diff --git a/bridges/snowbridge/primitives/router/src/outbound/mod.rs b/bridges/snowbridge/primitives/router/src/outbound/mod.rs index d3b6c116dd7a..80e5a1419094 100644 --- a/bridges/snowbridge/primitives/router/src/outbound/mod.rs +++ b/bridges/snowbridge/primitives/router/src/outbound/mod.rs @@ -268,7 +268,12 @@ where ensure!(reserve_assets.len() == 1, TooManyAssets); let reserve_asset = reserve_assets.get(0).ok_or(AssetResolutionFailed)?; - // If there was a fee specified verify it. + // Enough Fees are collected on Asset Hub, up front and directly from the user, to cover the + // complete cost of the transfer. Any additional fees provided in the XCM program are + // refunded to the beneficairy. We only validate the fee here if its provided to make sure + // the XCM program is well formed. Another way to think about this from an XCM perspective + // would be that the user offered to pay X amount in fees, but we charge 0 of that X amount + // (no fee) and refund X to the user. if let Some(fee_asset) = fee_asset { // The fee asset must be the same as the reserve asset. if fee_asset.id != reserve_asset.id || fee_asset.fun > reserve_asset.fun { @@ -374,7 +379,12 @@ where ensure!(reserve_assets.len() == 1, TooManyAssets); let reserve_asset = reserve_assets.get(0).ok_or(AssetResolutionFailed)?; - // If there was a fee specified verify it. + // Enough Fees are collected on Asset Hub, up front and directly from the user, to cover the + // complete cost of the transfer. Any additional fees provided in the XCM program are + // refunded to the beneficairy. We only validate the fee here if its provided to make sure + // the XCM program is well formed. Another way to think about this from an XCM perspective + // would be that the user offered to pay X amount in fees, but we charge 0 of that X amount + // (no fee) and refund X to the user. if let Some(fee_asset) = fee_asset { // The fee asset must be the same as the reserve asset. if fee_asset.id != reserve_asset.id || fee_asset.fun > reserve_asset.fun {