Scroll End - MRE

# /// script
# requires-python = ">=3.13"
# dependencies = [
#     "textual",
# ]
# ///

"""
This is a minimal reproducible example (MRE) to demonstrate a scroll-to-end issue in Textual.
The uv in-file config is used to specify dependencies and Python version, so no separate environment is needed.

## How to Run

### Using uv (recommended):
    uv run scroll_end_textual.py

### Using pip:
    pip install textual
    python scroll_end_textual.py
"""

from textual.app import App
from textual.containers import ScrollableContainer, Vertical
from textual.widgets import Static


class SimpleApp(App):
    MAIN = "main"
    CONTENT_WRAPPER = "wrapper"
    INSTRUCTIONS = "Press \[Enter] to add lines, 'c' to clear"

    def compose(self):
        yield ScrollableContainer(Vertical(id=self.MAIN), id=self.CONTENT_WRAPPER)

    async def add_to_screen(self, widget):
        # This is how widgets are added
        main = self.get_widget_by_id(self.MAIN)
        await main.mount(widget)
        await self.scroll_to_end()

    async def scroll_to_end(self):
        # This is the method used to scroll to the end
        container = self.get_widget_by_id(self.CONTENT_WRAPPER)
        container.scroll_end()

    # Maintained original styles and application method

    async def on_mount(self):
        self._style_content_wrapper()
        self._style_content_area()

        await self.add_to_screen(Static(self.INSTRUCTIONS))

    def _style_content_wrapper(self):
        container = self.get_widget_by_id(self.CONTENT_WRAPPER)
        container.styles.flex = 1
        container.styles.height = "1fr"
        container.styles.border = None
        container.styles.padding = (1, 1)
        container.styles.overflow_y = "auto"

    def _style_content_area(self):
        main = self.get_widget_by_id(self.MAIN)
        main.styles.border = None
        main.styles.padding = (0, 0, 0, 1)
        main.styles.min_height = "100%"
        main.styles.overflow_y = "auto"

    # Demonstration Related Methods

    async def add_lines(self, n):
        for line_count in range(n):
            await self.add_to_screen(Static(f"Line {line_count + 1}"))
        await self.scroll_to_end()

    async def clear_main(self):
        main = self.get_widget_by_id(self.MAIN)
        await main.remove_children()

    async def on_key(self, event):
        if event.key == "enter":
            await self.add_lines(20)
        elif event.key == "c":
            await self.clear_main()
            await self.add_to_screen(Static(self.INSTRUCTIONS))


#
#   Module Run
#
if __name__ == "__main__":
    SimpleApp().run()