Automated Odoo Contact Import

I need a clean, repeatable way to pull my customer contacts out of a csv export file and create or update them inside our Odoo instance through the official API (XML-RPC or JSON-RPC, whichever you prefer). The job is purely about customers—no suppliers or employees.

The flow I have in mind is straightforward: open the csv, map each field to its counterpart in Odoo’s res.partner model, handle duplicates gracefully, then post the data. After successful completion, the database IDs should be stored back into the csv file so that the script knows next time it runs, that it should update and not create the contact.
A Python script is what we're looking for, and the Python script should then run repeatedly in fixed intervals so that the odoo database is always kept up to date with the csv file.

Please include basic logging, an easy-to-tweak config file for credentials and field mappings, and a short read-me so I can run the import on demand.
Successful delivery means
* I can run the script, get a log,
* see my csv customers appear exactly once inside Odoo without manual cleanup.
* all relevant delivery and invoice addresses are handled correctly and added to the correct parent contacts

I will provide a csv file with all relevant information