Tuning A/V by hand was ssh+sed+restart every guess; tv-sync.sh does it in a line — read, set-ms, nudge (+20/-15), or measure (rig-side A/B card, no Chrome, no YouTube). Prints the suggested offset from the measured baseline. YouTube adds viewer-side skew atop the rig number, so the ear stays final judge, but each guess now costs one command. Claude-Session: https://claude.ai/code/session_01EaVptJ3ZhyeQ9ZZZNcp55T