There was no GC at W359.

However, I do not consider a replacement part of the ship to justify it as a new ship. In short, it’s a repair, as you said. 😎

We’ve only got successive script lines that suggest the saucers power systems are heavily damaged on dependent on stardrive and the stardrive takes two big hits to main engineering. The fact three Borg attacks take place would point to significant hull damage.

Enough to pause construction and fitting out of other GC to try and get ENTD back in shape. In my lore, there is a discussion about retiring ENTD due to the damage.

This is key to one of Trek’s misunderstandings.

Starfleet’s complacency wasn’t recent to 2340-2360s. It was acting: the massive fleet 'reset' started with the Galaxy family, it got caught out ‘in war & peace’, as you do. The complacency criticism is aimed at TMP/Lost Era.

Authors note: Most of the hybrid and trial Galaxy Class family ships were destroyed at Wolf 359. [A mix of TMP/Lost era with TNG]. This means the Galaxy Family has technically matured to its final models. It makes ships like the prototype Nebula very rare.

The ring is tech, a joint sensor/shield palette which also gives you the boundary of it. The module is just the bridge/deck one part.

Author notes: GALAXY cargo holds containing Borg debris. Damage to engines for pushing in the chase of ENTD/Borg require a short repair period including preparation for the mission that Starfleet has in mind to seek knowledge on the origin of the Borg cube that attacked Earth.

In a marathon meeting aboard ENTD, that included ENTD command staff, Starfleet Brass, GCP civilians and Federation Council executives, the decision to not retire ENTD is unanimous. The damage, while extensive, is recoverable, but if ENTD was the same again is an open question.

I have the OG files etc if that helps.