Confusing output when using output_metric="cosine"

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Hi there,

I'm getting some strange results when requesting the output metric of my results be "cosine", and I'm unsure whether it's my misinterpretation of what this is doing (probable) or a mistake in the code (less probable).
I assume that the output_metric argument means that this metric is the measure of distance to use to interpret the output points. As a test, I input a pre-calculated distance matrix:
[[0,1,2,1],
[1,0,1,2],
[2,1,0,1],
[1,2,1,0]]
which could describe 4 points, A,B,C,D, equally spaced around an origin point, measured with a cosine distance metric. I would therefore have expected the output points from UMAP to look something like that, and to have distance properties that closely match the input distance matrix.
Instead, I get 4 points all along the same line, which if I normalise, end up having almost the exact same coordinates, and therefore have a cosine distance of 0 between them all. Am I right in what I'm expecting as an output, or am I misinterpreting things?
One thing that seems to be missing is that a Euclidean space is unbounded, but cosine distance must be between 0 and 2, so I don't know how UMAP determines things to be as-far-apart-as-possible in a cosine distance metric space. Perhaps it's expecting points with an output distance of 2 in the cosine space to have a distance of 'Inf' in the input distance matrix and since the furthest distance in my matrix is 2, that's considered to be quite close? I can't see if there are any other input arguments to tell UMAP that 2 is actually the farthest apart two points can be - since it's a pre-calculated matrix, I can't give any more information about the distance matrix.

Danke,
BP

The issue names no source files or tests; begin by tracing how UMAP handles a precomputed distance matrix together with output_metric="cosine". Reproduce the four-point matrix case and determine whether the observed collinear output is expected behavior or a defect, then document or test the confirmed semantics.

Written by the indexing model from the issue text.