67 lines
2.4 KiB
Python
67 lines
2.4 KiB
Python
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"""MCP 协议常量与纯函数。
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本模块**不含任何 IO**，只做版本协商、信封构造与方法路由判定，便于单独测试。
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"""
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from . import __version__ as SERVER_VERSION
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# 本桥支持的协议版本，从新到旧。initialize 时按客户端请求协商。
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PROTOCOL_VERSIONS = ("2025-06-18", "2025-03-26", "2024-11-05")
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DEFAULT_VERSION = PROTOCOL_VERSIONS[0]
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SERVER_NAME = "cad-mcp-bridge"
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# classify() 的四种路由结果
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LOCAL = "local" # 由桥自己应答（基座没有实现）
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FORWARD = "forward" # 原样转发给 CAD 基座
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NOTIFY = "notify" # 通知，按规范不回包
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UNKNOWN = "unknown" # 未知方法，回 -32601
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_LOCAL_METHODS = frozenset({"initialize", "ping"})
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_FORWARD_METHODS = frozenset({"tools/list", "tools/call"})
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def negotiate_version(requested):
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"""协议版本协商：客户端请求的版本受支持则回显，否则回本桥支持的最新版本。
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依据 MCP 规范：服务端支持的版本必须原样返回；不支持时回退到自己支持的版本，
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由客户端决定是否继续。
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"""
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return requested if requested in PROTOCOL_VERSIONS else DEFAULT_VERSION
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def classify(method):
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"""把方法名映射到路由动作。"""
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if method in _LOCAL_METHODS:
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return LOCAL
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if method in _FORWARD_METHODS:
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return FORWARD
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if method.startswith("notifications/"):
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return NOTIFY
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return UNKNOWN
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def ok(msg_id, result):
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"""构造 JSON-RPC 成功响应。"""
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return {"jsonrpc": "2.0", "id": msg_id, "result": result}
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def err(msg_id, code, message):
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"""构造 JSON-RPC 错误响应。"""
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return {"jsonrpc": "2.0", "id": msg_id, "error": {"code": code, "message": message}}
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def initialize_result(params):
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"""合成 initialize 的 result（基座未实现生命周期，由桥代答）。"""
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requested = ""
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if isinstance(params, dict):
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requested = params.get("protocolVersion") or ""
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return {
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"protocolVersion": negotiate_version(requested),
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"capabilities": {"tools": {"listChanged": False}},
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"serverInfo": {"name": SERVER_NAME, "version": SERVER_VERSION},
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"instructions": (
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"本服务器通过 stdio 桥接本机 AutoCAD 的 cad_mcp_frame 基座。"
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"工具仅在 CAD 已启动且已加载插件时可用；未启动时调用会返回连接错误。"
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),
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}
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