fix: use a fee reserve and actual wallet fees

lnbits/core/services.py

@@ -34,15 +34,27 @@ def pay_invoice(*, wallet_id: str, bolt11: str, max_sat: Optional[int] = None) -
         if max_sat and invoice.amount_msat > max_sat * 1000:
             raise ValueError("Amount in invoice is too high.")
 
-        if invoice.amount_msat > get_wallet(wallet_id).balance_msat:
+        fee_reserve = max(1000, invoice.amount_msat * 0.01)
+        create_payment(
+            wallet_id=wallet_id,
+            checking_id=temp_id,
+            amount=-invoice.amount_msat,
+            fee=-fee_reserve,
+            memo=temp_id,
+        )
+
+        if get_wallet(wallet_id).balance_msat < 0:
             raise PermissionError("Insufficient balance.")
 
-        create_payment(wallet_id=wallet_id, checking_id=temp_id, amount=-invoice.amount_msat, memo=temp_id)
         ok, checking_id, fee_msat, error_message = WALLET.pay_invoice(bolt11)
 
         if ok:
             create_payment(
-                wallet_id=wallet_id, checking_id=checking_id, amount=-invoice.amount_msat, memo=invoice.description
+                wallet_id=wallet_id,
+                checking_id=checking_id,
+                amount=-invoice.amount_msat,
+                fee=fee_msat,
+                memo=invoice.description,
             )
 
     except Exception as e: