fix selection list breakage

src/textual/widgets/_selection_list.py

@@ -50,7 +50,8 @@ def __init__(
             disabled: The initial enabled/disabled state. Enabled by default.
         """
         if isinstance(prompt, str):
-            prompt = Text.from_markup(prompt)
+            prompt = Text.from_markup(prompt, overflow="ellipsis")
+        prompt.no_wrap = True
         super().__init__(prompt.split()[0], id, disabled)
         self._value: SelectionType = value
         """The value associated with the selection."""

tests/snapshot_tests/test_snapshots.py

@@ -2878,3 +2878,13 @@ def check_action(
             return True
 
     snap_compare(FooterApp())
+
+
+def test_selection_list_wrap(snap_compare):
+    """Regression test for https://github.com/Textualize/textual/issues/5326"""
+
+    class SelectionListApp(App):
+        def compose(self) -> ComposeResult:
+            yield SelectionList(("Hello World " * 100, 0))
+
+    snap_compare(SelectionListApp())