Nick Liu

`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.

Once I had six Claude Code sessions open at once, the most expensive part of my workflow was not writing code. It was patrol: cycling through tabs to see which agent was still running and which one had been sitting on a question for ten minutes. tmux has no concept of any of this. To tmux, every pane is a rectangle of terminal, equally interesting, equally mute. herdr’s pitch lands exactly on that pain: panes are still real terminals, but a sidebar shows each agent’s live state. So it got a one-month trial, with exit conditions written down before it started. The verdict lands on August 16, and this post is honest about still being inside the window.

After a month of overhauling my dotfiles with AI in the loop, the real value was not "the AI writes my configs". It was two much more boring properties: the research side keeps finding things I cannot see, and I verify every claim it makes before acting. Skip the first and you only ever fix problems you already knew about. Skip the second and a plausible-sounding wrong answer walks you into a ditch. The loop # claim fails verification

My dotfiles repo is public, which means any slip with a credential is permanent. History rewrites do not un-leak a key that a scraper already saw. So the defense cannot be one layer, and the interesting part of layering is not the count of tools. It is that each layer intercepts at a different moment: one before the commit exists, one at the moment of push, one sweeping the entire history in CI. The uncomfortable part, and the reason this post belongs to this series: one of my three layers used to be a decoration.

`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.