adam-p/markdown-here ? reverse-engineered prompt

Build me a browser extension that lets me write email in Markdown and then turn it into nicely formatted rich text before I send it.

It should work in common webmail and in Thunderbird, with a simple way to trigger the conversion from a right click menu, a toolbar button, and a keyboard shortcut. I want it to handle normal Markdown formatting, code blocks with syntax highlighting, and it should be able to turn the formatted content back into the original Markdown if I need to edit it again. It should also support converting only a selected part of a message, since sometimes I only want to format one section of a reply.

Make the experience feel smooth in the compose window, and keep the original message content intact when replying. If you need to check current browser extension docs or compatibility details, look them up online.