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chain_subscribeFinalizedHeads – Mythos JSON-RPC Method

Subscribes to GRANDPA-finalized block headers. Each notification contains the complete header, allowing backends to trigger settlement workflows as soon as blocks become irreversible.

Parameters

This subscription takes no parameters.

Returns

A subscription ID, followed by notifications containing header payloads.

Example (JavaScript)

import { ApiPromise, WsProvider } from '@polkadot/api';

const provider = new WsProvider('wss://api-mythos-archive.n.dwellir.com/YOUR_API_KEY');
const api = await ApiPromise.create({ provider });

const unsubscribe = await api.rpc.chain.subscribeFinalizedHeads((header) => {
console.log(`Finalized Mythos block #${header.number}:`, header.hash.toHex());
});

// Later, stop listening
// await unsubscribe();