Shiki would benefit from providing a pluggable plugin architecture.

Why?

• Modifications to the current HTML structure are only possible if someone uses renderHTML directly and provides their element definition.
• Modifications can be shared, but there are not built-in merge mechanisms if someone wants to apply their own modifications.
• By having plugins it frees project owners/contributors from work/requests - others can built themselves. ;-)
• It builds an ecosystem.

How?
Good question. I started to design an (opinionated) approach, you can look at it in #381