@solana/keychain-crossmint

Crossmint wallet signer for Solana transactions using Crossmint Wallets API.

Installation

pnpm add @solana/keychain-crossmint

Usage

import { createCrossmintSigner } from '@solana/keychain-crossmint';

const signer = await createCrossmintSigner({
    apiKey: process.env.CROSSMINT_API_KEY!,
    walletLocator: process.env.CROSSMINT_WALLET_LOCATOR!,
});

Configuration

| Field | Type | Required | Default | Description | |-------|------|----------|---------|-------------| | apiKey | string | Yes | - | Crossmint API key | | walletLocator | string | Yes | - | Crossmint wallet locator | | apiBaseUrl | string | No | https://www.crossmint.com/api | Base URL for Wallets API | | pollIntervalMs | number | No | 1000 | Poll interval for managed transaction flow | | maxPollAttempts | number | No | 60 | Max poll attempts before timeout | | signer | string | No | - | Optional delegated signer locator |

Behavior Notes

1. Crossmint executes transactions server-side and sponsors gas, which makes it the fee payer, so the message it signs generally differs from the one you submitted. Use signAndSendTransactions() (or signAndSendTransactionMessageWithSigners()): the returned value is the landed transaction's fee-payer signature, the identifier you can pass to getTransaction/confirmTransaction, not a signature over your message bytes. Under sponsorship the fee payer is Crossmint's sponsor key; your wallet's own signature is verified internally before the identifier is returned.
2. The signer is a SolanaSendingSigner (from @solana/keychain-core): it exposes no signTransactions and no signMessages. Kit classifies signers by method presence, so their absence is what routes the signer through Kit's sending flow instead of partial signing. Crossmint does not support message signing for Solana wallets.
3. Because it is a sending signer, it cannot be installed as a Kit client payer/identity (@solana/keychain-kit-plugin rejects the config at compile time). Call it directly, or via signAndSendTransactionMessageWithSigners().
4. Not retry-safe: any failure after the create is accepted rejects with SIGNER_BROADCAST_UNCONFIRMED carrying context.providerTransactionId; check that transaction with Crossmint before retrying. Each create carries an x-idempotency-key derived from the message bytes, so retrying the exact same bytes cannot create a second Crossmint transaction; a retry built with a fresh blockhash is a new transaction.

const [signature] = await signer.signAndSendTransactions([transaction]);

License

MIT