> I might be wildly misreading the code, but it seems like [1,2,3,a,b,c] diffed with [a,b,c,1,2,3] is going to appear as six lines of replacement.

A bit of a pickle.

The challenge I experienced with this is that either there are 6 changes (line for line comparison) or there are 3 lines the same and three lines moved, but three lines moved means a deletion of 3 lines from the first sample and 3 lines of insertion later in the second sample, which is still 6 differences. The output reads very differently, but the number of differences is identical, which is no change in precision.