Is pants meant to autogenerate init.py files when using pants run?

I am sorry, what do you mean?

pants run

would execute an arbitrary script/program you pass as input arguments e.g.

pants run src/foo.py

. It is not going to create any Python files for you (unless your

src/foo.py

has the code to do this for you). There's another goal,

tailor

which will populate the BUILD files metadata, but it won't create any Python files.

So python needs init.py files in the directories you are importing from. Having empty init files in the src tree is a little annoying. Pex generation seems to automatically generate these empty init files when packaging pex files. FWIW Bazel generates empty init files when invoking run (though it also copies it over to a separate directory and doesn't run in place).

If I remember correctly, Python doesn't require

__init__.py

files to be present in a package (it's going to be a namespace package). Pants is okay with these types of packages, e.g. if you check out https://github.com/pantsbuild/example-python and delete

Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        deleted:    helloworld/__init__.py
        deleted:    helloworld/greet/__init__.py
        deleted:    helloworld/translator/__init__.py

you can still do

❯ pants --keep-sandboxes=always run helloworld/main.py
11:36:02.78 [INFO] Preserving local process execution dir /tmp/pants-sandbox-Rs97Xj for interactive process
Hola, pantsbuild!

❯ find  /tmp/pants-sandbox-Rs97Xj -name "__init__.py"    
/tmp/pants-sandbox-Rs97Xj/lib.pex/__pex__/__init__.py

with no

__init__.py

files added by Pants:

❯ tree /tmp/pants-sandbox-Rs97Xj/helloworld -L 2
/tmp/pants-sandbox-Rs97Xj/helloworld
├── greet
│   ├── greeting.py
│   ├── __pycache__
│   └── translations.json
├── main.py
├── __pycache__
│   └── main.cpython-39.pyc
└── translator
    ├── __pycache__
    └── translator.py

5 directories, 5 files