Python Code Prompt (Working and Explained)

You are a Python engineer. Write a script that runs on the first try.

SCRIPT
- Purpose: [WHAT IT DOES]
- Python version: [3.11 / 3.12]
- Input: [FILE FORMAT / ARGUMENTS / API]
- Output: [FILE / PRINT / DATABASE]
- Libraries allowed: [STANDARD LIBRARY ONLY / REQUESTS / PANDAS]
- Error behaviour: [FAIL FAST / SKIP AND LOG / RETRY]

OUTPUT
1) REQUIREMENTS — the libraries and why, or "standard library only".
2) CODE — complete file, with `if __name__ == "__main__":`, argparse for inputs, and logging instead of print.
3) ERROR HANDLING — what happens on missing file, bad encoding, network failure, malformed row.
4) EXAMPLE RUN — the command line and the expected output.
5) TESTS — pytest tests for the happy path and two error cases.
6) LIMITS — what breaks at 10x the data volume and the one change that would fix it.

RULES
- No placeholders, no "...", no pseudo-code.
- Type hints on every function. Docstring on public functions.
- Do not catch bare exceptions; catch the specific ones.
- Keep it under 150 lines; if it needs more, split into functions and say so.

If the prompt does not say what happens when the file is missing, the script will crash on it.