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.cursor/rules/project.mdc

Cursor rules for Spring Boot

Cursor rules are a markdown file with a short frontmatter header. Cursor attaches them to the agent so it stops guessing how this repo builds, tests, and styles code. This copy is written for a Spring Boot project. This repository is a Spring Boot service. Controllers stay thin, transactions sit on the service the project already uses, and configuration comes from the environment.

The example uses a balanced, readable style, pragmatic tests, and comments only where the intent is not obvious. Open the generator to make the agent stricter, switch to test-first, quiet the comments, or pick a different file.

The example assumes Spring Boot with Maven or Gradle, whichever wrapper is in the repo. It does not assume WebFlux versus MVC, or a particular database. Follow the stack that is already on the classpath.

Customize in the generatorBrowse the library

Example file

Balanced strictness, readable style, pragmatic tests. Download name: project.mdc. Legacy path: .cursorrules

---
description: "Working rules for a Spring Boot repository"
globs: "**/*"
alwaysApply: true
---

# Project rules

Follow these rules on every task in this Spring Boot repository.
If the project still uses a root `.cursorrules` file, keep the same rules there.

## Stack

This repository is a Spring Boot service. Controllers stay thin, transactions sit on the service the project already uses, and configuration comes from the environment.

## Layout

- Controllers, services, and repositories follow the package split the project already has.
- DTOs are separate from JPA entities when the project already separates them.
- Configuration lives in application config and env vars. Do not hard-code a profile.

## Commands

- Test: `./mvnw test`
- Run: `./mvnw spring-boot:run`
- Package: `./mvnw package`

Use the script the repo already defines when it differs from the command above.

## Conventions

- Validate request bodies with Bean Validation. Do not parse maps by hand.
- Keep `@Transactional` on the service boundary the project uses, not on the controller.
- Use constructor injection. Do not add field injection.
- Return the response type the controller already declares. Do not leak lazy entities.
- Match MVC or WebFlux. Do not block inside a reactive chain.
- Use the existing test slice: `@WebMvcTest`, `@DataJpaTest`, or `@SpringBootTest` only when you need the whole context.

## Testing

Add or update tests when behavior changes.

Add a sliced test for the controller or service. Do not boot the entire context for a validation rule.

## Style

- Optimize for the next reader over the shortest diff.
- Comment only when the why is non-obvious.
- Name things the way neighboring files already do.
- Do not reformat code you did not change.

## Errors

- Fail at the boundary. Do not swallow errors.
- Use the project's exception handler for expected failures. A validation failure is 400, a missing row is 404.

## Scope

- Do the requested task. Do not refactor unrelated code.
- Match the rigor already in the repo. Fix what you touch.
- Ask one clarifying question only when the task cannot be finished without it. Otherwise state the assumption and continue.

## Avoid

- Do not catch Exception and return 200.
- Do not use the open-in-view pattern as an excuse to lazy-load in the controller.
- Do not commit `application-local` files that contain passwords.
- Do not add a new bean of a type that is already defined.

## Done when

- The requested behavior works.
- The module's tests pass. Use the Maven wrapper if it is present, otherwise the Gradle wrapper.
- The diff stays inside the task.
- You list anything you could not run.

Add it to the project

  1. 01

    Copy a starting file

    Copy the example Cursor rules on this page, or open the generator if you want different testing, strictness, or comment rules.

  2. 02

    Save it at .cursor/rules/project.mdc

    Save it at `.cursor/rules/project.mdc` in the Spring Boot repo and create the folders if they are missing. If the project still uses one root rules file, save the body as `.cursorrules`.

  3. 03

    Start a fresh agent session

    Rules files are read when a session starts. A chat that is already open may still be using the old instructions.

  4. 04

    Give it one small task

    Ask for one change a Spring Boot agent often gets wrong, such as a request DTO with Bean Validation that returns 400 on a bad body. If it ignores the file, confirm the path and start a new session.

Questions about this file

Where do I put Cursor rules in a Spring Boot repo?

Save it at `.cursor/rules/project.mdc` in the Spring Boot repo and create the folders if they are missing. If the project still uses one root rules file, save the body as `.cursorrules`.

Which tools read this Cursor rules?

Cursor reads `.cursor/rules/*.mdc` and, on older setups, a root `.cursorrules` file. Other tools ignore the frontmatter, so use AGENTS.md when more than one agent edits the repo.

What does the Spring Boot example assume?

The example assumes Spring Boot with Maven or Gradle, whichever wrapper is in the repo. It does not assume WebFlux versus MVC, or a particular database. Follow the stack that is already on the classpath.

Does VibeSpell upload my repository?

No. Recipe pages are static, and the generator builds the file in your browser from the options you pick. Your source code never leaves the machine.

Other files for Spring Boot

Cursor rules for other stacks