I have the following layout:

another
  b.py
  BUILD
src
  a.py
  main.py
  BUILD

where

main.py

has the following contents:

from a import foo


def app():
    foo()
    while True:
        pass


if __name__ == "__main__":
    app()

and

BUILD

in src is

python_sources()
pex_binary(
    name="app",
    entry_point="main.py",
    restartable=True,
)

I run

./pants run src:app

and get my output. After that I update

a.py

and it expectedly re-runs. Then I change

b.py

, which isn’t connected to my app target in any ways, but the app still restarts. Do I misunderstand something? Shouldn’t only the changes in inputs of the running target affect the app restart?

It is surprising that it is not what is happening in practice

What does

./pants dependencies --transitive src:app

show?

That will help establish if Pants is seeing a dep on

b

for some reason

There is a project (with some run logs as well), maybe you can check if it reproduces for you?