Some clarity on rotationQuats in BJS vs Unity

Questions
1

So if I have a transform node, where there is a parent and a child.

And I apply any sort of negitive scale to the parent node like (1,1,-1) and recalculate the nodes rotationQuat I get different results in Unity vs BJS even if the forward right up vectors of the Node are identical.

Ive noticed BJS will ne q.wzyx with the y being inverted while unity will be q.xyzw. Is there something I am missing about recalculating quats after a scale like that?

Is there something the two systems are doing different?

2

Ok I figured out that unity is ZXY axis rotation order and we are YXZ?

so I guess just manually simulate that order on my rotations.

Found what I am looking for with addRotation.

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