Help, privacy and the limits of browser input tests
DeviceCheck is a focused browser-observation tool. It cannot certify hardware health, physical latency or polling rate.
Active means focused
Each test starts explicitly and records only when its diagnostic area is the active element, the document is visible, and the window has focus. Leaving with Tab, selecting controls, switching tests, window blur or hiding the document pauses logging and clears live held/contact/controller state. Resume is explicit. There are no document-wide key collectors.
Session-only observations
No input contents are uploaded or saved automatically. Only ordinary application/font assets load from the host. No analytics, accounts, clipboard access, HID/USB requests, vibration or device-driver APIs are configured. Use test keys, not passwords. Clear/pagehide drop session references; this is not secure erasure of browser/OS memory.
Bounded history and export
The latest 1,000 diagnostic events are retained. The summary gives total/retained/dropped counts, per-test counts, up to 256 observed key codes, limits and browser-observation caveats. Live contacts are capped at 20, controllers at 16, buttons at 128 and axes at 64 per controller. Prepare session JSON pauses collection and provides a review step; download is explicit. New observations invalidate that prepared summary.
What a missing signal means
Reserved shortcuts, unavailable APIs, controller mappings, browser coalescing and focus rules can hide events. Absence alone is not proof of a broken device. Pressure/confidence/physical calibration claims are outside this tool. Test another supported environment and inspect the actual values rather than inferring a hardware diagnosis.
Verification scope
Automated checks use synthetic keyboard/pointer/gamepad fixtures plus browser mouse/keyboard automation. Physical keyboards, mice, multi-touch, pens and controllers; mobile hardware; Firefox/Edge/Safari; and screen-reader sessions need separate validation. No result is a resale certificate or hardware polling-rate measurement.