Changelog

All notable changes to python-agent-standards are documented here.

[3.0.0] — May 2026

Fat models and chainable custom QuerySet managers (PostQuerySet, PostManager)
Canonical model inner-class ordering (fields → managers → Meta → __str__ → save → get_absolute_url → custom methods)
TextChoices vs inline constant patterns with rules
URLconf delegation rules and app_name namespace guidance
Template naming conventions ([app]/[model]_[function].html, includes/ for partials)
Template style rules (quoted attributes, {% endblock name %}, alphabetical {% load %})
Static files vs media files setup (STATIC_ROOT vs MEDIA_ROOT)
django.conf.settings lazy access rule (never read at module import time)
Internationalisation patterns (gettext_lazy vs gettext, no f-strings for translatable strings)

§13.5 expanded: f-string expression constraints (plain access only, no function calls inside {})
§13.6 (new): NOQA/type-ignore/pylint suppression specificity rules
§12.11: Late binding closures — the loop-lambda gotcha and both fixes
§12.12: Python idioms reference (unpacking, __ throwaway, list multiplication trap, string join, set membership)
§12.13: Function argument design rules (positional vs keyword vs *args vs **kwargs)
§12.14: Pure functions and minimising side effects with before/after example
§12.15: Variable naming under dynamic typing — avoid same-name for different types

Section 0: Nine testing principles from the Hitchhiker's Guide (one-thing, independence, descriptive names, speed, debug-via-test, etc.)
Section 10: Django-specific testing (TestCase vs TransactionTestCase vs SimpleTestCase)
Section 10.2: Preferred Django assertion methods (assertRaisesMessage, assertIs(x, True))
Section 10.3: Conditional version pragmas (# pragma: only py>=3.11, # pragma: django>=4.2 branch)
Section 12: Assert method selection guide (full reference table)
Section 13: Skip decorators and @expectedFailure patterns
Section 14: Fixture lifecycle (setUp → addCleanup → setUpClass → setUpModule)
Section 15: subTest context manager for iteration-based testing
Section 16: IsolatedAsyncioTestCase for async tests

Section 10: Module and package design rules (import style table, __init__.py patterns, project pitfalls table, pure functions vs classes decision guide)

Configuration class hierarchy (Config → DevelopmentConfig / TestingConfig / ProductionConfig)
from_prefixed_env() loading pattern
Application context and g object (get_X / teardown_X pattern, LocalProxy)
Request lifecycle hook ordering (before_request → view → after_request → teardown_request → teardown_appcontext)
MethodView for REST APIs with decorators class attribute
Custom API error classes (APIError hierarchy, to_dict() pattern)
Blueprint 404/405 caveat (must be registered at app level)
View decorators (login_required, roles_required) with @functools.wraps rule
Security headers (X-Content-Type-Options, X-Frame-Options, Strict-Transport-Security, Content-Security-Policy)
Session hardening (session.clear() before setting, SESSION_COOKIE_SECURE/HTTPONLY/SAMESITE)
Celery integration (FlaskTask subclass, celery_init_app(), shared_task)
Async views — when useful, when not, asyncio.create_task cancellation trap
Testing patterns (session seeding, redirect following, test_request_context, CLI runner)

Core skill files: code-style, folder-structure, error-handling, logging, security, testing, db-design
Framework skills: FastAPI, Django, DRF, Flask
Cursor MDC rules: python-core, python-fastapi, python-django, python-testing, python-security
Claude Code slash commands: /load-skill, /new-endpoint, /review, /add-tests, /migrate
QA agent definition
Developer onboarding guide
New skills: performance.md, llm-patterns.md