View local HTML on iPhone by serving it
iPhone's Files app won't run interactive web pages, so serve them from the computer instead.
how it works
iOS Files preview runs no JavaScript and Safari isn't an .html handler; `python3 -m http.server --bind 0.0.0.0` and open the tailnet hostname.
Technique: A pattern or hard-won lesson, written down so it isn't learned twice.
The code for this one lives in a private repo. This page explains the idea so you can build your own.