GitHub Copilot vs OpenCode | agentconfig.ing

GitHub Copilot vs OpenCodeComparisonUpdated 2026-03-16

SUMMARY

GitHub Copilot (IDE) uses markdown configuration while OpenCode (CLI) 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	GitHub Copilot	OpenCode	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	✗	✗
IDE integration	✓	CLI
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

FILE MAPPING

Purpose	GitHub Copilot	OpenCode
Project instructions	.github/copilot-instructions.md	AGENTS.md
Project instructions	.github/instructions/*.instructions.md	CLAUDE.md

SIDE-BY-SIDE CODE SAMPLES

GitHub Copilot

.github/copilot-instructions.md

markdown

# Copilot Instructions

## Code Style
- Use TypeScript strict mode for all new files
- Prefer functional components with hooks over class components
- Use named exports, not default exports

## Libraries
- Use date-fns for date manipulation (not moment.js)
- Use zod for runtime validation
- Prefer fetch over axios for HTTP requests

## Testing
- Write tests using Vitest
- Use Testing Library for component tests
- Aim for integration tests over unit tests

## Conventions
- Use camelCase for variables, PascalCase for components
- Prefix interfaces with I (e.g., IUserProps)
- Keep files under 300 lines; extract if longer

OpenCode

AGENTS.md

markdown

# Project Instructions

## Overview
This is a TypeScript monorepo using pnpm workspaces.

## Code Style
- Use strict TypeScript with no implicit any
- Prefer functional components with hooks
- All exports should be named (no default exports)

## Architecture
- /packages/core — shared business logic
- /packages/ui — React component library
- /apps/web — Next.js frontend

## Build & Test
Run tests with: pnpm test
Build all packages: pnpm build
All PRs must have >80% coverage on changed files.

## Conventions
- Use conventional commits (feat:, fix:, chore:)
- Prefer composition over inheritance
- See @docs/api-guidelines.md for API design patterns

KEY DIFFERENCES

1. Global config

GitHub Copilot: Not supported. OpenCode: Supported.

2. IDE integration

GitHub Copilot: Supported. OpenCode: CLI.

WHICH SHOULD I USE?

Recommendation

Choose based on your IDE/CLI preference. If you use GitHub Copilot, configure .github/copilot-instructions.md. If you use OpenCode, 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