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mcp: add 2026-07-28 to the supported protocol versions (#1020)

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This PR adds the protocol version `2026-07-28` to the list of supported
protocol versions and fixes legacy tests hardcoding the legacy protocol
version for those use cases.
This commit is contained in:
Guglielmo Colombo 2026-06-24 12:02:56 +02:00 • committed by GitHub
commit 7f4aa4a0ce
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1 changed files with 355 additions and 218 deletions
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14
mcp/server.go
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@ -856,7 +856,9 @@ func (s *Server) getPrompt(ctx context.Context, req *GetPromptRequest) (*GetProm
// instructions, allowing clients to negotiate without performing the legacy
// initialize handshake.
func (s *Server) discover(_ context.Context, req *ServerRequest[*DiscoverParams]) (*DiscoverResult, error) {
req.Session.mu.Lock()
versions := req.Session.supportedVersions
req.Session.mu.Unlock()
if versions == nil {
versions = slices.Clone(supportedProtocolVersions)
}
@ -1335,7 +1337,17 @@ func (s *Server) Connect(ctx context.Context, t Transport, opts *ServerSessionOp
// Compute the protocol versions this session can serve, filtered by the
// transport's capabilities (if it implements [ProtocolVersionSupporter]).
// The list is consumed by the SEP-2575 server/discover handler.
//
// The write is guarded by ss.mu to establish a happens-before edge with
// the matching read in Server.discover, which runs on the jsonrpc2 read
// goroutine spawned inside connect(). The two are not concurrent in
// wall-clock terms (no incoming message is dispatched until the caller
// has fed the transport, which happens after Server.Connect returns),
// but without the lock the Go memory model gives the read goroutine no
// guarantee of seeing this write, and -race flags it.
ss.mu.Lock()
ss.supportedVersions = filterSupportedVersions(t)
ss.mu.Unlock()
// Start keepalive before returning the session to avoid race conditions with Close.
// This is safe because the spec allows sending pings before initialization (see ServerSession.handle for details).
@ -1795,7 +1807,7 @@ func (ss *ServerSession) handle(ctx context.Context, req *jsonrpc.Request) (any,
}
switch req.Method {
case methodInitialize, methodPing, notificationInitialized, methodSetLevel, methodSubscribe, methodUnsubscribe:
case methodInitialize, methodPing, notificationInitialized, notificationRootsListChanged, methodSetLevel, methodSubscribe, methodUnsubscribe:
if validatedMeta.usesNewProtocol {
ss.server.opts.Logger.Error("method removed in the new protocol", "method", req.Method)
return nil, &jsonrpc.Error{