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.cursor/rules/project.mdc

Cursor rules for Swift

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 Swift project. This repository is a Swift app for Apple platforms. Match SwiftUI or UIKit, whichever the target already uses. Stay off the main actor only for work that is actually background work.

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 a Swift iOS or multiplatform app. It does not assume SwiftData, a particular architecture acronym, or a third-party UI kit. Follow the UI stack already on screen.

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 Swift repository"
globs: "**/*"
alwaysApply: true
---

# Project rules

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

## Stack

This repository is a Swift app for Apple platforms. Match SwiftUI or UIKit, whichever the target already uses. Stay off the main actor only for work that is actually background work.

## Layout

- Features sit in the group or Swift package the project already uses.
- Views do not own networking. A type the project already has loads data.
- Preview providers stay next to the view they preview.

## Commands

- Tests: `xcodebuild test`
- Open: `Open the project in Xcode and build the app target`

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

## Conventions

- Do not force-unwrap input that can be missing. Use `if let` or `guard`.
- UI updates hop to the main actor.
- Prefer async/await over new callback pyramids when the file already uses concurrency.
- Keep `@State` local. Hoist state only when two views need it.
- Match the existing navigation API. Do not mix NavigationView and NavigationStack in new code.
- Name types the way the module already does.

## Testing

Add or update tests when behavior changes.

Add an XCTest for the type that owns the rule. Do not snapshot the whole screen as the only check.

## 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.
- Model recoverable failure as a thrown error or a Result the view can show. Do not `try!` on user input.

## 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 capture `self` strongly in a long-lived task without a reason.
- Do not block the main thread with file or network I/O.
- Do not add a new architecture layer for one screen.
- Do not disable a compiler warning to ship a force cast.

## Done when

- The requested behavior works.
- The app target builds and the XCTest for the type you changed passes.
- 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 Swift 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 Swift agent often gets wrong, such as a view model change that publishes on the main actor and has an XCTest. 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 Swift repo?

Save it at `.cursor/rules/project.mdc` in the Swift 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 Swift example assume?

The example assumes a Swift iOS or multiplatform app. It does not assume SwiftData, a particular architecture acronym, or a third-party UI kit. Follow the UI stack already on screen.

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 Swift

Cursor rules for other stacks