Backend part

• GET routes are updated and returns a post_processed_body or something equivalent
• POST route now support a format key with text|commonmark key (check in tracker for second key name)
• add a forgeupgrade to flag all existing comments as text ones
• changes are applied on description and comment

FrontEnd

• preview is returned by existing non rest route interpretecommonmark, to be called with fetch/result
• as of today we have 3 different implementation of preview in tracker, we should write a custom element only on help part (if design is consistent with tracker)
• we do have to many differences between behavior for the whole preview part so we'll need a full new dev
• when comment have code block it should be rendered with syntax highlighting (check what we did for tracker

Legacy

• REST route have inconsistent payload, we'll need to check with PO to check if we can suggest new payload

New comment won't be editable we'll do a dedicated story /!\ Description is already editable, we need to check that edit the description wont break markdown render of it