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mcp: do not call DELETE for sessionless & doc adjustments (#960)

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Maciej Kisiel 2026-05-15 21:47:34 +02:00 • committed by GitHub
commit 1253d17add
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1 changed files with 32 additions and 11 deletions
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27
mcp/streamable.go
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@ -128,13 +128,21 @@ func (i *sessionInfo) stopTimer() {
type StreamableHTTPOptions struct {
// Stateless controls whether the session is 'stateless'.
//
// A stateless server ignores the Mcp-Session-Id header, and uses a
// temporary session with default initialization parameters. Any
// A stateless server does not read or set the Mcp-Session-Id header, and
// uses a temporary session with default initialization parameters for each
// request. [ServerOptions.GetSessionID] is not consulted. Any
// server->client request is rejected immediately as there's no way for the
// client to respond. Server->Client notifications may reach the client if
// they are made in the context of an incoming request, as described in the
// documentation for [StreamableServerTransport].
// In Stateless mode DELETE requests will return 405 Method Not Allowed.
// In Stateless mode, GET and DELETE requests return 405 Method Not Allowed.
//
// This mode aligns with the sessionless direction of the MCP spec; see
// [SEP-2567]. The previous behavior, in which stateless servers still
// honored Mcp-Session-Id, can be restored temporarily via the
// MCPGODEBUG compatibility parameter "allowsessionsinstateless=1".
//
// [SEP-2567]: https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2567
Stateless bool
// TODO(#148): support session retention (?)
@ -1689,11 +1697,13 @@ func init() {
// Connect implements the [Transport] interface.
//
// The resulting [Connection] writes messages via POST requests to the
// transport URL with the Mcp-Session-Id header set, and reads messages from
// hanging requests.
// transport URL, and reads messages from hanging requests. If the server
// provides a session ID via the Mcp-Session-Id response header, subsequent
// requests include it; sessionless servers that omit the header are fully
// supported.
//
// When closed, the connection issues a DELETE request to terminate the logical
// session.
// When closed, the connection issues a DELETE request to terminate the
// session, unless no session was established.
func (t *StreamableClientTransport) Connect(ctx context.Context) (Connection, error) {
client := t.HTTPClient
if client == nil {
@ -2370,6 +2380,9 @@ func (c *streamableClientConn) Close() error {
c.closeOnce.Do(func() {
if errors.Is(c.failure(), ErrSessionMissing) {
// If the session is missing, no need to delete it.
} else if c.SessionID() == "" {
// No session was established (e.g. the server is stateless),
// so there is nothing to delete.
} else {
req, err := http.NewRequestWithContext(c.ctx, http.MethodDelete, c.url, nil)
if err != nil {