Cursor Project Rules: stop repeating your codebase conventions

The bad default is correcting the same coding habit in every Cursor chat. Project Rules let you keep reusable guidance in .cursor/rules/ as version-controlled .mdc files, then choose whether Agent applies a rule everywhere or only when matching files are in context. 1

Start with one repeated correction. Give it a narrow globs pattern, test it on one matching file, and keep the rule only when the scope is right. Project Rules guide Agent; they do not replace security controls. 1