Aider vs Gemini Code AssistUpdated 2026-03-18

SUMMARY

Aider (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

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

FILE MAPPING

PurposeAiderGemini Code Assist
Project instructionsCONVENTIONS.mdGEMINI.md

SIDE-BY-SIDE CODE SAMPLES

Aider
CONVENTIONS.md
markdown
# Project Conventions

## Language
- TypeScript strict mode, no `any` types
- Prefer const over let, never use var
- Use template literals over string concatenation

## Architecture
- Feature-based folder structure under src/features/
- Each feature exports through an index.ts barrel file
- Shared utilities go in src/lib/

## Error Handling
- Use Result<T, E> pattern for expected failures
- Throw only for programmer errors
- Always log errors with structured context

## Testing
- Colocate tests next to source files (*.test.ts)
- Use factories for test data, not fixtures
- Integration tests in __tests__/ directories

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. Hierarchy support

Aider: Not supported. Gemini Code Assist: Supported.

2. Global config

Aider: Supported. Gemini Code Assist: Not supported.

3. Ignore file

Aider: .aiderignore. Gemini Code Assist: Not supported.

4. IDE integration

Aider: CLI. Gemini Code Assist: Supported.

WHICH SHOULD I USE?

Recommendation

Choose based on your IDE/CLI preference. If you use Aider, configure .aider.conf.yml. 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)