A mouse press landed inside the viewport it was delivered to
Every trusted press lands within the viewport, allowing a pixel of rounding. N/A under pinch-zoom (severity: warn).
What a detector infers
A physical mouse press lands wherever the pointer is. If the pointer is outside the page's viewport, the press goes to the browser's own interface — the toolbar, a scrollbar — or to another window; it is never delivered to the page. The DevTools protocol has no such constraint: Input.dispatchMouseEvent sends a press at any coordinate, and Chrome delivers it to the page as trusted input even when the coordinate lies past the edge of the viewport.
Measured with Playwright: mouse.click(200, 920) in a viewport 720 pixels high produced a trusted pointerdown at clientY 920, targeted at <html>. So a press whose clientX or clientY falls outside 0 to innerWidth or innerHeight came from a client that does not know where the viewport ends. Only the failing side is measured; the passing side is how pointing devices work.
Pinch-zoom changes the relationship between client coordinates and the visible area, so a zoomed visual viewport is N/A, and a pixel of rounding is allowed at fractional device pixel ratios.
How to resolve it
Press only where the page is: scroll the target into view before clicking, and keep click coordinates within innerWidth and innerHeight. A coordinate past the edge belongs to the browser's interface, not the page.
Nearby checks in Input & behaviour
- Every raw pointer update carries at least its own sample
rawupdate-carries-its-samplepointerrawupdate fires for each pointer report as it arrives, without waiting for the next frame, and Chrome builds each one from a real… - An upper-case letter was typed with Shift or Caps Lock
shift-less-capitalsOn a physical keyboard, a capital letter is the letter key pressed with Shift held or Caps Lock on: the key event for 'H' arrives with code… - A move only reports a button down after that button was pressed
buttons-without-pressMouseEvent.buttons on a move reports which buttons are held, and a button can only be held after it has been pressed. - The pointer never crossed a long distance in one report from rest
pointer-jump-from-restWhen a hand starts moving a mouse that has been still, the first reports cover a few pixels each as the movement builds up. - The pointer came to rest on a control before pressing it
settle-before-pressA person brings the pointer onto a control and presses after it arrives: the hand has to stop, and then the finger has to act. - Pointer path curves the way a hand moves
pointer-path-linearityThe check captures the pointer path across the pad and measures two things about its geometry: the RMS perpendicular distance of every… - Pointer velocity and acceleration vary physically
pointer-kinematicsVelocity, acceleration reversals, direction changes, and timestamp quantisation catch constant-speed curved automation missed by linearity. - Pointer events arrive on hardware time
pointer-event-cadenceWhere the linearity check reads the path's shape, this one reads its clock.
Clearcote is a browser built for fingerprint coherence
It is a Chromium fork, maintained by the same people who wrote this reference. It ships as a compiled browser rather than as a stealth script injected into someone else's — which is a description of how it is built, and is not an argument about how it behaves on this check.
This audit takes no position on how Clearcote scores on Input & behaviour checks, on this one, or anywhere else. It has no baseline corpus of other people's fingerprints to rank you against and no vendor scoreboard — nearly every check is self-referential, asking one browser the same question through two independent APIs and reporting whether both answers can be true at once. It runs identically on any browser, including ours. Run it on yours and read the result yourself.
See the other checks in Input & behaviour — the family press-inside-viewport belongs to.