feat: Allow pasting newlines (#866)

Noticed that when pasting multi-line blocks, each newline was treated
like a new submission.
Update tui to handle Paste directly and map newlines to shift+enter.

# Test

Copied this into clipboard:
```
Do nothing.
Explain this repo to me.
```

Pasted in and saw multi-line input. Hitting Enter then submitted the
full block.

codex-rs/tui/Cargo.toml

@@ -21,7 +21,7 @@ codex-ansi-escape = { path = "../ansi-escape" }
 codex-core = { path = "../core" }
 codex-common = { path = "../common", features = ["cli", "elapsed"] }
 color-eyre = "0.6.3"
-crossterm = "0.28.1"
+crossterm = { version = "0.28.1", features = ["bracketed-paste"] }
 mcp-types = { path = "../mcp-types" }
 ratatui = { version = "0.29.0", features = [
     "unstable-widget-ref",

codex-rs/tui/src/app.rs

@@ -47,29 +47,52 @@ impl App<'_> {
             let app_event_tx = app_event_tx.clone();
             std::thread::spawn(move || {
                 while let Ok(event) = crossterm::event::read() {
-                    let app_event = match event {
-                        crossterm::event::Event::Key(key_event) => AppEvent::KeyEvent(key_event),
-                        crossterm::event::Event::Resize(_, _) => AppEvent::Redraw,
+                    match event {
+                        crossterm::event::Event::Key(key_event) => {
+                            if let Err(e) = app_event_tx.send(AppEvent::KeyEvent(key_event)) {
+                                tracing::error!("failed to send key event: {e}");
+                            }
+                        }
+                        crossterm::event::Event::Resize(_, _) => {
+                            if let Err(e) = app_event_tx.send(AppEvent::Redraw) {
+                                tracing::error!("failed to send resize event: {e}");
+                            }
+                        }
                         crossterm::event::Event::Mouse(MouseEvent {
                             kind: MouseEventKind::ScrollUp,
                             ..
                         }) => {
                             scroll_event_helper.scroll_up();
-                            continue;
                         }
                         crossterm::event::Event::Mouse(MouseEvent {
                             kind: MouseEventKind::ScrollDown,
                             ..
                         }) => {
                             scroll_event_helper.scroll_down();
-                            continue;
+                        }
+                        crossterm::event::Event::Paste(pasted) => {
+                            use crossterm::event::KeyModifiers;
+
+                            for ch in pasted.chars() {
+                                let key_event = match ch {
+                                    '\n' | '\r' => {
+                                        // Represent newline as <Shift+Enter> so that the bottom
+                                        // pane treats it as a literal newline instead of a submit
+                                        // action (submission is only triggered on Enter *without*
+                                        // any modifiers).
+                                        KeyEvent::new(KeyCode::Enter, KeyModifiers::SHIFT)
+                                    }
+                                    _ => KeyEvent::new(KeyCode::Char(ch), KeyModifiers::empty()),
+                                };
+                                if let Err(e) = app_event_tx.send(AppEvent::KeyEvent(key_event)) {
+                                    tracing::error!("failed to send pasted key event: {e}");
+                                    break;
+                                }
+                            }
                         }
                         _ => {
-                            continue;
+                            // Ignore any other events.
                         }
-                    };
-                    if let Err(e) = app_event_tx.send(app_event) {
-                        tracing::error!("failed to send event: {e}");
                     }
                 }
             });

codex-rs/tui/src/tui.rs

@@ -2,7 +2,9 @@ use std::io::Stdout;
 use std::io::stdout;
 use std::io::{self};
 
+use crossterm::event::DisableBracketedPaste;
 use crossterm::event::DisableMouseCapture;
+use crossterm::event::EnableBracketedPaste;
 use crossterm::event::EnableMouseCapture;
 use ratatui::Terminal;
 use ratatui::backend::CrosstermBackend;
@@ -19,6 +21,7 @@ pub type Tui = Terminal<CrosstermBackend<Stdout>>;
 pub fn init() -> io::Result<Tui> {
     execute!(stdout(), EnterAlternateScreen)?;
     execute!(stdout(), EnableMouseCapture)?;
+    execute!(stdout(), EnableBracketedPaste)?;
     enable_raw_mode()?;
     set_panic_hook();
     Terminal::new(CrosstermBackend::new(stdout()))
@@ -35,6 +38,7 @@ fn set_panic_hook() {
 /// Restore the terminal to its original state
 pub fn restore() -> io::Result<()> {
     execute!(stdout(), DisableMouseCapture)?;
+    execute!(stdout(), DisableBracketedPaste)?;
     execute!(stdout(), LeaveAlternateScreen)?;
     disable_raw_mode()?;
     Ok(())