What Every Python Developer Should Know About the CPython ABI
This is the ABI explainer to send to someone who knows that binary wheels are painful but has never seen the contract underneath them. Nathan Goldbaum separates the Python C API from the ABI, maps the compatibility layers, and explains why the limited API can trade some access and performance for far fewer builds. The coming abi3t work matters because free-threaded CPython otherwise multiplies that packaging surface again.
The Hacker News reaction gets the educational value right: ABI is often repeated as vocabulary long before it is understood as a deployment constraint. The practical conclusion is not that every extension should use the stable ABI. It is that maintainers should choose deliberately between newest interpreter capabilities and a wheel strategy that keeps upgrades from becoming a distribution emergency.