Motivation

• Expose and document a local-first installation mode that downloads packages before installing to allow offline or cached installs via PYWRAP_LOCAL_FIRST.
• Persist the chosen install behavior in the venv marker so venvs are reproducible and their creation parameters are inspectable.
• Add a regression test to ensure the local_first flag is recorded in the .venv/.pywrap/ok.json marker.

Description

• Documented the PYWRAP_LOCAL_FIRST environment variable in README.md and its behavior when set to 1.
• Extended the wrapper (python3) to accept a local_first flag from PYWRAP_LOCAL_FIRST, added a _pip_install helper that performs pip download into a temporary directory then pip install --no-index --find-links when enabled, and ensured the temp download directory is cleaned up.
• Persisted the local_first boolean into the venv marker written by _write_marker so the metadata includes the install mode.
• Added a unit test test_local_first_records_marker_flag in tests/test_wrapper.py to validate the marker contains local_first.

Testing

• Ran the unit test suite with python -m unittest tests/test_wrapper.py and it completed successfully.
• The test run reported Ran 9 tests and exited OK.

Codex Task