Get Expense from Stripe instead of Static Entry

functions/payments.php

@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * Extract the actual Stripe processing fee from a PaymentIntent.
+ * PI must have been created/retrieved with
+ * 'expand' => ['latest_charge.balance_transaction'].
+ * Returns ['fee' => float, 'currency' => 'USD'] or false if unavailable.
+ */
+function getStripeGatewayFee($payment_intent)
+{
+    $bt = $payment_intent->latest_charge->balance_transaction ?? null;
+
+    // Not expanded or not yet created (async payment methods)
+    if (!$bt || is_string($bt)) {
+        return false;
+    }
+
+    return [
+        'fee' => round($bt->fee / 100, 2),
+        'currency' => strtoupper($bt->currency),
+    ];
+}