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Gate 2026-07-28 result fields on negotiated protocol version (#1721) (#1753)

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Co-authored-by: Tarek Mahmoud Sayed <tarekms@ntdev.microsoft.com>
Copilot-Session: 80653343-5dcb-43cb-89b0-8ac8e572c4f7
This commit is contained in:
Tarek Mahmoud Sayed 2026-07-27 12:57:50 -07:00 • committed by GitHub
commit 6787c0cc19
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4 changed files with 219 additions and 27 deletions
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33
src/ModelContextProtocol.Core/Server/McpServerImpl.cs
View file

@ -609,7 +609,10 @@ internal sealed partial class McpServerImpl : McpServer
Instructions = options.ServerInstructions,
ServerInfo = options.ServerInfo ?? DefaultImplementation,
Capabilities = ServerCapabilities ?? new(),
ResultType = "complete",
// resultType is a 2026-07-28 result field. The initialize handshake is only available on
// 2025-11-25 and earlier revisions (2026-07-28+ negotiate via server/discover and throw
// above), so InitializeResult must never carry resultType (issue #1721).
};
},
McpJsonUtilities.JsonContext.Default.InitializeRequestParams,
@ -1635,8 +1638,12 @@ internal sealed partial class McpServerImpl : McpServer
return InvokeHandlerAsync(setLoggingLevelHandler, request!, jsonRpcRequest, cancellationToken);
}
// Otherwise, consider it handled.
return new ValueTask<EmptyResult>(EmptyResult.Instance);
// Otherwise, consider it handled. logging/setLevel is a legacy (<= 2025-11-25) method
// (2026-07-28+ is rejected above), so the response must not carry the 2026-07-28 resultType
// field. Return a fresh EmptyResult rather than the shared EmptyResult.Instance, which is
// pre-stamped with resultType="complete" for the 2026-07-28-only subscriptions/listen path
// (issue #1721).
return new ValueTask<EmptyResult>(new EmptyResult());
},
McpJsonUtilities.JsonContext.Default.SetLevelRequestParams,
McpJsonUtilities.JsonContext.Default.EmptyResult);
@ -1707,7 +1714,11 @@ internal sealed partial class McpServerImpl : McpServer
handler = async (request, cancellationToken) =>
{
var result = await innerHandler(request, cancellationToken).ConfigureAwait(false);
if (result is ICacheableResult cacheable)
// ttlMs and cacheScope are 2026-07-28 result fields; only stamp them when the request
// was negotiated under that revision or later. Earlier revisions (e.g. 2025-11-25) reject
// these as unrecognized keys (issue #1721).
if (result is ICacheableResult cacheable && IsJuly2026OrLaterProtocolRequest(request.JsonRpcRequest))
{
cacheable.TimeToLive ??= TimeSpan.Zero;
cacheable.CacheScope ??= CacheScope.Private;
@ -1723,7 +1734,12 @@ internal sealed partial class McpServerImpl : McpServer
handler = async (request, cancellationToken) =>
{
var result = await innerHandler(request, cancellationToken).ConfigureAwait(false);
if (result is Result protocolResult && protocolResult.ResultType is null)
// resultType is a 2026-07-28 result field; only stamp it when the request was negotiated
// under that revision or later. Earlier revisions (e.g. 2025-11-25) reject it as an
// unrecognized key (issue #1721).
if (result is Result protocolResult && protocolResult.ResultType is null &&
IsJuly2026OrLaterProtocolRequest(request.JsonRpcRequest))
{
protocolResult.ResultType = "complete";
}
@ -1750,7 +1766,12 @@ internal sealed partial class McpServerImpl : McpServer
handler = async (request, cancellationToken) =>
{
var result = await innerHandler(request, cancellationToken).ConfigureAwait(false);
if (!result.IsAlternate && result.Result is { ResultType: null } immediateResult)
// resultType is a 2026-07-28 result field; only stamp it when the request was negotiated
// under that revision or later. Earlier revisions (e.g. 2025-11-25) reject it as an
// unrecognized key (issue #1721).
if (!result.IsAlternate && result.Result is { ResultType: null } immediateResult &&
IsJuly2026OrLaterProtocolRequest(request.JsonRpcRequest))
{
immediateResult.ResultType = "complete";
}

34
tests/ModelContextProtocol.AspNetCore.Tests/RawHttpConformanceTests.cs
View file

@ -322,6 +322,40 @@ public class RawHttpConformanceTests(ITestOutputHelper outputHelper) : KestrelIn
Assert.Equal(HttpStatusCode.OK, response.StatusCode);
var json = await ReadJsonResponseAsync(response, TestContext.Current.CancellationToken);
Assert.Equal("2025-11-25", json["result"]!["protocolVersion"]!.GetValue<string>());
// resultType is a 2026-07-28 result field, and the initialize handshake only ever negotiates
// 2025-11-25 or earlier. It must not appear on the InitializeResult, or strict 2025-11-25 clients
// reject the handshake (issue #1721).
Assert.False(json["result"]!.AsObject().ContainsKey("resultType"),
"InitializeResult must not carry resultType on a 2025-11-25 handshake.");
}
[Fact]
public async Task DownlevelToolsList_On2025_11_25_OmitsResultTypeAndCacheHints()
{
await StartAsync();
// A 2025-11-25 client completes the initialize handshake and then sends subsequent requests with
// the MCP-Protocol-Version header pinned to the negotiated revision. The server must not decorate
// the result with the 2026-07-28-exclusive resultType/ttlMs/cacheScope fields (issue #1721).
var initBody = @"{""jsonrpc"":""2.0"",""id"":1,""method"":""initialize"",""params"":{""protocolVersion"":""2025-11-25"",""capabilities"":{},""clientInfo"":{""name"":""initialize-handshake"",""version"":""1.0""}}}";
using (var initRequest = new HttpRequestMessage(HttpMethod.Post, "") { Content = JsonContent(initBody) })
using (var initResponse = await HttpClient.SendAsync(initRequest, TestContext.Current.CancellationToken))
{
Assert.Equal(HttpStatusCode.OK, initResponse.StatusCode);
}
var body = @"{""jsonrpc"":""2.0"",""id"":2,""method"":""tools/list"",""params"":{}}";
using var request = new HttpRequestMessage(HttpMethod.Post, "") { Content = JsonContent(body) };
request.Headers.Add(ProtocolVersionHeader, McpProtocolVersions.November2025ProtocolVersion);
using var response = await HttpClient.SendAsync(request, TestContext.Current.CancellationToken);
Assert.Equal(HttpStatusCode.OK, response.StatusCode);
var json = await ReadJsonResponseAsync(response, TestContext.Current.CancellationToken);
var result = json["result"]!.AsObject();
Assert.False(result.ContainsKey("resultType"), "resultType must be absent on a 2025-11-25 tools/list result.");
Assert.False(result.ContainsKey("ttlMs"), "ttlMs must be absent on a 2025-11-25 tools/list result.");
Assert.False(result.ContainsKey("cacheScope"), "cacheScope must be absent on a 2025-11-25 tools/list result.");
}
[Fact]

67
tests/ModelContextProtocol.Tests/Server/McpServerTests.cs
View file

@ -283,7 +283,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<InitializeResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.Equal(expectedAssemblyName.Name, result.ServerInfo.Name);
Assert.Equal(expectedAssemblyName.Version?.ToString() ?? "1.0.0", result.ServerInfo.Version);
Assert.Equal("2024-11-05", result.ProtocolVersion);
@ -386,7 +386,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<InitializeResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.NotNull(result.Capabilities.Extensions);
Assert.True(result.Capabilities.Extensions.ContainsKey("io.myext"));
});
@ -406,7 +406,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<InitializeResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.NotNull(result.Capabilities.Experimental);
Assert.True(result.Capabilities.Experimental.ContainsKey("customFeature"));
});
@ -438,7 +438,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<InitializeResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
// Use reflection to verify every public property on ServerCapabilities is non-null.
// This catches cases where new capability properties are added but not copied
@ -485,7 +485,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<CompleteResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.Completion);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.Equal(["test"], result.Completion.Values);
Assert.Equal(2, result.Completion.Total);
Assert.True(result.Completion.HasMore);
@ -529,7 +529,7 @@ public class McpServerTests : LoggedTest
Assert.NotNull(response);
var result = JsonSerializer.Deserialize<CompleteResult>(response.Result, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.Completion);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.Equal(["cat"], result.Completion.Values);
Assert.Equal(1, result.Completion.Total);
@ -573,7 +573,7 @@ public class McpServerTests : LoggedTest
Assert.NotNull(response);
var result = JsonSerializer.Deserialize<CompleteResult>(response.Result, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.Completion);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.Empty(result.Completion.Values);
await transport.DisposeAsync();
@ -623,7 +623,7 @@ public class McpServerTests : LoggedTest
Assert.NotNull(response);
var result = JsonSerializer.Deserialize<CompleteResult>(response.Result, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.Completion);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.Equal(["us-east-1", "us-west-2"], result.Completion.Values);
Assert.Equal(2, result.Completion.Total);
@ -679,7 +679,7 @@ public class McpServerTests : LoggedTest
Assert.NotNull(response);
var result = JsonSerializer.Deserialize<CompleteResult>(response.Result, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.Completion);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
// Custom handler values + auto-populated values should be combined
Assert.Equal(["custom-value", "dog", "cat"], result.Completion.Values);
Assert.Equal(3, result.Completion.Total);
@ -727,7 +727,7 @@ public class McpServerTests : LoggedTest
Assert.NotNull(response);
var result = JsonSerializer.Deserialize<CompleteResult>(response.Result, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.Completion);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.Equal(["a", "b"], result.Completion.Values);
await transport.DisposeAsync();
@ -766,7 +766,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<ListResourceTemplatesResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.ResourceTemplates);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.NotEmpty(result.ResourceTemplates);
Assert.Equal("test", result.ResourceTemplates[0].UriTemplate);
});
@ -796,7 +796,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<ListResourcesResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.Resources);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.NotEmpty(result.Resources);
Assert.Equal("test", result.Resources[0].Uri);
});
@ -832,7 +832,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<ReadResourceResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.Contents);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.NotEmpty(result.Contents);
TextResourceContents textResource = Assert.IsType<TextResourceContents>(result.Contents[0]);
@ -870,7 +870,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<ListPromptsResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result?.Prompts);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.NotEmpty(result.Prompts);
Assert.Equal("test", result.Prompts[0].Name);
});
@ -900,7 +900,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<GetPromptResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.Equal("test", result.Description);
});
}
@ -935,7 +935,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<ListToolsResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.NotEmpty(result.Tools);
Assert.Equal("test", result.Tools[0].Name);
});
@ -971,7 +971,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<CallToolResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.NotEmpty(result.Content);
Assert.Equal("test", Assert.IsType<TextContentBlock>(result.Content[0]).Text);
});
@ -1011,6 +1011,31 @@ public class McpServerTests : LoggedTest
});
}
[Fact]
public async Task Can_Handle_SetLoggingLevel_Requests_WithoutHandler_OmitsResultType()
{
// With no custom SetLoggingLevelHandler configured, the server uses its default logging/setLevel
// handler. logging/setLevel is a legacy (<= 2025-11-25) method, so the default handler must also
// serialize its result as an empty object {} without the 2026-07-28 resultType field (issue #1721).
await Can_Handle_Requests(
new ServerCapabilities
{
Logging = new()
},
method: RequestMethods.LoggingSetLevel,
configureOptions: null,
assertResult: (_, response) =>
{
var result = JsonSerializer.Deserialize<EmptyResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Null(result.ResultType);
// The wire response must be exactly {} with no additional properties.
var obj = Assert.IsType<JsonObject>(response);
Assert.Empty(obj);
});
}
[Fact]
public async Task Can_Handle_Call_Tool_Requests_With_McpException()
{
@ -1033,7 +1058,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<CallToolResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.True(result.IsError);
Assert.NotEmpty(result.Content);
var textContent = Assert.IsType<TextContentBlock>(result.Content[0]);
@ -1062,7 +1087,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<CallToolResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.True(result.IsError);
Assert.NotEmpty(result.Content);
var textContent = Assert.IsType<TextContentBlock>(result.Content[0]);
@ -1098,7 +1123,7 @@ public class McpServerTests : LoggedTest
{
var result = JsonSerializer.Deserialize<CallToolResult>(response, McpJsonUtilities.DefaultOptions);
Assert.NotNull(result);
Assert.Equal("complete", result.ResultType);
Assert.Null(result.ResultType);
Assert.True(result.IsError, "Input validation errors should be returned as tool execution errors (IsError=true), not protocol errors");
Assert.NotEmpty(result.Content);
var textContent = Assert.IsType<TextContentBlock>(result.Content[0]);
@ -1359,7 +1384,7 @@ public class McpServerTests : LoggedTest
Assert.NotNull(response.Result);
var initResult = JsonSerializer.Deserialize<InitializeResult>(response.Result, McpJsonUtilities.DefaultOptions);
Assert.NotNull(initResult);
Assert.Equal("complete", initResult.ResultType);
Assert.Null(initResult.ResultType);
Assert.NotNull(initResult.ServerInfo);
await transport.DisposeAsync();

112
tests/ModelContextProtocol.Tests/Server/ProtocolVersionResultDecorationTests.cs Normal file
View file

@ -0,0 +1,112 @@
using Microsoft.Extensions.DependencyInjection;
using ModelContextProtocol.Client;
using ModelContextProtocol.Protocol;
using ModelContextProtocol.Server;
namespace ModelContextProtocol.Tests.Server;
/// <summary>
/// Regression tests for issue #1721: the SDK-provided <c>resultType</c>, <c>ttlMs</c>, and
/// <c>cacheScope</c> result decorations are exclusive to the 2026-07-28 protocol revision and
/// must be absent from result objects on a session negotiated to an earlier revision
/// (e.g. <c>2025-11-25</c>). Emitting them breaks clients that strictly validate the 2025-11-25
/// schema.
/// </summary>
/// <remarks>
/// These drive the in-process <see cref="ClientServerTestBase"/> client/server pair and inspect the
/// raw JSON-RPC result wire shape (via <see cref="McpSession.SendRequestAsync(JsonRpcRequest, System.Threading.CancellationToken)"/>)
/// so the assertions are about the actual serialized fields rather than deserialized objects.
/// <c>tools/list</c> exercises the <c>SetHandler</c> decoration path (its result is both an
/// <see cref="ICacheableResult"/> and a <see cref="Result"/>), while <c>tools/call</c> exercises the
/// <c>SetWithAlternateHandler</c> path.
/// </remarks>
public class ProtocolVersionResultDecorationTests : ClientServerTestBase
{
public ProtocolVersionResultDecorationTests(ITestOutputHelper testOutputHelper)
: base(testOutputHelper)
{
}
protected override void ConfigureServices(ServiceCollection services, IMcpServerBuilder mcpServerBuilder)
{
mcpServerBuilder.WithTools([McpServerTool.Create(() => "ok", new() { Name = "echo" })]);
}
[Fact]
public async Task ToolsList_On2025_11_25Session_OmitsResultTypeAndCacheHints()
{
await using var client = await CreateMcpClientForServer(
new McpClientOptions { ProtocolVersion = McpProtocolVersions.November2025ProtocolVersion });
Assert.Equal(McpProtocolVersions.November2025ProtocolVersion, client.NegotiatedProtocolVersion);
var response = await client.SendRequestAsync(
new JsonRpcRequest { Method = RequestMethods.ToolsList },
TestContext.Current.CancellationToken);
var result = response.Result!.AsObject();
Assert.False(result.ContainsKey("resultType"), "resultType must be absent on a 2025-11-25 tools/list result.");
Assert.False(result.ContainsKey("ttlMs"), "ttlMs must be absent on a 2025-11-25 tools/list result.");
Assert.False(result.ContainsKey("cacheScope"), "cacheScope must be absent on a 2025-11-25 tools/list result.");
}
[Fact]
public async Task ToolsCall_On2025_11_25Session_OmitsResultType()
{
await using var client = await CreateMcpClientForServer(
new McpClientOptions { ProtocolVersion = McpProtocolVersions.November2025ProtocolVersion });
Assert.Equal(McpProtocolVersions.November2025ProtocolVersion, client.NegotiatedProtocolVersion);
var response = await client.SendRequestAsync(
new JsonRpcRequest
{
Method = RequestMethods.ToolsCall,
Params = System.Text.Json.JsonSerializer.SerializeToNode(
new CallToolRequestParams { Name = "echo" }, McpJsonUtilities.DefaultOptions),
},
TestContext.Current.CancellationToken);
var result = response.Result!.AsObject();
Assert.False(result.ContainsKey("resultType"), "resultType must be absent on a 2025-11-25 tools/call result.");
}
[Fact]
public async Task ToolsList_On2026_07_28Session_IncludesResultTypeAndCacheHints()
{
await using var client = await CreateMcpClientForServer(
new McpClientOptions { ProtocolVersion = McpProtocolVersions.July2026ProtocolVersion });
Assert.Equal(McpProtocolVersions.July2026ProtocolVersion, client.NegotiatedProtocolVersion);
var response = await client.SendRequestAsync(
new JsonRpcRequest { Method = RequestMethods.ToolsList },
TestContext.Current.CancellationToken);
var result = response.Result!.AsObject();
Assert.Equal("complete", result["resultType"]!.GetValue<string>());
Assert.True(result.ContainsKey("ttlMs"), "ttlMs must be present on a 2026-07-28 tools/list result.");
Assert.True(result.ContainsKey("cacheScope"), "cacheScope must be present on a 2026-07-28 tools/list result.");
}
[Fact]
public async Task ToolsCall_On2026_07_28Session_IncludesResultType()
{
await using var client = await CreateMcpClientForServer(
new McpClientOptions { ProtocolVersion = McpProtocolVersions.July2026ProtocolVersion });
Assert.Equal(McpProtocolVersions.July2026ProtocolVersion, client.NegotiatedProtocolVersion);
var response = await client.SendRequestAsync(
new JsonRpcRequest
{
Method = RequestMethods.ToolsCall,
Params = System.Text.Json.JsonSerializer.SerializeToNode(
new CallToolRequestParams { Name = "echo" }, McpJsonUtilities.DefaultOptions),
},
TestContext.Current.CancellationToken);
var result = response.Result!.AsObject();
Assert.Equal("complete", result["resultType"]!.GetValue<string>());
}
}