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name: python-code-review description: Reviews Python code for type safety, async patterns, error handling, and common mistakes. Use when reviewing .py files, checking type hints, async/await usage, or exception handling.

Python Code Review

Quick Reference

Review Checklist

PEP8 Style

• 4-space indentation (no tabs)
• Line length ≤79 characters (≤72 for docstrings/comments)
• Two blank lines around top-level definitions, one within classes
• Imports grouped: stdlib → third-party → local (blank line between groups)
• No whitespace inside brackets or before colons/commas
• Naming: snake_case for functions/variables, CamelCase for classes, UPPER_CASE for constants
• Inline comments separated by at least two spaces

Type Safety

• Type hints on all function parameters and return types
• No Any unless necessary (with comment explaining why)
• Proper T | None syntax (Python 3.10+)

Async Patterns

• No blocking calls (time.sleep, requests) in async functions
• Proper await on all coroutines

Error Handling

• No bare except: clauses
• Specific exception types with context
• raise ... from to preserve stack traces

Common Mistakes

• No mutable default arguments
• Using logger not print() for output
• f-strings preferred over .format() or %

Valid Patterns (Do NOT Flag)

These patterns are intentional and correct - do not report as issues:

• Type annotation vs type assertion - Annotations declare types but are not runtime assertions; don't confuse with missing validation
• Using Any when interacting with untyped libraries - Required when external libraries lack type stubs
• Empty __init__.py files - Valid for package structure, no code required
• noqa comments - Valid when linter rule doesn't apply to specific case
• Using cast() after runtime type check - Correct pattern to inform type checker of narrowed type

Context-Sensitive Rules

Only flag these issues when the specific conditions apply:

When to Load References

• Reviewing code formatting/style → pep8-style.md
• Reviewing function signatures → type-safety.md
• Reviewing async def functions → async-patterns.md
• Reviewing try/except blocks → error-handling.md
• General Python review → common-mistakes.md

Review Questions

1. Does the code follow PEP8 formatting (indentation, line length, whitespace)?
2. Are imports properly grouped (stdlib → third-party → local)?
3. Do names follow conventions (snake_case, CamelCase, UPPER_CASE)?
4. Are all function signatures fully typed?
5. Are async functions truly non-blocking?
6. Do exceptions include meaningful context?
7. Are there any mutable default arguments?

Before Submitting Findings

Load and follow review-verification-protocol before reporting any issue.