docs: minor comments for private refunds/partial notes (#7447)

noir-projects/noir-contracts/contracts/private_token_contract/src/main.nr

@@ -201,6 +201,7 @@ contract PrivateToken {
     #[aztec(internal)]
     fn complete_refund(fee_payer_point: Point, user_point: Point) {
         // 1. We get the final note content hashes by calling the `complete_refund` on the note.
+        // We use 1:1 exchange rate between fee juice and token. So using `tx_fee` is enough
         let tx_fee = context.transaction_fee();
         let (fee_payer_note_content_hash, user_note_content_hash) = TokenNote::complete_refund(fee_payer_point, user_point, tx_fee);
 

noir-projects/noir-contracts/contracts/private_token_contract/src/types/token_note.nr

@@ -163,7 +163,7 @@ impl OwnedNote for TokenNote {
  * way to deduce what s is. This is the discrete log problem.
  *
  * However we can still perform addition/subtraction on points! That is why we generate those two points, which are:
- * incomplete_fee_payer_point := G_npk * fee_payer_npk + G_amt * fee_payer_randomness
+ * incomplete_fee_payer_point := G_npk * fee_payer_npk + G_rnd * fee_payer_randomness
  * incomplete_user_point := G_npk * user_npk + G_amt * funded_amount + G_rnd * user_randomness
  *
  * where `funded_amount` is the total amount in tokens that the sponsored user initially supplied, from which

yarn-project/end-to-end/src/e2e_fees/private_refunds.test.ts

@@ -187,6 +187,7 @@ class PrivateRefundPaymentMethod implements FeePaymentMethod {
    * @returns The function call to pay the fee.
    */
   async getFunctionCalls(gasSettings: GasSettings): Promise<FunctionCall[]> {
+    // we assume 1:1 exchange rate between fee juice and token. But in reality you would need to convert feeLimit (maxFee) to be in token denomination
     const maxFee = gasSettings.getFeeLimit();
 
     await this.wallet.createAuthWit({