fix(settings): reject fractional refresh intervals

app/pages/settings.py

@@ -70,6 +70,15 @@ def settings_page(workspace_id: str) -> None:
             return str(int(parsed))
         return str(parsed)
 
+    def as_positive_int(value: object) -> int | None:
+        try:
+            parsed = float(value)
+        except (TypeError, ValueError):
+            return None
+        if parsed < 1 or not parsed.is_integer():
+            return None
+        return int(parsed)
+
     def last_saved_status_text(config: PortfolioConfig) -> str:
         return save_status_text(config).replace("Saved:", "Last saved:", 1)
 
@@ -78,6 +87,10 @@ def settings_page(workspace_id: str) -> None:
         if parsed_loan_amount is None:
             raise ValueError("Loan amount must be zero or greater")
 
+        parsed_refresh_interval = as_positive_int(refresh_interval.value)
+        if parsed_refresh_interval is None:
+            raise ValueError("Refresh interval must be a whole number of seconds")
+
         return PortfolioConfig(
             gold_value=as_positive_float(gold_value.value),
             entry_price=as_positive_float(entry_price.value),
@@ -89,7 +102,7 @@ def settings_page(workspace_id: str) -> None:
             ltv_warning=float(ltv_warning.value),
             primary_source=str(primary_source.value),
             fallback_source=str(fallback_source.value),
-            refresh_interval=int(refresh_interval.value),
+            refresh_interval=parsed_refresh_interval,
             volatility_spike=float(vol_alert.value),
             spot_drawdown=float(price_alert.value),
             email_alerts=bool(email_alerts.value),