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mcp: bump protocol version from 2026-06-30 to 2026-07-28 (#1015)

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The new official date for the protocol version has been moved to
'2026-07-28'. Update all the references in the code of the old version.
This commit is contained in:
Guglielmo Colombo 2026-06-22 09:53:04 +02:00 • committed by GitHub
commit 17029489ff
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GPG key ID: B5690EEEBB952194
1 changed files with 137 additions and 137 deletions
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44
mcp/streamable.go
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@ -314,7 +314,7 @@ func (h *StreamableHTTPHandler) ServeHTTP(w http.ResponseWriter, req *http.Reque
//
// [§2.7]: https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#protocol-version-header
protocolVersion := req.Header.Get(protocolVersionHeader)
if protocolVersion != "" && !slices.Contains(supportedProtocolVersions, protocolVersion) && protocolVersion < protocolVersion20260630 {
if protocolVersion != "" && !slices.Contains(supportedProtocolVersions, protocolVersion) && protocolVersion < protocolVersion20260728 {
http.Error(w, fmt.Sprintf("Bad Request: Unsupported protocol version (supported versions: %s)", strings.Join(supportedProtocolVersions, ",")), http.StatusBadRequest)
return
}
@ -414,7 +414,7 @@ func (h *StreamableHTTPHandler) serveStatelessLegacyDELETE(w http.ResponseWriter
// ephemeralConnectOpts peeks at the request body to determine whether it
// contains an initialize or initialized message or whether the protocol version
// header indicates a protocol version >= 2026-06-30 (SEP-2575).
// header indicates a protocol version >= 2026-07-28 (SEP-2575).
//
// For old-protocol requests, default session state is synthesized so that
// the session's init gate doesn't reject the request.
@ -422,7 +422,7 @@ func (h *StreamableHTTPHandler) serveStatelessLegacyDELETE(w http.ResponseWriter
// It is used for both stateless servers and stateful servers with no session ID.
//
// The returned usesNewProtocol bool reports whether the protocol version
// header indicates a protocol version >= 2026-06-30 (SEP-2575).
// header indicates a protocol version >= 2026-07-28 (SEP-2575).
func (h *StreamableHTTPHandler) ephemeralConnectOpts(req *http.Request) (opts *ServerSessionOptions, usesNewProtocol bool, err error) {
protocolVersion := protocolVersionFromContext(req.Context())
if protocolVersion == "" {
@ -446,7 +446,7 @@ func (h *StreamableHTTPHandler) ephemeralConnectOpts(req *http.Request) (opts *S
case notificationInitialized:
hasInitialized = true
}
if protocolVersion >= protocolVersion20260630 {
if protocolVersion >= protocolVersion20260728 {
usesNewProtocol = true
}
}
@ -808,10 +808,10 @@ func (t *StreamableServerTransport) Connect(ctx context.Context) (Connection, er
}
// The streamable HTTP transport supports every legacy SDK protocol version,
// but the SEP-2575 >= 2026-06-30 protocol is only supported when the
// but the SEP-2575 >= 2026-07-28 protocol is only supported when the
// transport is configured as stateless.
func (t *StreamableServerTransport) SupportsProtocolVersion(version string) bool {
if version >= protocolVersion20260630 {
if version >= protocolVersion20260728 {
return t.Stateless && slices.Contains(supportedProtocolVersions, version)
}
return slices.Contains(supportedProtocolVersions, version)
@ -951,14 +951,14 @@ func (s *stream) release() {
// extractErrorStatus reports the HTTP status to send when the given
// outgoing message is a JSON-RPC error response under the SEP-2575 protocol
// (>= 2026-06-30).
// (>= 2026-07-28).
//
// Per SEP-2575:
// - MethodNotFound (-32601) MUST return HTTP 404.
// - InvalidParams (-32602) and UnsupportedProtocolVersion (-32004) MUST
// return HTTP 400.
func extractErrorStatus(ctx context.Context, msg jsonrpc.Message) int {
if protocolVersionFromContext(ctx) < protocolVersion20260630 {
if protocolVersionFromContext(ctx) < protocolVersion20260728 {
return 0
}
resp, ok := msg.(*jsonrpc.Response)
@ -986,7 +986,7 @@ func extractErrorStatus(ctx context.Context, msg jsonrpc.Message) int {
// requests have been responded to, the done channel is closed and set to nil.
//
// If overrideStatus is non-zero, data is treated as a SEP-2575 protocol-level
// error response (>= 2026-06-30): it is written as a single raw JSON-RPC
// error response (>= 2026-07-28): it is written as a single raw JSON-RPC
// response body with Content-Type: application/json and HTTP status
// overrideStatus.
//
@ -1065,7 +1065,7 @@ func (s *stream) doneLocked() bool {
}
func (c *streamableServerConn) newStream(ctx context.Context, requests map[jsonrpc.ID]struct{}, id string) (*stream, error) {
if c.eventStore != nil && protocolVersionFromContext(ctx) < protocolVersion20260630 {
if c.eventStore != nil && protocolVersionFromContext(ctx) < protocolVersion20260728 {
if err := c.eventStore.Open(ctx, c.sessionID, id); err != nil {
return nil, err
}
@ -1378,7 +1378,7 @@ func (c *streamableServerConn) servePOST(w http.ResponseWriter, req *http.Reques
// the HTTP request. If we didn't do this, a request with a bad method or
// missing ID could be silently swallowed.
if _, err := checkRequest(jreq, serverMethodInfos); err != nil {
if protocolVersion >= protocolVersion20260630 && errors.Is(err, jsonrpc2.ErrNotHandled) && jreq.IsCall() {
if protocolVersion >= protocolVersion20260728 && errors.Is(err, jsonrpc2.ErrNotHandled) && jreq.IsCall() {
writeJSONRPCError(w, http.StatusNotFound, jreq.ID, &jsonrpc.Error{
Code: jsonrpc.CodeMethodNotFound,
Message: err.Error(),
@ -1399,7 +1399,7 @@ func (c *streamableServerConn) servePOST(w http.ResponseWriter, req *http.Reques
// SEP-2575: requests carrying `_meta.protocolVersion` require the
// Mcp-Protocol-Version HTTP header to be present and to match the
// per-request `_meta.protocolVersion` value.
// The new (>= 2026-06-30) protocol is supported on the HTTP transport
// The new (>= 2026-07-28) protocol is supported on the HTTP transport
// only when [StreamableHTTPOptions.Stateless] is true.
//
// TODO: this validation can be moved within validateMcpHeaders.
@ -1407,7 +1407,7 @@ func (c *streamableServerConn) servePOST(w http.ResponseWriter, req *http.Reques
if meta := extractRequestMeta(jreq.Params); meta != nil {
metaVersion, _ = meta[MetaKeyProtocolVersion].(string)
}
if protocolVersion >= protocolVersion20260630 || metaVersion != "" {
if protocolVersion >= protocolVersion20260728 || metaVersion != "" {
// Extract again the protcol version from the context to see what the client
// is advertising in the Mcp-Protocol-Version HTTP header.
headerVersion := protocolVersionFromContext(req.Context())
@ -1462,8 +1462,8 @@ func (c *streamableServerConn) servePOST(w http.ResponseWriter, req *http.Reques
jreq.Extra.(*RequestExtra).CloseSSEStream = func(args CloseSSEStreamArgs) {
// This mechanism was designed to trigger client reconnection with
// Last-Event-ID for server-initiated disconnect scenarios. It is
// deprecated in protocol version 2026-06-30.
if protocolVersion >= protocolVersion20260630 {
// deprecated in protocol version 2026-07-28.
if protocolVersion >= protocolVersion20260728 {
return
}
c.mu.Lock()
@ -1592,8 +1592,8 @@ func (c *streamableServerConn) servePOST(w http.ResponseWriter, req *http.Reques
// SSE mode: write a priming event if supported.
//
// SEP-2575 removes Last-Event-ID-based resumable streams for protocol
// version >= 2026-06-30.
if c.eventStore != nil && effectiveVersion >= protocolVersion20251125 && effectiveVersion < protocolVersion20260630 {
// version >= 2026-07-28.
if c.eventStore != nil && effectiveVersion >= protocolVersion20251125 && effectiveVersion < protocolVersion20260728 {
// Write a priming event, as defined by [§2.1.6] of the spec.
//
// [§2.1.6]: https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#sending-messages-to-the-server
@ -1754,7 +1754,7 @@ func (c *streamableServerConn) Write(ctx context.Context, msg jsonrpc.Message) e
delivered := false
var errs []error
protocolVersion := protocolVersionFromContext(ctx)
if c.eventStore != nil && protocolVersion < protocolVersion20260630 {
if c.eventStore != nil && protocolVersion < protocolVersion20260728 {
if err := c.eventStore.Append(ctx, c.sessionID, s.id, data); err != nil {
errs = append(errs, err)
} else {
@ -1765,12 +1765,12 @@ func (c *streamableServerConn) Write(ctx context.Context, msg jsonrpc.Message) e
// Compute eventID for SSE streams with event store.
// Use s.lastIdx + 1 because deliverLocked increments before writing.
var eventID string
if c.eventStore != nil && protocolVersion < protocolVersion20260630 {
if c.eventStore != nil && protocolVersion < protocolVersion20260728 {
eventID = formatEventID(s.id, s.lastIdx+1)
}
// SEP-2575: map protocol-level JSON-RPC error codes to HTTP status codes
// on the new protocol (>= 2026-06-30). When non-zero, deliverLocked will
// on the new protocol (>= 2026-07-28). When non-zero, deliverLocked will
// write the body as raw application/json with the override status.
overrideStatus := extractErrorStatus(ctx, msg)
@ -1974,10 +1974,10 @@ func (c *streamableClientConn) sessionUpdated(state clientSessionState) {
c.initializedResult = state.InitializeResult
c.mu.Unlock()
// Under SEP-2575 (protocol version >= 2026-06-30) the standalone HTTP GET
// Under SEP-2575 (protocol version >= 2026-07-28) the standalone HTTP GET
// SSE stream is removed.
if state.InitializeResult == nil ||
state.InitializeResult.ProtocolVersion >= protocolVersion20260630 {
state.InitializeResult.ProtocolVersion >= protocolVersion20260728 {
return
}