diff --git a/apps/x/packages/core/src/models/defaults.ts b/apps/x/packages/core/src/models/defaults.ts
index dc704367..aa9453b0 100644
--- a/apps/x/packages/core/src/models/defaults.ts
+++ b/apps/x/packages/core/src/models/defaults.ts
@@ -14,7 +14,9 @@ const SIGNED_IN_DEFAULT_PROVIDER = "rowboat";
 const SIGNED_IN_KG_MODEL = "google/gemini-3.1-flash-lite";
 const SIGNED_IN_LIVE_NOTE_AGENT_MODEL = "google/gemini-3.1-flash-lite";
 const SIGNED_IN_AUTO_PERMISSION_DECISION_MODEL = "google/gemini-3.1-flash-lite";
-const SIGNED_IN_CHAT_TITLE_MODEL = "google/gemini-3.5-flash-lite";
+// 3.5-flash-lite is not on the gateway allowlist (only 3.1-flash-lite and
+// full 3.5-flash are) — the gateway 403s "Model not allowed" otherwise.
+const SIGNED_IN_CHAT_TITLE_MODEL = "google/gemini-3.1-flash-lite";
 
 export type ModelSelection = z.infer<typeof ModelRef>;