HCS‑18 API Reference

Sources

• Module folder: https://github.com/hashgraph-online/standards-sdk/tree/main/src/hcs-18
• base-client.ts: https://github.com/hashgraph-online/standards-sdk/blob/main/src/hcs-18/base-client.ts
• sdk.ts: https://github.com/hashgraph-online/standards-sdk/blob/main/src/hcs-18/sdk.ts
• browser.ts: https://github.com/hashgraph-online/standards-sdk/blob/main/src/hcs-18/browser.ts
• tx.ts: https://github.com/hashgraph-online/standards-sdk/blob/main/src/hcs-18/tx.ts
• types.ts: https://github.com/hashgraph-online/standards-sdk/blob/main/src/hcs-18/types.ts

Import Paths

import {
  HCS18Client,
  HCS18BrowserClient,
  DiscoveryOperation,
  type SDKHCS18ClientConfig,
  type BrowserHCS18ClientConfig,
  type DiscoveryMessage,
  type AnnounceData,
  type ProposeData,
  type RespondData,
  type CompleteData,
  type WithdrawData,
  buildHcs18DiscoveryMemo,
  buildHcs18CreateDiscoveryTopicTx,
  buildHcs18SubmitDiscoveryMessageTx,
  buildHcs18AnnounceMessage,
  buildHcs18ProposeMessage,
  buildHcs18RespondMessage,
  buildHcs18CompleteMessage,
  buildHcs18WithdrawMessage,
} from '@hashgraphonline/standards-sdk/hcs-18';

Enums

enum DiscoveryOperation { ANNOUNCE=0, PROPOSE=1, RESPOND=2, COMPLETE=3, WITHDRAW=4 }

Message Schema (canonical)

{ "p":"hcs-18", "op":0, "data": { /* per op */ }, "m":"optional" }

Node Client (HCS18Client)

constructor(config: SDKHCS18ClientConfig)

createDiscoveryTopic(options?: { ttlSeconds?: number; adminKey?: any; submitKey?: any; memoOverride?: string }): Promise<{ topicId: string }>

announce(params: { discoveryTopicId: string; data: AnnounceData; memo?: string }): Promise<{ receipt: import('@hashgraph/sdk').TransactionReceipt; sequenceNumber?: number }>
propose(params: { discoveryTopicId: string; data: ProposeData; memo?: string }): Promise<{ receipt: import('@hashgraph/sdk').TransactionReceipt; sequenceNumber?: number }>
respond(params: { discoveryTopicId: string; data: RespondData; memo?: string }): Promise<import('@hashgraph/sdk').TransactionReceipt>
complete(params: { discoveryTopicId: string; data: CompleteData; memo?: string }): Promise<import('@hashgraph/sdk').TransactionReceipt>
withdraw(params: { discoveryTopicId: string; data: WithdrawData; memo?: string }): Promise<import('@hashgraph/sdk').TransactionReceipt>

getDiscoveryMessages(topicId: string, options?: { limit?: number; order?: 'asc'|'desc' }): Promise<DiscoveryMessage[]>
isProposalReady(proposal: ProposeData): boolean

Source

• https://github.com/hashgraph-online/standards-sdk/blob/main/src/hcs-18/sdk.ts

Browser Client (HCS18BrowserClient)

Wallet‑signed equivalents for announce, propose, respond, complete, and withdraw.

Source

• https://github.com/hashgraph-online/standards-sdk/blob/main/src/hcs-18/browser.ts

Builders (tx.ts)

function buildHcs18DiscoveryMemo(ttlSeconds?: number, memoOverride?: string): string;
function buildHcs18CreateDiscoveryTopicTx(params: { ttlSeconds?: number; adminKey?: any; submitKey?: any; operatorPublicKey?: import('@hashgraph/sdk').PublicKey; memoOverride?: string }): import('@hashgraph/sdk').TopicCreateTransaction;
function buildHcs18SubmitDiscoveryMessageTx(params: { topicId: string; message: DiscoveryMessage; transactionMemo?: string }): import('@hashgraph/sdk').TopicMessageSubmitTransaction;
function buildHcs18AnnounceMessage(data: AnnounceData): DiscoveryMessage;
function buildHcs18ProposeMessage(data: ProposeData): DiscoveryMessage;
function buildHcs18RespondMessage(data: RespondData): DiscoveryMessage;
function buildHcs18CompleteMessage(data: CompleteData): DiscoveryMessage;
function buildHcs18WithdrawMessage(data: WithdrawData): DiscoveryMessage;

Source

• https://github.com/hashgraph-online/standards-sdk/blob/main/src/hcs-18/tx.ts

Example

const c = new HCS18Client({ network: 'testnet', operatorId, operatorKey });
const topicId = await c.createDiscoveryTopic({ ttlSeconds: 300 }).then(r => r.topicId);
await c.announce({ discoveryTopicId: topicId!, data: { account: '0.0.111', petal: { name: 'A', priority: 700 }, capabilities: { protocols: ['hcs-16','hcs-18'] } } });