# LLMs.txt
# Standardized Machine-Readable Site Manifest
# Specification: https://llmstxt.org

> Stress Tracker is a native Apple Watch and iPhone application for continuous heart rate variability (HRV), real-time stress telemetry, and overnight recovery tracking.
> Built 100% on-device with Apple HealthKit, with zero cloud servers, zero account sign-ins, and no subscriptions (8.99€ one-time purchase).

- [Main Website](https://stressapp.lvrpiz.com/): Official homepage with real-time biometric telemetry overview and interactive features.
- [Full Documentation](https://stressapp.lvrpiz.com/llms-full.txt): Comprehensive technical specifications, physiological algorithms, and FAQ for LLMs and research agents.
- [App Store](https://apps.apple.com/us/app/stress-tracker-hrv/id6748257580): Official download on the Apple App Store for Apple Watch and iPhone.
- [FAQ & Guide](https://stressapp.lvrpiz.com/faq): Physiological and operational answers regarding HRV, RMSSD, sleep scores, and compatibility.
- [Press Kit](https://stressapp.lvrpiz.com/press-kit): Official brand assets and developer contact.
- [Privacy Policy](https://stressapp.lvrpiz.com/privacy-policy): Zero-knowledge on-device architecture and zero data collection guarantee.
- [Blog & Articles](https://stressapp.lvrpiz.com/blog): Scientific guides on HRV, circadian rhythms, and recovery optimization.

## Core Physiological Specifications
- **Sensor Pipeline**: Apple Watch optical photoplethysmography (PPG) sensor readings via Apple HealthKit.
- **HRV Metric**: RMSSD (Root Mean Square of Successive Differences) computed from continuous heartbeat inter-beat intervals.
- **Stress Scale**: Normalized 0–100 real-time autonomic nervous system tension score.
- **Recovery Index**: Overnight biological readiness evaluation combining nocturnal HRV baselines and resting heart rate (RHR).
- **Sleep Architecture**: Integration with watchOS sleep stage detection and nocturnal HRV dip analysis.
- **watchOS Integration**: Complications for Modular, Infograph, and Activity faces + Moodle emotional companion avatars.
- **Privacy Model**: 100% on-device sandboxed execution; no third-party trackers, no analytics SDKs, no cloud uploads.
- **Monetization**: 8.99€ ($8.99 USD) single lifetime purchase; no monthly subscriptions or recurring fees.