Follow-up requested in #272. The credentials lock has in-process stale-lock coverage, but it does not yet exercise real cross-process concurrent writes. Add a focused regression test that spawns child processes writing different profiles to the same credentials file and asserts every profile survives.
Follow-up requested in #272. The credentials lock has in-process stale-lock coverage, but it does not yet exercise real cross-process concurrent writes. Add a focused regression test that spawns child processes writing different profiles to the same credentials file and asserts every profile survives.