One part. That is usually all it takes to lose a ramp for a day. The car is up, the wheel is off, and the brake disc that was meant to be on the shelf is not.
When a job is confirmed in the diary, the system reads what the job is and what the car is, and builds the parts list from the last three times you did that job on that model. Pads and discs for a 2018 Fiesta, filter and oil for a Transit service. It checks that list against whatever you keep stock in, which for most garages is a Google Sheet with a column called Qty and a column called Shelf.
Anything missing goes into one email to the supplier, in the format they want, with your account number and the job date in the subject line. The email sits as a draft in your Gmail or Outlook. You read it, you send it, or you delete it because you know the part is in the van.
Timing matters more than the list. The draft is written the moment the booking is confirmed, so a job booked on Monday for Thursday has its order out Monday afternoon and the parts arrive Wednesday. The ramp is not waiting on a courier.
Cancellations are the awkward bit. If the booking is cancelled, the system does not cancel the order, because it cannot know whether you still want the stock. It sends you a one-line note with the order reference instead.
This is the kind of thing we build. It runs in your own supplier accounts and your own stock sheet.