Exclude shortcut-modified input from TUI paste bursts (#38675)

## What changed

- Treat plain, Shift-modified, and Windows AltGr character events as text-producing input for paste-burst detection.
- Exclude Super, Hyper, and Meta character events from paste bursts, flushing any pending text before handling them as shortcuts.

## Testing

- Add coverage for plain and Shift-modified spaces, shortcut-modified spaces, pending burst flushes, and platform-specific AltGr input.

GitOrigin-RevId: 3c43224966307fd014eb1586dce0c53ee56c75aa

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

@@ -144,7 +144,8 @@
 //! `KeyCode::Char` and `KeyCode::Enter` key events instead of a single paste event.
 //!
 //! To avoid misinterpreting these bursts as real typing (and to prevent transient UI effects like
-//! shortcut overlays toggling on a pasted `?`), we feed "plain" character events into
+//! shortcut overlays toggling on a pasted `?`), we feed text-producing character events (plain,
+//! Shift, or Windows AltGr) into
 //! [`PasteBurst`](super::paste_burst::PasteBurst), which buffers bursts and later flushes them
 //! through [`ChatComposer::handle_paste`].
 //!
@@ -3514,8 +3515,8 @@ impl ChatComposer {
     ///
     /// - Always flush any *due* paste burst first so buffered text does not lag behind unrelated
     ///   edits.
-    /// - Then handle the incoming key, intercepting only "plain" (no Ctrl/Alt) char input.
-    /// - For non-plain keys, flush via `flush_before_modified_input()` before applying the key;
+    /// - Then handle the incoming key, intercepting only text-producing character input.
+    /// - For non-text keys, flush via `flush_before_modified_input()` before applying the key;
     ///   otherwise `clear_window_after_non_char()` can leave buffered text waiting without a
     ///   timestamp to time out against.
     fn handle_input_basic(&mut self, input: KeyEvent) -> (InputResult, bool) {
@@ -3550,19 +3551,21 @@ impl ChatComposer {
             return (InputResult::None, true);
         }
 
-        // Intercept plain Char inputs to optionally accumulate into a burst buffer.
+        let has_non_text_modifier = has_ctrl_or_alt(input.modifiers)
+            || input
+                .modifiers
+                .intersects(KeyModifiers::SUPER | KeyModifiers::HYPER | KeyModifiers::META);
+
+        // Intercept text-producing Char inputs to optionally accumulate into a burst buffer.
         //
-        // This is intentionally limited to "plain" (no Ctrl/Alt) chars so shortcuts keep their
-        // normal semantics, and so we can aggressively flush/clear any burst state when non-char
-        // keys are pressed.
+        // This preserves plain, Shift, and Windows AltGr input while keeping shortcut modifiers
+        // out of the burst detector and flushing any in-flight text before a non-text key.
         if let KeyEvent {
             code: KeyCode::Char(ch),
-            modifiers,
             ..
         } = input
         {
-            let has_ctrl_or_alt = has_ctrl_or_alt(modifiers);
-            if !has_ctrl_or_alt
+            if !has_non_text_modifier
                 && !self.draft.disable_paste_burst
                 && self.draft.textarea.allows_paste_burst()
             {
@@ -3650,14 +3653,10 @@ impl ChatComposer {
             self.reconcile_deleted_elements(elements_before);
         }
 
-        // Update paste-burst heuristic for plain Char (no Ctrl/Alt) events.
-        let crossterm::event::KeyEvent {
-            code, modifiers, ..
-        } = input;
-        match code {
+        // Update the paste-burst heuristic for text, shortcut, and non-char events.
+        match input.code {
             KeyCode::Char(_) => {
-                let has_ctrl_or_alt = has_ctrl_or_alt(modifiers);
-                if has_ctrl_or_alt {
+                if has_non_text_modifier {
                     self.draft.paste_burst.clear_window_after_non_char();
                 }
             }
@@ -11906,6 +11905,148 @@ mod tests {
         }
     }
 
+    #[test]
+    fn shortcut_modified_input_does_not_enter_paste_bursts() {
+        snapshot_composer_state(
+            "shortcut_modified_space_is_not_rendered",
+            /*enhanced_keys_supported*/ false,
+            |composer| {
+                let now = Instant::now();
+                for input in [
+                    KeyEvent::new(KeyCode::Char('a'), KeyModifiers::NONE),
+                    KeyEvent::new(KeyCode::Char(' '), KeyModifiers::SUPER),
+                    KeyEvent::new(KeyCode::Char('b'), KeyModifiers::NONE),
+                ] {
+                    composer.handle_input_basic_with_time(input, now);
+                }
+
+                assert!(
+                    composer.handle_paste_burst_flush(
+                        now + PasteBurst::recommended_active_flush_delay()
+                    )
+                );
+            },
+        );
+
+        for modifiers in [
+            KeyModifiers::SUPER,
+            KeyModifiers::SHIFT | KeyModifiers::SUPER,
+            KeyModifiers::HYPER,
+            KeyModifiers::META,
+        ] {
+            let (mut composer, _rx) = new_test_composer();
+            let now = Instant::now();
+
+            composer
+                .handle_input_basic_with_time(KeyEvent::new(KeyCode::Char(' '), modifiers), now);
+
+            assert!(
+                !composer.is_in_paste_burst(),
+                "shortcut modifiers {modifiers:?} must not start a paste burst"
+            );
+            assert!(
+                !composer.handle_paste_burst_flush(now + PasteBurst::recommended_flush_delay())
+            );
+            assert_eq!(composer.draft.textarea.text(), "");
+        }
+    }
+
+    #[test]
+    fn plain_and_shift_spaces_insert_normally() {
+        for modifiers in [KeyModifiers::NONE, KeyModifiers::SHIFT] {
+            let (mut composer, _rx) = new_test_composer();
+            let now = Instant::now();
+
+            composer
+                .handle_input_basic_with_time(KeyEvent::new(KeyCode::Char(' '), modifiers), now);
+
+            assert!(composer.is_in_paste_burst());
+            assert_eq!(composer.draft.textarea.text(), "");
+            assert!(composer.handle_paste_burst_flush(now + PasteBurst::recommended_flush_delay()));
+            assert_eq!(composer.draft.textarea.text(), " ");
+            assert!(!composer.is_in_paste_burst());
+
+            let snapshot_name = if modifiers == KeyModifiers::NONE {
+                "plain_space_is_rendered"
+            } else {
+                "shift_space_is_rendered"
+            };
+            snapshot_composer_state(
+                snapshot_name,
+                /*enhanced_keys_supported*/ false,
+                |composer| {
+                    let now = Instant::now();
+                    for input in [
+                        KeyEvent::new(KeyCode::Char('a'), KeyModifiers::NONE),
+                        KeyEvent::new(KeyCode::Char(' '), modifiers),
+                        KeyEvent::new(KeyCode::Char('b'), KeyModifiers::NONE),
+                    ] {
+                        composer.handle_input_basic_with_time(input, now);
+                    }
+
+                    assert!(composer.handle_paste_burst_flush(
+                        now + PasteBurst::recommended_active_flush_delay()
+                    ));
+                },
+            );
+        }
+    }
+
+    #[test]
+    fn non_text_input_flushes_pending_paste_without_inserting_text() {
+        let (mut composer, _rx) = new_test_composer();
+        let now = Instant::now();
+
+        composer.handle_input_basic_with_time(
+            KeyEvent::new(KeyCode::Char('a'), KeyModifiers::NONE),
+            now,
+        );
+        composer.handle_input_basic_with_time(
+            KeyEvent::new(KeyCode::Char('b'), KeyModifiers::NONE),
+            now,
+        );
+
+        assert!(composer.is_in_paste_burst());
+        assert_eq!(composer.draft.textarea.text(), "");
+
+        composer.handle_input_basic_with_time(
+            KeyEvent::new(KeyCode::Char(' '), KeyModifiers::SUPER),
+            now,
+        );
+
+        assert_eq!(composer.draft.textarea.text(), "ab");
+        assert!(!composer.is_in_paste_burst());
+        assert!(!composer.handle_paste_burst_flush(now + PasteBurst::recommended_flush_delay()));
+    }
+
+    #[test]
+    fn platform_specific_altgr_input_remains_text() {
+        for modifiers in [
+            KeyModifiers::CONTROL | KeyModifiers::ALT,
+            KeyModifiers::SHIFT | KeyModifiers::CONTROL | KeyModifiers::ALT,
+        ] {
+            let (mut composer, _rx) = new_test_composer();
+            let now = Instant::now();
+
+            composer
+                .handle_input_basic_with_time(KeyEvent::new(KeyCode::Char('@'), modifiers), now);
+
+            if cfg!(windows) {
+                assert!(composer.is_in_paste_burst());
+                assert!(
+                    composer.handle_paste_burst_flush(now + PasteBurst::recommended_flush_delay())
+                );
+                assert_eq!(composer.draft.textarea.text(), "@");
+            } else {
+                assert!(!composer.is_in_paste_burst());
+                assert!(
+                    !composer.handle_paste_burst_flush(now + PasteBurst::recommended_flush_delay())
+                );
+                assert_eq!(composer.draft.textarea.text(), "");
+            }
+        }
+    }
+
     /// Behavior: the first fast ASCII character is held briefly to avoid flicker; if no burst
     /// follows, it should eventually flush as normal typed input (not as a paste).
     #[test]

codex-rs/tui/src/bottom_pane/paste_burst.rs

@@ -9,8 +9,9 @@
 //! - Avoid flicker caused by inserting a typed prefix and then immediately reclassifying it as
 //!   paste once enough chars have arrived.
 //!
-//! This module provides the `PasteBurst` state machine. `ChatComposer` feeds it only "plain"
-//! character events (no Ctrl/Alt) and uses the full buffering decisions to either:
+//! This module provides the `PasteBurst` state machine. `ChatComposer` feeds it only
+//! text-producing character events (plain, Shift, or Windows AltGr) and uses the full buffering
+//! decisions to either:
 //!
 //! - briefly hold a first ASCII char (flicker suppression),
 //! - buffer a burst as a single pasted string, or
@@ -21,14 +22,15 @@
 //! `PasteBurst` is a pure state machine: it never mutates the textarea directly. The caller feeds
 //! it events and then applies the chosen action:
 //!
-//! - For each plain `KeyCode::Char`, call [`PasteBurst::on_plain_char`] (ASCII) or
+//! - For each text-producing `KeyCode::Char`, call [`PasteBurst::on_plain_char`] (ASCII) or
 //!   [`PasteBurst::on_plain_char_no_hold`] (non-ASCII/IME).
 //! - If the decision indicates buffering, the caller appends to `PasteBurst.buffer` via
 //!   [`PasteBurst::append_char_to_buffer`].
 //! - On a UI tick, call [`PasteBurst::flush_if_due`]. If it returns [`FlushResult::Typed`], insert
 //!   that char as normal typing. If it returns [`FlushResult::Paste`], treat the returned string as
 //!   an explicit paste.
-//! - Before applying non-char input (arrow keys, Ctrl/Alt modifiers, etc.), use
+//! - Before applying non-text input (arrow keys; Ctrl/Alt shortcuts other than Windows AltGr;
+//!   or Super, Hyper, and Meta modifiers), use
 //!   [`PasteBurst::flush_before_modified_input`] to avoid leaving buffered text "stuck", and then
 //!   [`PasteBurst::clear_window_after_non_char`] so subsequent typing does not get grouped into a
 //!   previous burst.
@@ -142,7 +144,8 @@
 //!   - [`FlushResult::Typed`]: insert that single char as normal typing.
 //!   - [`FlushResult::Paste`]: treat the returned string as an explicit paste.
 //!
-//! - When a non-plain key is pressed (Ctrl/Alt-modified input, arrows, etc.), callers should use
+//! - When non-text input is pressed (Ctrl/Alt shortcuts other than Windows AltGr; Super, Hyper,
+//!   and Meta modifiers; arrows; etc.), callers should use
 //!   [`PasteBurst::clear_window_after_non_char`] to prevent the next keystroke from being
 //!   incorrectly grouped into a previous burst.
 

codex-rs/tui/src/bottom_pane/snapshots/codex_tui__bottom_pane__chat_composer__tests__plain_space_is_rendered.snap

@@ -0,0 +1,13 @@
+---
+source: tui/src/bottom_pane/chat_composer.rs
+expression: terminal.backend()
+---
+"                                                                                                    "
+"› a b                                                                                               "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                 100% context left  "

codex-rs/tui/src/bottom_pane/snapshots/codex_tui__bottom_pane__chat_composer__tests__shift_space_is_rendered.snap

@@ -0,0 +1,13 @@
+---
+source: tui/src/bottom_pane/chat_composer.rs
+expression: terminal.backend()
+---
+"                                                                                                    "
+"› a b                                                                                               "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                 100% context left  "

codex-rs/tui/src/bottom_pane/snapshots/codex_tui__bottom_pane__chat_composer__tests__shortcut_modified_space_is_not_rendered.snap

@@ -0,0 +1,13 @@
+---
+source: tui/src/bottom_pane/chat_composer.rs
+expression: terminal.backend()
+---
+"                                                                                                    "
+"› ab                                                                                                "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                                    "
+"                                                                                 100% context left  "