I need to automate the full invoice flow between my Prestashop store and Billit. Every order completed in Prestashop should trigger an invoice that is pushed to Billit; once Billit processes or rejects it, the corresponding status must sync back to Prestashop so customers and staff always see the correct state. The Billit API allows two approaches—webhooks or polling—but I’m still weighing the pros and cons. Part of your mandate is to advise which path is the most stable and future-proof in a typical Prestashop environment and then implement it. There is currently no Prestashop plugin or middleware in place, so the module has to be built from scratch, installed, and documented. All relevant resources are available here: • API overview: https://www.billit.eu/en-int/peppol-access-point/connect-your-software-with-the-billit-peppol-access-point/ • Architecture diagram (PDF): https://www.billit.eu/media/fq4llng1/api-diagram.pdf Deliverables—acceptance criteria 1. A Prestashop module that captures completed orders, converts them to Billit-compliant invoices, and sends them automatically via the chosen method. 2. Real-time (or near-real-time) status updates from Billit reflected in Prestashop’s back office. 3. Error logging and basic retry logic so failed sends are visible and recoverable. 4. Installation guide plus a short screencast or screenshots proving the integration works with a live test order. When you reply, include a detailed project proposal that covers the recommended integration method, high-level architecture, milestones, and any dependencies you foresee.