Extract shared text selection helpers for the TUI (#46857)

## What changed

Move selection units, word and logical-line boundaries, click counting, and copy-key detection into `text_selection`, and update the transcript view to use them. Clamp selection offsets to valid UTF-8 boundaries and exclude key-release events from copy-key detection. Make `TranscriptView::cancel_search` accessible throughout the crate.

## Testing

Update existing text-layout tests to exercise the shared selection ranges for wrapped lines, combining characters, and empty logical lines.

GitOrigin-RevId: 6a8b44b4aa97fe2965a5e330121dc22fddc335b5

codex-rs/tui/src/lib.rs

@@ -216,6 +216,7 @@ mod terminal_probe;
 mod terminal_title;
 mod terminal_visualization_instructions;
 mod text_formatting;
+mod text_selection;
 mod theme_picker;
 mod thread_color;
 mod thread_transcript;

codex-rs/tui/src/text_selection.rs

@@ -0,0 +1,76 @@
+//! Shared selection gestures and source-text boundaries; each view owns its hit testing and state.
+
+use crossterm::event::KeyCode;
+use crossterm::event::KeyEvent;
+use crossterm::event::KeyEventKind;
+use crossterm::event::KeyModifiers;
+use std::ops::Range;
+use std::time::Duration;
+use std::time::Instant;
+use unicode_segmentation::UnicodeSegmentation;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) enum SelectionUnit {
+    Character,
+    Word,
+    Line,
+}
+
+impl SelectionUnit {
+    pub(crate) fn from_clicks(clicks: u8) -> Self {
+        match clicks {
+            2 => Self::Word,
+            3 => Self::Line,
+            _ => Self::Character,
+        }
+    }
+
+    pub(crate) fn range(self, text: &str, offset: usize) -> Range<usize> {
+        let offset = text.floor_char_boundary(offset.min(text.len()));
+        match self {
+            Self::Character => offset..offset,
+            Self::Word => text
+                .split_word_bound_indices()
+                .map(|(start, word)| start..start + word.len())
+                .find(|range| range.contains(&offset))
+                .unwrap_or(text.len()..text.len()),
+            // Logical lines include their hard newline, regardless of visual wrapping.
+            Self::Line => {
+                let start = text[..offset]
+                    .rfind('\n')
+                    .map_or(/*default*/ 0, |newline| newline + 1);
+                let end = text[offset..]
+                    .find('\n')
+                    .map_or(text.len(), |newline| offset + newline + 1);
+                start..end
+            }
+        }
+    }
+}
+
+pub(crate) fn click_count(
+    last_click: &mut Option<(Instant, u16, u16, u8)>,
+    column: u16,
+    row: u16,
+) -> u8 {
+    let now = Instant::now();
+    let clicks = last_click
+        .filter(|(at, x, y, _)| {
+            now.duration_since(*at) < Duration::from_millis(/*millis*/ 400)
+                && *x == column
+                && *y == row
+        })
+        .map_or(/*default*/ 1, |(_, _, _, clicks)| clicks % 3 + 1);
+    *last_click = Some((now, column, row, clicks));
+    clicks
+}
+
+pub(crate) fn is_copy_key(key: KeyEvent) -> bool {
+    // Kitty reports Cmd+C as Super+C, including over SSH. Crossterm may report
+    // Ctrl+Shift+C as uppercase C with only Control set.
+    let (code, modifiers) = crate::key_hint::normalize_key_parts(key.code, key.modifiers);
+    key.kind != KeyEventKind::Release
+        && code == KeyCode::Char('c')
+        && (matches!(modifiers, KeyModifiers::CONTROL | KeyModifiers::SUPER)
+            || modifiers == (KeyModifiers::CONTROL | KeyModifiers::SHIFT))
+}

codex-rs/tui/src/transcript_view/input.rs

@@ -9,8 +9,6 @@ use crossterm::event::MouseButton;
 use crossterm::event::MouseEvent;
 use crossterm::event::MouseEventKind;
 use ratatui::layout::Position as ScreenPosition;
-use std::time::Duration;
-use std::time::Instant;
 
 use super::*;
 
@@ -230,14 +228,7 @@ impl TranscriptView {
         key: KeyEvent,
         cells: &[Arc<dyn HistoryCell>],
     ) -> Option<ViewAction> {
-        // Kitty keyboard reporting delivers macOS Cmd+C as Super+C, including over SSH to
-        // non-macOS hosts. Ghostty forwards it when there is no terminal-native selection.
-        // Crossterm can encode Ctrl+Shift+C as uppercase C with only Control set.
-        let (code, modifiers) = crate::key_hint::normalize_key_parts(key.code, key.modifiers);
-        if (matches!(modifiers, KeyModifiers::CONTROL | KeyModifiers::SUPER)
-            && code == KeyCode::Char('c'))
-            || (modifiers == (KeyModifiers::CONTROL | KeyModifiers::SHIFT)
-                && code == KeyCode::Char('c'))
+        if crate::text_selection::is_copy_key(key)
             || (key.modifiers == KeyModifiers::NONE && key.code == KeyCode::Enter)
         {
             return Some(
@@ -316,16 +307,8 @@ impl TranscriptView {
                 .link_at(visible.row, event.column.saturating_sub(self.area.x))
                 .map(ViewAction::OpenLink);
         }
-        let now = Instant::now();
-        let clicks = self
-            .last_click
-            .filter(|(at, column, row, _)| {
-                now.duration_since(*at) < Duration::from_millis(/*millis*/ 400)
-                    && *column == event.column
-                    && *row == event.row
-            })
-            .map_or(/*default*/ 1, |(_, _, _, clicks)| clicks % 3 + 1);
-        self.last_click = Some((now, event.column, event.row, clicks));
+        let clicks =
+            crate::text_selection::click_count(&mut self.last_click, event.column, event.row);
         if clicks >= 2
             && visible
                 .layout

codex-rs/tui/src/transcript_view/search.rs

@@ -215,7 +215,7 @@ impl TranscriptView {
     }
 
     /// Restore the pre-search presentation before an explicit return or cancellation.
-    pub(super) fn cancel_search(&mut self) {
+    pub(crate) fn cancel_search(&mut self) {
         if !self.search.active {
             return;
         }

codex-rs/tui/src/transcript_view/selection.rs

@@ -6,6 +6,7 @@ use ratatui::layout::Position as ScreenPosition;
 use unicode_segmentation::UnicodeSegmentation;
 
 use super::*;
+use crate::text_selection::SelectionUnit;
 
 pub(super) struct Selection {
     pub(super) snapshot: ViewSnapshot,
@@ -20,23 +21,6 @@ pub(super) struct Selection {
     preferred_column: Option<u16>,
 }
 
-#[derive(Clone, Copy)]
-enum SelectionUnit {
-    Character,
-    Word,
-    Line,
-}
-
-impl SelectionUnit {
-    fn range(self, layout: &TextLayout, offset: usize) -> std::ops::Range<usize> {
-        match self {
-            Self::Character => offset..offset,
-            Self::Word => layout.word_range(offset),
-            Self::Line => layout.line_range(offset),
-        }
-    }
-}
-
 impl TranscriptView {
     pub(super) fn begin_selection(
         &mut self,
@@ -49,12 +33,8 @@ impl TranscriptView {
             return;
         };
         self.cancel_beginning();
-        let unit = match clicks {
-            2 => SelectionUnit::Word,
-            3 => SelectionUnit::Line,
-            _ => SelectionUnit::Character,
-        };
-        let range = unit.range(&layout, anchor.offset);
+        let unit = SelectionUnit::from_clicks(clicks);
+        let range = unit.range(layout.text(), anchor.offset);
         let snapshot = self.capture_snapshot(cells);
         self.held_reading = None;
         let start = Anchor {
@@ -130,7 +110,7 @@ impl TranscriptView {
             return;
         };
         let cells = Arc::clone(&selection.snapshot.cells);
-        let range = selection.unit.range(&layout, end.offset);
+        let range = selection.unit.range(layout.text(), end.offset);
         let origin = selection.origin;
         let backwards = (self.resolve(&cells, end), end.offset)
             < (self.resolve(&cells, origin.0), origin.0.offset);

codex-rs/tui/src/transcript_view/text.rs

@@ -282,14 +282,6 @@ impl TextLayout {
         }
     }
 
-    pub(super) fn word_range(&self, offset: usize) -> Range<usize> {
-        self.text
-            .split_word_bound_indices()
-            .map(|(start, word)| start..start + word.len())
-            .find(|range| range.contains(&offset))
-            .unwrap_or(self.text.len()..self.text.len())
-    }
-
     /// Resolve the displayed link using the same destination policy as terminal OSC-8 output.
     pub(super) fn link_at(&self, row: usize, column: u16) -> Option<String> {
         let row = self.rows.get(row)?;
@@ -301,18 +293,6 @@ impl TextLayout {
             .terminal_destination()
     }
 
-    /// Select a logical line, including its terminating hard newline when present.
-    pub(super) fn line_range(&self, offset: usize) -> Range<usize> {
-        let offset = self.text.floor_char_boundary(offset.min(self.text.len()));
-        let start = self.text[..offset]
-            .rfind('\n')
-            .map_or(/*default*/ 0, |newline| newline + 1);
-        let end = self.text[offset..]
-            .find('\n')
-            .map_or(self.text.len(), |newline| offset + newline + 1);
-        start..end
-    }
-
     fn visible_rows(&self, area: Rect, start_row: usize) -> impl Iterator<Item = (u16, &TextRow)> {
         let height = if area.width == 0 { 0 } else { area.height };
         debug_assert!(area.width == 0 || area.width == self.width);

codex-rs/tui/src/transcript_view/text_tests.rs

@@ -4,6 +4,7 @@ use super::TextLayout;
 use crate::terminal_hyperlinks::HyperlinkLine;
 use crate::terminal_hyperlinks::adaptive_wrap_hyperlink_lines;
 use crate::terminal_hyperlinks::prefix_hyperlink_lines;
+use crate::text_selection::SelectionUnit;
 use crate::wrapping::RtOptions;
 use pretty_assertions::assert_eq;
 use ratatui::buffer::Buffer;
@@ -28,7 +29,7 @@ fn copying_wrapped_text_preserves_only_hard_newlines() {
         (11, 1),
     );
     assert_eq!(
-        &layout.text()[layout.line_range(/*offset*/ 12)],
+        &layout.text()[SelectionUnit::Line.range(layout.text(), /*offset*/ 12)],
         "alpha beta gamma\n"
     );
 
@@ -69,7 +70,10 @@ fn hit_testing_uses_graphemes_and_does_not_select_padding() {
             .collect::<Vec<_>>(),
         vec![0, 1, 1, 4, 7, 7, 18, 18, 18, 18, 18, 18],
     );
-    assert_eq!(&layout.text()[layout.word_range(/*offset*/ 4)], "e\u{301}");
+    assert_eq!(
+        &layout.text()[SelectionUnit::Word.range(layout.text(), /*offset*/ 4)],
+        "e\u{301}"
+    );
 }
 
 #[test]
@@ -151,8 +155,8 @@ fn empty_logical_lines_keep_their_hard_breaks() {
         (
             layout.text(),
             layout.row_count(),
-            layout.line_range(/*offset*/ 0),
-            layout.line_range(/*offset*/ 5)
+            SelectionUnit::Line.range(layout.text(), /*offset*/ 0),
+            SelectionUnit::Line.range(layout.text(), /*offset*/ 5)
         ),
         ("\ntext\n", 3, 0..1, 1..6),
     );