JetBrains AI / Junie vs Lovable

JetBrains AI / Junie vs LovableComparisonUpdated 2026-03-16

SUMMARY

JetBrains AI / Junie (IDE) uses markdown configuration while Lovable (Platform) uses markdown. They differ on 2 of 11 compared features. Both tools provide AI-assisted development but take different approaches to project configuration.

FEATURE COMPARISON

Feature	JetBrains AI / Junie	Lovable	Notes
Config format	markdown	markdown
Hierarchy support	✗	✗	Whether config files can be placed at multiple directory levels
Global config	✗	✗	User-wide configuration outside any project
Project config	✓	✓
Subdirectory scoping	✗	✗	Config files in subdirectories that apply only to that subtree
File inclusion / imports	✗	✗	Ability to include or reference other files from config
Ignore file	.aiignore	✗
IDE integration	✓	Platform
Schema / structure	Free-form (Markdown)	Free-form (Markdown)	Whether config uses structured schema or free-form content
Git committed	✓	✓	Whether primary config files are intended to be version-controlled
Encoding	UTF-8	UTF-8

SIDE-BY-SIDE CODE SAMPLES

JetBrains AI / Junie

.aiassistant/rules/*.md

markdown

# 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

Lovable

AGENTS.md

markdown

# Project Instructions

## Stack
- React 19 with TypeScript
- Supabase for backend (auth, database, storage)
- TailwindCSS v4 + shadcn/ui components
- Vite for building

## Architecture
- Feature-based folder structure
- Each feature owns its components, hooks, and types
- Shared components in src/components/ui/
- All API calls go through src/lib/supabase.ts

## Conventions
- Use shadcn/ui components before creating custom ones
- Mobile-first responsive design
- Use Supabase RLS policies for authorization
- Prefer server-side filtering over client-side

## Brand
- Primary color: #6366F1 (indigo)
- Font: Inter for body, Cal Sans for headings
- Rounded corners (radius-lg) on all cards

KEY DIFFERENCES

1. Ignore file

JetBrains AI / Junie: .aiignore. Lovable: Not supported.

2. IDE integration

JetBrains AI / Junie: Supported. Lovable: Platform.

WHICH SHOULD I USE?

Recommendation

Choose based on your IDE/CLI preference. If you use JetBrains AI / Junie, configure .aiassistant/rules/*.md. If you use Lovable, configure AGENTS.md. Many projects include config files for multiple tools so each team member can use their preferred editor.

PORTABILITY TIP

sync-instructions.sh

bash

# Maintain a single source of truth:
cp AI-INSTRUCTIONS.md CLAUDE.md
cp AI-INSTRUCTIONS.md .cursorrules
cp AI-INSTRUCTIONS.md AGENTS.md