Address PR review feedback from Koichi

- Move event_stream_parser from Gemfile to gemspec as runtime dependency
- Add brief descriptions to TODO comments in client/http.rb and
  streamable_http_transport.rb
- Add description to spec URL comment in client.rb
- Use SESSION_ID_HEADER constant for session ID header lookup in connect

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: atesgoral

Gemfile

@@ -10,7 +10,6 @@ gem "rubocop-minitest", require: false
 gem "rubocop-rake", require: false
 gem "rubocop-shopify", ">= 2.18", require: false if RUBY_VERSION >= "3.1"
 
-gem "event_stream_parser", ">= 1.0"
 gem "puma", ">= 5.0.0"
 gem "rack-cors"
 gem "rackup", ">= 2.1.0"

lib/mcp/client.rb

@@ -6,7 +6,8 @@
 
 module MCP
   class Client
-    # https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#streamable-http
+    # Protocol version and header constants for Streamable HTTP transport.
+    # See: https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#streamable-http
     LATEST_PROTOCOL_VERSION = "2025-11-25"
     SESSION_ID_HEADER = "Mcp-Session-Id"
     PROTOCOL_VERSION_HEADER = "MCP-Protocol-Version"
@@ -86,8 +87,8 @@ def connect(client_info:, protocol_version: LATEST_PROTOCOL_VERSION, capabilitie
 
       response = transport.post(body: request_body)
 
-      # Faraday normalizes headers to lowercase
-      @session_id = response.headers["mcp-session-id"]
+      # Faraday normalizes header names to lowercase
+      @session_id = response.headers[SESSION_ID_HEADER.downcase]
       @protocol_version = response.body.dig("result", "protocolVersion") || protocol_version
 
       response.body

lib/mcp/client/http.rb

@@ -2,8 +2,10 @@
 
 module MCP
   class Client
-    # TODO: https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#listening-for-messages-from-the-server
-    # TODO: https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#resumability-and-redelivery
+    # TODO: HTTP GET for SSE streaming is not yet implemented.
+    #   See: https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#listening-for-messages-from-the-server
+    # TODO: Resumability and redelivery with Last-Event-ID is not yet implemented.
+    #   See: https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#resumability-and-redelivery
 
     class HTTP
       ACCEPT_HEADER = "application/json, text/event-stream"

lib/mcp/server/transports/streamable_http_transport.rb

@@ -6,7 +6,8 @@
 module MCP
   class Server
     module Transports
-      # TODO: https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#resumability-and-redelivery
+      # TODO: Resumability and redelivery with Last-Event-ID is not yet implemented.
+      #   See: https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#resumability-and-redelivery
 
       class StreamableHTTPTransport < Transport
         def initialize(server, stateless: false, session_idle_timeout: nil)

mcp.gemspec

@@ -31,4 +31,5 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_dependency("json-schema", ">= 4.1")
+  spec.add_dependency("event_stream_parser", ">= 1.0")
 end