>I have to wonder though... Is the sphere
>still fold-capable?
>
I don't think the sphere was ever fold-capable. You should have noticed that large number of Zentradi ships spaces equally around both the inside and outside of the sphere; it's been documented multiple places (including the original source material) that a ship's fold "envelope" is a sphere of a diameter somewhat larger than the largest dimension of the ship. As a result, if all of the ships in the Kridinik fleet synchronized their fold systems and essentially merged their fold envelopes, they folded and pulled they sphere along with it.

You're right that making a fold drive big enough for the ZCDS would be incredible. I'd argue that what the actually did to bring it to its present location is actually a greater feat of engineering...

Offsides

[...] in order to be a realist you must believe in miracles.
-- David Ben Gurion
EPU RCW #π
#include <stdsig.h>