SUMMARY
Cursor (IDE) uses mdc configuration while JetBrains AI / Junie (IDE) uses markdown. They differ on 6 of 11 compared features. Both tools provide AI-assisted development but take different approaches to project configuration.
FEATURE COMPARISON
| Feature | Cursor | JetBrains AI / Junie |
|---|---|---|
| Config format | mdc | markdown |
| Hierarchy support | ✓ | ✗ |
| Global config | ✓ | ✗ |
| Project config | ✓ | ✓ |
| Subdirectory scoping | ✓ | ✗ |
| File inclusion / imports | ✗ | ✗ |
| Ignore file | .cursorignore | .aiignore |
| IDE integration | ✓ | ✓ |
| Schema / structure | Hybrid (MDC frontmatter + Markdown) | Free-form (Markdown) |
| Git committed | ✓ | ✓ |
| Encoding | UTF-8 | UTF-8 |
FILE MAPPING
| Purpose | Cursor | JetBrains AI / Junie |
|---|---|---|
| Project rules | .cursor/rules/*.mdc | .aiassistant/rules/*.md |
| Ignore patterns | .cursorignore | .aiignore |
SIDE-BY-SIDE CODE SAMPLES
---
description: React component conventions and patterns
globs: "*.tsx"
alwaysApply: false
---
# React Component Rules
- Use functional components with explicit return types
- Define props interface directly above the component
- Export components as named exports, never default
- Use Tailwind CSS utility classes exclusively
# Kotlin Conventions
## Language Features
- Use Kotlin 2.x with coroutines for async work
- Prefer data classes for DTOs and value objects
- Use sealed classes/interfaces for domain errors
- Extension functions over utility classes
## Spring Boot
- Constructor injection (no field injection)
- Use @ConfigurationProperties over @Value
- Prefer WebFlux for reactive endpoints
- Use Spring Security with method-level security
## Testing
- JUnit 5 with Kotest assertions
- MockK for mocking (not Mockito)
- Testcontainers for integration tests
- Use @Nested for test organization
KEY DIFFERENCES
Cursor: mdc. JetBrains AI / Junie: markdown.
Cursor: Supported. JetBrains AI / Junie: Not supported.
Cursor: Supported. JetBrains AI / Junie: Not supported.
Cursor: Supported. JetBrains AI / Junie: Not supported.
Cursor: .cursorignore. JetBrains AI / Junie: .aiignore.
Cursor: Hybrid (MDC frontmatter + Markdown). JetBrains AI / Junie: Free-form (Markdown).
WHICH SHOULD I USE?
Choose based on your IDE/CLI preference. If you use Cursor, configure .cursorrules. If you use JetBrains AI / Junie, configure .aiassistant/rules/*.md. Many projects include config files for multiple tools so each team member can use their preferred editor.
PORTABILITY TIP
# Maintain a single source of truth:
cp AI-INSTRUCTIONS.md CLAUDE.md
cp AI-INSTRUCTIONS.md .cursorrules
cp AI-INSTRUCTIONS.md AGENTS.md