Use this skill when you need to compile CPython, run tests, verify your changes work, check if a fix is correct, or debug test failures. Covers building from source with ./configure and make, ccache for faster rebuilds, Argument Clinic regeneration, and the unittest-based test system (NOT pytest). Essential for any task that requires running code or tests.
Use this skill when working in the CPython repository for any development task - fixing bugs, adding features, understanding code, or making contributions. Provides codebase orientation and coordinates loading of specialized skills (build, style, docs, jit) as your workflow progresses.
Use this skill when editing documentation, working with files in Doc/, adding versionadded or versionchanged markers, creating NEWS entries for bug fixes or features, updating What's New (Doc/whatsnew/), or building the HTML docs. Covers reStructuredText (.rst) format, documentation validation, and NEWS file requirements.
Use this skill when working on CPython's experimental JIT compiler - modifying Tools/jit/ build scripts, editing Python/jit.c runtime code, changing bytecode that affects JIT stencils, debugging JIT failures, or working with the copy-and-patch compilation pipeline. Covers LLVM toolchain setup, stencil generation, JIT configure flags, and the template.c to jit_stencils.h build flow.
Use this skill when preparing commits, running pre-commit hooks, checking code style, or validating changes before pushing. Covers PEP 7 (C code) and PEP 8 (Python) compliance, trailing whitespace rules, the no-type-annotations-in-Lib policy, and patchcheck validation. Note: patchcheck requires a build directory - load the `build` skill first if you haven't built CPython yet.
Use this skill when backporting a merged CPython change to a maintenance branch (3.14, 3.13, etc.) - whether invoked as /cpython:backport <version> [PR], asked to backport or cherry-pick a fix from main, or handling a failed automated miss-islington backport. Produces a cherry_picker-convention branch and offers to open the backport PR.