Import rules

Import order

Groups separated by blank line:

1. stdlib (import os, from typing import ...)
2. third-party (import pendulum, import semver)
3. local dlt (from dlt.common import ...)
4. (tests only) test utilities (from tests.utils import ...)

• Stdlib imports are ALWAYS at module level -- never inline in functions. This includes contextlib, io, warnings, sys, os, re, etc.
• No relative imports.

Logging

from dlt.common import logger, then logger.info(...) -- never import logging directly (except in logger.py itself or runtime infrastructure).

TYPE_CHECKING imports

• Optional deps for annotations only: if TYPE_CHECKING: from X import Y with else: Y = Any
• Destination factories: client class under TYPE_CHECKING, actual import deferred to runtime method

Optional dependencies

When importing pyarrow, pandas, numpy, pydantic, sqlalchemy, ibis, deltalake, pyiceberg: See common-libs.md