chore: import upstream snapshot with attribution

examples/stories/lifespan/client.py

@@ -0,0 +1,22 @@
+"""Prove the lifespan-yielded state is reachable from a tool call."""
+
+from mcp_types import TextContent
+
+from mcp.client import Client
+from stories._harness import Target, run_client
+
+
+async def main(target: Target, *, mode: str = "auto") -> None:
+    async with Client(target, mode=mode) as client:
+        listed = await client.list_tools()
+        assert [t.name for t in listed.tools] == ["lookup"]
+
+        result = await client.call_tool("lookup", {"key": "alpha"})
+        assert isinstance(result.content[0], TextContent) and result.content[0].text == "one", result
+
+        result = await client.call_tool("lookup", {"key": "beta"})
+        assert isinstance(result.content[0], TextContent) and result.content[0].text == "two", result
+
+
+if __name__ == "__main__":
+    run_client(main)