When working with lockfiles (pants 2,13, using poetry lock files) is there a way to tell which first party dependency is responsible for a given transitive dependency (pypi packages) ?

Not that I can think of, but that would be a really great feature to have, since this info is all available in the lockfile.

in lockfiles generated by pip-compile this info is in the comments. not sure if the poetry or pex lock file have the option to include this info.

pex lockfile has this explicitly in the graph structure, afaik