Use Mcp-Session-Id

Author: keisku

examples/streamable_http_client.rb

@@ -31,7 +31,7 @@ def connect_sse(session_id, logger)
 
   Net::HTTP.start(uri.host, uri.port) do |http|
     request = Net::HTTP::Get.new(uri)
-    request["MCP-Session-Id"] = session_id
+    request["Mcp-Session-Id"] = session_id
     request["Accept"] = "text/event-stream"
     request["Cache-Control"] = "no-cache"
 

lib/mcp/client.rb

@@ -4,7 +4,7 @@ module MCP
   class Client
     # https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#streamable-http
     LATEST_PROTOCOL_VERSION = "2025-11-25"
-    SESSION_ID_HEADER = "MCP-Session-Id"
+    SESSION_ID_HEADER = "Mcp-Session-Id"
     PROTOCOL_VERSION_HEADER = "MCP-Protocol-Version"
 
     # Initializes a new MCP::Client instance.