var capabilities = new ServerCapabilities
-        {
-            Tools = new ToolsCapability(),
-            Extensions = new Dictionary<string, object> { ["io.test"] = new JsonObject { ["enabled"] = true } }
-        };
-
-        string json = JsonSerializer.Serialize(capabilities, options);
-        Assert.Contains("\"extensions\"", json);
-        Assert.Contains("\"tools\"", json);
-
-        var deserialized = JsonSerializer.Deserialize<ServerCapabilities>(json, options)!;
-        Assert.NotNull(deserialized.Tools);
-        Assert.NotNull(deserialized.Extensions);
-        Assert.True(deserialized.Extensions.ContainsKey("io.test"));
-    }
-
-    [Fact]
-    public void ExperimentalProperties_RoundTrip_WithDefaultOptions()
-    {
-        var capabilities = new ClientCapabilities
-        {
-            Extensions = new Dictionary<string, object> { ["io.test"] = new JsonObject { ["enabled"] = true } }
-        };
-
-        string json = JsonSerializer.Serialize(capabilities, McpJsonUtilities.DefaultOptions);
-        Assert.Contains("\"extensions\"", json);
-
-        var deserialized = JsonSerializer.Deserialize<ClientCapabilities>(json, McpJsonUtilities.DefaultOptions)!;
-        Assert.NotNull(deserialized.Extensions);
-        Assert.True(deserialized.Extensions.ContainsKey("io.test"));
-    }
-}
-
-[JsonSerializable(typeof(Tool))]
-[JsonSerializable(typeof(ServerCapabilities))]
-[JsonSerializable(typeof(ClientCapabilities))]
-[JsonSerializable(typeof(CallToolResult))]
-[JsonSerializable(typeof(CallToolRequestParams))]
-[JsonSerializable(typeof(CreateMessageRequestParams))]
-[JsonSerializable(typeof(ElicitRequestParams))]
-internal partial class ConsumerJsonContext : JsonSerializerContext;