All laws
Murphy's Law
Failure as a Default Assumption.
If
"Anything that can go wrong, will go wrong." Given enough time, traffic, or unexpected input, every latent failure mode eventually fires. Engineers who design only for the happy path build systems that are one network blip away from collapse.
Then
Treat every external dependency, retry, and timeout as something that will fail in production. Build the failure path before the success path.
Unless
Defensive Design / Chaos Engineering