I run a directory site. People arrive, look at listings, and some of them click through to an external booking page. Those outbound clicks are the only thing on the site that correlates with money, so they are logged: what was clicked, from which page, on what device, and — if the person happens to be signed in — which account.

Out of 1,372 recorded clicks, six carried an account.

Six. Not six percent. Six clicks, across eight months, belonging to four distinct people.

That number reads as a broken integration. Something in the chain that attaches identity to an event is dropping it, and 99.56% of the time nobody notices because the click still gets recorded and the dashboard still fills in. So I went looking for the break.

The chain was fine