add keyboard enhancements to support shift_return (#1743)

For terminal that supports [keyboard
enhancements](https://docs.rs/libcrossterm/latest/crossterm/enum.KeyboardEnhancementFlags.html),
adds the enhancements (enabling [kitty keyboard
protocol](https://sw.kovidgoyal.net/kitty/keyboard-protocol/)) to
support shift+enter listener.

Those users (users with terminals listed on
[KPP](https://sw.kovidgoyal.net/kitty/keyboard-protocol/)) should be
able to press shift+return for new line

---------

Co-authored-by: easong-openai <easong@openai.com>

codex-rs/tui/src/tui.rs

@@ -5,6 +5,9 @@ use std::io::stdout;
 use codex_core::config::Config;
 use crossterm::event::DisableBracketedPaste;
 use crossterm::event::EnableBracketedPaste;
+use crossterm::event::KeyboardEnhancementFlags;
+use crossterm::event::PopKeyboardEnhancementFlags;
+use crossterm::event::PushKeyboardEnhancementFlags;
 use ratatui::backend::CrosstermBackend;
 use ratatui::crossterm::execute;
 use ratatui::crossterm::terminal::disable_raw_mode;
@@ -20,6 +23,17 @@ pub fn init(_config: &Config) -> Result<Tui> {
     execute!(stdout(), EnableBracketedPaste)?;
 
     enable_raw_mode()?;
+    // Enable keyboard enhancement flags so modifiers for keys like Enter are disambiguated.
+    // chat_composer.rs is using a keyboard event listener to enter for any modified keys
+    // to create a new line that require this.
+    execute!(
+        stdout(),
+        PushKeyboardEnhancementFlags(
+            KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES
+                | KeyboardEnhancementFlags::REPORT_EVENT_TYPES
+                | KeyboardEnhancementFlags::REPORT_ALTERNATE_KEYS
+        )
+    )?;
     set_panic_hook();
 
     let backend = CrosstermBackend::new(stdout());
@@ -37,6 +51,7 @@ fn set_panic_hook() {
 
 /// Restore the terminal to its original state
 pub fn restore() -> Result<()> {
+    execute!(stdout(), PopKeyboardEnhancementFlags)?;
     execute!(stdout(), DisableBracketedPaste)?;
     disable_raw_mode()?;
     Ok(())