Proposal: icrc1_minting_account endpoint

ICRC-1.did

@@ -1,7 +1,7 @@
 // Number of nanoseconds since the UNIX epoch in UTC timezone.
 type Timestamp = nat64;
 
-// Number of nanoseconds between two [Timestamp]service
+// Number of nanoseconds between two [Timestamp]s.
 type Duration = nat64;
 
 type Subaccount = blob;
@@ -44,6 +44,7 @@ service : {
     icrc1_decimals : () -> (nat8) query;
     icrc1_fee : () -> (nat) query;
     icrc1_total_supply : () -> (nat) query;
+    icrc1_minting_account : () -> (opt Account) query;
     icrc1_balance_of : (Account) -> (nat) query;
     icrc1_transfer : (TransferArgs) -> (variant { Ok: nat; Err: TransferError; });
     icrc1_supported_standards : () -> (vec record { name : text; url : text }) query;

README.md

@@ -64,12 +64,20 @@ icrc1_metadata : () -> (vec record { text; Value }) query;
 
 ### icrc1_total_supply
 
-Returns the total token supply.
+Returns the total number of tokens on all accounts except for the [minting account](#minting_account).
 
 ```candid "Methods" +=
 icrc1_total_supply : () -> (nat) query;
 ```
 
+### icrc1_minting_account
+
+Returns the [minting account](#minting_account) if this ledger supports minting and burning tokens.
+
+```candid "Methods" +=
+icrc1_minting_account : () -> (opt Account) query;
+```
+
 ### icrc1_balance_of
 
 Returns the balance of the account given as argument.
@@ -166,6 +174,23 @@ Namespace `icrc1` is reserved for keys defined in this standard.
 | `icrc1:decimals` | `variant { Nat = 8 }` | The number of decimals the token uses. For example, 8 means to divide the token amount by 10<sup>8</sup> to get its user representation. When present, should be the same as the result of the [`icrc1_decimals`](#decimals_method) query call. |
 | `icrc1:fee` | `variant { Nat = 10_000 }` | The default transfer fee. When present, should be the same as the result of the [`icrc1_fee`](#fee_method) query call. |
 
+## Minting account <span id="minting_account"></span>
+
+The minting account is a unique account that can create new tokens and acts as the receiver of burnt tokens.
+
+Transfers _from_ the minting account act as _mint_ transactions depositing fresh tokens on the destination account.
+Mint transactions have no fee.
+
+Transfers _to_ the minting account act as _burn_ transactions, removing tokens from the token supply.
+Burn transactions have no fee but might have minimal burn amount requirements.
+If the client tries to burn an amount that is too small, the ledger SHOULD reply with
+
+```
+variant { Err = variant { BadBurn = record { min_burn_amount = ... } } }
+```
+
+The minting account is also the receiver of the fees burnt in regular transfers.
+
 <!--
 ```candid ICRC-1.did +=
 <<<Type definitions>>>

ref/ICRC1.mo

@@ -283,6 +283,10 @@ actor class Ledger(init : {
     totalSupply(log)
   };
 
+  public query func icrc1_minting_account() : async ?Account {
+    ?init.minting_account
+  };
+
   public query func icrc1_name() : async Text {
     init.token_name
   };