Class: VSM::Ports::MCP::ServerStdio

Inherits:
VSM::Port
  • Object
show all
Defined in:
lib/vsm/ports/mcp/server_stdio.rb

Overview

Exposes the capsule’s tools as an MCP server over stdio (NDJSON JSON-RPC). Implemented methods: tools/list, tools/call.

Instance Method Summary collapse

Methods inherited from VSM::Port

#ingress, #render_out, #should_render?

Constructor Details

#initialize(capsule:) ⇒ ServerStdio

Returns a new instance of ServerStdio.



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# File 'lib/vsm/ports/mcp/server_stdio.rb', line 11

def initialize(capsule:)
  super(capsule: capsule)
  @waiters = {}
  @waiters_mutex = Mutex.new
end

Instance Method Details

#egress_subscribe ⇒ Object 



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# File 'lib/vsm/ports/mcp/server_stdio.rb', line 17

def egress_subscribe
  # Single subscriber that resolves tool_result waiters by corr_id
  @capsule.bus.subscribe do |m|
    next unless m.kind == :tool_result
    q = nil
    @waiters_mutex.synchronize { q = @waiters.delete(m.corr_id.to_s) }
    q&.enqueue(m)
  end
  super
end

#loop ⇒ Object 



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# File 'lib/vsm/ports/mcp/server_stdio.rb', line 28

def loop
  $stdout.sync = true
  while (line = $stdin.gets)
    begin
      req = JSON.parse(line)
    rescue => e
      write_err(nil, code: -32700, message: "Parse error: #{e.message}")
      next
    end

    id = req["id"]
    method = req["method"]
    params = req["params"] || {}
    case method
    when "tools/list"
      write_ok(id, { tools: list_tools })
    when "tools/call"
      name = params["name"].to_s
      args = params["arguments"] || {}
      res = call_local_tool(id, name, args)
      write_ok(id, { content: [{ type: "text", text: res.to_s }] })
    else
      write_err(id, code: -32601, message: "Method not found: #{method}")
    end
  end
end