Line trace between 2 objects that avoids obstacles

[Balaurul]

I have 2 objects. One of them has a large invisible sphere attached to it. The second object is also inside the sphere. I want to know if there is a path between these 2 objects without leaving the sphere.

Here, there is no path:

Here, there is a path:

Here, the path exceeds the bounds of the sphere so the result is no path:

This is happening in 3D space not 2D. The use of line trace was my idea, but feel free to use other low-cost methods to find the path.