# Alerts must not fire on the past

> An alert for a threshold already crossed fires at once, and teaches the user to ignore every alert.

Building block · Building software that holds up · found 2026-09-21 · by John Kingola

## What I was looking for

How runway alerts should behave when someone switches them on late.

## What I found

CreditWatch warns at 12, 6 and 1 hours of runway. If runway is already 4 hours and you enable the 6-hour alert, a naive build fires immediately. An alert that reports history looks the same as one that warns.

The shipped behaviour refuses to arm any threshold below the current runway, and says so in the dialog.

## The move

For anything that warns, I ask what happens when it is switched on after the event, not before.

Web version: https://kingola.dev/notes/alerts-must-not-fire-on-the-past/