I'm not sure why a contract would have a sentience of its own. The box expresses a desire to remain with the characters. It doesn't want to fall into the gith patrol hands any more than it wants to be taken by the Absolute, which the narrator tells us in the scene with the githyanki.
Regarding the infernal puzzle box possibility... maybe. I mean, it certainly seems similar'ish in nature, but it's worth noting that it's covered in gith script as opposed to infernal.
Yes, I’d also assumed that the fact that the script was gith rather than infernal meant it wasn’t an infernal puzzle box, though I guess that might be explained and I can see there might be similarities.
But I agree that the sentience of the box implies there’s more in it than a contract. I’m not sure how big it would need to be to contain a consciousness or prison pocket dimension. Or possibly it is an infernal puzzle box containing a contract, but has a connection to a sentience that’s located elsewhere.
I had also assumed that Shadowheart’s secret mission was to steal the box from the gith (perhaps for Shar as a means of defeating the Absolute from whom I assume she’d not appreciate competition). But again, there are many more possibilities here!
EDIT: Of course, the box is also referred to as a “weapon†by both the Absolute and the githyanki dragon rider, at least I assume they’re referring to the box. I wonder in what sense a prison or contract could be a weapon? Of course, people who call it that might be misled or misleading, and I can think of possible ways those things *might* be weaponised.
