fix: sanitize rejected Realtime token responses

server/providers/openai/realtime.js

@@ -132,19 +132,25 @@ function createRealtimeTokenHandler({
       });
       const body = await response.text();
       res.statusCode = response.status;
-      res.setHeader(
-        'Content-Type',
-        response.headers.get('content-type') || 'application/json',
-      );
       // Which tier/model this secret was actually minted for. The upstream
-      // body is passed through untouched (the client parses it verbatim), so
-      // these headers are the authoritative echo — including the case where a
-      // bogus ?tier= was silently downgraded to standard.
+      // success body is passed through untouched (the client parses it
+      // verbatim), so these headers are the authoritative echo — including the
+      // case where a bogus ?tier= was silently downgraded to standard.
       res.setHeader('X-GEV-Voice-Tier', tier);
       res.setHeader('X-GEV-Voice-Model', model);
       if (requestedTier && !isKnownVoiceTier(requestedTier)) {
         res.setHeader('X-GEV-Voice-Tier-Fallback', '1');
       }
+      if (!response.ok) {
+        console.warn(`[realtime-token] upstream HTTP ${response.status}`);
+        res.setHeader('Content-Type', 'application/json; charset=utf-8');
+        res.end(JSON.stringify({ error: 'Failed to create Realtime token' }));
+        return;
+      }
+      res.setHeader(
+        'Content-Type',
+        response.headers.get('content-type') || 'application/json',
+      );
       res.end(body);
     } catch {
       // For a network fault this was a resolver message naming the upstream