Ensure input is focused when command palette launches (#4763)

* Ensure input is focused when command palette launches

* Update changelog

* Use AUTO_FOCUS to focus the CommandInput in the CommandPalette

Author: darrenburns

CHANGELOG.md

@@ -29,6 +29,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Fixed `Tree` and `DirectoryTree` horizontal scrolling off-by-2 https://github.com/Textualize/textual/pull/4744
 - Fixed text-opacity in component styles https://github.com/Textualize/textual/pull/4747
 - Ensure `Tree.select_node` sends `NodeSelected` message https://github.com/Textualize/textual/pull/4753
+- Fixed `CommandPalette` not focusing the input when opened when `App.AUTO_FOCUS` doesn't match the input https://github.com/Textualize/textual/pull/4763
 - `SelectionList.SelectionToggled` will now be sent for each option when a bulk toggle is performed (e.g. `toggle_all`). Previously no messages were sent at all. https://github.com/Textualize/textual/pull/4759
 
 ### Changed

src/textual/command.py

@@ -421,6 +421,8 @@ class CommandInput(Input):
 class CommandPalette(SystemModalScreen[CallbackType]):
     """The Textual command palette."""
 
+    AUTO_FOCUS = "CommandInput"
+
     COMPONENT_CLASSES: ClassVar[set[str]] = {
         "command-palette--help-text",
         "command-palette--highlight",