Seeing reverse scrolling?

A “Possible opposite-direction events observed” result means some events opposed the requested direction. That observation alone does not identify a cause.

Common causes

• Touchpad inertia or free-spin coasting after the motion ends.
• Browser smoothing and OS scroll acceleration reshaping the event stream.
• A correction you made mid-run — the tool cannot tell intent from input.
• A worn or dirty wheel encoder, which is only one candidate among several.

Repeating a run

Run the same direction and duration twice. Save the first with “Save as Run A” and compare with “Compare Run B” on the compare page. A pattern that repeats across runs and devices is worth more than any single run.

When to worry

Consider the hardware suspect only if reverse input repeats with a standard notched wheel, across browsers, and the pattern follows the mouse to another machine. Even then, this tool offers an observation — not a warranty verdict.