fix: add MPTAmount support in Issue model

packages/ripple-binary-codec/HISTORY.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+### Fixed
+- add `MPTAmount` support in `Issue` (rippled internal type)
+
 ## 2.3.0 (2025-2-13)
 
 ### Added

packages/ripple-binary-codec/src/types/issue.ts

@@ -4,24 +4,35 @@ import { BinaryParser } from '../serdes/binary-parser'
 import { AccountID } from './account-id'
 import { Currency } from './currency'
 import { JsonObject, SerializedType } from './serialized-type'
+import { Hash192 } from './hash-192'
 
+interface XRPIssue extends JsonObject {
+  currency: string
+}
+
+interface IOUIssue extends JsonObject {
+  currency: string
+  issuer: string
+}
+interface MPTIssue extends JsonObject {
+  mpt_issuance_id: string
+}
 /**
  * Interface for JSON objects that represent amounts
  */
-interface IssueObject extends JsonObject {
-  currency: string
-  issuer?: string
-}
+type IssueObject = XRPIssue | IOUIssue | MPTIssue
 
 /**
  * Type guard for AmountObject
  */
 function isIssueObject(arg): arg is IssueObject {
   const keys = Object.keys(arg).sort()
-  if (keys.length === 1) {
-    return keys[0] === 'currency'
-  }
-  return keys.length === 2 && keys[0] === 'currency' && keys[1] === 'issuer'
+  const isXRP = keys.length === 1 && keys[0] === 'currency'
+  const isIOU =
+    keys.length === 2 && keys[0] === 'currency' && keys[1] === 'issuer'
+  const isMPT = keys.length === 1 && keys[0] === 'mpt_issuance_id'
+
+  return isXRP || isIOU || isMPT
 }
 
 /**
@@ -47,12 +58,26 @@ class Issue extends SerializedType {
     }
 
     if (isIssueObject(value)) {
-      const currency = Currency.from(value.currency).toBytes()
-      if (value.issuer == null) {
+      if (value.currency) {
+        const currency = Currency.from(value.currency.toString()).toBytes()
+
+        //IOU case
+        if (value.issuer) {
+          const issuer = AccountID.from(value.issuer.toString()).toBytes()
+          return new Issue(concat([currency, issuer]))
+        }
+
+        //XRP case
         return new Issue(currency)
       }
-      const issuer = AccountID.from(value.issuer).toBytes()
-      return new Issue(concat([currency, issuer]))
+
+      // MPT case
+      if (value.mpt_issuance_id) {
+        const mptIssuanceIdBytes = Hash192.from(
+          value.mpt_issuance_id.toString(),
+        ).toBytes()
+        return new Issue(mptIssuanceIdBytes)
+      }
     }
 
     throw new Error('Invalid type to construct an Amount')
@@ -79,7 +104,15 @@ class Issue extends SerializedType {
    * @returns the JSON interpretation of this.bytes
    */
   toJSON(): IssueObject {
+    // If the buffer is exactly 24 bytes, treat it as an MPT amount.
+    if (this.toBytes.length === Hash192.width) {
+      return {
+        mpt_issuance_id: this.toHex().toUpperCase(),
+      }
+    }
+
     const parser = new BinaryParser(this.toString())
+
     const currency = Currency.fromParser(parser) as Currency
     if (currency.toJSON() === 'XRP') {
       return { currency: currency.toJSON() }