chore: import upstream snapshot with attribution

examples/stories/reconnect/client.py

@@ -0,0 +1,44 @@
+"""Probe server/discover once, persist the result, reconnect with zero round-trips — a fresh `Client` via `targets`."""
+
+from mcp_types import DiscoverResult
+from mcp_types.version import LATEST_MODERN_VERSION
+
+from mcp.client import Client
+from stories._harness import TargetFactory, run_client
+
+
+async def main(targets: TargetFactory, *, mode: str = "auto") -> None:
+    # The caller's mode (the real-user "auto" default) probes server/discover inside
+    # __aenter__ and caches the result; a hard version pin would skip the probe and
+    # never see the server's real DiscoverResult.
+    async with Client(targets(), mode=mode) as client:
+        discovered = client.session.discover_result
+        assert discovered is not None, "mode='auto' against a modern server populates discover_result"
+        assert client.protocol_version == LATEST_MODERN_VERSION
+        assert client.server_info.name == "reconnect-example"
+        assert LATEST_MODERN_VERSION in discovered.supported_versions
+
+        result = await client.call_tool("add", {"a": 2, "b": 3})
+        assert result.structured_content == {"result": 5}, result
+
+    # Round-trip through JSON to model loading the result from an on-disk cache.
+    saved = discovered.model_dump_json(by_alias=True)
+    rehydrated = DiscoverResult.model_validate_json(saved)
+    assert rehydrated == discovered
+
+    # Reconnect: a version pin plus the cached DiscoverResult adopts the prior state with
+    # zero round-trips on entry. A Client cannot be re-entered after exit, so targets()
+    # yields a fresh one. Without prior_discover= a bare pin would synthesize a blank
+    # server_info — the cache is what makes the era-neutral accessors useful here.
+    async with Client(targets(), mode=LATEST_MODERN_VERSION, prior_discover=rehydrated) as second:
+        assert second.protocol_version == LATEST_MODERN_VERSION
+        assert second.server_info.name == "reconnect-example"
+        assert second.server_capabilities.tools is not None
+        assert second.session.discover_result == rehydrated
+
+        result = await second.call_tool("add", {"a": 1, "b": 1})
+        assert result.structured_content == {"result": 2}, result
+
+
+if __name__ == "__main__":
+    run_client(main)