# Two systems that disagree

Prompt · Architecture and hidden complexity · A04

Finds data kept in two places (a saved copy and a table, the browser and the server) that can quietly disagree.

## Prompt

```text
Find places where two systems can disagree about the same truth. Trace their ownership, synchronization, cache invalidation, and recovery behavior.
```

**What it returns:** Pairs of stores with the field, who writes each, how they sync, and a sequence of events that makes them diverge.

**Skip it when:** Read-only copies that are rebuilt from scratch on every load.

**Tools:** Repository and read-only database access.

**Changes:** Changes nothing

**Sessions:** Look first, then fix in a new session

## Related

- [Updates that overwrite each other](https://www.atlasscope.dev/prompts/updates-that-overwrite-each-other): Finds updates that overwrite newer data because two things wrote at once.
- [Screens showing a change that was refused](https://www.atlasscope.dev/prompts/screens-showing-a-change-that-was-refused): Finds screens that show a change right away and keep showing it after the server refused it.
- [Where did this number come from?](https://www.atlasscope.dev/prompts/where-did-this-number-come-from): Checks that every number on screen can be traced back to a source document.
- [Map every place that writes to the database](https://www.atlasscope.dev/prompts/map-every-place-that-writes-to-the-database): Several jobs, functions, APIs or agents change the same data, or nobody is sure who owns it.
- [Are we storing the same truth multiple times?](https://www.atlasscope.dev/prompts/are-we-storing-the-same-truth-multiple-times): Caches, aggregates, materialized views or derived columns drift from the raw facts.

Source: https://www.atlasscope.dev/prompts/two-systems-that-disagree