feat: add MCP tool integration

backend/tests/test_tool_executor_mcp.py

@@ -0,0 +1,105 @@
+import unittest
+
+from models import RuntimeMcpServer, RuntimeTool
+from services.runtime_variables import DynamicVariableStore
+from services.tool_executor import ToolExecutionError, ToolExecutor
+from services.tools import McpClientError
+
+
+def mcp_tool() -> RuntimeTool:
+    return RuntimeTool(
+        id="tool_mcp_order",
+        name="查询订单",
+        function_name="query_order",
+        type="mcp",
+        description="查询订单状态",
+        definition={
+            "schema_version": 1,
+            "type": "mcp",
+            "config": {
+                "remote_tool_name": "get_order",
+                "input_schema": {
+                    "type": "object",
+                    "properties": {
+                        "order_id": {
+                            "type": "string",
+                            "description": "订单编号",
+                        }
+                    },
+                    "required": ["order_id"],
+                },
+                "dynamic_variable_assignments": {
+                    "order_status": "structuredContent.status"
+                },
+            },
+        },
+        mcp_server=RuntimeMcpServer(
+            id="mcp_orders",
+            name="订单服务",
+            url="https://mcp.example.com/{{tenant}}",
+            headers={"X-Tenant": "{{tenant}}"},
+            secret_headers={"Authorization": "Bearer secret"},
+        ),
+    )
+
+
+class FakeMcpClient:
+    def __init__(self):
+        self.calls = []
+        self.error: Exception | None = None
+
+    async def call_tool(self, server, remote_tool_name, arguments):
+        self.calls.append((server, remote_tool_name, arguments))
+        if self.error:
+            raise self.error
+        return {
+            "text": "订单已发货",
+            "structuredContent": {"status": "shipped"},
+            "content": [{"type": "text", "text": "订单已发货"}],
+        }
+
+
+class ToolExecutorMcpTests(unittest.IsolatedAsyncioTestCase):
+    def test_mcp_schema_is_exposed_to_llm(self):
+        properties, required = ToolExecutor.schema_parts(mcp_tool())
+
+        self.assertEqual(properties["order_id"]["type"], "string")
+        self.assertEqual(required, ["order_id"])
+
+    async def test_mcp_execution_renders_connection_and_assigns_result(self):
+        store = DynamicVariableStore(
+            {"tenant": "school-a"},
+            variable_types={"order_status": "string"},
+        )
+        client = FakeMcpClient()
+        executor = ToolExecutor(store, mcp_client=client)
+
+        result = await executor.execute(
+            mcp_tool(),
+            {"order_id": "A-100"},
+        )
+
+        self.assertEqual(result["status"], "ok")
+        self.assertEqual(result["updated_variables"], ["order_status"])
+        self.assertEqual(store.values["order_status"], "shipped")
+        server, remote_name, arguments = client.calls[0]
+        self.assertEqual(server.url, "https://mcp.example.com/school-a")
+        self.assertEqual(server.headers["X-Tenant"], "school-a")
+        self.assertEqual(server.secret_headers["Authorization"], "Bearer secret")
+        self.assertEqual(remote_name, "get_order")
+        self.assertEqual(arguments, {"order_id": "A-100"})
+
+    async def test_mcp_client_errors_use_shared_tool_error(self):
+        client = FakeMcpClient()
+        client.error = McpClientError("远端不可用")
+        executor = ToolExecutor(
+            DynamicVariableStore({"tenant": "school-a"}),
+            mcp_client=client,
+        )
+
+        with self.assertRaisesRegex(ToolExecutionError, "远端不可用"):
+            await executor.execute(mcp_tool(), {"order_id": "A-100"})
+
+
+if __name__ == "__main__":
+    unittest.main()