feat(wasm-utxo): add helper functions for PSBT testing and OP_RETURN scripts

packages/wasm-utxo/js/fixedScriptWallet/chains.ts

@@ -21,10 +21,13 @@ const chainCodeSet = new Set<number>(chainCodes);
 const chainToMeta = new Map<ChainCode, { scope: Scope; scriptType: OutputScriptType }>();
 const scriptTypeToChain = new Map<OutputScriptType, { internal: ChainCode; external: ChainCode }>();
 
-// Initialize from WASM (called once at load time)
-function assertChainCode(n: number): ChainCode {
+/**
+ * Assert that a number is a valid chain code.
+ * @throws Error if the number is not a valid chain code
+ */
+export function assertChainCode(n: number): ChainCode {
   if (!chainCodeSet.has(n)) {
-    throw new Error(`Invalid chain code from WASM: ${n}`);
+    throw new Error(`Invalid chain code: ${n}`);
   }
   return n as ChainCode;
 }

packages/wasm-utxo/js/fixedScriptWallet/index.ts

@@ -5,8 +5,14 @@ export { RootWalletKeys, type WalletKeysArg, type IWalletKeys } from "./RootWall
 export { ReplayProtection, type ReplayProtectionArg } from "./ReplayProtection.js";
 export { outputScript, address } from "./address.js";
 export { Dimensions } from "./Dimensions.js";
-export { type OutputScriptType, type InputScriptType, type ScriptType } from "./scriptType.js";
-export { ChainCode, chainCodes, type Scope } from "./chains.js";
+export {
+  outputScriptTypes,
+  inputScriptTypes,
+  type OutputScriptType,
+  type InputScriptType,
+  type ScriptType,
+} from "./scriptType.js";
+export { ChainCode, chainCodes, assertChainCode, type Scope } from "./chains.js";
 
 // Bitcoin-like PSBT (for all non-Zcash networks)
 export {
@@ -61,3 +67,23 @@ import type { ScriptType } from "./scriptType.js";
 export function supportsScriptType(coin: CoinName, scriptType: ScriptType): boolean {
   return FixedScriptWalletNamespace.supports_script_type(coin, scriptType);
 }
+
+/**
+ * Create an OP_RETURN output script with optional data
+ *
+ * @param data - Optional data bytes to include in the OP_RETURN script
+ * @returns The OP_RETURN script as a Uint8Array
+ *
+ * @example
+ * ```typescript
+ * // Empty OP_RETURN
+ * const script = createOpReturnScript();
+ *
+ * // OP_RETURN with data
+ * const data = new Uint8Array([1, 2, 3, 4]);
+ * const script = createOpReturnScript(data);
+ * ```
+ */
+export function createOpReturnScript(data?: Uint8Array): Uint8Array {
+  return FixedScriptWalletNamespace.create_op_return_script(data);
+}

packages/wasm-utxo/js/fixedScriptWallet/scriptType.ts

@@ -1,30 +1,43 @@
 /**
- * Fixed-script wallet output script types (2-of-3 multisig)
+ * All output script types for fixed-script wallets (2-of-3 multisig)
  *
- * This type represents the abstract script type, independent of chain (external/internal).
+ * This represents the abstract script type, independent of chain (external/internal).
  * Use this for checking network support or when you need the script type without derivation info.
  */
-export type OutputScriptType =
-  | "p2sh"
-  | "p2shP2wsh"
-  | "p2wsh"
-  | "p2tr" // alias for p2trLegacy
-  | "p2trLegacy"
-  | "p2trMusig2";
+export const outputScriptTypes = [
+  "p2sh",
+  "p2shP2wsh",
+  "p2wsh",
+  "p2trLegacy",
+  "p2trMusig2",
+] as const;
 
 /**
- * Input script types for fixed-script wallets
+ * Output script type for fixed-script wallets
+ *
+ * Note: "p2tr" is an alias for "p2trLegacy" for backward compatibility.
+ */
+export type OutputScriptType = (typeof outputScriptTypes)[number] | "p2tr";
+
+/**
+ * All input script types for fixed-script wallets
  *
  * These are more specific than output types and include single-sig and taproot variants.
  */
-export type InputScriptType =
-  | "p2shP2pk"
-  | "p2sh"
-  | "p2shP2wsh"
-  | "p2wsh"
-  | "p2trLegacy"
-  | "p2trMusig2ScriptPath"
-  | "p2trMusig2KeyPath";
+export const inputScriptTypes = [
+  "p2shP2pk",
+  "p2sh",
+  "p2shP2wsh",
+  "p2wsh",
+  "p2trLegacy",
+  "p2trMusig2ScriptPath",
+  "p2trMusig2KeyPath",
+] as const;
+
+/**
+ * Input script type for fixed-script wallets
+ */
+export type InputScriptType = (typeof inputScriptTypes)[number];
 
 /**
  * Union of all script types that can be checked for network support