My wife and I used to tag-team. Only one person got to lose it at a time. As soon as one person got that distant, exasperated look, Parent 2 jumped in and Parent 1 could go cool down, watch a show, have a drink, or take a bath. If solo, we’d use distraction and humor. If too much, you stick them in a playpen with toys and let them self-sooth.
If it’s any consolation, they won’t remember diddly-squat of anything that happened before ages 5-6.
Not a formal audit, but a more recent review of the protocol: https://soatok.blog/2025/02/18/reviewing-the-cryptography-used-by-signal/