[🐛 BUG] Async callback submodule scoping issue

[arcanaxion]

🔍 What went wrong?

When using async callback in a submodule/page, the state cannot access its state variables.

# main.py
from pages import home
from taipy.gui import Gui, State


def on_change(state: State, var_name: str, var_value):
    print(var_name, type(var_value), var_value)


pages = {"/": "", "home": home.home_page}

if __name__ == "__main__":
    gui = Gui(pages=pages)
    gui.run(run_browser=False)

# pages/home.py
import time

import taipy.gui.builder as tgb
from taipy.gui import State

counter = 0


async def count_to_10(state: State):
    for i in range(10):
        state.counter = i + 1
        time.sleep(1)


with tgb.Page() as home_page:
    tgb.button("Count to 10", on_action=count_to_10)
    tgb.text("{counter}")

Click button, then console:

/home/testbench/.venv-git-2026-02-24/lib/python3.12/site-packages/taipy/gui/gui.py:2340: TaipyGuiWarning: Variable 'counter' is not available in the '__main__' module.
  _warn(

📦 Taipy Version

develop

📋 Additional Context (Optional)

📜 Code of Conduct

• I have checked the existing issues to avoid duplicates.
• I am willing to work on this issue (optional)

✅ Acceptance Criteria

• A reproducible unit test is added.
• Code coverage is at least 90%.
• The bug reporter validated the fix.
• Relevant documentation updates or an issue created in