I already have a pre-approved promotional template and a list of phone numbers sitting in Google Sheets. What I need is a clean Google Apps Script (or small set of scripts) that connects to WhatsApp Cloud API, authenticates with my Meta token, and fires that single template message to every number in the sheet. Scope of work • Authorise the script with WhatsApp Cloud API, store the access token securely, and handle refresh logic. • Build a simple menu item or button inside the Sheet so I can trigger the send on demand. • Read numbers from a designated column, batch the calls to respect WhatsApp rate limits, and log success / failure back into the sheet in real time. • Provide clear setup instructions so I can reuse or copy the script to other sheets later. Acceptance criteria • Running the script delivers the exact promotional template (no personalisation) to every valid number in the sheet. • Status column updates with “Sent”, “Failed” plus error code when relevant. • No quota or authentication errors during a 500-number test run. If you’ve wired Apps Script to external REST APIs before, this should feel straightforward. Include any previous examples of Cloud API or similar integrations in your reply so I can gauge fit.