fix(input): preserve shift in kitty alternate reports (#2479)

refs #2435

1 files changed, 34 insertions, 1 deletions

diff --git a/src/input/parse.rs b/src/input/parse.rs
index 861280dd..085757c3 100644
--- a/src/input/parse.rs
+++ b/src/input/parse.rs
@@ -39,8 +39,17 @@ fn parse_kitty_key_sequence(data: &str) -> Option<TerminalKey> {
 
     let code = kitty_codepoint_to_keycode(codepoint)?;
     let kind = parse_kitty_event_type(event_type)?;
+    let mut modifiers = key_modifiers_from_u8(modifier);
+    // Kitty permits the shifted alternate only while Shift is active. Normalize
+    // contradictory reports here so they cannot dispatch an unshifted command.
+    if matches!(code, KeyCode::Char(_))
+        && shifted_codepoint
+            .is_some_and(|shifted| shifted != codepoint && char::from_u32(shifted).is_some())
+    {
+        modifiers |= KeyModifiers::SHIFT;
+    }
 
-    let mut key = TerminalKey::new(code, key_modifiers_from_u8(modifier)).with_kind(kind);
+    let mut key = TerminalKey::new(code, modifiers).with_kind(kind);
     if let Some(shifted_codepoint) = shifted_codepoint {
         key = key.with_shifted_codepoint(shifted_codepoint);
     }
@@ -599,6 +608,30 @@ mod tests {
     }
 
     #[test]
+    fn parse_kitty_sequence_recovers_omitted_shift_modifier() {
+        for (sequence, kind) in [
+            ("\x1b[114:82;1u", crossterm::event::KeyEventKind::Press),
+            ("\x1b[114:82;1:2u", crossterm::event::KeyEventKind::Repeat),
+            ("\x1b[114:82;1:3u", crossterm::event::KeyEventKind::Release),
+        ] {
+            let key = parse_terminal_key_sequence(sequence).unwrap();
+            assert_eq!(key.code, KeyCode::Char('r'));
+            assert_eq!(key.modifiers, KeyModifiers::SHIFT);
+            assert_eq!(key.kind, kind);
+            assert_eq!(key.shifted_codepoint, Some('R' as u32));
+        }
+    }
+
+    #[test]
+    fn parse_kitty_sequence_does_not_infer_shift_without_distinct_shifted_alternate() {
+        for sequence in ["\x1b[114;1u", "\x1b[114:114;1u", "\x1b[114::113;1u"] {
+            let key = parse_terminal_key_sequence(sequence).unwrap();
+            assert_eq!(key.code, KeyCode::Char('r'));
+            assert_eq!(key.modifiers, KeyModifiers::empty());
+        }
+    }
+
+    #[test]
     fn parse_kitty_sequence_preserves_non_us_shift_pairs() {
         for (sequence, base, shifted) in [
             ("\x1b[50:34;2:1u", '2', '"'),