Compatibility

ML4T libraries support every stable CPython release from Python 3.12 through the latest stable version on Linux, macOS, and Windows.

Each supported Python and operating-system combination must pass:

1. dependency resolution and installation from the built wheel;
2. public-package import;
3. the non-hardware-dependent test suite;
4. ruff lint and format checks;
5. ty type checking; and
6. source distribution and wheel builds with metadata validation.

The next CPython prerelease enters CI after beta 1. Before final release, core installation and the non-hardware-dependent tests must pass on Linux, macOS, and Windows. Prerelease support is tested but not advertised as stable.

When that CPython release becomes final, it joins the supported matrix and failures block releases. Dropping an older Python version requires an ecosystem decision and a documented deprecation period.

For releases before 2026-10-01, the stable matrix is Python 3.12 through 3.14 and the blocking prerelease target is Python 3.15. A package metadata upper bound that prevents installation on the prerelease target fails this standard.

A library may temporarily retain an upper bound only through a machine-readable exception in config/libraries.toml. The exception replaces the prerelease jobs with an explicit validation job; it does not remove the stable operating-system matrix. The validation fails when the exception is missing, applied to another repository, outside its version scope, or expired.

Hardware-specific capabilities such as CUDA require a separate matrix. Passing the general matrix does not establish hardware support.