PDM Migration Specialist

Focused skill for migrating pyproject.toml files from pre-PDM 2.0 legacy syntax to modern PEP-compliant format.

When to Use

Activate when the user:

• Needs to migrate from [tool.pdm.dev-dependencies] to [dependency-groups]
• Wants to update legacy pyproject.toml to PEP 621 standards
• Asks about old vs new PDM syntax
• Needs to understand modern dependency specification
• Mentions PDM migration, legacy format, or pre-2.0 syntax
• Encounters deprecated PDM configuration patterns

Core Capabilities

• Dev Dependencies Migration: Convert [tool.pdm.dev-dependencies] → [dependency-groups]
• PEP 621 Compliance: Migrate to standardized [project] table
• Dependency Specification: Modern PEP 440/508 formats
• Build Backend Updates: Migrate to pdm-backend
• Local Dependencies: Convert to file:///${PROJECT_ROOT}/ syntax
• Context7 Integration: Fetch latest PDM migration docs

Quick Migration Patterns

Development Dependencies (Most Common)

Old (Pre-2.0):

[tool.pdm.dev-dependencies]
test = ["pytest>=6.0", "pytest-cov"]
lint = ["flake8", "black"]

New (PEP 735):

[dependency-groups]
test = ["pytest>=6.0", "pytest-cov"]
lint = ["flake8", "black"]

Project Metadata

Old (Legacy):

[tool.pdm]
name = "myproject"
version = "1.0.0"

New (PEP 621):

[project]
name = "myproject"
version = "1.0.0"
dependencies = ["requests>=2.28.0"]
requires-python = ">=3.11"

Build Backend

Old:

[build-system]
requires = ["setuptools", "wheel"]
build-backend = "setuptools.build_meta"

New:

[build-system]
requires = ["pdm-backend"]
build-backend = "pdm.backend"

Key Differences

| Aspect | Pre-2.0 | Modern (2.0+) | |--------|---------|---------------| | Dev Dependencies | [tool.pdm.dev-dependencies] | [dependency-groups] | | Project Metadata | [tool.pdm] or non-standard | [project] (PEP 621) | | Optional Deps | Various formats | [project.optional-dependencies] | | Local Paths | Relative paths | file:///${PROJECT_ROOT}/ | | Build Backend | setuptools/flit | pdm-backend preferred |

CLI Changes

Adding Dev Dependencies:

# Old approach (still works but deprecated)
pdm add --dev pytest

# New approach (PEP 735)
pdm add -dG test pytest

Reference Documentation

• Detailed Migration Guide: See reference.md in this directory
• Real Migration Examples: See examples.md in this directory
• Context7 Library ID: /pdm-project/pdm
• Relevant PEPs: PEP 621 (project metadata), PEP 735 (dependency groups)