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Python Notes

good to use libs, for things I commonly do.

  1. typer - cli
  2. fastapi + sqlalchemy + sqlmodel - BE Service + DB thing, sqlmodel allows bridging SQLAlchemy and Pydantic
  3. pydantic + pydantic-settings - pydantic for validation and pydantic-settings for config stuff
  4. openpyxl - excel sheets, avoid pandas if you don’t need the additional stuff.
  5. paramiko + fabric - SSH client, pure python
  6. rich - nice logs and console stuff. use Console() and work from there.
  7. httpx2 - HTTP client, sync + async behind one API. Not httpx, that stopped at v0.28.1 in Dec 2024 and the tracker closed Feb 2026. Pydantic Services took it over with the original author, drop-in for common use. Starlette moved in May 2026.
  8. psycopg (v3) - postgres. psycopg[binary] in images, bundles libpq.
  9. dateparser - messy human dates, many languages. “last Tuesday”, “vor 3 Tagen”. Right tool when the source picks a different format every document.
  10. whenever - dateparser makes datetimes out of strings, whenever replaces stdlib datetime with DST-correct arithmetic and separate aware/plain types. Parse with one, compute with the other.
  11. alembic - migrations, works even when the app cannot run DDL. alembic revision --autogenerate against a throwaway DB, then alembic upgrade head --sql > ddl.sql. Models stay source of truth, platform team gets reviewable DDL. Autogenerate still needs some DB to diff against.
  12. tenacity - retries with backoff and jitter. Worth it against flaky enterprise services and LLM APIs.
  13. structlog - only if logs go to an aggregator. Pipeline, not a renderer, composes with rich rather than replacing it. Pretty on a TTY, JSON lines otherwise. Rich boxes are hostile inside Loki.
  14. polars - dataframes. Only if you were about to reach for pandas. Reading a spreadsheet is still openpyxl.
  15. pytest + pytest-cov + pytest-asyncio + ruff - test and lint base. Nothing in it type-checks. --cov-fail-under in CI or coverage is a number nobody reads.
  16. mypy or pyright - the gap in 15.
  17. testcontainers - real postgres instead of sqlite-that-lies. Matters once psycopg and SQLAlchemy are involved.
  18. hypothesis - property based. Good for parsing, validation, extraction.
  19. time-machine - freeze time, faster than freezegun.
  20. pytest-randomly - finds tests that secretly depend on each other.
  21. pytest-mock, pytest-xdist, pre-commit.