fix(templates): encode MandalaToken assetId in outpoint byte order

encodeAssetId wrote the txid in display (id) byte order; on-chain it must be the
internal/reversed (tx.hash()) order + little-endian vout, so the embedded assetId
matches the genesis transaction's outpoint as it appears in a tx. decodeAssetId
reverses back, leaving the "<txid>.<vout>" display string unchanged. Enables direct
outpoint comparisons in smart-contract validation. Breaking on-chain format.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: sirdeggen

packages/helpers/ts-templates/CHANGELOG.md

@@ -13,7 +13,13 @@ All notable changes to this project will be documented in this file. The format
 - (Include new features or significant user-visible enhancements here.)
 
 ### Changed
-- (Detail modifications that are non-breaking but relevant to the end-users.)
+- **MandalaToken assetId on-chain encoding (breaking on-chain format):** `encodeAssetId`
+  now writes the txid in outpoint (internal/reversed, `tx.hash()`) byte order followed
+  by the 4-byte little-endian vout, matching how an outpoint appears in a transaction.
+  `decodeAssetId` reverses it back, so the `"<txid>.<vout>"` display string is
+  unchanged. This lets smart contracts compare a token's embedded assetId directly
+  against the genesis transaction's outpoint. Tokens minted under the previous
+  (non-reversed) encoding will not decode to the same assetId.
 
 ### Deprecated
 - (List features that are in the process of being phased out or replaced.)

packages/helpers/ts-templates/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@bsv/templates",
-  "version": "1.7.1",
+  "version": "1.7.2",
   "type": "module",
   "description": "BSV Blockchain Script Templates",
   "main": "dist/cjs/mod.js",

packages/helpers/ts-templates/src/__tests/mandala-encoding.test.ts

@@ -35,4 +35,13 @@ describe('mandala-encoding', () => {
     const assetId = `${'a'.repeat(64)}.4294967295`
     expect(decodeAssetId(encodeAssetId(assetId))).toBe(assetId)
   })
+
+  it('encodes the txid in outpoint (internal/reversed) byte order + LE vout', () => {
+    // Distinct first/last bytes so reversal is observable.
+    const txid = '11' + 'aa'.repeat(30) + '22' // 32 bytes: 0x11 .. 0x22
+    const bytes = encodeAssetId(`${txid}.1`)
+    expect(bytes[0]).toBe(0x22)  // display last byte → first on-chain (reversed)
+    expect(bytes[31]).toBe(0x11) // display first byte → last on-chain
+    expect(bytes.slice(32)).toEqual([1, 0, 0, 0]) // vout little-endian
+  })
 })

packages/helpers/ts-templates/src/mandala-encoding.ts

@@ -60,14 +60,19 @@ export const encodeAssetId = (assetId: string): number[] => {
   const vout = Number(assetId.slice(dot + 1))
   if (txid.length !== 64) throw new Error('assetId txid must be 32 bytes (64 hex chars)')
   if (!Number.isInteger(vout) || vout < 0) throw new Error('assetId vout must be a non-negative integer')
-  const txidBytes = Utils.toArray(txid, 'hex')
+  // On-chain assetId bytes use outpoint format: the txid in internal (hash) byte
+  // order — i.e. the display hex reversed (tx.hash() vs tx.id('hex')) — followed by
+  // the 4-byte little-endian vout. This lets a contract compare the embedded assetId
+  // directly against the genesis transaction's outpoint as it appears in the tx.
+  const txidBytes = Utils.toArray(txid, 'hex').reverse()
   const voutBytes = [vout & 0xff, (vout >> 8) & 0xff, (vout >> 16) & 0xff, (vout >> 24) & 0xff]
   return [...txidBytes, ...voutBytes]
 }
 
 export const decodeAssetId = (bytes: number[]): string => {
   if (bytes.length !== 36) throw new Error('assetId bytes must be exactly 36 bytes')
-  const txid = Utils.toHex(bytes.slice(0, 32))
+  // Reverse the internal (hash) byte order back to display txid hex.
+  const txid = Utils.toHex(bytes.slice(0, 32).reverse())
   const v = bytes.slice(32)
   const vout = (v[0] + (v[1] << 8) + (v[2] << 16) + (v[3] << 24)) >>> 0
   return `${txid}.${vout}`