feat(tui2): add copy selection shortcut + UI affordance (#8462)

- Detect Ctrl+Shift+C vs VS Code Ctrl+Y and surface in footer hints
- Render clickable “⧉ copy” pill near transcript selection (hidden while
dragging)
- Handle copy hotkey + click to copy selection
- Document updated copy UX

VSCode:
<img width="1095" height="413" alt="image"
src="https://github.com/user-attachments/assets/84be0c82-4762-4c3e-80a4-c751c078bdaa"
/>

Ghosty:
<img width="505" height="68" alt="image"
src="https://github.com/user-attachments/assets/109cc1a1-f029-4f7e-a141-4c6ed2da7338"
/>

codex-rs/tui2/src/bottom_pane/chat_composer.rs

@@ -1,3 +1,5 @@
+use crate::key_hint;
+use crate::key_hint::KeyBinding;
 use crate::key_hint::has_ctrl_or_alt;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;
@@ -121,6 +123,7 @@ pub(crate) struct ChatComposer {
     transcript_scrolled: bool,
     transcript_selection_active: bool,
     transcript_scroll_position: Option<(usize, usize)>,
+    transcript_copy_selection_key: KeyBinding,
     skills: Option<Vec<SkillMetadata>>,
     dismissed_skill_popup_token: Option<String>,
 }
@@ -172,6 +175,7 @@ impl ChatComposer {
             transcript_scrolled: false,
             transcript_selection_active: false,
             transcript_scroll_position: None,
+            transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             skills: None,
             dismissed_skill_popup_token: None,
         };
@@ -1540,6 +1544,7 @@ impl ChatComposer {
             transcript_scrolled: self.transcript_scrolled,
             transcript_selection_active: self.transcript_selection_active,
             transcript_scroll_position: self.transcript_scroll_position,
+            transcript_copy_selection_key: self.transcript_copy_selection_key,
         }
     }
 
@@ -1571,10 +1576,12 @@ impl ChatComposer {
         scrolled: bool,
         selection_active: bool,
         scroll_position: Option<(usize, usize)>,
+        copy_selection_key: KeyBinding,
     ) {
         self.transcript_scrolled = scrolled;
         self.transcript_selection_active = selection_active;
         self.transcript_scroll_position = scroll_position;
+        self.transcript_copy_selection_key = copy_selection_key;
     }
 
     fn sync_popups(&mut self) {

codex-rs/tui2/src/bottom_pane/footer.rs

@@ -25,6 +25,7 @@ pub(crate) struct FooterProps {
     pub(crate) transcript_scrolled: bool,
     pub(crate) transcript_selection_active: bool,
     pub(crate) transcript_scroll_position: Option<(usize, usize)>,
+    pub(crate) transcript_copy_selection_key: KeyBinding,
 }
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
@@ -115,7 +116,7 @@ fn footer_lines(props: FooterProps) -> Vec<Line<'static>> {
             }
             if props.transcript_selection_active {
                 line.push_span(" · ".dim());
-                line.push_span(key_hint::ctrl(KeyCode::Char('y')));
+                line.push_span(props.transcript_copy_selection_key);
                 line.push_span(" copy selection".dim());
             }
             vec![line]
@@ -467,6 +468,7 @@ mod tests {
                 transcript_scrolled: false,
                 transcript_selection_active: false,
                 transcript_scroll_position: None,
+                transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             },
         );
 
@@ -482,6 +484,7 @@ mod tests {
                 transcript_scrolled: true,
                 transcript_selection_active: true,
                 transcript_scroll_position: Some((3, 42)),
+                transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             },
         );
 
@@ -497,6 +500,7 @@ mod tests {
                 transcript_scrolled: false,
                 transcript_selection_active: false,
                 transcript_scroll_position: None,
+                transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             },
         );
 
@@ -512,6 +516,7 @@ mod tests {
                 transcript_scrolled: false,
                 transcript_selection_active: false,
                 transcript_scroll_position: None,
+                transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             },
         );
 
@@ -527,6 +532,7 @@ mod tests {
                 transcript_scrolled: false,
                 transcript_selection_active: false,
                 transcript_scroll_position: None,
+                transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             },
         );
 
@@ -542,6 +548,7 @@ mod tests {
                 transcript_scrolled: false,
                 transcript_selection_active: false,
                 transcript_scroll_position: None,
+                transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             },
         );
 
@@ -557,6 +564,7 @@ mod tests {
                 transcript_scrolled: false,
                 transcript_selection_active: false,
                 transcript_scroll_position: None,
+                transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             },
         );
 
@@ -572,6 +580,7 @@ mod tests {
                 transcript_scrolled: false,
                 transcript_selection_active: false,
                 transcript_scroll_position: None,
+                transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             },
         );
 
@@ -587,6 +596,7 @@ mod tests {
                 transcript_scrolled: false,
                 transcript_selection_active: false,
                 transcript_scroll_position: None,
+                transcript_copy_selection_key: key_hint::ctrl_shift(KeyCode::Char('c')),
             },
         );
     }

codex-rs/tui2/src/bottom_pane/mod.rs

@@ -386,9 +386,14 @@ impl BottomPane {
         scrolled: bool,
         selection_active: bool,
         scroll_position: Option<(usize, usize)>,
+        copy_selection_key: crate::key_hint::KeyBinding,
     ) {
-        self.composer
-            .set_transcript_ui_state(scrolled, selection_active, scroll_position);
+        self.composer.set_transcript_ui_state(
+            scrolled,
+            selection_active,
+            scroll_position,
+            copy_selection_key,
+        );
         self.request_redraw();
     }