BUG: Functional Interface generates two sessions

[noppelmax]

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of pytask.
• (optional) I have confirmed this bug exists on the main branch of pytask.

---

Hey,

I again tried to use the functional interface. Actually, I wanted to use pytask for the very same task as last time when I failed to get it working with pytask (#625). I tested the latest version from pip (5.1.0) and today's main branch (https://github.com/pytask-dev/pytask/tree/5804f526e01ed1d7a262a43a0dbff8d9aed06e15) with the following code from https://pytask-dev.readthedocs.io/en/stable/how_to_guides/functional_interface.html:

from pathlib import Path
from typing import Annotated

import pytask
from pytask import task


def task_create_first_file() -> Annotated[str, Path("first.txt")]:
    return "Hello, "


task_create_second_file = task(
    name="task_create_second_file", produces=Path("second.txt")
)(lambda *x: "World!")


def task_merge_files(
    first: Path = Path("first.txt"), second: Path = Path("second.txt")
) -> Annotated[str, Path("hello_world.txt")]:
    return first.read_text() + second.read_text()

session = pytask.build(
    tasks=[task_create_first_file, task_merge_files, task_create_second_file]
)

And I got the following result:

(bestofbothworlds) mnoppel@gpu08:~/bestofbothworlds$ python demo.py 
───────────────────────────────────────────── Start pytask session ─────────────────────────────────────────────
Platform: linux -- Python 3.11.7, pytask 0.5.2.dev13+g5804f52, pluggy 1.5.0
Root: /home/i56/mnoppel/bestofbothworlds
Configuration: /home/i56/mnoppel/bestofbothworlds/pyproject.toml
Plugins: pytask_parallel-0.5.0
/home/i56/mnoppel/bestofbothworlds
───────────────────────────────────────────── Start pytask session ─────────────────────────────────────────────
Platform: linux -- Python 3.11.7, pytask 0.5.2.dev13+g5804f52, pluggy 1.5.0
Root: /home/i56/mnoppel/bestofbothworlds
Configuration: /home/i56/mnoppel/bestofbothworlds/pyproject.toml
Plugins: pytask_parallel-0.5.0
Exit: pytask tried to launch a second live display which is impossible. the issue occurs when you use pytask on 
the command line on a task module that uses the programmatic interface of pytask at the same time. Use either 
the command line or the programmatic interface.
Collected 3 tasks.


────────────────────────────────────────────────────────────────────────────────────────────────────────────────
╭──────────────── Summary ─────────────────╮
│  3  Collected tasks                      │
│  3  Skipped because unchanged  (100.0%)  │
╰──────────────────────────────────────────╯
────────────────────────────────────────── Succeeded in 0.07 seconds ───────────────────────────────────────────

So, for some reason it starts two sessions. But my code only starts one and is equivalent to the example.

Problem description

Mainly, it is a display bug again, similar to #621.

Expected Output

I was expecting only one pytask session to show up.

[tobiasraabe]

Hi @noppelmax, thanks for spending the effort on reproducing the issue on the main branch as well.

Unfortunately, when I copy over the script and execute it, everything works

1. Copy the script to script.py.
2. uv init
3. uv add pytask pytask-parallel

> uv run python .\script.py
──────────────────────────── Start pytask session ─────────────────────────────
Platform: win32 -- Python 3.11.7, pytask 0.5.1, pluggy 1.5.0
Root: C:\Users\tobia\git\test
Plugins: pytask_parallel-0.5.0
Collected 3 tasks.

╭────────────────────────────────────┬─────────╮
│ Task                               │ Outcome │
├────────────────────────────────────┼─────────┤
│ script.py::task_create_first_file  │ .       │
│ script.py::task_create_second_file │ .       │
│ script.py::task_merge_files        │ .       │
╰────────────────────────────────────┴─────────╯

───────────────────────────────────────────────────────────────────────────────
╭─────────── Summary ────────────╮
│  3  Collected tasks            │
│  3  Succeeded        (100.0%)  │
╰────────────────────────────────╯
────────────────────────── Succeeded in 0.09 seconds ──────────────────────────

I get a similar, not the same, output as you do, if I execute

> uv run pytask .\task_script.py
──────────────────────────── Start pytask session ─────────────────────────────
Platform: win32 -- Python 3.11.7, pytask 0.5.1, pluggy 1.5.0
Root: C:\Users\tobia\git\test
Plugins: pytask_parallel-0.5.0
──────────────────────────── Start pytask session ─────────────────────────────
Platform: win32 -- Python 3.11.7, pytask 0.5.1, pluggy 1.5.0
Root: C:\Users\tobia\git\test
Plugins: pytask_parallel-0.5.0
Exit: pytask tried to launch a second live display which is impossible. the    
issue occurs when you use pytask on the command line on a task module that uses
the programmatic interface of pytask at the same time. Use either the command 
line or the programmatic interface.
Collected 2 tasks.

╭────────────────────────────────────────┬─────────╮
│ Task                                   │ Outcome │
├────────────────────────────────────────┼─────────┤
│ task_script.py::task_create_first_file │ .       │
│ task_script.py::task_merge_files       │ .       │
╰────────────────────────────────────────┴─────────╯

───────────────────────────────────────────────────────────────────────────────
╭─────────── Summary ────────────╮
│  2  Collected tasks            │
│  2  Succeeded        (100.0%)  │
╰────────────────────────────────╯
────────────────────────── Succeeded in 0.06 seconds ──────────────────────────

Is maybe something else necessary to reproduce the issue?