update from user testing payment platform

frontend/src/lib/forms.ts

@@ -0,0 +1,38 @@
+import { goto } from '$app/navigation';
+
+/**
+ * Resolve-callback factory for `use:enhance`.
+ *
+ * Follows `result.type === 'redirect'` automatically (actions like login,
+ * billing portal, and logged-out pricing choose throw redirects), then hands
+ * everything else to the optional handler — falling back to the default
+ * `update()` when none is given.
+ *
+ * Usage:
+ *   <form method="POST" use:enhance={handleResult(({ result }) => {...})}>
+ *   <form method="POST" use:enhance={handleResult()}>
+ */
+export function handleResult(
+	handler?: (ctx: { result: any; update: () => Promise<void> }) => Promise<void>
+) {
+	return async ({ result, update }: any) => {
+		if (result?.type === 'redirect') {
+			const target = String(result.location);
+			const isExternal = /^https?:\/\//i.test(target) && !target.startsWith(window.location.origin);
+			if (isExternal) {
+				window.location.assign(target);
+			} else {
+				await goto(target);
+			}
+			return;
+		}
+		if (result?.type === 'error') {
+			// Unhandled server exception — never let these vanish silently.
+			const { notices } = await import('$lib/stores/notices.svelte');
+			notices.error('Something went wrong', result.error?.message || 'Internal error.');
+			return;
+		}
+		if (handler) await handler({ result, update });
+		else await update();
+	};
+}