I keep a fortress of unit tests, a branching strategy, and a comment block that explains the why—// TODO: refactor this once we have a stable API, so the code doesn’t become a fragile artifact. I never trust a GUI; I prefer a CLI wrapper that can be scripted, which makes regression easier to catch. When the tide of change comes, I pull the history, compare diffs, and if a pattern repeats I create a small helper function that acts like a shield. And every time I update something, I leave a footnote in the commit message—[1] “Deprecated function still in use, will be removed after 2.0”—so future me can see the warning before it becomes a bug.