diff --git a/src/status.ts b/src/status.ts
index 427086d..b8dee4a 100644
--- a/src/status.ts
+++ b/src/status.ts
@@ -97,15 +97,24 @@ function getBus(): Promise<BusClient> {
   if (!_busPromise) {
     _busPromise = BusClient.connect({
       onWarn: (msg, ...args) => {
+        const details = args
+          .map((a) => {
+            try {
+              return typeof a === "object" && a !== null ? JSON.stringify(a) : String(a);
+            } catch {
+              return "[unserializable]";
+            }
+          })
+          .join(" ");
         _client?.app?.log({
           body: {
             service: "brain",
             level: "warn",
             message: msg,
-            extra: { details: args.map(a => typeof a === 'object' ? JSON.stringify(a) : String(a)).join(" ") }
-          }
+            extra: { details },
+          },
         }).catch(() => {});
-      }
+      },
     }).catch((err) => {
       _client?.app?.log({ body: { service: "brain", level: "warn", message: "BusClient connect failed", extra: { error: String(err) } } }).catch(() => {});
       _busPromise = null;  // allow retry on next call