Fusion vs TabnineUpdated 2026-03-16

SUMMARY

Fusion (IDE) uses mdc configuration while Tabnine (IDE) 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

FeatureFusionTabnine
Config formatmdcmarkdown
Hierarchy support
Global config
Project config
Subdirectory scoping
File inclusion / imports
Ignore file
IDE integration
Schema / structureHybrid (MDC frontmatter + Markdown)Free-form (Markdown)
Git committed
EncodingUTF-8UTF-8

FILE MAPPING

PurposeFusionTabnine
Project instructionsAGENTS.md.tabnine/guidelines/*.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

Tabnine
.tabnine/guidelines/*.md
markdown
# Application Guidelines

## Architecture
- This is a monorepo managed with Turborepo
- Apps: web (Next.js), api (Express), mobile (React Native)
- Shared packages: ui, config, types

## Code Standards
- TypeScript strict mode in all packages
- Use barrel exports (index.ts) for public APIs
- No default exports; use named exports everywhere
- Prefer async/await over raw Promises

## API Design
- RESTful endpoints follow /api/v1/{resource} pattern
- All responses use { data, error, meta } envelope
- Validate request bodies with Zod schemas
- Return 4xx for client errors, 5xx for server errors

## Database
- Use Prisma ORM for all database operations
- Migrations checked into source control
- Soft-delete pattern: use deletedAt timestamp, never hard delete
- All timestamps stored as UTC

## Testing
- Jest for unit tests, Playwright for E2E
- Test files colocated: foo.ts -> foo.test.ts
- Mock external services, never call real APIs in tests

KEY DIFFERENCES

1. Config format

Fusion: mdc. Tabnine: markdown.

2. Schema / structure

Fusion: Hybrid (MDC frontmatter + Markdown). Tabnine: 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 Tabnine, configure .tabnine/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

File references:
agentconfig.ing2026-03-16COMPARE(1)