HCS-18 Transactions

Note

• These builders are for direct transaction construction (e.g., with the Standards Agent Kit or custom pipelines).
• For most applications, prefer the higher‑level client (Node/Go) or browser client (wallet).

Sources

• TypeScript: GitHub
• Go: GitHub

Create Discovery Topic

TypeScript

import { buildHcs18CreateDiscoveryTopicTx } from '@hashgraphonline/standards-sdk';

const tx = buildHcs18CreateDiscoveryTopicTx({
  ttlSeconds: 300,
  adminKey: true,
  submitKey: true,
});

Go

import "github.com/hashgraph-online/standards-sdk-go/pkg/hcs18"

tx := hcs18.BuildCreateDiscoveryTopicTx(hcs18.CreateDiscoveryTopicTxParams{
	TTLSeconds: 300,
	AdminKey:   operatorPublicKey,
	SubmitKey:  operatorPublicKey,
})

response, _ := tx.Execute(hederaClient)

Submit Discovery Message

TypeScript

import { buildHcs18SubmitDiscoveryMessageTx } from '@hashgraphonline/standards-sdk';

const tx = buildHcs18SubmitDiscoveryMessageTx({
  topicId: '0.0.555',
  message: msg, // a DiscoveryMessage from one of the builders below
  transactionMemo: 'optional',
});

Go

tx, err := hcs18.BuildSubmitDiscoveryMessageTx("0.0.555", msg, "optional")
if err != nil {
	log.Fatal(err)
}

response, _ := tx.Execute(hederaClient)

Announce

TypeScript

import { buildHcs18AnnounceMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18AnnounceMessage({
  account: '0.0.123',
  petal: { name: 'A', priority: 700 },
  capabilities: { protocols: ['hcs-16', 'hcs-18'] },
  valid_for: 300,
});

Go

msg := hcs18.BuildAnnounceMessage(hcs18.AnnounceData{
	Account:  "0.0.123",
	Petal:    hcs18.PetalInfo{Name: "A", Priority: 700},
	Capabilities: hcs18.Capabilities{
		Protocols: []string{"hcs-16", "hcs-18"},
	},
	ValidFor: 300,
})

Propose

TypeScript

import { buildHcs18ProposeMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18ProposeMessage({
  proposer: '0.0.1',
  members: [{ account: '0.0.2', priority: 500 }],
  config: { name: 'Demo Flora', threshold: 2 },
});

Go

msg := hcs18.BuildProposeMessage(hcs18.ProposeData{
	Proposer: "0.0.1",
	Members:  []hcs18.ProposeMember{{Account: "0.0.2", Priority: 500}},
	Config:   hcs18.ProposeConfig{Name: "Demo Flora", Threshold: 2},
})

Respond

TypeScript

import { buildHcs18RespondMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18RespondMessage({
  responder: '0.0.2',
  proposal_seq: 10,
  decision: 'accept',
});

Go

msg := hcs18.BuildRespondMessage(hcs18.RespondData{
	Responder:   "0.0.2",
	ProposalSeq: 10,
	Decision:    "accept",
})

Complete

TypeScript

import { buildHcs18CompleteMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18CompleteMessage({
  proposer: '0.0.1',
  proposal_seq: 10,
  flora_account: '0.0.500',
  topics: { communication: '0.0.600', transaction: '0.0.601', state: '0.0.602' },
});

Go

msg := hcs18.BuildCompleteMessage(hcs18.CompleteData{
	Proposer:     "0.0.1",
	ProposalSeq:  10,
	FloraAccount: "0.0.500",
	Topics: hcs18.FloraTopics{
		Communication: "0.0.600",
		Transaction:   "0.0.601",
		State:         "0.0.602",
	},
})

Withdraw

TypeScript

import { buildHcs18WithdrawMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18WithdrawMessage({
  account: '0.0.2',
  announce_seq: 42,
  reason: 'going offline',
});

Go

msg := hcs18.BuildWithdrawMessage(hcs18.WithdrawData{
	Account:     "0.0.2",
	AnnounceSeq: 42,
	Reason:      "going offline",
})

Notes

• Use the builders to ensure the p: 'hcs-18' and op fields are correct.
• Builders return typed messages; pair with BuildSubmitDiscoveryMessageTx to create a signed transaction.