pyprojx

Version-aware intelligence for pyproject.toml—check, explain, and safely evolve your Python configuration.

Python project configuration brings together packaging standards and settings for tools that evolve independently. pyprojx aims to help you understand and safely maintain that configuration for the versions your project actually uses, with analysis as the foundation for useful explanations and reviewable improvements.

Planned capabilities

• Validate Python/PyPA sections and tool-specific configuration, starting with uv, Ruff, and ty.
• Explain configuration issues, including unknown settings, deprecated options, and conflicts, with useful diagnostics and suggested fixes.
• Provide formatting, a pyprojx CLI, and language-server features such as completion, hover documentation, and quick fixes.

Guided editing, configuration migrations, and generation are possible future directions built on that foundation—not committed features or current capabilities.

The focus is pyproject.toml, not general project management. pyprojx is intended to complement tools like uv, Ruff, and ty—not replace package management, Python source linting, or type checking.

Current status

pyprojx is in early development. pyprojx check reports TOML syntax errors, invalid UTF-8, and byte order marks in pyproject.toml, warns about TOML 1.1 syntax that tomllib in Python 3.14 and earlier rejects, and validates [build-system], [project] (including dependencies, extras, license metadata, and trove classifiers), and [dependency-groups]. It also reports features, such as license expressions, that the build backend versions allowed by [build-system] lack, and checks [tool.ruff], [tool.ty], and [tool.uv] options and values, Ruff's rule selectors, ty's rules, and the indexes, extras, and groups [tool.uv] refers to, against the Ruff, ty, and uv versions the project uses: those locked in uv.lock or pylock.toml if there is one, otherwise those its requirements or required-version allow. Each of those diagnostics says which versions it was checked against and where they came from. pyprojx check --fix fixes what it can without changing what the configuration means, such as moving Ruff's top-level linter settings into lint, keeping the rest of the file as it was. The other capabilities above are not implemented yet.

$ pyprojx check
error[invalid-toml]: missing value
 --> pyproject.toml:2:14
  |
2 | line-length =
  |              ^

Found 1 error.

pyprojx check checks the nearest pyproject.toml in the current directory or its parents, or the file or directory you pass. It exits with 0 when there are no errors (warnings do not fail the check), 1 when there are, and 2 when the file cannot be checked.

With --fix, it applies safe fixes, which tools read as they read the original, writes the file, and reports what is left. --unsafe-fixes adds fixes that may change what the configuration means, such as renaming a misspelled key to the closest known one; review those before committing them.

pyprojx is written in Rust and distributed on PyPI as prebuilt binaries, like Ruff and uv, so no Rust toolchain is needed to install it. Run it with uvx pyprojx check, or install it with uv tool install pyprojx.

Learn more and contribute

• Project vision: intended capabilities, inspiration, and scope.
• Contributing: development setup, validation, and proposing changes.
• Publishing guide: maintainer release instructions and current automation limits.

License

MIT, copyright 2026 Jake Van Slyke.