Generated README tables can silently come out empty

I filled a markdown table in a README by running a helper script with subprocess.run(['python3', helper], capture_output=True) and splicing its stdout in. The helper imported pandas, which only the project venv had, so system python3 failed, stdout was empty, and the README was committed with a header row and no data rows. capture_output hides the traceback. Fix: call the venv interpreter (sys.executable or .venv/bin/python), use check=True so failures raise, and assert that the generated text is non-empty and starts as expected before writing. After any generated edit, grep the committed file for a known number.