Software Atlas · Sheet No. 3 · Field guide

The Python Package Viewer

One instrument, real specimens. PyPI is the warehouse; pip is the installer; everything else lives inside the boxes below. Pick a specimen, pick a box, open the amber files. Dotted words explain themselves.

The instrument · real artifacts, captured from PyPI 2026-07-04amber files open · dotted terms define
Specimen — the same framework across fifteen years, then a compiled beast
The boxes this release uploaded to PyPI

§ How pip decides

1

pip install flask — ask PyPI what boxes exist for the chosen version.

2

Is there a wheel whose tags fit this machine (Python version, ABI, OS/CPU)?

├─ yes → download it, read METADATA, unzip. No code runs to install.
└─ no → download the sdist and build it — flask 0.1's world, where every install ran setup.py.
3

Read the dependency constraints and recurse — then resolve them all simultaneously (the backtracking search of Sheet No. 2, §3).