linting-and-formatting

name	linting-and-formatting
description	Code style and quality rules for NeMo AutoModel — ruff configuration, naming conventions, type hints, docstrings, copyright headers, and the code review checklist.
when_to_use	Writing or reviewing code for style compliance, fixing ruff errors, understanding type hint or docstring conventions, copyright header questions, or pre-commit failures.

Linting and Formatting

Single source of truth for code style in NeMo AutoModel. Read this before writing new code or reviewing PRs.

Formatting and Linting

Run before every commit:

# Auto-format all source files (line length, quotes, trailing commas, etc.)
ruff format .

# Lint and auto-fix what can be fixed (unused imports, isort, etc.)
ruff check --fix .

To check without modifying files:

ruff format --check .   # exits non-zero if any file would change
ruff check .            # exits non-zero on lint violations

To lint a single file or directory:

ruff format nemo_automodel/components/models/llama/model.py
ruff check --fix nemo_automodel/components/models/llama/

What ruff enforces (from pyproject.toml)

Rule	ID	Description
Line length	—	120 characters (formatter)
Quote style	—	Double quotes
Unused imports	F401	Auto-removed by --fix (ignored in __init__.py)
Unused variables	F841	Auto-removed by --fix
Undefined names	F821	Error
f-string without placeholders	F541	Error
Import sorting	I	isort-compatible ordering, auto-fixed
Docstring convention	D101/D103	Google style (currently ignored — selected then suppressed)
No pickle	S301/S403	Security: forbids pickle.load
Ambiguous variable names	E741	Error (e.g., l, O, I)

Tests (tests/) are excluded from lint checks. Docstring rules (D) are also relaxed in test files.

Type Hints

Required on all public API functions and methods.

• Use T | None instead of Optional[T]
• Use X | Y instead of Union[X, Y]
• Use built-in generics (list, dict, tuple) instead of typing equivalents

Docstrings

Google-style where docstrings are added:

def build_model(config: dict) -> torch.nn.Module:
    """Instantiate and shard the model from config.

    Args:
        config: Mapping with _target_ and model hyperparameters.

    Returns:
        Fully initialized model ready for distributed training.
    """

NVIDIA Copyright Header

Every Python file must start with the NVIDIA copyright block. Do not remove or modify it. Use the current year (2026).

# Copyright (c) 2026, NVIDIA CORPORATION.  All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

Additional Style Conventions

• Explicit over implicit. Inline logic where possible; avoid hiding behavior behind unnecessary layers of indirection.
• No speculative abstractions. Do not add features, parameters, or generalization beyond what is explicitly asked for.
• Optional dependencies must be guarded with safe_import() from nemo_automodel.shared.import_utils. Never let an optional import crash module loading.
• Components must not import each other — enforced by import-linter (see pyproject.toml).

Code Review Checklist

1. Copyright header present on all new Python files
2. Type hints on all public functions and methods
3. Docstrings on public classes and functions (Google style)
4. Double quotes for strings
5. No bare print() — use logging.getLogger(__name__)
6. No commented-out code without explanation
7. Optional imports guarded with safe_import()
8. No cross-component imports between components/ subdirectories