server.h

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#pragma once
 
#include <neograph/api.h>
#include <neograph/graph/cancel.h>
#include <neograph/mcp/types.h>
 
#include <cstddef>
#include <functional>
#include <istream>
#include <memory>
#include <optional>
#include <ostream>
#include <string>
 
namespace neograph::mcp {
 
inline constexpr const char* MCP_PROTOCOL_VERSION = "2025-11-25";
 
struct NEOGRAPH_API MCPServerConfig {
    json        server_info = json::object();
    std::string instructions;
    std::size_t max_concurrent_calls = 4;
    std::size_t max_pending_calls = 64;
};
 
class NEOGRAPH_API MCPServer {
  public:
    using ToolHandler = std::function<CallToolResult(
        const json&, const std::shared_ptr<graph::CancelToken>&)>;
 
    using RawToolHandler =
        std::function<json(const json&, const std::shared_ptr<graph::CancelToken>&, const json&)>;
 
    using MethodHandler = std::function<json(const json&, const json&)>;
 
    using ResponseSink = std::function<void(const json&)>;
 
    using NoResponseSink = std::function<void(const json& id)>;
 
    explicit MCPServer(MCPServerConfig config);
    ~MCPServer();
 
    MCPServer(const MCPServer&) = delete;
    MCPServer& operator=(const MCPServer&) = delete;
 
    void register_tool(ToolDefinition definition, ToolHandler handler);
 
    void register_raw_tool(ToolDefinition definition, RawToolHandler handler);
 
    void register_method(std::string method, MethodHandler handler);
 
    void register_extension(std::string identifier, json settings = json::object());
 
    using Reply = std::function<void(std::optional<json>)>;
 
    json handle_message(const json& envelope);
 
    void handle_message(const json& message, Reply reply);
 
    void run(std::istream& in, std::ostream& out);
    void run();
 
    void set_response_sink(ResponseSink sink);
 
    void set_response_sink(ResponseSink sink, NoResponseSink no_response);
 
    void stop();
 
    bool initialized() const;
    bool is_running() const;
 
    std::string protocol_version() const;
 
  private:
    struct Impl;
    std::unique_ptr<Impl> impl_;
};
 
} // namespace neograph::mcp