The Supply Chain tab on a product now handles supplier associations end to end. Link an existing supplier or create a new one from the tab; already-linked suppliers cannot be selected again, and each attempt reports success or failure inline. Saving a purchase order also links its products to its supplier automatically, so a supplier that appears on a PO is a supplier on the product without a second step.
Each supplier card shows Part Number, Default MOQ, Purchase Orders, and Cost Estimates in a responsive grid. The Purchase Orders count includes every matching PO for that supplier and product, independent of what the table shows, and refreshes when a PO changes. Cost Estimates opens the existing estimate workflow filtered to that supplier, with adding, editing, duplicating, and deleting; a new estimate opened from here keeps the supplier automatically. Part Number and Default MOQ have their own cards on larger screens; clicking either opens a dialog that edits or clears just that value and leaves the rest of the relationship intact.
Edit supplier, Contact supplier, and Create PO are grouped under an Actions menu on each card. Default Lead Time stays on the supplier profile and appears in the summary alongside incoterms and quality rating.