The obvious reading is that the two gig-up scripts are forks that drifted. They
are not. gig-up.sh is a LAUNCHER (start things in order) and tools/gig-up.sh is
a GATE (14 assertions over the repo and the saved session) — two different tools
wearing one name. And a third, tools/gig-preflight.py, is already the gate over
the live machine; its own docstring says '--quiet (for gig-up.sh)', so the gate
was always meant to be called by the launcher and never was.

So the merge is a separation, not a diff: gig-up does, check-gig proves,
gig-up-window owns the terminal. Three entry points become two, each answering
one question, and the launcher ends by calling the gate — which makes today's
failure (a gate that existed but was unreachable from the path actually pressed)
structurally impossible.

Six phases, each independently revertable, and phase 0 is a harness because
neither script nor the preflight has any test coverage today. Nothing is deleted
until the phase replacing it has run on a real launch: a bad gig-up at a venue
is not recoverable under pressure.