Supported subset: the principles (refuse rather than guess), what is not supported, and
where each part of the supported subset is described.
Command line: py2axum and py2axum check, every option.
Environment variables: what the binary, and the Python-side recorder, read at run time.
Python semantics: values, functions, classes, modules, asyncio and threading.
Standard library: the modules the runtime implements, and pickle.
Libraries: the third-party libraries the runtime implements.
Versioning and deprecation: what semver covers from 1.0 (command lines, environment
variables, supported subset, JSON of check, error codes) and how a deprecation works.
Versions: the tested version ranges of FastAPI, Starlette, Pydantic, SQLAlchemy and Python.