@psalm-immutable

The @psalm-immutable tag declares a class as immutable. It is Psalm's real, currently-supported counterpart to this library's own not-yet-implemented @immutable tag, which documents the same concept in a tool-agnostic way.

This library recognizes it as an alias: it parses identically to the canonical tag above and produces the exact same tag instance, keeping the vendor-prefixed name it was written with.