feat: add a cap for transfer fee

protocol/0057-TRAN-transfers.md

@@ -155,7 +155,7 @@ Note: if there is no market with contribution to the reward metric - no transfer
 
 A fee is taken from all transfers, and paid out to validators in a similar manner to the existing [infrastructure fees](0061-REWP-pos_rewards.md). For recurring transfers, the fee is charged each time the transfer occurs.
 
-The fee is set by the `transfer.fee.factor` [network parameter](#network-parameters) that defines the proportion of each transfer taken as a fee.
+The fee is determined by the `transfer.fee.factor` and is subject to a cap defined by the multiplier `transfer.fee.maxQuantumAmount` as specified in the network parameters, which governs the proportion of each transfer taken as a fee.
 The fee is taken from the transfer initiator's account immediately on execution, and is taken on top of the total amount transferred.
 It is [paid in to the infrastructure fee pool](./0029-FEES-fees.md#collecting-and-distributing-fees).
 Fees are charged in the asset that is being transferred.
@@ -217,6 +217,7 @@ message CancelTransfer {
 | `spam.protection.maxUserTransfersPerEpoch` | String (integer) | strictly greater than `0`   | `"20"`         | The most transfers a use can initiate per epoch |
 | `transfer.minTransferQuantumMultiple`      | String (decimal) | greater than or equal to `0`| `"0.1"`        | This, when multiplied by `quantum` (which is specified per asset) determines the minimum transfer amount |
 | `transfer.fee.factor`                      | String (decimal) | in `[0.0,1.0]`              | `"0.001"`      | The proportion of the transfer charged as a fee  |
+| `transfer.fee.maxQuantumAmount`            | String (decimal) | in `[0.0,1.0]`              | `"0.001"`      | The miltiplier of the transfer fee  |
 
 ## Acceptance criteria
 
@@ -230,11 +231,16 @@ message CancelTransfer {
 - As a user I cannot transfer funds from accounts I own but from the type is not supported:
   - for accounts created in a futures market, bond and margin (<a name="0057-TRAN-006" href="#0057-TRAN-006">0057-TRAN-006</a>)
   - for accounts created in a spot market, bond and holding (<a name="0057-TRAN-063" href="#0057-TRAN-063">0057-TRAN-063</a>)
-- As a user I can do a transfer from any of the valid accounts (I control them and they're a valid source), and fees are taken from the source account when the transfer is executed. (<a name="0057-TRAN-007" href="#0057-TRAN-007">0057-TRAN-007</a>)
+- As a user I can do a transfer from any of the valid accounts (I control them and they're a valid source), and fees are taken from the source account when the transfer is executed (when `transfer.fee.maxQuantumAmount` = 1). (<a name="0057-TRAN-007" href="#0057-TRAN-007">0057-TRAN-007</a>)
   - The fee cost is correctly calculated using the network parameter
   - If I have enough funds to pay transfer and fees, the transfer happens.
   - If I do not have enough funds to pay transfer and fees, the transfer is cancelled.
   - The fees are being paid into the infrastructure pool
+- As a user I can do a transfer from any of the valid accounts (I control them and they're a valid source), and fees are taken from the source account when the transfer is executed (when `transfer.fee.maxQuantumAmount` = 0.02). (<a name="0057-TRAN-011" href="#0057-TRAN-011">0057-TRAN-011</a>)
+  - The fee cost is correctly calculated using the network parameter `transfer.fee.Maxfactor`
+  - If I have enough funds to pay transfer and fees, the transfer happens.
+  - If I do not have enough funds to pay transfer and fees, the transfer is cancelled.
+  - The fees are being paid into the infrastructure pool
 - As a user, when I initiate a delayed transfer, the funds are taken from my account immediately (<a name="0057-TRAN-008" href="#0057-TRAN-008">0057-TRAN-008</a>)
   - The funds arrive in the target account when the transaction is processed (i.e. with the correct delay), which is not before the timestamp occurs
   - A delayed transfer that is invalid (to an invalid account type) is rejected when it is received, and the funds are not taken from the origin account.
@@ -256,7 +262,7 @@ As a user I can create a recurring transfer _that decreases over time_ (<a name=
 - I specify a start and end epoch, and a factor of `0.7`
 - Until the start epoch is reached not transfers are executed
 - Once I reach the start epoch transfers happen and the first transfer is for the `start amount`. The fee amount taken from the source account is `start amount x transfer.fee.factor` and transferred to the infrastructure fee account for the asset.
-- The transfer at end of  `start epoch + 1` is `0.7 x start amount` and the fee amount is `0.7 x start amount x transfer.fee.factor`.
+- The transfer at end of  `start epoch + 1` is `0.7 x start amount` and the fee amount is `0.7 x start amount x transfer.fee.factor x transfer.fee.maxQuantumAmount`.
 - The amount transferred every epoch decreases.
 - After I reach the epoch `?`, no transfers are executed anymore
 
@@ -313,6 +319,9 @@ A user's recurring transfer to a reward account does not occur if there are no p
 If the network parameter `transfer.fee.factor` is modified, this modification is applied
 immediately, i.e., transfers are accepted/rejected according to the new parameter. This holds for both increase and decrease. (<a name="0057-TRAN-062" href="#0057-TRAN-062">0057-TRAN-062</a>)
 
+If the network parameter `transfer.fee.maxQuantumAmount` is modified, this modification is applied
+immediately, i.e., transfers are accepted/rejected according to the new parameter. This holds for both increase and decrease. (<a name="0057-TRAN-064" href="#0057-TRAN-064">0057-TRAN-064</a>)
+
 If the network parameter `spam.protection.maxUserTransfersPerEpoch` is modified, this modification is applied immediately, i.e., transfers are accepted/rejected according to the new parameter. This holds for both increase and decrease. In the case of a decrease, existing recurring transfers are not cancelled. (<a name="0057-TRAN-060" href="#0057-TRAN-060">0057-TRAN-060</a>)
 
 If the network parameter `transfer.minTransferQuantumMultiple` is modified, this modification is applied