A teardown of the four formats your coding agents read — what each does, where each breaks, and the setup that stopped me maintaining four copies of the same rules. I have the same standards in every repo I touch: small diffs, tests that fail before the fix, conventional commits, no secrets in code. For about a year, I maintained those standards by hand in every format my agents read. This is what I found when I actually audited them — and what I'd tell myself a year ago. ...