🎨 Palette: Add placeholders to empty input fields

.Jules/palette.md

@@ -4,7 +4,7 @@
 
 **Action:** Update `notice_line` in `src/shell/status_bar.rs` to include a visual indicator (e.g., prefix with an info/warning symbol like `i` or `!`, or Nerd Font icon if supported, but simpler is safer if we want it to work without Nerd Fonts. Actually, let's use standard unicode characters like `✓` for success/info and `⚠` for error).
 
-## $(date +%Y-%m-%d) - Edit Mode Notice Consistency
+## 2026-10-14 - Edit Mode Notice Consistency
 **Learning:** Edit mode specific notices (`EditState.notice`) previously bypassed the standard `notice_line` styling, resulting in warnings (unsaved changes) and errors (save failed) lacking visual distinction (color and icon) from normal hints.
 **Action:** Always ensure nested or state-specific notice mechanisms reuse the top-level standard styling to provide a consistent visual language across all modes.
 
@@ -19,3 +19,6 @@
 ## 2024-11-21 - Centering Empty States for TUI Lists
 **Learning:** Rendering an empty list message (like "no matches") in the top-left corner of the list area can look unbalanced, especially when rendering lists in large UI components or side panes.
 **Action:** Always center the text for empty state indicators in lists visually (using `.alignment(ratatui::layout::Alignment::Center)`) and vertically (using `center_text(msg, area.height)`) when using `Paragraph` to render empty states in a list widget.
+## 2026-10-14 - Placeholder Text in Input Fields
+**Learning:** Empty input fields (like the ones in Finder and Grep) lack visual guidance, making it unclear what the user is supposed to type or do, especially in a TUI environment. They just render a blank space or a lone cursor.
+**Action:** When implementing or modifying search/filter input fields in TUI applications, always provide a descriptive placeholder text (e.g., "type to filter", "search workspace") styled distinctively (e.g., `Color::DarkGray`) when the query is empty. This improves discoverability. Ensure padding calculations account for the placeholder text width if the layout depends on the input's visual length.

src/component/finder/view.rs

@@ -36,17 +36,40 @@ pub(crate) fn draw_finder(frame: &mut Frame, finder: &mut Finder, scanning: bool
 fn draw_finder_input(frame: &mut Frame, finder: &Finder, area: Rect) {
     let query_text = format!("> {}", finder.query);
     let count = format!("{}/{}", finder.matches.len(), finder.total());
+
+    let mut spans = vec![Span::raw(query_text)];
+
+    // Placeholder text if query is empty
+    let placeholder = "type to filter";
+    let is_empty = finder.query.is_empty();
+
+    // カーソル
+    spans.push(Span::styled(
+        " ",
+        Style::default().add_modifier(Modifier::REVERSED),
+    ));
+
+    if is_empty {
+        spans.push(Span::styled(
+            placeholder,
+            Style::default().fg(Color::DarkGray),
+        ));
+    }
+
     // 入力とカーソルの右側を件数表示までスペースで埋める。入力欄がそれより
     // 狭ければ埋めず単純に連結するだけにする (折り返しは Paragraph に任せる)
-    let used = query_text.chars().count() + 1 + count.chars().count();
+    let base_used = finder.query.chars().count() + 2 + 1 + count.chars().count(); // "> " + query + cursor + count
+    let used = if is_empty {
+        base_used + placeholder.chars().count()
+    } else {
+        base_used
+    };
     let pad = (area.width as usize).saturating_sub(used);
-    let line = Line::from(vec![
-        Span::raw(query_text),
-        // 常に末尾に立つ簡易カーソル (他の入力行と同じ表現)
-        Span::styled(" ", Style::default().add_modifier(Modifier::REVERSED)),
-        Span::raw(" ".repeat(pad)),
-        Span::styled(count, Style::default().fg(Color::DarkGray)),
-    ]);
+
+    spans.push(Span::raw(" ".repeat(pad)));
+    spans.push(Span::styled(count, Style::default().fg(Color::DarkGray)));
+
+    let line = Line::from(spans);
     frame.render_widget(Paragraph::new(line), area);
 }
 

src/component/grep/view.rs

@@ -53,11 +53,23 @@ fn title(grep: &GrepState) -> String {
 }
 
 fn draw_input(frame: &mut Frame, grep: &GrepState, area: Rect) {
-    let line = Line::from(vec![
-        Span::raw(format!("> {}", grep.query)),
-        // 常に末尾に立つ簡易カーソル (Finder と同じ表現)
-        Span::styled(" ", Style::default().add_modifier(Modifier::REVERSED)),
-    ]);
+    let mut spans = vec![Span::raw(format!("> {}", grep.query))];
+
+    // 常に末尾に立つ簡易カーソル (Finder と同じ表現)
+    spans.push(Span::styled(
+        " ",
+        Style::default().add_modifier(Modifier::REVERSED),
+    ));
+
+    // Placeholder text if query is empty
+    if grep.query.is_empty() {
+        spans.push(Span::styled(
+            "search workspace",
+            Style::default().fg(Color::DarkGray),
+        ));
+    }
+
+    let line = Line::from(spans);
     frame.render_widget(Paragraph::new(line), area);
 }