fix: wire enable_tracing UI toggle to backend and optimize agent lookup

- Map enable_tracing form field to require_trace_id_on_calls_by_agent in
  buildAgentDataFromForm and parseAgentForForm so the tracing toggle
  actually takes effect end-to-end
- Replace O(n) linear scan in AgentRegistry.get_agent_by_id with O(1)
  dict lookup via _agent_by_id index, reducing latency in auth hot path
- Update test cleanup to preserve _agent_by_id consistency

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

litellm/proxy/agent_endpoints/agent_registry.py

@@ -15,14 +15,21 @@ from litellm.types.agents import AgentConfig, AgentResponse, PatchAgentRequest
 class AgentRegistry:
     def __init__(self):
         self.agent_list: List[AgentResponse] = []
+        self._agent_by_id: Dict[str, AgentResponse] = {}
 
     def reset_agent_list(self):
         self.agent_list = []
+        self._agent_by_id = {}
 
     def register_agent(self, agent_config: AgentResponse):
         self.agent_list.append(agent_config)
+        if agent_config.agent_id:
+            self._agent_by_id[agent_config.agent_id] = agent_config
 
     def deregister_agent(self, agent_name: str):
+        for agent in self.agent_list:
+            if agent.agent_name == agent_name and agent.agent_id:
+                self._agent_by_id.pop(agent.agent_id, None)
         self.agent_list = [
             agent for agent in self.agent_list if agent.agent_name != agent_name
         ]
@@ -358,16 +365,9 @@ class AgentRegistry:
         agent_id: str,
     ) -> Optional[AgentResponse]:
         """
-        Get an agent by its ID from the database
+        Get an agent by its ID using O(1) dict lookup
         """
-        try:
-            for agent in self.agent_list:
-                if agent.agent_id == agent_id:
-                    return agent
-
-            return None
-        except Exception as e:
-            raise Exception(f"Error getting agent from DB: {str(e)}")
+        return self._agent_by_id.get(agent_id)
 
     def get_agent_by_name(self, agent_name: str) -> Optional[AgentResponse]:
         """

tests/test_litellm/test_a2a_registry_lookup.py

@@ -56,8 +56,9 @@ def test_a2a_registry_integration():
         
         # Register and test
         original_agents = global_agent_registry.agent_list.copy()
+        original_agent_by_id = global_agent_registry._agent_by_id.copy()
         global_agent_registry.register_agent(test_agent)
-        
+
         try:
             litellm.completion(
                 model="a2a/test-agent",
@@ -68,6 +69,7 @@ def test_a2a_registry_integration():
             assert "registry-url.example.com" in str(e) or "APIConnectionError" in str(type(e).__name__)
         finally:
             global_agent_registry.agent_list = original_agents
+            global_agent_registry._agent_by_id = original_agent_by_id
             
     except ImportError:
         pytest.skip("Registry not available (not in proxy context)")

ui/litellm-dashboard/src/components/agents/agent_config.ts

@@ -278,6 +278,7 @@ export const buildAgentDataFromForm = (values: any, existingAgent?: any) => {
   if (values.cost_per_query) params.cost_per_query = parseFloat(values.cost_per_query);
   if (values.input_cost_per_token) params.input_cost_per_token = parseFloat(values.input_cost_per_token);
   if (values.output_cost_per_token) params.output_cost_per_token = parseFloat(values.output_cost_per_token);
+  if (values.enable_tracing !== undefined) params.require_trace_id_on_calls_by_agent = values.enable_tracing;
 
   if (Object.keys(params).length > 0) {
     agentData.litellm_params = params;
@@ -316,5 +317,6 @@ export const parseAgentForForm = (agent: any) => {
     cost_per_query: agent.litellm_params?.cost_per_query,
     input_cost_per_token: agent.litellm_params?.input_cost_per_token,
     output_cost_per_token: agent.litellm_params?.output_cost_per_token,
+    enable_tracing: agent.litellm_params?.require_trace_id_on_calls_by_agent,
   };
 };