refactor(a2a): use direct typed access in protocol binding normalization

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/a2a_protocol/card_resolver.py

@@ -67,11 +67,9 @@ def normalize_agent_card_protocol_bindings(agent_card: "AgentCard") -> "AgentCar
     case-sensitively against its uppercase TransportProtocol constants and fails
     with "no compatible transports found." for spec-adjacent casings.
     """
-    interfaces: Final = getattr(agent_card, "supported_interfaces", None) or ()
-    for interface in interfaces:
-        binding: str = getattr(interface, "protocol_binding", "") or ""
-        canonical = _CANONICAL_PROTOCOL_BINDINGS.get(binding.lower())
-        if canonical is not None and binding != canonical:
+    for interface in agent_card.supported_interfaces:
+        canonical: str | None = _CANONICAL_PROTOCOL_BINDINGS.get(interface.protocol_binding.lower())
+        if canonical is not None and canonical != interface.protocol_binding:
             interface.protocol_binding = canonical
     return agent_card
 

tests/test_litellm/a2a_protocol/test_main.py

@@ -344,6 +344,7 @@ async def test_lowercase_protocol_binding_in_agent_card_still_gets_a_client(isol
     response = await _send_message(a2a_client, _send_request("lc"))
 
     assert type(response.root.result).__name__ == "Message"
+    assert a2a_client._litellm_agent_card.supported_interfaces[0].protocol_binding == "JSONRPC"
 
 
 @pytest.mark.asyncio