@novasamatech/host-api-wrapper

An easy way to embed Polkadot host functionality into your dapp.

Overview

Product SDK provides a set of tools to integrate your application with any Polkadot host application. Core features:

• Generic injectWeb3 provider similar to polkadot-js extension
• Chat module integration
• Statement store integration
• Accounts provider for product accounts and signing
• Redirect PAPI requests to host application
• Receive additional information from host application - supported chains, theme, etc.
• Local storage for persisting data in the host application
• Preimage manager for looking up and submitting preimages

Installation

npm install @novasamatech/host-api-wrapper --save -E

Usage

Injecting account provider into injectedWeb3 interface

Product SDK can provide account information and signers with the same interface as any other Polkadot-compatible wallet.

import { injectSpektrExtension, SpektrExtensionName } from '@novasamatech/host-api-wrapper';
import { connectInjectedExtension, type InjectedPolkadotAccount } from '@polkadot-api/pjs-signer';

async function getSpektrExtension() {
  const ready = await injectSpektrExtension();

  if (ready) {
    return connectInjectedExtension(SpektrExtensionName)
  }

  return null;
}

async function getAccounts(): Promise<InjectedPolkadotAccount[]> {
  const extension = await getSpektrExtension();

  if (extension) {
    return extension.getAccounts()
  }

  // fallback to other providers
  return [];
}

Redirecting PAPI requests to host application

You can wrap your PAPI provider with Spektr provider to support redirecting requests to the host application.

import { createClient, type PolkadotClient } from 'polkadot-api';
import { getWsProvider } from 'polkadot-api/ws-provider';
import { createPapiProvider, WellKnownChain } from '@novasamatech/host-api-wrapper';

function createPapiClient(): PolkadotClient {
  const polkadotEndpoint = 'wss://...';

-  const provider = getWsProvider(polkadotEndpoint);
+  const provider = createPapiProvider({
+    chainId: WellKnownChain.polkadotRelay,
+    fallback: getWsProvider(polkadotEndpoint),
+  });

  return createClient(provider);
}

Subscribing host connection status

import { metaProvider } from '@novasamatech/host-api-wrapper';

const unsubscribe = metaProvider.subscribeConnectionStatus((status) => {
  console.log('connection status changed', status);
});

Chat Integration

import { createProductChatManager } from '@novasamatech/host-api-wrapper';

// Create manager instance
const chat = createProductChatManager();

// Register your product as a chat contact
const roomRegistrationStatus = await chat.registerRoom({
  roomId: 'my-product-room',
  name: 'My Product',
  icon: 'https://example.com/icon.png'
});

// Register your product as a chat bot
const botRegistrationStatus = await chat.registerBot({
  botId: 'my-product-bot',
  name: 'My Product',
  icon: 'https://example.com/icon.png'
});

// Send a message
const { messageId } = await chat.sendMessage('my-product-room', {
  tag: 'Text',
  value: 'Hello dear user!'
});

// Subscribing to chat actions (incoming messages, etc.)
const subscriber = chat.subscribeAction((action) => {
  console.log('Room:', action.roomId);
  console.log('Sender:', action.peer);

  const payload = action.payload;

  if (payload.tag === 'MessagePosted') {
    console.log('Received message:', action.value);
  }
  if (payload.tag === 'ActionTriggered') {
    console.log('User triggered action:', action.value)
  }
});

// Subscribing to chat room list updates
const chatListSubscriber = chat.subscribeChatList((rooms) => {
  console.log('Chat rooms updated:', rooms);
});

// Sending a custom message
await chat.sendMessage('my-product-room', {
  tag: 'Custom',
  value: { messageType: 'my-custom-type', payload: new Uint8Array([/* ... */]) }
});

// Handling custom message rendering requests from host
const unsubscribeRenderer = chat.onCustomMessageRenderingRequest((messageType, payload, render) => {
  // Build a CustomRendererNode tree and pass it to render()
  render({
    tag: 'Text',
    value: {
      modifiers: undefined,
      props: { style: undefined, color: undefined },
      children: [{ tag: 'String', value: 'Custom message content' }],
    },
  });

  return () => {
    // cleanup when subscription ends
  };
});

Note: Messages sent before registration will be queued and sent automatically after successful registration.

Statement Store

The Statement Store provides a decentralized way to store statements (messages). It can be used for various purposes like p2p communication, storing temp data, etc.

import { createStatementStore } from '@novasamatech/host-api-wrapper';
import type {
  Topic,
  Statement,
  SignedStatement,
  StatementTopicFilter,
  ProductAccountRef,
} from '@novasamatech/host-api-wrapper';

// Create statement store instance
const statementStore = createStatementStore();

// Define topics (32-byte identifiers) to categorize statements
const topic: Topic = new Uint8Array(32);

// Subscribe to statements matching ALL listed topics (AND semantics)
const filter: StatementTopicFilter = { matchAll: [topic] };
const subscription = statementStore.subscribe(filter, (page) => {
  // page.isComplete is true once the initial historical dump is done
  console.log('Received statements:', page.statements, 'synced:', page.isComplete);
});

// Create a proof for a new statement
// [DotNS identifier, account selector]. The selector is a plain index or a raw
// 32-byte index (RFC 0022).
const accountId: ProductAccountRef = ['product.dot', 0];
const statement: Statement = {
  proof: undefined,
  decryptionKey: undefined,
  priority: undefined,
  channel: undefined,
  topics: [topic],
  data: new Uint8Array([/* your data */]),
};

const proof = await statementStore.createProof(accountId, statement);

// Submit a signed statement
const signedStatement: SignedStatement = {
  ...statement,
  proof,
};

await statementStore.submit(signedStatement);

// Unsubscribe when done
subscription.unsubscribe();

Accounts Provider

The Accounts Provider allows you to access product accounts and create signers for signing transactions.

import { accounts } from '@novasamatech/host-api-wrapper';
import type { ProductAccount, ProofContext } from '@novasamatech/host-api-wrapper';

// Get the user's primary DotNS username (RFC-0014)
// — prompts for permission on first call
const userIdResult = await accounts.getUserId();

if (userIdResult.isOk()) {
  const { primaryUsername } = userIdResult.value;
  console.log('Primary username:', primaryUsername);
} else {
  const err = userIdResult.error;
  if (err.tag === 'NotConnected') {
    console.log('User is not logged in');
  } else if (err.tag === 'PermissionDenied') {
    console.log('User denied disclosure of their primary username');
  }
}

// Request login — triggers host sign-in UI; reason is shown to the user
const loginResult = await accounts.requestLogin('Sign in to access your account');

if (loginResult.isOk()) {
  const outcome = loginResult.value; // 'success' | 'alreadyConnected' | 'rejected'
  if (outcome === 'rejected') {
    console.log('User cancelled login');
  }
} else {
  console.error('Login error:', loginResult.error);
}

// Get a product account by DotNS identifier and account selector. The selector
// is a plain index (the primary, enumerable form) or a raw 32-byte index
// (RFC 0022); it defaults to index 0, the product's default account.
const accountResult = await accounts.getProductAccount('product.dot', 0);
// …or, for a byte-valued selector:
// const accountResult = await accounts.getProductAccount('product.dot', raw32);

if (accountResult.isOk()) {
  const account: ProductAccount = accountResult.value;
  console.log('Public key:', account.publicKey);
}

// Ring VRF: a contextual alias and a proof are addressed by an explicit member
// key handle, a product-scoped `context` (`[productId, suffix]`) and a `ring`
// location on a chain (RFC 0004, amended by RFC 0024). The suffix is the same
// selector as an account's derivation index and expands to the same 32-byte
// value (RFC 0022).
const context: ProofContext = ['product.dot', 0]; // [productId, selector]
const ring = {
  chainId: '0x…', // 32-byte chain genesis hash
  junctions: [{ tag: 'PalletInstance', value: 42 }],
};

// Register a key your own product owns for that ring. Permissionless and
// prompt-free — ownership is the calling product, never a parameter. Returns the
// member public key. Registering the same index for another ring extends the
// existing entry rather than adding a second one.
const registerResult = await accounts.registerRingVrfKey(0, ring);

// Discover another product's keys. Handles are opaque: select by the rings an
// entry declares, NEVER by index — the index is the owner's implementation
// detail and hardcoding it breaks the moment the owner rotates or adds a key.
const keysResult = await accounts.listRingVrfKeys('peopl.dot'); // 'Anonymized' by default
const personKey = keysResult.isOk()
  ? keysResult.value.find(entry => entry.rings.some(r => r.chainId === ring.chainId))
  : undefined;

// A key handle for one of your own keys — for a foreign key use the handle from
// `listRingVrfKeys` verbatim instead.
import { ringVrfKeyHandle } from '@novasamatech/host-api-wrapper';

const ownHandle = ringVrfKeyHandle('product.dot', 0);

// Get the contextual alias for that (handle, context, ring).
const aliasResult = await accounts.getContextualAlias(ownHandle, context, ring);

if (aliasResult.isOk()) {
  const { context: contextBytes, alias } = aliasResult.value;
  console.log('Alias:', alias);
}

// Create a ring VRF proof binding `message` with an explicit member key.
// A proof is a bearer token for its context's alias, so a *foreign* handle is
// admitted only when its owner allowlisted your product in its manifest — there
// is no user-prompt fallback, and you get `NotAllowlisted` otherwise.
const proofResult = await accounts.createRingVRFProof(ownHandle, context, ring, new Uint8Array([0x48, 0x69]));

if (proofResult.isOk()) {
  const { proof, contextualAlias, ringIndex, ringRevision } = proofResult.value;
  console.log('Proof:', proof, 'at ring index', ringIndex, 'revision', ringRevision);
}

// Sign with the member key itself rather than proving membership anonymously
// (RFC 0024). No context and no ring: it derives no alias and proves nothing, so
// there is nothing for either to scope. Verified against the member public key,
// which makes the signature linkable to every other use of that key.
const signatureResult = await accounts.ringVrfSign(ownHandle, new Uint8Array([0x48, 0x69]));

// sr25519 VRF signature over a product account (RFC-0023). The transcript is a
// recipe — a root label plus ordered `(label, value)` items — that the host
// replays verbatim (`Transcript::new(label)` then one `append_message` per item)
// and signs. It never injects a `signer` item; pass the account's public key
// yourself if the transcript needs one.
import type { VrfTranscriptItem } from '@novasamatech/host-api-wrapper';

const transcriptLabel = new TextEncoder().encode('my-product-lottery');
const items: VrfTranscriptItem[] = [{ label: new TextEncoder().encode('round'), value: new Uint8Array([7]) }];

const vrfResult = await accounts.signVrf('product.dot', 0, transcriptLabel, items);

if (vrfResult.isOk()) {
  const { preOutput, proof } = vrfResult.value; // 32-byte VRFPreOut, 64-byte VRFProof
  console.log('VRF pre-output:', preOutput, 'proof:', proof);
} else {
  // err.tag: 'NotConnected' | 'Rejected' | 'Unknown'
  console.error('signVrf failed:', vrfResult.error.tag);
}

// Get legacy accounts (external wallets)
const legacyAccountsResult = await accounts.getLegacyAccounts();

if (legacyAccountsResult.isOk()) {
  console.log('Legacy accounts:', legacyAccountsResult.value);
}

// Subscribe to account connection status changes
const unsubscribe = accounts.subscribeAccountConnectionStatus((status) => {
  // status: 'connected' | 'disconnected'
  console.log('Account connection status:', status);
});

// Create a signer for a product account (for use with PAPI).
// Resolve the account first, then hand it to the signer factory.
const productAccountResult = await accounts.getProductAccount('product.dot', 0);

if (productAccountResult.isOk()) {
  const productSigner = accounts.getProductAccountSigner(productAccountResult.value);
  const signedTx = await tx.signAndSubmit(productSigner);
}

// Create a signer for a legacy account.
// Fetch the legacy account list, pick one, then pass it to the signer factory.
const legacyAccountsResult = await accounts.getLegacyAccounts();

if (legacyAccountsResult.isOk()) {
  const [legacyAccount] = legacyAccountsResult.value;
  if (legacyAccount) {
    const legacySigner = accounts.getLegacyAccountSigner(legacyAccount);
    const signedTx = await tx.signAndSubmit(legacySigner);
  }
}

If you need a non-default transport (e.g. for tests or multi-host setups), use createAccountsProvider(transport) to build your own instance with the same API.

Local Storage

The Local Storage module provides a way to persist data in the host application's storage.

import { hostLocalStorage, createLocalStorage } from '@novasamatech/host-api-wrapper';

// Use the default instance
const storage = hostLocalStorage;

// Or create a custom instance with a different transport
// const storage = createLocalStorage(customTransport);

// Write and read raw bytes
await storage.writeBytes('key', new Uint8Array([1, 2, 3]));
const bytes = await storage.readBytes('key');

// Write and read strings
await storage.writeString('greeting', 'Hello, World!');
const greeting = await storage.readString('greeting');

// Write and read JSON
await storage.writeJSON('config', { theme: 'dark', fontSize: 14 });
const config = await storage.readJSON('config');

// Clear a key
await storage.clear('key');

// Subscribe to a key. The callback fires with the current value right away,
// then on every later write or clear. `undefined` means the key is absent.
const sub = storage.subscribeBytes('key', (bytes) => {
  console.log('key changed:', bytes);
});
storage.subscribeString('greeting', (text) => console.log(text));
storage.subscribeJSON('config', (value) => console.log(value));

// Stop receiving updates
sub.unsubscribe();

Derive Entropy

The Derive Entropy function allows products to derive deterministic 32-byte entropy scoped to the product and a caller-chosen key.

import { deriveEntropy } from '@novasamatech/host-api-wrapper';

const result = await deriveEntropy(new Uint8Array([1, 2, 3]));

if (result.isOk()) {
  const entropy: Uint8Array = result.value;
  console.log('Derived entropy:', entropy);
}

Permissions

Products can request device and remote permissions from the host. Decisions are prompted once and persisted permanently — subsequent calls for the same permission resolve immediately without prompting.

import { requestDevicePermission, requestPermission } from '@novasamatech/host-api-wrapper';

// Request a single device permission
const deviceResult = await requestDevicePermission('Camera');
if (deviceResult.isOk()) {
  console.log('Camera granted:', deviceResult.value); // boolean
}

// Request remote permissions in a batch (single user prompt for all)
const remoteResult = await requestPermission([
  { tag: 'Remote', value: ['api.coingecko.com', '*.example.com'] },
  { tag: 'ChainSubmit', value: undefined },
]);
if (remoteResult.isOk()) {
  console.log('All remote permissions granted:', remoteResult.value); // boolean
}

Available device permission values: 'Notifications', 'Camera', 'Microphone', 'Bluetooth', 'NFC', 'Location', 'Clipboard', 'OpenUrl', 'Biometrics'.

Available remote permission tags: 'Remote' (HTTP/WS domain patterns), 'WebRTC', 'ChainSubmit', 'PreimageSubmit', 'StatementSubmit'.

Note: remote_chain_transaction_broadcast, remote_preimage_submit, and remote_statement_store_submit implicitly trigger a permission prompt if the relevant permission has not yet been resolved. Call requestPermission(...) proactively before entering those flows for a controlled UX.

Preimage Manager

The Preimage Manager allows you to lookup and submit preimages to the host application.

import { preimageManager, createPreimageManager } from '@novasamatech/host-api-wrapper';

// Use the default instance
const manager = preimageManager;

// Or create a custom instance with a different transport
// const manager = createPreimageManager(customTransport);

// Lookup a preimage by its hash key
const subscription = manager.lookup('0x1234...', (preimage) => {
  if (preimage) {
    console.log('Preimage found:', preimage);
  } else {
    console.log('Preimage not found');
  }
});

// Unsubscribe when done
subscription.unsubscribe();

// Submit a preimage
const preimageKey = await manager.submit(new Uint8Array([1, 2, 3, 4]));

Payment manager

import { createPaymentManager } from '@novasamatech/host-api-wrapper';

const payments = createPaymentManager();

// Subscribe to the user's payment balance (host will prompt for consent)
const balanceSub = payments.subscribeBalance(balance => {
  console.log('Available:', balance.available);
  console.log('Pending:', balance.pending);
});
balanceSub.onInterrupt(() => console.log('Balance access denied or lost'));

// Top up the user's balance from one of the calling product's accounts.
// `derivationIndex` is the same selector as `accounts.getProductAccount` takes:
// a plain index or a raw 32-byte index (RFC 0022).
//
// The last argument is a product-chosen, opaque 32-byte id. It makes the call
// idempotent — a retry with the same id rejects with
// `PaymentTopUpErr.AlreadyExists` instead of starting a second top up — and it
// is the handle the status subscription is opened on. Persist it before
// calling, so a product that dies mid-flight can pick the outcome back up: the
// host drives a registered top up to a terminal status on its own, across a
// full host restart, and keeps that status indefinitely.
const topUpId = crypto.getRandomValues(new Uint8Array(32));

// Resolves once the host has registered the top up, not when the funds land.
// Rejects with `PaymentTopUpErr.SourceBusy` if the source still carries a top up
// that has not reached a terminal status — one live top up per source.
await payments.topUp(1_000_000n, { type: 'productAccount', derivationIndex: 0 }, topUpId);

// Track the outcome. `claimed` with `finalized: true`, `claimedPartially` and
// `notClaimed` are terminal — nothing is sent, and nothing is done, after them.
const topUpSub = payments.subscribeTopUpStatus(topUpId, status => {
  switch (status.type) {
    case 'detecting':
      return console.log('Waiting for the funds to appear on the source');
    case 'claiming':
      return console.log('Claim in progress');
    case 'claimed':
      return console.log(status.finalized ? 'Claimed and finalized' : 'Claimed at best head');
    case 'claimedPartially':
      // The source never held enough to cover the request — send it the
      // remainder and register a new top up.
      return console.log('Only claimed', status.actualClaimed);
    case 'notClaimed':
      // The host never observed any balance at the source.
      return console.log('Nothing could be claimed');
  }
});
topUpSub.onInterrupt(reason => console.log('Top up status lost:', reason));

// Request a payment from the user's balance to a destination account (host
// shows confirmation UI). Like `topUp`, the product supplies an opaque 32-byte
// id: a retry with the same id rejects with `PaymentRequestErr.AlreadyExists`
// instead of paying twice, and the id is the handle the status subscription is
// opened on. Persist it before calling — the host drives a registered payment to
// a terminal status on its own, across a full host restart, and keeps that
// status indefinitely.
const destination = new Uint8Array(32); // 32-byte AccountId
const paymentId = crypto.getRandomValues(new Uint8Array(32));

// Resolves once the host has registered the payment, not when it settles.
await payments.requestPayment(500_000n, destination, paymentId);

// Track settlement. `completed`, `failed` and `partiallyClaimed` are terminal.
const statusSub = payments.subscribePaymentStatus(paymentId, status => {
  switch (status.type) {
    case 'processing':
      return console.log('Payment in progress');
    case 'completed':
      return console.log('Payment settled');
    case 'failed':
      return console.log('Payment failed:', status.reason);
    case 'partiallyClaimed':
      // Only part of the amount reached the destination.
      return console.log('Only delivered', status.actualClaimed);
  }
});
statusSub.onInterrupt(reason => console.log('Payment status lost:', reason));

Coin payment (RFC 0017)

Firewalled purses, cheques, and receivables. The long-running operations (rebalance, delete, deposit, refund, listen) stream clearing status through a callback and return a Subscription; onInterrupt fires with a CoinPaymentErr if the host tears the stream down.

import { createCoinPayment } from '@novasamatech/host-api-wrapper';

const coinPayment = createCoinPayment();

// Create a purse and read it back
const purse = await coinPayment.createPurse('Terminal purse');
const info = await coinPayment.queryPurse(purse);
console.log('balance:', info.balance);

// Pay a receivable with a cheque
const receivable = await coinPayment.createReceivable(purse);
const cheque = await coinPayment.createCheque(purse, receivable, 1000);

// Claim the cheque, watching the coins clear
const sub = coinPayment.deposit(cheque, status => {
  if (status.tag === 'Done') console.log('cleared:', status.value.cleared);
  if (status.tag === 'Failed') console.log('failed:', status.value.error);
});
sub.onInterrupt(err => console.log('deposit interrupted:', err));

// Wait for a cheque delivered over a standard channel
coinPayment.listenForPayment(receivable, item => {
  if (item.tag === 'Cheque') console.log('received cheque:', item.value.amount);
});