How arrival at a stop is verified

When a visitor says they have arrived, their phone reports where it thinks it is and **the server** measures the distance to the stop. The decision is never made on the device, so a stamp always means somebody was actually there.

Two things can stop a check from succeeding:
- **Too far away.** The visitor is told roughly how far they still have to go.
- **The location fix is too rough.** A reading worse than about 100 metres is not evidence of anything. Indoors, in a narrow street, or under heavy cover, the fix degrades. Stepping into the open usually fixes it.

**What is kept.** The coordinates a visitor sends are used for that one comparison and then discarded. What is stored is that the stop was reached, when, and how precise the fix was — nothing else. There is no location history in Adventures, which means there is no trail of somebody's movements to lose, hand over, or have to delete later.

If a stop repeatedly fails for visitors, the usual cause is a coordinate that is a few metres off or an arrival radius set too tight. Widen the radius before you move the pin.