Draft-mode enables your thoughts to flow into your drafts by disabling the ability to edit what you've already written and inserting any new text always at the end of the buffer.
Using draft-mode usually results in pretty rough drafts with a ton of
typing errors, but makes it harder to forget things that could be lost
when focusing on editing and restructuring text. draft-mode is a minor
mode and can be used with any major mode.
Add draft-mode.el to your load-path:
(add-to-list 'load-path "~/.emacs.d/vendor/draft-mode")
Alternatively you can install it from Melpa with
M-x package-install draft-mode
Enabling draft-mode should work on most buffers:
M-x draft-mode