Between two working subsystems
A team can validate the sensor, communications channel, controller and platform separately—and still see the full system fail. The cause is often not a component. It is an agreement between components that nobody made explicit.
An interface is a system
Interfaces define formats, timing expectations, units, loss-of-data behaviour and responsibility for errors. When one of those conditions stays implicit, working subsystems can form a failing whole.
Latency contract
Turn risk into a scenario
A useful scenario names the condition, variable, expected behaviour and failure threshold. That makes uncertainty testable and gives the result a direct path into the next engineering decision.
Preserve negative evidence
A failure is valuable when its configuration, sequence and data are retained. It narrows uncertainty, exposes the system boundary and makes the next cycle cheaper.