Frequently asked questions
Privacy + data
Is my workout data sent anywhere?
By default, your workout data stays on your device and (if iCloud Sync is on) in your private iCloud. The only data that leaves your device is what you explicitly send to cloud AI — short, categorical training summaries used to generate a recommendation or run the memory engine. Every cloud call is logged in Settings → AI Use.
Can I turn off cloud AI?
Yes — during onboarding, decline the cloud-AI consent. Or flip it off any time in Settings → Privacy → Cloud AI. The deterministic parser still works without cloud, and local-only recommendations + memory still function with a lighter feature set.
Can I turn off iCloud Sync?
Yes — Settings → Privacy → iCloud Sync. With sync off, everything stays on this device only. Useful if you want device-local privacy or if you're on a shared iCloud account.
Where can I read the full privacy policy?
Cloud AI
Which AI does Stone use?
xAI's Grok models, accessed via a Cloudflare Worker. The Worker proxies every call so xAI never sees your device identifier or Apple ID. Default model is grok-4.3 (high-quality); a faster grok-4-1-fast option is available in Settings if you want lower cost.
How much does cloud AI cost?
During the beta, all cloud calls are paid by the developer. No subscription or in-app purchase. After the beta, a small subscription may be introduced to cover ongoing costs — pricing is still TBD.
Is my workout data used to train AI models?
No. xAI's API tier is configured for ZDR (zero data retention) for inference, and the Worker doesn't enable any training-data opt-ins. The current retention policy is documented in Settings → AI Use and in the AI Disclosure.
Sync + multi-device
Does Stone work on two devices?
Yes, via iCloud Sync. Both devices need to be signed into the same iCloud account. Sync is on by default; turn it off in Settings → Privacy if you only want one device to hold your data.
My second device isn't seeing data from my first device.
CloudKit sync is eventual and depends on network. Check:
- Both devices signed into the same iCloud account (Settings → Apple ID).
- Stone has iCloud Sync enabled in both apps (Settings → Privacy).
- Both devices on a network for a minute or two.
If sync still doesn't work after that, file a TestFlight feedback report.
HealthKit
Why does Stone ask for HealthKit access?
Three signals improve the recommendation engine: body weight, resting heart rate, and heart rate variability. All three reads are opt-in via Settings → Privacy → Health. Write-back of workout data to HealthKit is separately opt-in and off by default.
Does Stone share HealthKit data with anyone?
No. HealthKit data is read on-device only and never leaves the device. The recommendation engine uses it to inform AI prompts but the actual health values are not transmitted to the cloud.
Account + login
Do I need to sign in?
No. Stone works fully without an account. Sign in with Apple is optional and adds an elevated quota tier for cloud-AI calls when signed in.
What happens if I delete the app?
Local data goes with the app. iCloud data persists in your private iCloud until you also delete it via Settings → Privacy → Delete your data → "Also delete from iCloud". Server-side rate-limit counters (no personal data) expire automatically within 24 hours.
Bugs + feedback
How do I report a bug?
TestFlight feedback is preferred — see the main support page. Apple includes device, iOS version, and build automatically. Screenshots help a lot.
Can I see a list of known issues?
Yes — known limitations.