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.cursor/rules/security.mdc

Cursor security rule for Bevy

A focused Cursor `.mdc` rule for auth, secrets, and untrusted input. It attaches when those files change, instead of repeating security policy in every chat. This copy is written for a Bevy project. This repository is a Bevy game. Data lives in components, behavior lives in systems, and schedules stay explicit. Do not reach for a God object.

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 Bevy. It does not assume a particular physics crate or UI crate unless Cargo.toml already depends on it.

Customize in the generatorBrowse the library

Example file

Balanced strictness, readable style, pragmatic tests. Download name: security.mdc

---
description: "Security rules for a Bevy repository"
globs: "**/*{auth,Auth,secret,config,Config}*"
alwaysApply: false
---

# Security rules

Attach these rules when editing auth, config, or secret-handling code in this Bevy repository.
This repository is a Bevy game. Data lives in components, behavior lives in systems, and schedules stay explicit. Do not reach for a God object.

## Secrets and trust

- Do not trust network payloads as components without validation.
- Keep tokens out of the client binary.
- Do not use unsafe to skip a bounds check on player-controlled input.

## Errors

- Fail at the boundary. Do not swallow errors.
- Log a missing asset and skip the spawn. A missing optional component is absence, not a panic.

## Done when

- Untrusted input is validated before a side effect.
- No secret was added to source, logs, or a client bundle.
- `cargo test` passes and `cargo clippy --all-targets -- -D warnings` is clean for non-trivial changes.

Add it to the project

  1. 01

    Copy a starting file

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

  2. 02

    Save it at .cursor/rules/security.mdc

    Save it at `.cursor/rules/security.mdc` in the Bevy repo. Narrow the globs if your auth and config files live in a known folder.

  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 Bevy agent often gets wrong, such as a system that queries the components it needs and does not spawn entities every frame by accident. If it ignores the file, confirm the path and start a new session.

Questions about this file

Where do I put Cursor security rule in a Bevy repo?

Save it at `.cursor/rules/security.mdc` in the Bevy repo. Narrow the globs if your auth and config files live in a known folder.

Which tools read this Cursor security rule?

Cursor loads `.cursor/rules/security.mdc` for files that match its globs. Pair it with the always-on project rule. It is not a substitute for code review.

What does the Bevy example assume?

The example assumes Bevy. It does not assume a particular physics crate or UI crate unless Cargo.toml already depends on it.

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 Bevy

Cursor security rule for other stacks