fix(ui): sync toolStreamRef on tool.result to prevent stale overwrite

tool.result updated React state via functional update but didn't sync
toolStreamRef.current. When the next tool.call arrived and set state
to toolStreamRef.current (direct value), it overwrote completed
statuses with stale "calling" phase — causing tool cards to stay
stuck at "Running..." forever.

ui/web/src/pages/chat/hooks/use-chat-messages.ts

@@ -144,18 +144,20 @@ export function useChatMessages(sessionKey: string, agentId: string) {
         }
         case "tool.result": {
           const isError = event.payload?.is_error;
-          setToolStream((prev) =>
-            prev.map((t) =>
-              t.toolCallId === event.payload?.id
-                ? {
-                    ...t,
-                    phase: isError ? "error" : "completed",
-                    errorContent: isError ? event.payload?.content : undefined,
-                    updatedAt: Date.now(),
-                  }
-                : t,
-            ),
+          const resultId = event.payload?.id;
+          const now = Date.now();
+          // Update ref first so subsequent tool.call events don't overwrite with stale data.
+          toolStreamRef.current = toolStreamRef.current.map((t) =>
+            t.toolCallId === resultId
+              ? {
+                  ...t,
+                  phase: isError ? ("error" as const) : ("completed" as const),
+                  errorContent: isError ? event.payload?.content : undefined,
+                  updatedAt: now,
+                }
+              : t,
           );
+          setToolStream(toolStreamRef.current);
           break;
         }
         case "run.completed": {