Privacy Policy

Eunoia Signals · Last updated: April 11, 2026

Short version: Eunoia Signals is a personal mood and pattern-tracking app. Almost all data stays on your device. You can optionally contribute anonymous, aggregated check-in data to improve mania-detection research — but this is always opt-in and you can revoke it at any time. We never read your notes, never collect your name or Apple ID, and never sell data to anyone.

1. Who We Are

Eunoia Signals is an iOS app developed by TJ Bryant (contact@eunoia-signal.com). References to "we," "us," or "our" throughout this policy mean the developer of this app.

2. What Eunoia Signals Does

Eunoia Signals is a personal wellness tool that helps you track mood states, log check-ins, and notice patterns related to mood and energy levels over time. It is not a medical device and is not intended to diagnose, treat, cure, or prevent any condition.

3. Data That Never Leaves Your Device

The following data is stored locally on your device using Apple's SwiftData framework and is never transmitted to us or any third party:

Your check-in history (mood states, severity ratings, labels, and timestamps)
Your journal/note text — your words are yours alone
Your Apple Health data — raw biometric samples never leave your device
All computed signal scores and trend history
Your app theme and display preferences

4. Apple Health (HealthKit)

With your permission, Eunoia Signals reads the following data types from Apple Health to compute supporting biometric signals:

Sleep analysis
Heart rate variability (HRV)
Resting heart rate
Step count
Active energy burned
Respiratory rate

This data is read from HealthKit on-device, processed into summary averages, and never shared with third parties for advertising, marketing, or any purpose unrelated to the app's health and fitness functionality. This complies with Apple's HealthKit developer guidelines.

You can revoke HealthKit access at any time in Settings → Privacy & Security → Health → Eunoia Signals.

5. Optional Research Data Sharing

The first time you launch the app, you will be asked whether you'd like to contribute anonymous data to improve mania-detection research. This is entirely optional.

If you opt in, we collect:

Your mood state selection, severity level (1–10), and selected labels per check-in
The character count of your note (never the text itself)
Biometric summaries: recent averages and baselines for sleep, HRV, resting HR, step count, active energy, and respiratory rate
Computed risk scores, trend direction, and sub-scores for each check-in
An anonymous device ID — a random UUID stored in your device's Keychain that cannot be linked to your Apple ID, name, email, or any personal identifier
App version and a UTC timestamp of the check-in

What we never collect — even if you opt in:

Your note text or journal entries
Your name, Apple ID, email address, or phone number
Your location or IP address
Raw HealthKit sample data (only derived summaries)

How research data is transmitted:

Data is sent over an encrypted HTTPS connection to eunoia-signal.com each time you save a check-in. If your device is offline, the payload is stored locally and sent the next time a connection is available (up to 500 queued entries; oldest are dropped if this limit is reached).

How to opt out:

Go to the Settings tab → Research Data and toggle the switch off. We immediately stop sending new data. Previously submitted data may be retained in our research dataset in anonymized form, as it cannot be attributed to your device once the anonymous ID is no longer associated with active data.

6. How We Use Research Data

Research data is used solely to:

Improve the accuracy and reliability of pattern-detection algorithms in Eunoia Signals
Understand population-level trends in mood and biometric patterns

We do not sell, rent, or share research data with advertisers, data brokers, or any third party for commercial purposes.

7. Data Retention

On-device data: retained until you delete the app or clear its data.
Research data: retained on our servers in anonymized form for as long as the research dataset is active. Because submissions contain no personal identifiers, we cannot fulfill deletion requests for past submissions once received.

8. Children's Privacy

Eunoia Signals is not directed at children under 13. We do not knowingly collect data from children under 13. If you believe a child has submitted data, please contact us and we will remove it from our research dataset to the extent possible.

9. Third-Party Services

Eunoia Signals uses no third-party analytics SDKs, advertising networks, or tracking frameworks. The only external network calls are to our own research API at eunoia-signal.com, and only when you have opted in to research data sharing.

10. Changes to This Policy

We may update this policy as the app evolves. Significant changes will be communicated via an in-app notice or a revised "last updated" date above. Continued use of the app after changes constitutes acceptance of the updated policy.

11. Contact

Questions, concerns, or requests related to this privacy policy:
contact@eunoia-signal.com