COS / PRIVACY

Effective: 31 August 2026 · Last updated: 14 September 2026

This policy covers the COS Wear OS companion app (com.vitcalindaniel.cos) and the COS Watch Face (com.vitcalindaniel.cos.watchface). Both are developed and operated by Calin Vit, an independent developer in the United Kingdom. This policy explains what data each product uses, why it uses it, and where that data is kept.

Summary

Data used by the COS companion app

Approximate location

With permission, the COS companion app obtains approximate foreground location from Android. It uses the location on the watch for local Sun and Moon calculations and to select local weather. The companion app does not request precise or background location.

When weather is requested, approximate coordinates are sent over HTTPS to the COS backend. The backend validates them, rounds them to 0.05 degrees (approximately five kilometres, varying by latitude), and sends only the rounded area to OpenWeather. Weather responses are cached by rounded area so nearby users can share a result. Current conditions are normally fresh for 30 minutes; forecast and air-quality results are normally fresh for 60 minutes; and stale fallback data may be retained for a further six hours. Expired weather cache entries are deleted automatically.

The most recent location fix and weather response are also stored locally on the watch for fallback and offline use. They are excluded from Android backup. Clearing the COS companion app's data or uninstalling it removes these local copies.

Daily steps and step goal

With Activity Recognition permission, the COS companion app reads the Wear OS Health Services daily-step total to display today's step count and progress toward a selected goal. The daily count is stored locally on the watch and is not sent to the COS backend or any other service. Daily step counts are excluded from backup.

The selected step goal may be included in Android backup or device-to-device transfer. Cloud backup is permitted only when Android provides encryption capabilities. The goal is a preference, not a record of completed activity.

The companion app's optional step display is a general fitness and wellness feature. It is not a medical device and does not provide medical diagnosis, monitoring, or treatment advice.

Installation identifier

When weather or live Voyager information is used, the COS companion app sends a randomly generated app-installation identifier to the COS backend. It is not an advertising ID, hardware ID, account ID, or contact detail. It is used only for short-term abuse and rate-limit protection. The backend converts it to a one-way hash before its strict one-minute counter is stored. The identifier is stored locally until the companion app's data is cleared or the app is uninstalled, is excluded from backup, and is not included in COS operational reports. The COS Watch Face does not create or send this identifier.

Diagnostic sensors

The companion app's diagnostics screen can display live barometer, accelerometer, and magnetometer readings. These readings are used in memory for the on-screen graphs and are not stored or transmitted by COS.

Catalogue updates and Voyager information

The companion app periodically downloads public astronomy and mission catalogue files from the COS backend. No COS installation identifier or location is attached to those catalogue requests. When Voyager 1 telemetry is opened and a refresh is due, the companion app requests it from the COS backend. The backend requests one shared set of public ephemeris data from NASA/JPL Horizons using fixed spacecraft parameters and dates. The shared result is normally fresh for 24 hours, with stale fallback retained for a further seven days. The watch also keeps a local copy for offline use. Voyager requests contain no location, step, or account data.

Data displayed by the COS Watch Face

The COS Watch Face is built with Watch Face Format. Its app bundle contains no executable app code, declares no Android permissions, and makes no direct network requests. It does not contact the COS backend, Cloudflare, OpenWeather, or NASA/JPL.

The watch face can display time and date, battery state, weather, Moon phase, and other values made available by Wear OS or by system data providers selected or configured by the user. This information is rendered on the watch and is not transmitted to the developer by the COS Watch Face. Any collection or storage performed by Wear OS, the device manufacturer, or a selected data provider is governed by that provider's settings and privacy policy.

The watch face also offers tap targets that can open system apps or the separately installed COS companion app. Opening another app transfers control to that app; the watch face does not receive data from the opened app.

Service providers and normal network data

For the companion app, the COS backend is hosted by Cloudflare, weather data is supplied by OpenWeather, and public Voyager data is supplied by NASA/JPL. As with ordinary internet connections, Cloudflare receives network information such as an IP address to deliver app responses; NASA/JPL receives the backend's request, not the watch's installation identifier. COS does not add network information to its operational counters or use it for advertising or profiling. The COS Watch Face does not connect to these services.

The backend keeps aggregate operational totals such as weather and Voyager requests, cache hits, upstream calls, failures, and refusals. These reports do not contain coordinates, IP addresses, installation identifiers, or individual usage histories.

Optional external actions

The companion app's INSTRUMENT page shows a Buy Me a Coffee QR code and a feedback email address. COS does not transmit data merely by displaying them. Scanning the QR code, opening the privacy link, or sending email leaves COS and is governed by the selected external service. If you email the developer, your email address, message, and any attachments you choose to send are used to read and respond to the message.

Security, choice, and deletion

Off-device companion-app requests use HTTPS. Backend credentials and the OpenWeather key are not included in either COS package. Location and Activity Recognition permissions in the companion app are optional and can be denied or revoked in Android settings. Other companion-app features remain available, although local weather, Sun/Moon accuracy, or step display may be limited. The COS Watch Face itself declares no permissions.

COS has no account or server-side user profile. Local companion-app data can be removed through Android's Clear storage control or by uninstalling the app. The watch face and its local configuration can be removed through Wear OS or by uninstalling the COS Watch Face. Data retained by a system provider must be managed through that provider. Shared, rounded weather cache entries cannot be linked back to an individual user and expire automatically. Privacy questions or requests concerning a feedback email previously sent to the developer can be directed to the address below.

Children

The COS products are general-audience astronomy, weather, and fitness utilities and are not directed to children under 13. COS does not knowingly create profiles of children or collect age information.

Changes

This policy may be updated when COS features, providers, or legal requirements change. The last-updated date above will be revised, and the current policy will remain available at this URL.

Contact

Calin Vit
cos.companion.feedback@gmail.com