/**
 * Pick which wallet account signs. We must sign with the account the user
 * actually connected — never guess. A wrong signer produces a useless signature
 * for a payment, so we throw instead of silently falling back.
 */
export function resolveSigningAccount<T extends { address: string }>(
  accounts: ReadonlyArray<T>,
  connectedAddress: string | null | undefined
): T {
  if (connectedAddress) {
    const match = accounts.find(a => a.address === connectedAddress)
    if (!match) {
      throw new Error(
        'Connected Solana account not found in the wallet — refusing to sign with a different account'
      )
    }
    return match
  }
  // No explicit selection is only safe when the wallet has exactly one account.
  if (accounts.length === 1) return accounts[0]!
  throw new Error(
    'Cannot determine which Solana account to sign with — multiple accounts and none selected'
  )
}