Aider: CONVENTIONS.md, .aider.conf.yml and API keys

Aider has no special conventions format. You create a short markdown file listing your guidelines, for example preferred libraries or type hints, and add it to the chat. Loading it with --read or the /read command marks it read-only, and it is cached if prompt caching is enabled.

- Prefer httpx over requests for making http requests.
- Use types everywhere possible.

aider --read CONVENTIONS.md useragent.py

# one file
read: CONVENTIONS.md

# or several files
# read: [CONVENTIONS.md, anotherfile.txt]

• Your home directory.
• The root of your git repo.
• The current directory.

Aider loads these files in that order, and files loaded last take priority. Passing --config with a filename loads only that one config file. Most options can also be set as AIDER_ environment variables, for example AIDER_DARK_MODE=true.

• model: the model for the main chat.
• auto-commits: commit LLM changes automatically (default true).
• dirty-commits: commit when the repo is found dirty (default true).
• lint-cmd and auto-lint: lint commands per language, and automatic linting after changes (default true).
• test-cmd and auto-test: the test command, and automatic testing after changes (default false).
• read: read-only files to add to every chat.
• yes-always: always say yes to every confirmation (default false).

model: YOUR_MODEL
auto-commits: false
dirty-commits: true
auto-lint: true
test-cmd: YOUR_TEST_COMMAND
auto-test: true
read:
  - CONVENTIONS.md

Aider looks for a .env file in your home directory, the git repo root, the current directory, and any file passed with --env-file, loading them in that order with later files taking priority. A .env file works for every provider and can also hold general aider options.

OPENAI_API_KEY=YOUR_VALUE
ANTHROPIC_API_KEY=YOUR_VALUE
GEMINI_API_KEY=YOUR_VALUE
AIDER_MODEL=YOUR_MODEL

OpenAI and Anthropic keys also have dedicated switches and YAML entries. Other providers use --api-key provider=YOUR_VALUE on the command line or the api-key list in YAML, which sets the matching PROVIDER_API_KEY environment variable.

openai-api-key: YOUR_VALUE
anthropic-api-key: YOUR_VALUE
api-key:
  - gemini=YOUR_VALUE
  - openrouter=YOUR_VALUE