When ChatGPT allowed me to calculate stress and load bearing tolerances for a camper based on different materials, suggesting better designs, with the math and sources to back it all up. Then it helped plan and fill out paperwork for a residential solar project, including full code-compliant electrical work, again with sources to verify. Then there was an open source app that wouldn't run on an old version of MacOS due to them not supporting older OSes, and a coding agent backported support for the old OS and got it up and running.