internal/mcp: rename StdIO->Stdio

In CL 682976, Alan Donovan correctly points out that the term in the MCP
spec is 'stdio', and therefore the correct capitalization is Stdio.

Change-Id: Ib5bbe04f1a61de886298b4d0adc13aefd6aadd9c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/683075
Reviewed-by: Alan Donovan <adonovan@google.com>
Auto-Submit: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

mcp/cmd_test.go

@@ -33,7 +33,7 @@ func runServer() {
 	server := mcp.NewServer("greeter", "v0.0.1", nil)
 	server.AddTools(mcp.NewServerTool("greet", "say hi", SayHi))
 
-	if err := server.Run(ctx, mcp.NewStdIOTransport()); err != nil {
+	if err := server.Run(ctx, mcp.NewStdioTransport()); err != nil {
 		log.Fatal(err)
 	}
 }

mcp/mcp.go

@@ -26,7 +26,7 @@
 //
 // A [Transport] connects a bidirectional [Connection] of jsonrpc2 messages. In
 // practice, transports in the MCP spec are are either client transports or
-// server transports. For example, the [StdIOTransport] is a server transport
+// server transports. For example, the [StdioTransport] is a server transport
 // that communicates over stdin/stdout, and its counterpart is a
 // [CommandTransport] that communicates with a subprocess over its
 // stdin/stdout.

mcp/transport.go

@@ -52,9 +52,9 @@ type Connection interface {
 	Close() error // may be called concurrently by both peers
 }
 
-// A StdIOTransport is a [Transport] that communicates over stdin/stdout using
+// A StdioTransport is a [Transport] that communicates over stdin/stdout using
 // newline-delimited JSON.
-type StdIOTransport struct {
+type StdioTransport struct {
 	ioTransport
 }
 
@@ -68,10 +68,10 @@ func (t *ioTransport) Connect(context.Context) (Connection, error) {
 	return newIOConn(t.rwc), nil
 }
 
-// NewStdIOTransport constructs a transport that communicates over
+// NewStdioTransport constructs a transport that communicates over
 // stdin/stdout.
-func NewStdIOTransport() *StdIOTransport {
-	return &StdIOTransport{ioTransport{rwc{os.Stdin, os.Stdout}}}
+func NewStdioTransport() *StdioTransport {
+	return &StdioTransport{ioTransport{rwc{os.Stdin, os.Stdout}}}
 }
 
 // An InMemoryTransport is a [Transport] that communicates over an in-memory