Side by side or a diff view would be great.

Happy to see there's now a toggle between "your solution" and "optimal" once you've submitted. Makes it much easier to see what you missed.

I agree. Also, knowing the max score in advance would be better, so you know when to stop/whether to keep going.

I'm happy not knowing myself but the answer can be found easily in DevTools. All the max scores are there (for current and previous days only).

that gives away too much information, instead i'd go with something that tells you that you've found the best solution. you'll still be able to know whether or not to keep going, but you get no information that makes finding the ideal solution easier.

This is now implemented on daily levels! Click the link below your score after submission.

Thanks for the pleasant experience of providing a feedback loop for my suggestion, felt rewarding and the implementation works nicely.

Same.

I took a screenshot of my solution and the optimal one - and then I could compare like this.