Python

Python’s “What’s New in 3.x” pages double as the known-issues file. Every release page includes a “Removed” and “Deprecated” section that operates as a list of things you will discover broke when you upgrade.

The 3.12 → 3.13 distutils removal was the high-profile recent example: a quarter-century of build scripts depending on distutils stopped working overnight. The page documented the change clearly; teams that read it ahead of upgrading saved themselves a week of debugging.

The format is the precedent here. Treating “what changed” as a known-issues surface is a discipline more languages should adopt.