But projeqtor is not a chat system.
Well, just in your previous message you wrote:
Activity stream is designed as a Chat interface, just to enter text.
That's why I was referring to chat systems.
Ok, I understand that you don't consider "rich text" support in the activity stream input box to be needed, so I don't want to push this.
However, just out of curiosity:
Markdown system would involve heavy coding to store text that can be read in notes, with html formating : so we'd have to ensure consistency between html dis^lay/coding and makdown display/coding. A real mess I don't want to enter into.
I think CKeditor works on the HTML DOM and you're probably storing HTML internally - is this the case? If so, then I'd expect it only to be necessary to convert Markdown to HTML (eg.
github.com/erusev/parsedown, FOSS under MIT license) once, when it's entered - afterwards, it will already be in the proper format for CKeditor if the note is edited again.