fix: address PR bugfix review for a2a discovery + metadata forwarding

- agent create form (add_agent_form.tsx): drop the skills.length > 0
  guard so an admin can clear all discovered skills during creation,
  matching the edit form's overlay behavior (consistency between
  create and edit flows).

- agent_card_discovery.tsx: stop including savedAgentCard in the
  handleDiscover useCallback deps. Read it via a ref inside
  resetSelections instead, so a parent-driven re-render that hands us
  a new savedAgentCard object reference (e.g. a background refresh of
  the agent record) does not recreate handleDiscover and re-fire the
  auto-discover effect, which would otherwise overwrite in-progress
  user edits in parent-driven mode (debounceMs = 0).

- a2a_endpoints.invoke_agent_a2a: skip 'metadata' when moving
  litellm params off of A2A MessageSendParams into body. The A2A
  protocol defines params.metadata as a first-class request-level
  field, and the completion bridge's get_forward_metadata is supposed
  to merge it with message.metadata. Previously the proxy always
  stripped params.metadata before constructing MessageSendParams, so
  the params-level branch in get_forward_metadata was dead code in
  the proxy flow.

Co-authored-by: Yassin Kortam <yassin@berri.ai>

litellm/proxy/agent_endpoints/a2a_endpoints.py

@@ -332,9 +332,14 @@ async def invoke_agent_a2a(  # noqa: PLR0915
 
         if params:
             # extract any litellm params from the params - eg. 'guardrails'
+            # ``metadata`` is intentionally excluded: it's a first-class A2A
+            # ``MessageSendParams`` field that the completion bridge forwards
+            # downstream via ``get_forward_metadata``. Stripping it here would
+            # collide with litellm's spend-tracking ``metadata`` kwarg and
+            # silently drop the caller's A2A request-level metadata.
             params_to_remove = []
             for key, value in params.items():
-                if key in all_litellm_params:
+                if key in all_litellm_params and key != "metadata":
                     params_to_remove.append(key)
                     body[key] = value
             for key in params_to_remove:

ui/litellm-dashboard/src/components/agents/add_agent_form.tsx

@@ -254,8 +254,9 @@ const AddAgentForm: React.FC<AddAgentFormProps> = ({
         const discovered = appliedDiscoveredSelection.selected_card;
         agentData.agent_card_params = {
           ...agentData.agent_card_params,
-          ...(Array.isArray(discovered.skills) &&
-            discovered.skills.length > 0 && { skills: discovered.skills }),
+          ...(Array.isArray(discovered.skills) && {
+            skills: discovered.skills,
+          }),
           ...(discovered.capabilities && {
             capabilities: discovered.capabilities,
           }),

ui/litellm-dashboard/src/components/agents/agent_card_discovery.tsx

@@ -96,16 +96,6 @@ const AgentCardDiscovery: React.FC<AgentCardDiscoveryProps> = ({
     Record<string, boolean>
   >({});
 
-  const resetSelections = (fresh: DiscoveredAgentCard) => {
-    const initial = savedAgentCard
-      ? selectionsFromSavedAgentCard(fresh, savedAgentCard)
-      : selectionsFromUpstreamCard(fresh);
-    setEditedName(initial.editedName);
-    setEditedDescription(initial.editedDescription);
-    setSelectedSkillIds(initial.selectedSkillIds);
-    setSelectedCapabilities(initial.selectedCapabilities);
-  };
-
   const onApplyRef = useRef(onApply);
   onApplyRef.current = onApply;
   const discoverRequestIdRef = useRef(0);
@@ -118,6 +108,25 @@ const AgentCardDiscovery: React.FC<AgentCardDiscoveryProps> = ({
   // the callback / effect only re-run when content actually changes.
   const discoveryRequestRef = useRef(discoveryRequest);
   discoveryRequestRef.current = discoveryRequest;
+  // Hold ``savedAgentCard`` in a ref so ``resetSelections`` always sees the
+  // latest value without making it a dependency of ``handleDiscover``.
+  // Putting ``savedAgentCard`` directly in the callback deps means any parent
+  // re-render that hands us a new object reference (e.g. a background
+  // agent-data refresh during editing) recreates ``handleDiscover``, which
+  // re-fires the auto-discover effect and overwrites in-progress user edits.
+  const savedAgentCardRef = useRef(savedAgentCard);
+  savedAgentCardRef.current = savedAgentCard;
+
+  const resetSelections = (fresh: DiscoveredAgentCard) => {
+    const saved = savedAgentCardRef.current;
+    const initial = saved
+      ? selectionsFromSavedAgentCard(fresh, saved)
+      : selectionsFromUpstreamCard(fresh);
+    setEditedName(initial.editedName);
+    setEditedDescription(initial.editedDescription);
+    setSelectedSkillIds(initial.selectedSkillIds);
+    setSelectedCapabilities(initial.selectedCapabilities);
+  };
 
   const discoveryMode = discoveryRequest?.discovery_mode;
   const discoveryParamsKey = useMemo(
@@ -176,9 +185,12 @@ const AgentCardDiscovery: React.FC<AgentCardDiscoveryProps> = ({
     // ``discoveryMode`` / ``discoveryParamsKey`` are primitive proxies for
     // ``discoveryRequest`` content; the actual object is read via the ref
     // above so identity churn from the parent doesn't recreate this callback.
-    // ``savedAgentCard`` is captured indirectly via ``resetSelections``: if
-    // the parent refetches the agent and hands us a new saved card, we need
-    // a fresh callback so "Re-discover" pre-selects against the latest data.
+    // ``savedAgentCard`` is intentionally NOT a dep — it's read via
+    // ``savedAgentCardRef`` inside ``resetSelections``. Including it here
+    // would recreate this callback whenever the parent hands us a new
+    // ``savedAgentCard`` object (e.g. a background refresh of agent data
+    // during editing), which would re-fire the auto-discover effect and
+    // wipe in-progress user selections.
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [
     accessToken,
@@ -186,7 +198,6 @@ const AgentCardDiscovery: React.FC<AgentCardDiscoveryProps> = ({
     isParentDriven,
     discoveryMode,
     discoveryParamsKey,
-    savedAgentCard,
   ]);
 
   // Auto-discover when the URL (or parent plan) becomes available.