Fusion vs Replit | agentconfig.ing

Fusion vs ReplitComparisonUpdated 2026-03-16

SUMMARY

Fusion (IDE) uses mdc configuration while Replit (Platform) 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

Feature	Fusion	Replit	Notes
Config format	mdc	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	✗	✗
IDE integration	✓	Platform
Schema / structure	Hybrid (MDC frontmatter + 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

FILE MAPPING

Purpose	Fusion	Replit
Project instructions	AGENTS.md	replit.md

SIDE-BY-SIDE CODE SAMPLES

Fusion

.builder/rules/*.mdc

mdc

---
description: React component conventions
globs: src/components/**/*.tsx
alwaysApply: false
---

# React Component Rules

## Structure
- Use functional components with TypeScript
- Define props interface above the component
- Export components as named exports

## Styling
- Use the project design system tokens for spacing and colors
- Prefer utility classes over custom CSS
- Keep component-specific styles colocated

## Patterns
- Wrap async data in Suspense boundaries
- Use forwardRef for reusable interactive components
- Keep components under 150 lines; extract hooks for logic

## Accessibility
- All interactive elements need aria-labels
- Use semantic HTML elements (nav, main, section)
- Ensure keyboard navigation works for custom widgets

Replit

replit.md

markdown

# My Project

## Overview
This is a Next.js e-commerce storefront with Stripe payments, NextAuth
authentication, and a PostgreSQL database via Prisma ORM.

## Tech Stack
- Framework: Next.js 14 (App Router, server components by default)
- Database: PostgreSQL with Prisma ORM
- Auth: NextAuth.js with GitHub and Google providers
- Payments: Stripe Checkout and webhooks
- Styling: Tailwind CSS with shadcn/ui components

## Development Phase
Currently building the product catalog and cart system. Authentication
and payment flows are complete. Next up: order history and admin dashboard.

## Code Style
- TypeScript strict mode enabled
- Prefer server components; use "use client" only when needed
- Use server actions for mutations (app/actions/)
- Validate all inputs with Zod schemas

## Commands
- `npm run dev` — start development server on port 3000
- `npm run build` — production build
- `npm run db:push` — push Prisma schema to database
- `npm run db:seed` — seed database with sample data
- `npm test` — run Jest test suite

## External Resources
- Design system: https://ui.shadcn.com
- API docs: Stripe API at https://stripe.com/docs/api

KEY DIFFERENCES

1. Config format

Fusion: mdc. Replit: markdown.

2. IDE integration

Fusion: Supported. Replit: Platform.

3. Schema / structure

Fusion: Hybrid (MDC frontmatter + Markdown). Replit: Free-form (Markdown).

WHICH SHOULD I USE?

Recommendation

Choose based on your IDE/CLI preference. If you use Fusion, configure .builder/rules/*.mdc. If you use Replit, configure replit.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