# Correctness and reliability

What happens when something runs twice, fails, times out or happens in the wrong order, and whether people can tell a stand-in value from the real one.

- [Safe to run twice?](https://atlasscope.dev/prompts/safe-to-run-twice): Finds actions that do damage when they run twice: double sends, double charges, duplicate rows.
- [Fallbacks that look like real data](https://atlasscope.dev/prompts/fallbacks-that-look-like-real-data): Finds screens that show a confident zero or an empty list when the real answer is 'we could not load this'.
- [Rules the data never enforces](https://atlasscope.dev/prompts/rules-the-data-never-enforces): Finds the rules everyone assumes (one owner per task, no negative balance) that nothing actually checks.
- [Dates, times and time zones](https://atlasscope.dev/prompts/dates-times-and-time-zones): Finds the date bugs that show up twice a year, at midnight, or in another time zone.
- [Updates that overwrite each other](https://atlasscope.dev/prompts/updates-that-overwrite-each-other): Finds updates that overwrite newer data because two things wrote at once.
- [Half-finished failures](https://atlasscope.dev/prompts/half-finished-failures): Finds what is left behind when something fails halfway.
- [Lost place: Back, refresh and shared links](https://atlasscope.dev/prompts/lost-place-back-refresh-and-shared-links): Finds the everyday friction where Back closes the wrong thing, a filter resets, or a pasted link opens the wrong view.

Source: https://atlasscope.dev/prompts/correctness-and-reliability