use-pixi

name	use-pixi
description	Use when explaining, creating, or changing a Pixi workspace, including manifests, dependencies, platforms, targets, features, environments, tasks, lockfiles, editable Python packages, CI commands, or IDE interpreter setup.

Use Pixi

Use Pixi as the command and environment boundary for this repository.

Inspect before editing

1. Run pixi --version, pixi info, and pixi task list when available.
2. Locate both pixi.toml and pyproject.toml. Pixi discovers an explicit --manifest-path first, then a local pixi.toml, then a local pyproject.toml, then parent manifests. A sibling pixi.toml therefore wins over pyproject.toml.
3. Read the selected manifest, its workspace.platforms, targets, features, environments, tasks, and editable path dependencies.
4. Read pixi.lock when reproducibility or CI behavior matters. Do not hand-edit the lockfile.

Choose the dependency owner

• Put Python itself and command-line/system packages supplied by conda-forge under Pixi dependencies.
• Put Python distributions resolved from PyPI under pypi-dependencies or [project.dependencies], according to the repository's existing ownership boundary.
• Represent a local Python project as { path = ".", editable = true } or another relative editable path in Pixi.
• Use target.<platform> for dependencies limited to one supported platform.
• Use a feature when a dependency set is optional and reusable; compose features into named environments.
• Do not use bare pip install inside a Pixi-managed repository. Use pixi add, a manifest edit, and a new lock instead.

Understand the model

• A workspace declares channels and every platform solved into pixi.lock.
• A target narrows configuration to a platform such as linux-64, win-64, or osx-arm64.
• A feature groups optional dependencies, tasks, activation, and targets.
• An environment selects features and produces an installable prefix under .pixi/envs/ by default; named or detached configuration may select another prefix.
• A task is a reproducible command executed inside an environment.
• The lockfile records exact conda and PyPI resolutions for every declared platform.

Make and verify changes

Use the smallest applicable commands:

pixi add PACKAGE
pixi add --pypi PACKAGE
pixi remove PACKAGE
pixi remove --pypi PACKAGE
pixi update PACKAGE
pixi install
pixi run TASK
pixi shell  # interactive use only
pixi task list
pixi lock --check

Install an editable local Python project

From the workspace root, add a local PyPI project in editable mode with a PEP 508 file URL:

pixi add --pypi --editable \
  "DISTRIBUTION_NAME @ ./RELATIVE_PROJECT_PATH"

• Read DISTRIBUTION_NAME from the local project's [project].name; do not assume it matches the Python import name.
• Inspect the local project's requires-python first and select a compatible workspace Python version, for example pixi add python=3.11.
• Expect the command to update the manifest, lockfile, and current environment. Pixi may serialize the expanded file URL as an absolute path.
• For a manifest that must work across clones or machines, prefer or restore a relative declaration such as:

[tool.pixi.pypi-dependencies]
distribution_name = { path = "relative/project/path", editable = true }

After a manual relative-path edit, run pixi lock and pixi install. Verify against the actual import package:

pixi run python -c "import IMPORT_NAME; print(IMPORT_NAME.__file__)"
pixi lock --check

When adding or removing a dependency, use --feature FEATURE for a named feature and --platform PLATFORM for a platform-specific table. Combine the selectors only when both scopes apply.

For local, intentional manifest changes, run pixi lock, the relevant pixi run task, and pixi lock --check. Inspect the manifest diff and lockfile diff before reporting success.

Keep the lockfile immutable in CI:

pixi install --locked
pixi run --locked TASK

--locked prevents lockfile updates; it does not make environment installation or task execution read-only. Inspect task definitions before running them in any no-write workflow.

CI must not run pixi lock, because that command mutates the lockfile.

IDE boundary

Run pixi install before selecting an interpreter. For this template, .pixi/envs/default is the conventional default prefix and may be used as the VS Code python.defaultInterpreterPath folder for analysis and debugging. Locate named or detached environments using the prefix reported by pixi info --json, but never commit the returned absolute machine path. Documentation, automation, and terminal commands should use pixi run; Windows and POSIX interpreter paths differ.

Safeguards

• Keep all declared platforms solvable; do not validate only the current host.
• Do not add CUDA or another platform-only dependency to unconditional common dependencies.
• Do not remove or regenerate unrelated environments.
• Do not claim success until the lockfile is current and the requested task passes.