**Grade: 7**

### Bugs
- No apparent bugs identified in the current code.

### Optimizations
- Ensure consistency by renaming properties in the nested `CodingData` struct to match the public `Numbers` struct for easier understanding and maintainability, or vice versa.
- Provide validation for the initializer to prevent negative numbers if they are inappropriate for the application context.
- Consider defining default values or using optionals if there is a scenario where some of the values might not be available, rather than forcing the input of all integers.

### Good points
- The code correctly conforms to both `Hashable` and `Sendable` protocols, ensuring that the `Numbers` structure can be used in various collections and safely across concurrency boundaries if needed.
- It provides a clear structure and separation of responsibilities, making it easy to extend or modify without affecting other parts of the code.
- Good use of `Codable` for easy serialization and deserialization of data.

### Summary
The code is well-structured and achieves the intended functionality effectively. It defines a struct `Numbers` with a straightforward purpose of encapsulating user activity metrics, with the addition of a nested `CodingData` struct for encoding/decoding operations. However, property naming inconsistencies could be improved for better clarity, and additional input validations could enhance robustness. The implementation is clean and follows good practices in terms of data encoding and conforming to Swift protocols.

### Open source alternatives
- Swift's built-in `Decodable` and `Encodable` can be effectively used as alternatives to model JSON data without needing separate struct declarations.
- If using this as part of a larger application, consider frameworks like **SwiftJSON** or **Alamofire** for more comprehensive data handling.