PromptInputLine: fixup per code review

Apply my suggestions from code review.

closes: #6007

docs/config/lua/keyassignment/PromptInputLine.md

@@ -22,7 +22,7 @@ upon the input.
   and/or use [wezterm.format](../wezterm/format.md).  Defaults to: `"> "`. {{since('nightly', inline=True)}}
 * `initial_value` - optional.  If provided, the initial content of the input
   field will be set to this value.  The user may edit it prior to submitting
-  the input.
+  the input. {{since('nightly', inline=True)}}
 
 ## Example of interactively renaming the current tab
 

termwiz/src/lineedit/mod.rs

@@ -299,6 +299,14 @@ impl<'term> LineEditor<'term> {
     /// accepted, or until an error is detected.
     /// Returns Ok(None) if the editor was cancelled eg: via CTRL-C.
     pub fn read_line(&mut self, host: &mut dyn LineEditorHost) -> Result<Option<String>> {
+        self.read_line_with_optional_initial_value(host, None)
+    }
+
+    pub fn read_line_with_optional_initial_value(
+        &mut self,
+        host: &mut dyn LineEditorHost,
+        initial_value: Option<&str>,
+    ) -> Result<Option<String>> {
         ensure!(
             self.state == EditorState::Inactive,
             "recursive call to read_line!"
@@ -311,7 +319,7 @@ impl<'term> LineEditor<'term> {
 
         self.terminal.set_raw_mode()?;
         self.state = EditorState::Editing;
-        let res = self.read_line_impl(host);
+        let res = self.read_line_impl(host, initial_value);
         self.state = EditorState::Inactive;
 
         if let Some(move_end) = self.move_to_editor_end.take() {
@@ -810,7 +818,15 @@ impl<'term> LineEditor<'term> {
         Ok(())
     }
 
-    fn read_line_impl(&mut self, host: &mut dyn LineEditorHost) -> Result<Option<String>> {
+    fn read_line_impl(
+        &mut self,
+        host: &mut dyn LineEditorHost,
+        initial_value: Option<&str>,
+    ) -> Result<Option<String>> {
+        self.line.clear();
+        if let Some(value) = initial_value {
+            self.line.set_line_and_cursor(value, value.len());
+        }
         self.history_pos = None;
         self.bottom_line = None;
         self.clear_completion();

wezterm-gui/src/overlay/prompt.rs

@@ -68,10 +68,8 @@ pub fn show_line_prompt_overlay(
     let mut host = PromptHost::new();
     let mut editor = LineEditor::new(&mut term);
     editor.set_prompt(&args.prompt);
-    if let Some(value) = &args.initial_value {
-        editor.set_line_and_cursor(value, value.len());
-    }
-    let line = editor.read_line(&mut host)?;
+    let line =
+        editor.read_line_with_optional_initial_value(&mut host, args.initial_value.as_deref())?;
 
     promise::spawn::spawn_into_main_thread(async move {
         trampoline(name, window, pane, line);