@usebutr/polkadot

Discovery

discoverInjectedPolkadotAdapters(onAdapter, options?) reads window.injectedWeb3 without prompting. It returns an unsubscribe function that cancels pending polls. InjectedPolkadotDiscoveryOptions accepts pollMs (offsets in milliseconds; default [250, 750]) and target (a host override for tests or iframes).

import { createWalletSource } from "@usebutr/core";
import { discoverInjectedPolkadotAdapters } from "@usebutr/polkadot";

export const discovery = createWalletSource(discoverInjectedPolkadotAdapters);

discoverPolkadotWalletStandardAdapters(onAdapter) discovers wallets advertising polkadot:* features. This path requires @wallet-standard/app. polkadotDiscoverer is the PlatformDiscoverer used by autoDiscovery(): injectedWeb3 is primary, and Wallet Standard is a deferred fallback when no primary adapter has been found.

Adapter builders

• buildInjectedPolkadotAdapter(extensionName, displayName, provider) creates a Polkadot adapter. connect() enables the extension; construction does not.
• buildPolkadotWalletStandardAdapter(wallet, registerDisconnector) creates an adapter for a compatible Wallet Standard wallet, or returns null.

Signer

Injected adapters return PolkadotSignerHandle from getSigner():

import { isPolkadotSignerHandle } from "@usebutr/polkadot";
import type { ConnectedWallet } from "@usebutr/core";

export const getInjectedSigner = async (wallet: ConnectedWallet) => {
  const signer = await wallet.connector.getSigner();
  if (!isPolkadotSignerHandle(signer)) {
    throw new Error("This wallet does not expose an injectedWeb3 signer");
  }
  return signer.extension.signer;
};

The handle carries address (SS58), extensionName (the injected registry key), and extension (the enabled provider). Wallet Standard adapters return the Wallet Standard wallet instead. See the PAPI integration for transaction construction and submission.

Capabilities

resolveInjectedPolkadotCapabilities() enables message signing, subscriptions, and local chain switching. resolveWalletStandardPolkadotCapabilities(input) uses advertised message-signing and event features plus the chain count. Neither path advertises standalone transaction signing or sending.

Injected message signing wraps bytes in <Bytes>…</Bytes> before signRaw. Verify the returned signedMessage, which contains that wrapper.

Chains

POLKADOT_CHAINS has polkadot, kusama, paseo, and westend entries; POLKADOT_CHAINS_LIST is their array form. CAIP-2 identifiers use the polkadot: namespace and the first 32 hexadecimal characters of the genesis hash. Accounts retain their SS58 address.

switchChain() changes butr's local chain context; it does not switch an RPC connection. Injected wallets default to Polkadot. Use Paseo for the demo.

No RPC

Balance reads, receipts, extrinsic construction, and submission belong to your chain client. Use getSigner() with PAPI; the adapter does not fetch chain metadata.

Types

InjectedPolkadotDiscoveryOptions, PolkadotSignerHandle, WalletStandardPolkadotCapabilityInput, PolkadotSignMessageFeature, PolkadotSignMessageInput, and PolkadotSignMessageOutput.

Source: packages/polkadot/src/index.ts.