Copilot instructions

1---
2description: 'Python specific coding instructions for production code.'
3applyTo: '**.py, **.pyx'
4---
5 
6# Python Instructions
7 
8> Auto-loads when editing Python files. For comprehensive standards, load the skill.
9 
10**Skill**: [.github/skills/languages/python/SKILL.md](../skills/languages/python/SKILL.md)
11 
12## Key Rules
13 
14- Follow PEP 8 style guide
15- Use type hints for all function signatures (PEP 484)
16- Maximum line length: 88 characters (Black formatter)
17- Use `ruff` for linting and formatting
18- Google style docstrings
19- Catch specific exceptions, never bare `except:`
20- pytest for testing, pytest-asyncio for async
21- Name tests: `test_function_name_scenario_expected`
22 
23## Critical Rules (Embedded -- Always Active)
24 
25### Security
26- Validate/sanitize ALL inputs at API boundaries
27- Parameterize SQL via ORM or `cursor.execute(sql, params)` -- NEVER f-strings or `.format()`
28- Secrets in env vars (`os.environ`) or Key Vault -- NEVER hardcode
29- Use `secrets.compare_digest()` for constant-time comparisons
30 
31### Testing
32- 80%+ code coverage required (`pytest --cov`)
33- Pyramid: 70% unit, 20% integration, 10% e2e
34- AAA pattern (Arrange-Act-Assert) in every test
35- No bare `assert True` -- assert specific values
36 
37### Error Handling
38- Catch specific exceptions (`ValueError`, `KeyError`, etc.)
39- Log with context: `logger.error("msg", extra={"agent": ..., "issue": ...})`
40- Retry transient failures with exponential backoff (`tenacity`)
41- Fail fast on invalid input at module boundaries
42 
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