Lever

Two Huberman breathing protocols in one offline-capable page — physiological sigh to calm down, cyclic hyperventilation with retention to charge up. Pick one. No accounts, no streaks, no upsell.

Live: breathingcyclic.netlify.app

Single HTML file (~46 KB). Runs offline once loaded.

What it does

Mode	Protocol	When
Calm	Physiological sigh — two inhales through the nose, one long exhale through the mouth	Acute stress, before sleep, between meetings
Charge	Cyclic hyperventilation — 20 deep breaths, exhale fully, hold lungs-empty as long as comfortable, recovery breath	Morning alertness, pre-workout, low energy
Quick sigh	Three physiological sighs, 30 seconds	Right now, in pocket, no thinking

Two cards on the home screen plus the Quick Sigh shortcut. That's the entire surface outside session screens.

Why only two

Most breathing apps add twenty techniques, mood tracking, streaks, and a paywall. The stripped-down timers don't teach the rhythm. This is two protocols, one decision — closer to a flashlight than a journal. For someone who already knows the science and needs a tool that gets out of the way.

Tech

• Single HTML file, ~46 KB. No build step, no bundler, no framework.
• Vanilla JS, CSS transitions, inline SVG. No React, no Tailwind, no dependencies beyond Google Fonts.
• Offline-capable once loaded.
• PWA-installable — Add to Home Screen on iOS/Android runs fullscreen.
• iOS audio — primes AudioContext on user gesture so Safari's autoplay restriction doesn't silently block phase tones.
• iOS haptics — uses the <input type="checkbox" switch> trick (Safari 17.4+) since Safari has no Vibration API.
• Wake Lock API keeps the screen on during sessions.

Run it

Use the live version at breathingcyclic.netlify.app. Or:

git clone https://github.com/iamdanielkitchen/lever.git
cd lever
open index.html  # macOS
# or just double-click the file

To install on iPhone — open in Safari, tap Share, tap Add to Home Screen.

Case study

• Design document — original spec, including features deliberately excluded
• Build journal — how it shipped, three real bugs, what they show about AI-collaborative coding
• Screenshots — home, session, settings

Deliberately excluded

• No streaks, badges, or gamification
• No social features or sharing
• No additional techniques — no box breathing, 4-7-8, alternate nostril
• No journaling or mood logging
• No content library, podcasts, or videos
• No AI chatbot
• No accounts, sync, or cloud
• No subscription
• No push notifications by default

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MIT. Built by Daniel Kitchen.

Not medical advice. Cyclic hyperventilation should never be done in or near water, while driving, or by anyone with cardiovascular or seizure conditions for which hyperventilation is contraindicated.