feat(utxo-core): improve fromFixedScriptWallet descriptor handling

Add support for handling all script types by returning null for unsupported
types like p2tr and p2trMusig2. Include type guard function to properly
verify supported script types.

This makes it more explicit which script types are supported and which ones
are not.

Issue: BTC-2170

Co-authored-by: llm-git <[email protected]>

Author: OttoAllmendinger

modules/utxo-core/src/descriptor/fromFixedScriptWallet.ts

@@ -1,8 +1,6 @@
 import * as utxolib from '@bitgo/utxo-lib';
 import { Descriptor, ast } from '@bitgo/wasm-miniscript';
 
-import { DescriptorMap } from './DescriptorMap';
-
 /** Expand a template with the given root wallet keys and chain code */
 function expand(rootWalletKeys: utxolib.bitgo.RootWalletKeys, keyIndex: number, chainCode: number): string {
   if (keyIndex !== 0 && keyIndex !== 1 && keyIndex !== 2) {
@@ -42,12 +40,28 @@ export function getDescriptorForScriptType(
   }
 }
 
-export function getNamedDescriptorsForRootWalletKeys(rootWalletKeys: utxolib.bitgo.RootWalletKeys): DescriptorMap {
-  const scriptTypes = ['p2sh', 'p2shP2wsh', 'p2wsh'] as const;
+function isSupportedScriptType(
+  scriptType: utxolib.bitgo.outputScripts.ScriptType2Of3
+): scriptType is 'p2sh' | 'p2shP2wsh' | 'p2wsh' {
+  return ['p2sh', 'p2shP2wsh', 'p2wsh'].includes(scriptType);
+}
+
+/**
+ * Get a map of named descriptors for the given root wallet keys.
+ * Unsupported script types will have a value of null.
+ * Currently supports p2sh, p2shP2wsh, and p2wsh script types.
+ * @param rootWalletKeys
+ */
+export function getNamedDescriptorsForRootWalletKeys(
+  rootWalletKeys: utxolib.bitgo.RootWalletKeys
+): Map<string, Descriptor | null> {
   const scopes = ['external', 'internal'] as const;
   return new Map(
-    scriptTypes.flatMap((scriptType) =>
-      scopes.map((scope) => [`${scriptType}/${scope}`, getDescriptorForScriptType(rootWalletKeys, scriptType, scope)])
+    utxolib.bitgo.outputScripts.scriptTypes2Of3.flatMap((scriptType) =>
+      scopes.map((scope) => [
+        `${scriptType}/${scope}`,
+        isSupportedScriptType(scriptType) ? getDescriptorForScriptType(rootWalletKeys, scriptType, scope) : null,
+      ])
     )
   );
 }

modules/utxo-core/test/descriptor/fromFixedScriptWallet.ts

@@ -19,7 +19,7 @@ const customPrefixes: (utxolib.bitgo.Triple<string> | undefined)[] = [
   ['1/2', '1/2', '1/2'], // Custom prefixes for testing
   ['1/2', '3/4', '5/6'], // Different custom prefixes
 ];
-const scriptTypes = ['p2sh', 'p2shP2wsh', 'p2wsh'] as const;
+const scriptTypes = utxolib.bitgo.outputScripts.scriptTypes2Of3;
 const scope = ['external', 'internal'] as const;
 const index = [0, 1, 2];
 
@@ -111,6 +111,10 @@ function runTestGetDescriptorMap(customPrefix: utxolib.bitgo.Triple<string> | un
         const key = `${scriptType}/${s}`;
         it(`should have a correct descriptor for ${key}`, function () {
           const descriptorFromMap = descriptorMap.get(key);
+          if (scriptType === 'p2tr' || scriptType === 'p2trMusig2') {
+            assert.equal(descriptorFromMap, null, `Descriptor for ${key} should be null`);
+            return;
+          }
           assert.ok(descriptorFromMap, `Descriptor for ${key} should exist`);
           const expectedDescriptor = getDescriptorForScriptType(rootWalletKeys, scriptType, s);
           assert.equal(descriptorFromMap.toString(), expectedDescriptor.toString());
@@ -124,7 +128,9 @@ customPrefixes.forEach((customPrefix) => {
   scriptTypes.forEach((scriptType) => {
     index.forEach((index) => {
       scope.forEach((scope) => {
-        runTestGetDescriptorWithScriptType(customPrefix, scriptType, index, scope);
+        if (scriptType !== 'p2tr' && scriptType !== 'p2trMusig2') {
+          runTestGetDescriptorWithScriptType(customPrefix, scriptType, index, scope);
+        }
       });
     });
   });