fix: make initializeNewAccount polymorphic so subclasses get their own runtime type

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Bug Fixes
 
+- **`SafeAccountV1_5_0_M_0_3_0.initializeNewAccount` returns the right runtime type.** The subclass factory delegated to `SafeAccountV0_3_0.initializeNewAccount`, which hard-coded `new SafeAccountV0_3_0(...)`, so the returned instance failed `instanceof SafeAccountV1_5_0_M_0_3_0` and lost subclass behavior. The base factory now instantiates polymorphically through `new this(...)`, so any subclass (including consumer-defined ones) gets its own type back. Detached calls (the factory extracted into a bare function, where strict-mode `this` is undefined) fall back to constructing the base class, preserving the previous behavior for plain-JS callers. (#116)
 - **Legacy transaction `v` precision for chain IDs above 2^53.** `createAndSignLegacyRawTransaction` computed the EIP-155 `v` field via `Number(chainId)`, silently rounding large chain IDs and producing a transaction whose signature recovers to the wrong sender. The computation now stays in `BigInt`. (#128)
 - **`sendJsonRpcRequest` accepts Tenderly-style `simulation_results` responses again.** The transport refactor made the URL path return only when the JSON body has a `result` field, so non-standard endpoints answering with `{ simulation_results: ... }` fell through to the (undefined) `error` branch and threw a `TypeError`. The `simulation_results` branch is restored, matching the documented behavior and the `JsonRpcResponse` type. (#182)
 - **Gas estimation no longer mutates the caller's UserOperation.** `baseEstimateUserOperationGas` on `SafeAccount` and `Simple7702Account` (and their public `estimateUserOperationGas` wrappers) overwrote the operation's `signature` with a dummy and zeroed `maxFeePerGas`/`maxPriorityFeePerGas` in place, restoring the fees only on success. A bundler error left the caller's operation corrupted (zeroed fees, dummy signature). Estimation now runs on an internal shallow copy and the passed operation is never touched. (#132)

src/account/Safe/SafeAccountV0_3_0.ts

@@ -87,17 +87,25 @@ export class SafeAccountV0_3_0 extends SafeAccount {
 	 * The account address is deterministically computed but not yet deployed on-chain.
 	 * The first UserOperation sent will deploy it automatically via factory data.
 	 *
+	 * Instantiates through `new this(...)`, so subclasses calling this
+	 * factory (directly or via `super`) get an instance of the subclass,
+	 * not a plain SafeAccountV0_3_0. A detached call (the method extracted
+	 * into a bare function, where `this` is undefined) falls back to
+	 * constructing a SafeAccountV0_3_0, matching the pre-polymorphic
+	 * behavior.
+	 *
 	 * @param owners - Array of owner signers (at least one required)
 	 * @param overrides - Override default initialization values
-	 * @returns A SafeAccountV0_3_0 instance with factory data set for deployment
+	 * @returns An instance of the calling class with factory data set for deployment
 	 *
 	 * @example
 	 * const smartAccount = SafeAccountV0_3_0.initializeNewAccount(["0xOwnerAddress"]);
 	 */
-	public static initializeNewAccount(
+	public static initializeNewAccount<T extends typeof SafeAccountV0_3_0>(
+		this: T,
 		owners: Signer[],
 		overrides: InitCodeOverrides = {},
-	): SafeAccountV0_3_0 {
+	): InstanceType<T> {
 		let isInitWebAuthn = false;
 		let x = 0n;
 		let y = 0n;
@@ -122,7 +130,13 @@ export class SafeAccountV0_3_0 extends SafeAccount {
 				overrides.safeModuleSetupAddress ?? SafeAccountV0_3_0.DEFAULT_SAFE_MODULE_SETUP_ADDRESS,
 			);
 
-		const safe = new SafeAccountV0_3_0(accountAddress, {
+		// Plain-JS callers may invoke this factory detached
+		// (`const init = SafeAccountV0_3_0.initializeNewAccount; init(...)`),
+		// leaving strict-mode `this` undefined; fall back to this class so
+		// such calls keep working instead of throwing on `new this(...)`.
+		// biome-ignore lint/complexity/noThisInStatic: polymorphic factory; subclasses must get their own type back
+		const ctor = (this as T | undefined) ?? SafeAccountV0_3_0;
+		const safe: SafeAccountV0_3_0 = new ctor(accountAddress, {
 			safe4337ModuleAddress: overrides.safe4337ModuleAddress,
 			entrypointAddress: overrides.entrypointAddress,
 			onChainIdentifierParams: overrides.onChainIdentifierParams,
@@ -137,7 +151,7 @@ export class SafeAccountV0_3_0 extends SafeAccount {
 			safe.y = y;
 		}
 
-		return safe;
+		return safe as InstanceType<T>;
 	}
 
 	/**

src/account/Safe/SafeAccountV1_5_0_M_0_3_0.ts

@@ -97,10 +97,11 @@ export class SafeAccountV1_5_0_M_0_3_0 extends SafeAccountV0_3_0 {
 	 * @example
 	 * const smartAccount = SafeAccountV1_5_0_M_0_3_0.initializeNewAccount(["0xOwnerAddress"]);
 	 */
-	public static initializeNewAccount(
+	public static initializeNewAccount<T extends typeof SafeAccountV0_3_0>(
+		this: T,
 		owners: Signer[],
 		overrides: InitCodeOverrides = {},
-	): SafeAccountV1_5_0_M_0_3_0 {
+	): InstanceType<T> {
 		const modOverrides = {
 			...overrides,
 			safeAccountSingleton: overrides.safeAccountSingleton ?? Safe_L2_V1_5_0,
@@ -111,7 +112,11 @@ export class SafeAccountV1_5_0_M_0_3_0 extends SafeAccountV0_3_0 {
 				overrides.eip7212WebAuthnContractVerifierForSharedSigner ??
 				SafeAccountV1_5_0_M_0_3_0.DEFAULT_WEB_AUTHN_CONTRACT_VERIFIER,
 		};
-		return SafeAccountV0_3_0.initializeNewAccount(owners, modOverrides);
+		// `super` keeps `this` bound to the calling class, so the base
+		// factory's `new this(...)` constructs an instance of this class
+		// (SafeAccountV1_5_0_M_0_3_0 or a subclass), not SafeAccountV0_3_0.
+		// biome-ignore lint/complexity/noThisInStatic: polymorphic factory dispatch through super
+		return super.initializeNewAccount(owners, modOverrides) as InstanceType<T>;
 	}
 
 	/**

test/safe/initializeNewAccountRuntimeType.test.js

@@ -0,0 +1,52 @@
+// Unit tests for issue #116: SafeAccountV1_5_0_M_0_3_0.initializeNewAccount
+// must return a SafeAccountV1_5_0_M_0_3_0 instance at runtime, not a plain
+// SafeAccountV0_3_0. No network required.
+
+const ak = require("../../dist/index.cjs");
+
+const OWNER = "0x2222222222222222222222222222222222222222";
+
+describe("initializeNewAccount runtime type (#116)", () => {
+	test("SafeAccountV1_5_0_M_0_3_0.initializeNewAccount returns a SafeAccountV1_5_0_M_0_3_0", () => {
+		const account = ak.SafeAccountV1_5_0_M_0_3_0.initializeNewAccount([OWNER]);
+		expect(account).toBeInstanceOf(ak.SafeAccountV1_5_0_M_0_3_0);
+	});
+
+	test("instance address matches the class's createAccountAddress (v1.5.0 singleton)", () => {
+		const account = ak.SafeAccountV1_5_0_M_0_3_0.initializeNewAccount([OWNER]);
+		expect(account.accountAddress).toBe(ak.SafeAccountV1_5_0_M_0_3_0.createAccountAddress([OWNER]));
+	});
+
+	test("SafeAccountV0_3_0.initializeNewAccount still returns a plain SafeAccountV0_3_0", () => {
+		const account = ak.SafeAccountV0_3_0.initializeNewAccount([OWNER]);
+		expect(account).toBeInstanceOf(ak.SafeAccountV0_3_0);
+		expect(account).not.toBeInstanceOf(ak.SafeAccountV1_5_0_M_0_3_0);
+		expect(account.accountAddress).toBe(ak.SafeAccountV0_3_0.createAccountAddress([OWNER]));
+	});
+
+	test("a consumer subclass inheriting the factory gets its own type back", () => {
+		class CustomSafe extends ak.SafeAccountV0_3_0 {}
+		const account = CustomSafe.initializeNewAccount([OWNER]);
+		expect(account).toBeInstanceOf(CustomSafe);
+	});
+
+	// Plain-JS consumers may extract the factory into a bare function,
+	// leaving strict-mode `this` undefined. That worked before the
+	// polymorphic factory and must keep working (falling back to the
+	// pre-polymorphic behavior of constructing the base class).
+	test("detached base factory call still works and returns a SafeAccountV0_3_0", () => {
+		const init = ak.SafeAccountV0_3_0.initializeNewAccount;
+		const account = init([OWNER]);
+		expect(account).toBeInstanceOf(ak.SafeAccountV0_3_0);
+		expect(account.accountAddress).toBe(ak.SafeAccountV0_3_0.createAccountAddress([OWNER]));
+	});
+
+	test("detached subclass factory call still works with v1.5.0 defaults applied", () => {
+		const init = ak.SafeAccountV1_5_0_M_0_3_0.initializeNewAccount;
+		const account = init([OWNER]);
+		// Pre-polymorphic behavior: the wrapper class degrades to the base,
+		// but the v1.5.0 singleton/verifier overrides still apply.
+		expect(account).toBeInstanceOf(ak.SafeAccountV0_3_0);
+		expect(account.accountAddress).toBe(ak.SafeAccountV1_5_0_M_0_3_0.createAccountAddress([OWNER]));
+	});
+});