pyproject.toml: The Project Contract

Every modern Python project declares itself in pyproject.toml (TOML — read it in the sandbox with tomllib):

[build-system]
requires = ["setuptools>=68"]
build-backend = "setuptools.build_meta"

[project]
name = "tasknoter"
version = "0.1.0"
description = "A typed, tested task manager"
requires-python = ">=3.12"
dependencies = []

[project.scripts]
tasknoter = "tasknoter.cli:main"

What each block promises:

• build-system — which tool turns this into an installable package (setuptools here; alternatives exist).
• project — identity: name, version, supported Python, and dependencies with version constraints (requests>=2.31,<3).
• project.scripts — console commands to generate (next lesson).

requires-python is a promise to your users: the tool refuses to install on older interpreters. Versioning your own project with semver-like bumps (0.1.0 → 0.2.0 for features, +0.0.1 for fixes) is the cheapest coordination tool you will ever adopt.

On your own machine, pip install -e . installs the project in editable mode — the sandbox can't run pip (no network), so this course verifies the file is well-formed instead.