Claude Code vs Gemini Code AssistUpdated 2026-03-18

SUMMARY

Claude Code (CLI) uses markdown configuration while Gemini Code Assist (IDE) uses markdown. They differ on 4 of 11 compared features. Both tools provide AI-assisted development but take different approaches to project configuration.

FEATURE COMPARISON

FeatureClaude CodeGemini Code Assist
Config formatmarkdownmarkdown
Hierarchy support
Global config
Project config
Subdirectory scoping
File inclusion / imports
Ignore file.claudeignore
IDE integrationCLI
Schema / structureFree-form (Markdown)Free-form (Markdown)
Git committed
EncodingUTF-8UTF-8

FILE MAPPING

PurposeClaude CodeGemini Code Assist
Project instructionsCLAUDE.mdGEMINI.md

SIDE-BY-SIDE CODE SAMPLES

Claude Code
CLAUDE.md
markdown
# Project Name

> TypeScript + React monorepo. Deployed on Vercel.

## Code Style

- TypeScript strict mode — no `any`, no `ts-ignore`
- Named exports only (no default exports)
- Prefer functional patterns: map/filter/reduce over for-loops
- Error handling: use Result<T, E> from `src/lib/result.ts`

## Architecture

- `src/routes/`   — Route handlers (thin layer, delegates to services)
- `src/services/`  — Business logic, one file per domain entity
- `src/db/`        — Drizzle ORM schema and query helpers
- `src/lib/`       — Shared utilities (logger, result type, validation)

## Commands

```bash
pnpm install          # Install dependencies
pnpm dev              # Start dev server (port 3000)
pnpm test             # Run Vitest suite
pnpm test:e2e         # Run Playwright tests
pnpm lint             # ESLint + Prettier check
pnpm db:migrate       # Run pending Drizzle migrations
```

## Git Conventions

- Conventional Commits: `feat:`, `fix:`, `chore:`, `docs:`
- Branch naming: `feat/short-description`, `fix/issue-number`
- Squash merge to main; delete branches after merge

## Notes

- The `src/legacy/` directory is being migrated. Do not add new code there.
- All dates are stored as UTC. Never use local time.

@docs/api-patterns.md
@docs/database-conventions.md
Gemini Code Assist
GEMINI.md
markdown
# Project Rules

## Overview
E-commerce platform built with Go microservices and React frontend.
All services communicate via gRPC with Protocol Buffers.

## Go Services
- Follow standard Go project layout (cmd/, internal/, pkg/)
- Use structured logging with slog (not log or fmt.Println)
- Error handling: always wrap errors with fmt.Errorf("%w", err)
- Database access through repository pattern in internal/repo/
- All public functions must have godoc comments

## API Design
- Proto files live in proto/ directory with buf for linting
- Use field masks for partial updates
- Pagination via cursor-based tokens, not offset

## Testing
- Table-driven tests for all business logic
- Use testcontainers-go for integration tests
- Minimum 80% coverage on internal/ packages
- Mock external services with gomock interfaces

## Do Not
- Use global variables or init() functions
- Import internal packages across service boundaries
- Commit generated .pb.go files (CI generates them)

KEY DIFFERENCES

1. Global config

Claude Code: Supported. Gemini Code Assist: Not supported.

2. File inclusion / imports

Claude Code: Supported. Gemini Code Assist: Not supported.

3. Ignore file

Claude Code: .claudeignore. Gemini Code Assist: Not supported.

4. IDE integration

Claude Code: CLI. Gemini Code Assist: Supported.

WHICH SHOULD I USE?

Recommendation

Choose based on your IDE/CLI preference. If you use Claude Code, configure CLAUDE.md. If you use Gemini Code Assist, configure GEMINI.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)