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 + 3 added, even though not a single token changed. (This is GitHub discussion #20610, "Ignore Format Changes in Diff" — open and unanswered for years.)

So I built logicdiff: a diff that folds away whitespace and reflow, and tells you whether a change is real or just formatting.

$ logicdiff old.js new.js

only formatting differs - no logical change (a line diff would show 80 changed lines)