Structured archive entry for the session, written as standalone learning rather
than a board line. Fourteen findings, of which the four that will outlive the
task: SoundCloud accumulates generations and never replaces (so a stale upload
is permanent until deleted); the wrong cut wore the cover art, which is why
PLN's ear beat every tool to it; the 'matches to the second' tolerance was the
bug, because full_duration is millisecond-exact and a loose window made two
different cuts identical; and roll call cannot find a stray, because a check
that only looks where it expects a thing never discovers it elsewhere.

Written for a reader months out with no memory of any of it.