Debug pip installing into the system Python in the project virtualenv

Do not start with a speculative fix for the project virtualenv. Force the failure on purpose, save the before output, then change one cause at a time. Retries are allowed only for transient conditions—not for bad input that will fail forever on python-virtual-environments.

which python; python -c "import sys; print(sys.prefix)"

After repair, rerun the exact reproduction command. Keep the failing fixture as a regression seed for the observability page. For the isolated project venv with pinned pandas, remember the claim you are restoring: activated venv imports pandas at a recorded version while a second project stays untouched.

Store a one-command reproduction for: pip installing into the system Python, or activating the wrong venv. The command should use project dir lab-env/ with requirements.txt containing pandas==2.2.2 or a minimal mutant of it. Paste the failing output into notes/failure-before.txt (or your shell scrollback as copied text). After the fix, paste notes/failure-after.txt and keep both.

Retries belong only on transient faults. If the failure is bad input, a bad allowlist, or a logic bug in the project virtualenv, retrying will amplify cost without repairing trust around install project packages without mutating the global interpreter.

Classify the failure as prevent, detect, contain, or recover—using this lab’s language, not a generic poster. For python-virtual-environments, the first fix should usually be detect+prevent at the boundary, because pip installing into the system Python, or activating the wrong venv is cheaper to stop early than to explain in production prose.

At the debugging stage for python-virtual-environments, the job is narrower than finishing a product demo. You are creating one progressive evidence piece about project dir lab-env/ with requirements.txt containing pandas==2.2.2 that later pages inherit without redefining success. Keep that fixture small enough to inspect by hand, keep outputs copy-pasteable as text, and refuse to narrate this baseline as if it were a production SLA: record global site-packages pandas version (or absence) before creating the venv.

For this page specifically, success looks like before/after evidence for the characteristic failure while still centering the user decision to install project packages without mutating the global interpreter. If you cannot point to a file, command, or assertion that proves that for the project virtualenv, stay on this page instead of advancing.

Set up a virtual environment

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