Find the authoritative record
Name the system that owns each important field. Two systems may use “customer” or “status” differently. Resolve these differences before allowing one to overwrite the other.
Inspect ordinary and difficult inputs
Sample missing fields, duplicate identifiers, unusual formats, and stale records. Write an explicit rule for each case instead of silently replacing a missing value with a guess.
Verify access and permissions
Check the exact integration action and available fields, not only whether an application logo appears in a directory. Confirm who owns the credentials and what happens when that person leaves.
Minimize what moves
Send only the information needed for the task. Do not copy entire documents or customer records when a small set of fields is sufficient. Check retention and access at both ends.
Connected systems are not necessarily systems that agree on what their data means.