ADR-0001 · Build backend: hatchling

Status: Accepted · Date: 2026-05-14

Context

The legacy setup.py is gone. PEP 621 metadata lives in pyproject.toml, and we need a PEP 517 build backend that:

• single-sources __version__ from src/rglob/__init__.py
• supports a src/ layout out of the box
• has zero plugin friction for typical packaging tasks (sdist/wheel)
• is well maintained in 2026

Decision

Use hatchling as the build backend, configured via [tool.hatch.build.*] in pyproject.toml. Run builds with the hatch CLI (make build → hatch build).

Consequences

• [tool.hatch.version] path = "src/rglob/__init__.py" reads the version string at build time — no manual sync between source and metadata.
• [tool.hatch.build.targets.wheel] packages = ["src/rglob"] makes the src/ layout work without extra glue.
• We get a low-noise, fast build with first-class PyPI OIDC compatibility.
• Alternatives considered: setuptools (more legacy baggage), flit (less flexible for our metadata footprint), pdm-backend (good but PDM-flavoured).