Why the GitHub Action installs project dependencies via pip download + pip install --find-links

Documentation

In action.yml, the GitHub Action installs project dependencies with:

"$VENV_PYTHON" -m pip download --dest="$VENV"/deps .
"$VENV_PYTHON" -m pip install -U --find-links="$VENV"/deps "$VENV"/deps/*

instead of a more direct approach such as:

"$VENV_PYTHON" -m pip install .

I looked through the current file and the original commit that introduced the action (e02804510), but I could not find an explanation for why this two-step install flow was
chosen.

Could you document the intended reason for this design?

Questions I am trying to answer:

1. Is there a functional advantage over pip install . for this action?
2. Is the goal to stage artifacts locally before installation, improve debuggability, or work around some pip / GitHub Actions behavior?
3. If there is no longer a strong reason, would simplifying this step be acceptable?

A short comment in action.yml or a note in the action documentation would help future readers understand the tradeoff.

Beginne mit action.yml und dem im Issue erwähnten ursprünglichen Commit e02804510; vergleiche den zweistufigen pip-Ablauf mit der vorgeschlagenen direkten Installation und untersuche die umgebende Action-Konfiguration. Dokumentiere die bestätigte Begründung in action.yml oder der Action-Dokumentation, einschließlich der Frage, ob der Ansatz weiterhin notwendig ist und welche Kompromisse er mit sich bringt.