import Foundation public enum PerplexityAPIError: LocalizedError, Sendable, Equatable {    case missingToken    case invalidCookie    case invalidToken    case networkError(String)    case apiError(String)    case parseFailed(String)     public var errorDescription: String? {        switch self {        case .missingToken:            "Perplexity session token is missing. Please log into Perplexity in your browser."        case .invalidCookie:            "Perplexity manual cookie header is empty or invalid."        case .invalidToken:            "Perplexity session token is invalid or expired. Please log in again."        case let .networkError(message):            "Perplexity network error: \(message)"        case let .apiError(message):            "Perplexity API error: \(message)"        case let .parseFailed(message):            "Failed to parse Perplexity usage data: \(message)"        }    }}