Yes, this sounds like a good idea. You should also be able to choose if new blocks should have auto detection turned on or off.

Yeah, auto detection features seems a little bit weird that is not detecting on the fly. I think the user have to use the split command to split some contents when create a block so that the auto detection can work correctly? Otherwise it's always plain text.

Auto-detection is detecting on the fly, but for performance reasons, it's not done on every single keystroke. Instead, the auto-detection only runs when a significant portion of the block has changed. That is when the Levenshtein distance between the last check and the new content is greater than 10% of the length of the block content.

Otherwise it's always plain text.

For me it is the same. Tested to start a block writing markdown, but after ten lines of markdown text, language is still Plain Text (auto).
Maybe detecting markdown is corrupted?

Same here - no matter the number of lines of markdown in a block. When splitting to a new block it's back to plain text. Being able to state a default language would be great. Then without such a default then current behavior can persist.

Many thanks for this great software.