Three systems, each convinced it owns the product description, is a support ticket generator. The fix is boring and organisational rather than technical.
The ownership matrix
Produce a table listing every shared object — product, price, stock, customer, order, invoice — and for each one record the owning system, the direction of sync, the frequency, and the conflict rule. Get it signed off by the people who own each system, not just by IT.
One direction wherever possible
Bi-directional sync is occasionally unavoidable, but each bi-directional flow roughly doubles the debugging surface. Where you cannot avoid it, define the conflict rule explicitly: last-write-wins, or system-of-record-wins, and never “whichever ran most recently”.
Build for observability
Log every sync with a correlation ID, keep failed payloads, and give the operations team a screen where they can see what failed and retry it without a developer. Integrations that can only be debugged by reading server logs become the first thing nobody wants to touch.
