The manual described the signature-change refusal as though it were the
design. It is not, and session.ml already said so at the refusal: a
signature change should make a new version, leave old callers on the old
one, and warn at the stale sites. plan.org calls it signature generations
and stale-caller warnings, and it is milestone 7's unfinished half.
The struct-layout rejection is the decided one and stays. Conflating them
made a placeholder look like a rule.
The site's Emacs section is a key table and four paragraphs -- a
reference for someone who already knows the shape. This is the other
document: how to set it up, what the loop actually is, what each buffer's
own keys do, and what to do when something is refused.
The three buffer keymaps were never written down anywhere a user would
look; they were only in the define-key calls.
