`mdls kMDItemLastUsedDate` returned `(null)` for Microsoft Word. I read the null as "never opened" and put Office on a removal list: 10.1 GB, four apps. One last check saved me. My home directory held 150 Office documents, a conference presentation edited two weeks earlier, and a PowerPoint lock file, which only exists while the file is open. The proof that the null was misleading had been sitting in my own diagnostic report for an hour. That was one of five. In a single day of hardening this machine, five different tools told me things that were not true. None of the answers looked like an error. Each one arrived as a clean, confident finding, and under each one a check had quietly failed or asked the wrong question. All five had the same shape underneath. Once I could name the shape, I stopped falling for it.
`env -u VAR command` did nothing. Exit code 0, no output, no error. A different command, same thing. A different variable, same thing. Any invocation that started with `env` just quietly evaporated. What finally made the problem visible was a `git init` that reported success while creating no `.git` directory at all. That was a year ago. The case closed last month, and the culprit was not uv, not some third-party installer, not anything exotic. It was this repo’s own bootstrap script. The thing that caught it was the regression test I had written for the original incident.
My dotfiles repo has a CLAUDE.md, and the CLAUDE.md has a rule in bold: every commit must pass the test suite, no exceptions. Within the first hour of an audit this July, I learned that this rule had been enforced exactly zero times since the day it was written. The hook file existed, its contents were correct, it even had its executable bit. It was just sitting at a path that yadm stopped reading a major version ago. No error message. No warning. To yadm, a hook in the wrong place and no hook at all are the same thing.
Every developer eventually reaches the point where their configs become too valuable to lose. Here's how I use **yadm** to manage my macOS dotfiles with automated testing, daily maintenance, and a pre-commit workflow that keeps everything in check. For me, the turning point was spending a weekend setting up a new MacBook and realizing I couldn’t reproduce my environment reliably. That’s when I started managing my dotfiles properly.