API designLaw

Hyrum’s Law

Given enough users, every observable behavior becomes somebody’s dependency.

A plain-language paraphrase. Original sources below.

The idea behind it

An API’s written contract is not the whole contract its users experience. Output ordering, timing, error messages, and other incidental details may become assumptions in downstream systems. Changing an undocumented behavior can still break a real consumer; plan compatibility work around actual usage.

Go to the source

Hyrum’s Law — Hyrum Wright

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Hyrum WrightLaw of implicit interfacescompatibility