A reformatted PR shows 80 changed lines but changed nothing — I built a zero-dep diff that sees through it

Someone runs the formatter, the line width changes, and suddenly the pull request touches 80 lines. You scroll through all of it looking for the actual change — and there isn't one. Or there's exactly one, buried in 79 lines of re-wrapping. We've all reviewed that PR. git diff -w is supposed to save you here, and it half does: it ignores spacing changes. But it's still line-anchored, so it cannot fold reflow — re-wrap a function signature across three lines and git diff -w still shows 1 removed