@parity/product-sdk-tx

--- package/src/dev-signers.ts (excerpt) ---
// Copyright 2026 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0
import { DEV_PHRASE } from "@polkadot-labs/hdkd-helpers";
import { seedToAccount } from "@parity/product-sdk-keys";
import type { PolkadotSigner } from "polkadot-api";

import type { DevAccountName } from "./types.js";

/**
 * Create a PolkadotSigner for a standard Substrate dev account.
 *
 * Dev accounts use the well-known Substrate dev mnemonic (`DEV_PHRASE`) with
 * Sr25519 key derivation at the path `//{Name}`. These accounts have known
 * private keys and are pre-funded on dev/test chains.
 *
 * Only for local development, scripts, and testing. Never use in production.
 *
 * @param name - Dev account name ("Alice", "Bob", "Charlie", "Dave", "Eve", or "Ferdie").
 * @returns A PolkadotSigner that can sign transactions.
 *
 * @example
 * ```ts
 * import { createDevSigner } from "@parity/product-sdk-tx";
 *
 * const alice = createDevSigner("Alice");
 * const result = await submitAndWatch(tx, alice);
 * ```
 */
export function createDevSigner(name: DevAccountName): PolkadotSigner {
    return seedToAccount(DEV_PHRASE, `//${name}`).signer;
}

/**
 * Get the public key bytes for a dev account.
 *
 * Useful for address derivation or identity checks in tests without
 * needing the full signer.
 *
 * @param name - Dev account name.
 * @returns 32-byte Sr25519 public key.
 */
export function getDevPublicKey(name: DevAccountName): Uint8Array {
    return seedToAccount(DEV_PHRASE, `//${name}`).pub