The environment dictionary pins PATH

A packaged macOS app can carry environment variables in its property list under LSEnvironment — the Launch Services environment dictionary. It is the normal way to set an allocator flag, a runtime toggle or a debug switch for a shipped app.

It has one side effect that is easy to miss and expensive to find:

Declaring the dictionary at all pins the process PATH to /usr/bin:/bin:/usr/sbin:/sbin.

Not any particular key — the presence of the dictionary. Anything the app then starts as an external process sees only those four directories. Tools installed by a package manager, in the user's home, or anywhere under /usr/local are simply not found.

Two properties of the dictionary decide when it applies: