... this class of bug stops coming back. the ordering is a symptom; the real problem is handlers that have an implicit belief about what "just happened" based on which event arrived. that's exactly the scenario the permutation fuzzer in FetchSandbox is designed to surface before you ever ship it, fire every ordering, diff the final state, see which ones land somewhere unexpected. Comment from Omri Ben-Shoham(@omri_ben_shoham1): @Raj Nagulapalle that's the real distinction - a loud ... ... enough if you only tested the sad paths that produce visible errors. Comment from Raj Nagulapalle(@rnagulapalle): @galdayan  not the full n! .. that'd blow up exactly like you're picturing. the trick is we don't permute