Systems
Build the check, then break it
Twenty-seven checks on a production email, a token lint, and a fact gate that will not ship a guess.
Eyes miss things
Most files get checked by eye. Eyes miss things. In one file built to demonstrate a design system, a reviewer missed border-radius: 7px. I build the check, then I break it on purpose.
The 500px floor
Headless Chrome will not open a window narrower than about 500 pixels. Every earlier render I had been calling 375 was really 500. I fixed the check so it renders at a true 375.
On the same work, the fact gate corrected the spec speeds to 334, 334, 329, and 360, and made draw-length qualifiers mandatory.
verify-email.py
One command runs 27 checks. It checks the structure. Then it renders the file at 600 pixels and at a true 375, with webfonts and without them. A pixel diff checks that a dark-mode lock stays quiet.
I proved the checker by injecting eight real bugs, one at a time. Each one tripped its own check. The email that had passed was the control.
$ verify-email.py 27 checks static structure 600px and a true 375px with webfonts, and without dark-mode pixel diff 8 bugs injected, one at a time each tripped its own check exit 0
hoyt-design-lint
A deterministic HTML and CSS lint against the design tokens. Same input, same output. No model call. It exits non-zero to block a ship. Rules that need judgment are listed for a person, not silently passed.
On the demos, one page returned 13 errors and exit 1. Two pages came back clean.
$ hoyt-design-lint 7 errors no-border-radius display-weight display-family display-tracking-negative body-tracking-positive display-not-uppercase red-large-fill 3 warnings display-undersized gradient-primary-surface off-spec-red one demo page: 13 errors, exit 1 two demo pages: clean
Facts that cannot ship until they are sourced
Every product fact is tagged Documented, Stated, Derived, ASSUMED, or GAP. A gap blocks external use. It started with the Concept XTS source of truth and knowledge audit, in August 2026, and the product-knowledge pipeline reused it for the hunting launch.
It held an engine-made motion draft at Revise until the 4.23 lb weight basis was confirmed.
A check I have not seen fail is not a check.