The session is saved on every change and runs on wall-clock time, so closing or reloading the page and coming back resumes exactly where it would have been. Durations lock while a session is running; the number of O₂ periods can be changed at any time, even mid-session (periods already started stay). Chamber pressure is optional: once entered it is remembered and recorded with each session, and it can be changed at any time. Keep this page in front so the screen stays awake and cues fire on time; if beeps are silent on iPhone, flip the ringer switch on. On a phone, add this page to your Home Screen (Share → Add to Home Screen) to run it full-screen like an app. While a session runs, the Lock Screen's Now Playing card shows the countdown with pause and skip buttons. Keyboard: Space start/pause, ← → prev/next. Tap a bar segment to jump to that phase.

Every completed session is logged here automatically with its pressure and protocol. The log is stored in this browser only. Tap Remove twice to delete an entry.