python-backend-quality

name	python-backend-quality
description	Improve quality and reliability of Python backend changes in burndown-chart

Skill: Python Backend Quality

Use this skill when working in callbacks/, data/, visualization/, or related Python backend code.

Goals

• Reduce defects and regressions.
• Keep implementation aligned with repository architecture.
• Deliver minimal, validated changes quickly.

Workflow

1. Build a file context map for the requested change.
2. Apply minimal edits that preserve architecture boundaries.
3. Verify diagnostics with get_errors.
4. Run targeted tests for modified behavior where available.
5. Report concrete outcomes and any residual risk.

Enforcement points

• callbacks/ may route only; business logic lives in data/.
• Type hints required (except Dash callbacks/test fixtures).
• Parameterized SQL only.
• No emoji in code/logging/comments.
• No customer data or credentials in code, logs, or tests.
• All imports at module top level. PLC0415 violations are blocking defects.
• Never add # noqa: PLC0415 without either a wrapper function docstring or a # circular import guard comment naming the specific cycle being broken.
• Before any cross-module import change, run: .venv\Scripts\python.exe -c "from callbacks import register_all_callbacks; print('OK')" A startup crash means a new circular import was introduced.
• If you need a lazy import, load the circular-import-safety skill first.

Suggested validations

• get_errors for changed files.
• pytest tests/unit/ -v when unit-level behavior changes.
• ruff check . and pyright . before completion.
• python -m djlint --lint <template_dir> when template files are touched (if applicable).
• npm run lint:md when markdown files are touched.