Google Antigravity vs JunieUpdated 2026-03-18

SUMMARY

Google Antigravity (IDE) uses markdown configuration while Junie (Agent) uses markdown. They differ on 3 of 11 compared features. Both tools provide AI-assisted development but take different approaches to project configuration.

FEATURE COMPARISON

FeatureGoogle AntigravityJunie
Config formatmarkdownmarkdown
Hierarchy support
Global config
Project config
Subdirectory scoping
File inclusion / imports
Ignore file
IDE integrationAgent
Schema / structureFree-form (Markdown)Free-form (Markdown)
Git committed
EncodingUTF-8UTF-8

FILE MAPPING

PurposeGoogle AntigravityJunie
Project instructionsAGENTS.md.junie/guidelines.md
Project instructionsGEMINI.mdAGENTS.md

SIDE-BY-SIDE CODE SAMPLES

Google Antigravity
AGENTS.md
markdown
# Project Instructions

## Architecture
- Monorepo with apps/ and packages/ directories
- Each app is a standalone Next.js deployment
- Shared packages use TypeScript project references

## Code Standards
- TypeScript strict mode everywhere
- Use Zod for runtime validation at API boundaries
- Prefer server components; use "use client" only when needed
- All database queries go through the data-access layer

## Testing
- Unit tests with Vitest for business logic
- Integration tests for API routes
- E2E tests with Playwright for critical user flows

## Deployment
- Preview deployments on every PR
- Production deploys from main branch only
- Environment variables managed via .env.local (never committed)
Junie
.junie/guidelines.md
markdown
# Project Guidelines

## Language & Framework
- Kotlin with Spring Boot 3.x
- Gradle with Kotlin DSL
- JDK 21 with virtual threads

## Architecture
- Hexagonal architecture (ports & adapters)
- Domain events for cross-module communication
- CQRS for read-heavy endpoints

## Code Standards
- Follow Kotlin coding conventions
- Use data classes for DTOs
- Prefer sealed classes for domain errors
- Extension functions over utility classes

## Testing
- JUnit 5 with Kotest assertions
- Testcontainers for integration tests
- MockK for mocking (not Mockito)

## Build & Run
- Build: ./gradlew build
- Test: ./gradlew test
- Run: ./gradlew bootRun

KEY DIFFERENCES

1. Hierarchy support

Google Antigravity: Supported. Junie: Not supported.

2. Subdirectory scoping

Google Antigravity: Supported. Junie: Not supported.

3. IDE integration

Google Antigravity: Supported. Junie: Agent.

WHICH SHOULD I USE?

Recommendation

Choose based on your IDE/CLI preference. If you use Google Antigravity, configure AGENTS.md. If you use Junie, configure .junie/guidelines.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

SEE ALSO

agentconfig.ing2026-03-18COMPARE(1)