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Transactions — HCS‑15 Builders

Note

  • These builders are for direct transaction construction (e.g., Standards Agent Kit, custom pipelines).
  • For most apps, prefer the higher‑level Node or Browser clients which wrap these builders.

Sources

Base Account — buildHcs15BaseAccountCreateTx​

Creates a base account with ECDSA key and EVM alias suitable for HCS‑15 usage.

Signature

buildHcs15BaseAccountCreateTx(params: {
  publicKey: PublicKey;
  initialBalance?: Hbar | number;
  maxAutomaticTokenAssociations?: number;
  accountMemo?: string;
}): AccountCreateTransaction

Node example

import { Client, PrivateKey, Hbar } from '@hashgraph/sdk';
import { buildHcs15BaseAccountCreateTx } from '@hashgraphonline/standards-sdk';

const client = Client.forTestnet().setOperator(process.env.HEDERA_ACCOUNT_ID!, process.env.HEDERA_PRIVATE_KEY!);
const key = PrivateKey.generateECDSA();
const tx = buildHcs15BaseAccountCreateTx({ publicKey: key.publicKey, initialBalance: new Hbar(1), accountMemo: 'HCS‑15 Base' });
const receipt = await (await tx.execute(client)).getReceipt(client);

Notes

  • Uses the SDK’s “ECDSA + alias” setter so an immutable EVM alias is assigned on creation.
  • Set maxAutomaticTokenAssociations if you expect many token airdrops.

Petal Account — buildHcs15PetalAccountCreateTx​

Creates a Petal (shadow) account that reuses the base account’s public key and does not set an alias.

Signature

buildHcs15PetalAccountCreateTx(params: {
  publicKey: PublicKey;                    // shared ECDSA key from base
  initialBalance?: Hbar | number;
  maxAutomaticTokenAssociations?: number;
  accountMemo?: string;
}): AccountCreateTransaction

Node example

import { Client, PrivateKey } from '@hashgraph/sdk';
import { buildHcs15PetalAccountCreateTx } from '@hashgraphonline/standards-sdk';

const client = Client.forTestnet().setOperator(process.env.HEDERA_ACCOUNT_ID!, process.env.HEDERA_PRIVATE_KEY!);
const baseKey = PrivateKey.generateECDSA();
const tx = buildHcs15PetalAccountCreateTx({ publicKey: baseKey.publicKey, initialBalance: 0.5, accountMemo: 'HCS‑15 Petal' });
const receipt = await (await tx.execute(client)).getReceipt(client);

Browser example

import type { DAppSigner } from '@hashgraph/hedera-wallet-connect';
import { PrivateKey } from '@hashgraph/sdk';
import { buildHcs15PetalAccountCreateTx } from '@hashgraphonline/standards-sdk';

async function createPetal(signer: DAppSigner) {
  const baseKey = PrivateKey.generateECDSA();
  const tx = buildHcs15PetalAccountCreateTx({ publicKey: baseKey.publicKey, initialBalance: 0.5 });
  const frozen = await tx.freezeWithSigner(signer);
  const res = await frozen.executeWithSigner(signer);
  const receipt = await res.getReceiptWithSigner(signer);
  return receipt.accountId?.toString();
}

Notes

  • Petal accounts are meant to be controlled by the same private key as the base—do not set an alias.
  • Combine with HCS‑11 to inscribe per‑Petal profiles and HCS‑10 to create per‑Petal communication topics.