Codable Models

Use Codable for JSON serialization. Add explicit CodingKeys when API field names differ from Swift property names, and use decodeIfPresent for optional fields.

struct UserResponse: Codable {
    let id: String
    let displayName: String
    let avatarUrl: String?

    enum CodingKeys: String, CodingKey {
        case id
        case displayName = "display_name"
        case avatarUrl = "avatar_url"
    }

    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        id = try c.decode(String.self, forKey: .id)
        displayName = try c.decode(String.self, forKey: .displayName)
        avatarUrl = try c.decodeIfPresent(String.self, forKey: .avatarUrl)
    }
}

Never force-unwrap decoded values. Use decodeIfPresent or provide defaults for fields that might be absent.