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Relax legacy request metadata validation (#1852)

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Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Tarek Mahmoud Sayed <10833894+tarekgh@users.noreply.github.com>
This commit is contained in:
Stephen Halter 2026-09-13 16:30:42 -07:00 • committed by GitHub
commit 324ccd83c3
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1 changed files with 780 additions and 391 deletions
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36
tests/ModelContextProtocol.Tests/Server/RawStreamConformanceTests.cs
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@ -166,14 +166,14 @@ public sealed class RawStreamConformanceTests : LoggedTest, IAsyncDisposable
}
[Fact]
public async Task MixedSequence_Discover_Then_Initialize_Then_ToolsCall_AllSucceed()
public async Task MixedSequence_FailedDiscoverProbe_Then_Initialize_Then_ToolsCall_AllSucceed()
{
// Dual-path servers must accept 2026-07-28 per-request metadata and initialize-handshake traffic
// on the same connection. The exact mix below is what a permissive client running against an unknown
// server would emit while probing.
await SendAsync(@"{""jsonrpc"":""2.0"",""id"":1,""method"":""server/discover"",""params"":{" + July2026ProtocolMetaFragment() + "}}");
// Dual-path servers must accept an initialize-handshake fallback after a 2026-07-28 probe fails.
// This is the sequence a permissive client emits against an unknown server: the failed probe never
// establishes a version, so initialize is still available.
await SendAsync(@"{""jsonrpc"":""2.0"",""id"":1,""method"":""server/discover"",""params"":{" + July2026ProtocolMetaFragment("9999-99-99") + "}}");
var discover = await ReadAsync();
Assert.NotNull(discover["result"]);
Assert.Equal((int)McpErrorCode.UnsupportedProtocolVersion, discover["error"]!["code"]!.GetValue<int>());
await SendAsync(@"{""jsonrpc"":""2.0"",""id"":2,""method"":""initialize"",""params"":{""protocolVersion"":""2025-11-25"",""capabilities"":{},""clientInfo"":{""name"":""initialize-handshake"",""version"":""1.0""}}}");
var init = await ReadAsync();
@ -186,5 +186,29 @@ public sealed class RawStreamConformanceTests : LoggedTest, IAsyncDisposable
var call = await ReadAsync();
Assert.Equal("echo:after-init", call["result"]!["content"]![0]!["text"]!.GetValue<string>());
}
[Theory]
[InlineData("tools/list")]
[InlineData("server/discover")]
public async Task Initialize_AfterEstablishedModernRequest_IsRejected(string establishingMethod)
{
// A modern request locks the session's protocol version. initialize declares nothing on stdio, so
// without this gate it would force the session back to a handshake version and make the modern
// _meta on in-flight requests opaque.
await SendAsync(@"{""jsonrpc"":""2.0"",""id"":1,""method"":""" + establishingMethod + @""",""params"":{" + July2026ProtocolMetaFragment() + "}}");
var established = await ReadAsync();
Assert.NotNull(established["result"]);
await SendAsync(@"{""jsonrpc"":""2.0"",""id"":2,""method"":""initialize"",""params"":{""protocolVersion"":""2025-11-25"",""capabilities"":{},""clientInfo"":{""name"":""initialize-handshake"",""version"":""1.0""}}}");
var init = await ReadAsync();
Assert.Equal((int)McpErrorCode.MethodNotFound, init["error"]!["code"]!.GetValue<int>());
// The session is still modern: a request carrying full per-request metadata keeps working.
await SendAsync(
@"{""jsonrpc"":""2.0"",""id"":3,""method"":""tools/call"",""params"":{""name"":""echo"",""arguments"":{""text"":""still-modern""}," +
July2026ProtocolMetaFragment() + "}}");
var call = await ReadAsync();
Assert.Equal("echo:still-modern", call["result"]!["content"]![0]!["text"]!.GetValue<string>());
}
}
#endif