The 20,000-line PR that was actually 47 lines: building ClearPR

Some time back, a teammate opened a PR. The diff said 20,847 lines changed . I clicked, my MacBook fan kicked in, and GitHub started painting the page in those familiar green and red blocks. I scrolled. Scrolled some more. Then a bit more. Eventually I got to the part where I realised what had happened: someone had run Prettier on the whole repo before pushing.

The actual change was 47 lines.

I sat there for a moment thinking about the rest of my afternoon, which was now going to involve scrolling past twenty thousand lines of trailing-comma additions and quote-style flips just to find the part of the code that actually did something different. I tried the GitHub "Hide whitespace" toggle. It did nothing useful, because Prettier does not just touch whitespace. It rewraps lines. It reorders imports. It changes single quotes to double quotes.…