What is the main rule you always tell AI coding tools before generating app logic?

built a simple app with an AI builder and it worked great when it was just me using it.

as soon as a second person signed in and started making changes, they kept overwriting everything. turns out the AI saved all list data into one giant record because I never told it to handle multiple people editing at once.

what basic rules or prompts do you always give AI tools to avoid silly setup bugs like this?