fix: use correct REST path for Get Extended Agent Card operation (#769)

The path is /extendedAgentCard now: [5.3. Method Mapping
Reference](https://a2a-protocol.org/latest/specification/#53-method-mapping-reference).

Re #559

Author: ishymko

src/a2a/client/transports/rest.py

@@ -347,7 +347,7 @@ async def get_extended_agent_card(
             context,
         )
         response_data = await self._send_get_request(
-            '/card', {}, modified_kwargs
+            '/extendedAgentCard', {}, modified_kwargs
         )
         response: AgentCard = ParseDict(response_data, AgentCard())
 

src/a2a/server/apps/rest/rest_adapter.py

@@ -252,7 +252,7 @@ def routes(self) -> dict[tuple[str, str], Callable[[Request], Any]]:
             ),
         }
         if self.agent_card.capabilities.extended_agent_card:
-            routes[('/card', 'GET')] = functools.partial(
+            routes[('/extendedAgentCard', 'GET')] = functools.partial(
                 self._handle_request, self.handle_authenticated_agent_card
             )
 

tests/client/test_client_factory.py

@@ -188,7 +188,7 @@ async def test_client_factory_connect_with_resolver_args(
         )
 
         agent_url = 'http://example.com'
-        relative_path = '/card'
+        relative_path = '/extendedAgentCard'
         http_kwargs = {'headers': {'X-Test': 'true'}}
 
         # The resolver args are only passed if an httpx_client is provided in config
@@ -219,7 +219,7 @@ async def test_client_factory_connect_resolver_args_without_client(
         )
 
         agent_url = 'http://example.com'
-        relative_path = '/card'
+        relative_path = '/extendedAgentCard'
         http_kwargs = {'headers': {'X-Test': 'true'}}
 
         await ClientFactory.connect(

tests/e2e/push_notifications/test_default_push_notification_support.py

@@ -74,7 +74,7 @@ def agent_server(notifications_client: httpx.AsyncClient):
     )
     process.start()
     try:
-        wait_for_server_ready(f'{url}/card')
+        wait_for_server_ready(f'{url}/extendedAgentCard')
     except TimeoutError as e:
         process.terminate()
         raise e