[eric] models: the free lane's haiku default can no longer outlive the lane or get persisted by the guard (ENG-343)

backend/apps/settings/store.py

@@ -84,6 +84,9 @@ def migrate_legacy_fields(raw: dict) -> dict:
     if raw.get("connection_mode") == "free-trial":
         raw["connection_mode"] = "own_key"
         raw.pop("free_trial_token", None)
+        # The free lane's forced Haiku default must not outlive the lane (ENG-343): dropping the field lets the real default take over.
+        if raw.get("default_model") == "haiku":
+            raw.pop("default_model", None)
     return raw
 
 

frontend/src/app/Main.tsx

@@ -376,6 +376,9 @@ const DefaultModelGuard: React.FC<{ children: React.ReactNode }> = ({ children }
     const currentExists = flat.some((m) => m.value === settings.default_model);
     if (currentExists) return;
 
+    // Nothing real connected means the synthesized free row is the whole list; persisting it would brand haiku as the user's default forever (ENG-343).
+    if (!flat.some((m) => m.billing_kind !== 'free')) return;
+
     const fallback = pickFallbackModel(byProvider);
     if (!fallback || fallback.value === settings.default_model) return;