Class: Tina4::McpServer

Inherits:
Object
  • Object
show all
Defined in:
lib/tina4/mcp.rb

Overview

── McpServer ─────────────────────────────────────────────────────

Constant Summary collapse

SUPPORTED_PROTOCOL_VERSIONS =

MCP protocol versions this server can speak, newest first. The 2025-* versions are the Streamable HTTP era; 2024-11-05 is the legacy HTTP+SSE transport we still accept for older clients (Claude Desktop et al.).

%w[2025-06-18 2025-03-26 2024-11-05].freeze
LATEST_PROTOCOL_VERSION = 
SUPPORTED_PROTOCOL_VERSIONS.first

Class Attribute Summary collapse

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path, name: "Tina4 MCP", version: "1.0.0") ⇒ McpServer

Returns a new instance of McpServer.



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# File 'lib/tina4/mcp.rb', line 236

def initialize(path, name: "Tina4 MCP", version: "1.0.0")
  @path        = path.chomp("/")
  @name        = name
  @version     = version
  @tools       = {}
  @resources   = {}
  @initialized = false
  # Streamable HTTP sessions: id => opened-at epoch. `initialize` mints one
  # (returned in the Mcp-Session-Id header); a request bearing an unknown id
  # gets a 404 so the client re-initializes.
  @sessions    = {}
  self.class.instances << self
end

Class Attribute Details

.instances ⇒ Object (readonly)

Returns the value of attribute instances.



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# File 'lib/tina4/mcp.rb', line 233

def instances
  @instances
end

Instance Attribute Details

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/tina4/mcp.rb', line 228

def name
  @name
end

#path ⇒ Object (readonly)

Returns the value of attribute path.



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# File 'lib/tina4/mcp.rb', line 228

def path
  @path
end

#version ⇒ Object (readonly)

Returns the value of attribute version.



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# File 'lib/tina4/mcp.rb', line 228

def version
  @version
end

Instance Method Details

#close_session(session_id) ⇒ Object

Forget a session (client DELETE or SSE stream close). Returns true when a live session was actually removed.



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# File 'lib/tina4/mcp.rb', line 326

def close_session(session_id)
  !@sessions.delete(session_id).nil?
end

#dispatch_http(raw_data, session_id = "") ⇒ Object

Transport-agnostic Streamable HTTP POST handler. Every transport calls this so the wire behaviour stays identical:

- `initialize` mints a session id, returned in the Mcp-Session-Id header.
- a non-initialize request carrying an unknown session id is a 404
(JSON-RPC error) so the client knows to re-initialize.
- a notification / response-only POST (no id) yields 202 with an empty
body.
- anything else returns 200 with the JSON-RPC response as
application/json (the MCP Streamable HTTP spec permits a POST that
resolves to a single response to answer inline).

Returns { status:, headers:, body: }.



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# File 'lib/tina4/mcp.rb', line 350

def dispatch_http(raw_data, session_id = "")
  is_init = peek_method(raw_data) == "initialize"
  if !is_init && !session_id.to_s.empty? && !is_valid_session(session_id)
    return {
      status: 404,
      headers: {},
      body: McpProtocol.encode_error(nil, McpProtocol::INVALID_REQUEST, "session not found")
    }
  end

  body = handle_message(raw_data)
  headers = {}
  headers["Mcp-Session-Id"] = open_session if is_init
  return { status: 202, headers: headers, body: "" } if body.nil? || body.empty?

  { status: 200, headers: headers, body: body }
end

#handle_message(raw_data) ⇒ Object

Process an incoming JSON-RPC message and return the response string.



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# File 'lib/tina4/mcp.rb', line 278

def handle_message(raw_data)
  begin
    method, params, request_id = McpProtocol.decode_request(raw_data)
  rescue ArgumentError => e
    return McpProtocol.encode_error(nil, McpProtocol::PARSE_ERROR, e.message)
  end

  handler_method = {
    "initialize"                 => :_handle_initialize,
    "notifications/initialized"  => :_handle_initialized,
    "tools/list"                 => :_handle_tools_list,
    "tools/call"                 => :_handle_tools_call,
    "resources/list"             => :_handle_resources_list,
    "resources/read"             => :_handle_resources_read,
    "ping"                       => :_handle_ping
  }[method]

  if handler_method.nil?
    return McpProtocol.encode_error(request_id, McpProtocol::METHOD_NOT_FOUND, "Method not found: #{method}")
  end

  begin
    result = send(handler_method, params)
    return "" if request_id.nil? # Notification -- no response
    McpProtocol.encode_response(request_id, result)
  rescue => e
    McpProtocol.encode_error(request_id, McpProtocol::INTERNAL_ERROR, e.message)
  end
end

#is_valid_session(session_id) ⇒ Object

True when session_id was issued by this server and is still open.



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# File 'lib/tina4/mcp.rb', line 320

def is_valid_session(session_id)
  !session_id.to_s.empty? && @sessions.key?(session_id)
end

#negotiate_protocol_version(requested) ⇒ Object

Pick the protocol version to run on. Echo the client's requested version when we support it (proper negotiation), else fall back to the newest version we speak so an unversioned/old client still connects.



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# File 'lib/tina4/mcp.rb', line 333

def negotiate_protocol_version(requested)
  return requested if SUPPORTED_PROTOCOL_VERSIONS.include?(requested)

  LATEST_PROTOCOL_VERSION
end

#open_session ⇒ Object

Mint a new session id and remember it. Called on initialize.



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# File 'lib/tina4/mcp.rb', line 313

def open_session
  sid = SecureRandom.hex(16)
  @sessions[sid] = Time.now.to_f
  sid
end

#register_resource(uri, handler, description = "", mime_type = "application/json") ⇒ Object

Register a resource URI.



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# File 'lib/tina4/mcp.rb', line 267

def register_resource(uri, handler, description = "", mime_type = "application/json")
  @resources[uri] = {
    "uri"         => uri,
    "name"        => description.empty? ? uri : description,
    "description" => description.empty? ? uri : description,
    "mimeType"    => mime_type,
    "handler"     => handler
  }
end

#register_routes(router = nil) ⇒ Object

Register HTTP routes for this MCP server on the Tina4 router. Custom (developer-created) MCP servers use this; the built-in dev server mounts the same transport via DevAdmin's dispatcher.



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# File 'lib/tina4/mcp.rb', line 371

def register_routes(router = nil)
  server    = self
  base_path = @path
  msg_path  = "#{@path}/message"
  sse_path  = "#{@path}/sse"

  # Streamable HTTP (current transport) — single POST endpoint.
  Tina4::Router.post(base_path) do |request, response|
    out = server.dispatch_http(request.body, (request.header("mcp-session-id") || "").to_s)
    out[:headers].each { |k, v| response.header(k, v) }
    response.call(out[:body], out[:status], "application/json")
  end

  # DELETE terminates the session (Streamable HTTP spec).
  Tina4::Router.delete(base_path) do |request, response|
    server.close_session((request.header("mcp-session-id") || "").to_s)
    response.call("", 204)
  end

  # GET on the endpoint is a server->client stream we do not open here.
  Tina4::Router.get(base_path) do |_request, response|
    response.header("allow", "POST, DELETE")
    response.call({ "error" => "Method Not Allowed" }, 405, "application/json")
  end

  # Legacy HTTP+SSE POST target — inline, session-lenient.
  Tina4::Router.post(msg_path) do |request, response|
    out = server.dispatch_http(request.body, "")
    out[:headers].each { |k, v| response.header(k, v) }
    response.call(out[:body], out[:status], "application/json")
  end

  # Legacy HTTP+SSE handshake — one-shot endpoint event.
  Tina4::Router.get(sse_path) do |request, response|
    endpoint_url = "#{request.url.sub(%r{/sse\z}, "")}/message"
    sse_data = "event: endpoint\ndata: #{endpoint_url}\n\n"
    response.call(sse_data, 200, "text/event-stream")
  end
end

#register_tool(name, handler, description = "", schema = nil) ⇒ Object

Register a tool callable.

Parameters:

  • name (String)
  • handler (Method, Proc, #call) —

    the callable

  • description (String) (defaults to: "")
  • schema (Hash, nil) (defaults to: nil) —

    override auto-detected schema



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# File 'lib/tina4/mcp.rb', line 256

def register_tool(name, handler, description = "", schema = nil)
  schema ||= Tina4.schema_from_method(handler)
  @tools[name] = {
    "name"        => name,
    "description" => description.empty? ? name : description,
    "inputSchema" => schema,
    "handler"     => handler
  }
end

#resources ⇒ Object

Access registered resources (for testing)



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# File 'lib/tina4/mcp.rb', line 442

def resources
  @resources
end

#tools ⇒ Object

Access registered tools (for testing)



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# File 'lib/tina4/mcp.rb', line 437

def tools
  @tools
end

#write_claude_config(port = 7145) ⇒ Object

Write/update .claude/settings.json with this MCP server config.



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# File 'lib/tina4/mcp.rb', line 412

def write_claude_config(port = 7145)
  config_dir = File.join(Dir.pwd, ".claude")
  FileUtils.mkdir_p(config_dir)
  config_file = File.join(config_dir, "settings.json")

  config = {}
  if File.exist?(config_file)
    begin
      config = JSON.parse(File.read(config_file))
    rescue JSON::ParserError, IOError
      # ignore corrupt file
    end
  end

  config["mcpServers"] ||= {}
  server_key = @name.downcase.gsub(" ", "-")
  config["mcpServers"][server_key] = {
    "type" => "http",
    "url"  => "http://localhost:#{port}#{@path}"
  }

  File.write(config_file, JSON.pretty_generate(config) + "\n")
end