chore: import upstream snapshot with attribution

tests/test_oaiconv_resume_response_id.py

@@ -0,0 +1,44 @@
+"""Tests for OpenAIServerConversationTracker.hydrate_from_state response_id seeding."""
+
+from typing import Any
+
+from agents.items import ModelResponse
+from agents.run_internal.oai_conversation import OpenAIServerConversationTracker
+from agents.usage import Usage
+
+
+def _make_response(response_id: str | None) -> ModelResponse:
+    response = object.__new__(ModelResponse)
+    response.output = []
+    response.usage = Usage()
+    response.response_id = response_id
+    return response
+
+
+def test_hydrate_from_state_uses_latest_non_none_response_id() -> None:
+    """Resume should chain to the most recent response_id, not None when last response lacks id.
+
+    A run might produce model responses across providers where some have no `response_id`
+    (e.g., a non-Responses fallback). `track_server_items` skips updates when response_id is
+    None, so live runs preserve the last known id. Resume hydration should match that
+    behavior — falling back to the last id-bearing response instead of forgetting the chain.
+    """
+    tracker = OpenAIServerConversationTracker(
+        conversation_id=None,
+        previous_response_id=None,
+        auto_previous_response_id=True,
+    )
+
+    responses: list[Any] = [
+        _make_response("resp_first"),
+        _make_response("resp_second"),
+        _make_response(None),
+    ]
+
+    tracker.hydrate_from_state(
+        original_input=[],
+        generated_items=[],
+        model_responses=responses,
+    )
+
+    assert tracker.previous_response_id == "resp_second"