It’s the always-on REPL that’s the kicker.
(defun invert-case ()
(backward-delete-char-untabify 1)
(insert (funcall (if (< last-command-event ?a)
#'downcase
#'upcase)
last-command-event)))
(add-hook 'post-self-insert-hook #'invert-case)
Then C-u C-M-x
on invert-case
to convey the larger point that emacs is always running within a gdb-like harness. Your buddy will immediately bristle at the prohibitive investment necessary to achieve this pointless and trivial hack, at which point he’ll have truly grokked emacs.
For each pipeline and stage I have my own little literate org file
Damn, your verbose description checks all the boxes for a bullshit job.