Long-form entries for the two tasks the XPS24 session closed. Written for a
reader months from now with no memory of it, because these are the source
material for the blog post (#22) that was deliberately blocked on this outcome
so its ending could be 'it played' rather than 'it should'.

The through-line worth keeping: six blockers on the second machine and not one
of them produced an error message. A hijacking startup.scd, a quark cloned but
unregistered, tidal built against the wrong ghc, a 644 installer, no pip at all,
and a Pulsar package whose documented install command silently downgrades the
rig. Every one of them was invisible on the box the setup was written on, which
is the actual lesson: config that has only ever run on one machine has been
observed working, not tested.

Also recorded, because they are about the measuring instruments rather than the
rig: the doctor's coverage check counts bank names and so reported all 281 banks
present while 15 GB was still copying, and its fix text for missing units named a
tool that cannot install them. And the tilde traps -- File.exists('~/x') is
false, nowExecutingPath is nil inside waitForBoot -- each of which would have
turned a portability fix into a permanently-false guard.