Imports Style Guide

General Rules

• Source code (src/): use relative imports. from ..agents.llm_agent import LlmAgent
• Tests (tests/): use absolute imports. from google.adk.agents.llm_agent import LlmAgent
• Import from the module, not the package. from ..agents.llm_agent import LlmAgent, never from ..agents import LlmAgent. Importing through __init__.py inside the framework creates import cycles and forces the package to eagerly load unrelated modules.
• CLI package (cli/):
  • Treat it as an external package.
  • Use relative imports for files within cli/.
  • Use absolute imports for files outside cli/.
  • Dependency direction: cli/ may import from the rest of the codebase; nothing outside cli/ may import from it. scripts/compliance_checks.py fails the commit on any from ...cli... import ... outside the package.

One name per line

isort's google profile puts every imported name on its own line, so from typing import Any, Optional becomes two lines. Ordering is case-insensitive and does not group by type, which is why PrivateAttr sorts after model_validator:

from typing import Any
from typing import Optional

from pydantic import BaseModel
from pydantic import Field
from pydantic import model_validator
from pydantic import PrivateAttr

Three groups, blank-line separated: standard library, third party, then relative. In tests, google.adk sorts into the third-party group (known_third_party in pyproject.toml), alongside google.genai and pytest.

Don't wrap a long import

The 80-character limit does not apply to imports: isort is configured with line_length = 200 and pyink leaves import lines intact. A long from ... import ... stays on one line — the codebase has no parenthesized from-imports. Adding parentheses or a line break will be reverted by the next format run.

TYPE_CHECKING Imports

Use TYPE_CHECKING for imports needed only by type hints, to avoid circular imports at runtime:

from __future__ import annotations

from typing import TYPE_CHECKING

if TYPE_CHECKING:
  from ..agents.invocation_context import InvocationContext

This works because from __future__ import annotations makes annotations strings (deferred evaluation), so the import is never needed at runtime.