fix: prevent release key fallback from doubling input

refs #769

1 files changed, 76 insertions, 1 deletions

diff --git a/src/pane/terminal.rs b/src/pane/terminal.rs
index ed5d1061..e573f958 100644
--- a/src/pane/terminal.rs
+++ b/src/pane/terminal.rs
@@ -1019,7 +1019,11 @@ impl GhosttyPaneTerminal {
             return crate::input::encode_terminal_key(key, protocol);
         };
         match encoder.encode(&event) {
-            Ok(bytes) if !bytes.is_empty() => bytes,
+            Ok(bytes)
+                if !bytes.is_empty() && encoded_key_preserves_event_kind(&bytes, key, protocol) =>
+            {
+                bytes
+            }
             Ok(_) | Err(_) => crate::input::encode_terminal_key(key, protocol),
         }
     }
@@ -1291,6 +1295,23 @@ impl GhosttyPaneTerminal {
     }
 }
 
+fn encoded_key_preserves_event_kind(
+    bytes: &[u8],
+    key: crate::input::TerminalKey,
+    protocol: crate::input::KeyboardProtocol,
+) -> bool {
+    if !protocol.reports_event_types() || key.kind == crossterm::event::KeyEventKind::Press {
+        return true;
+    }
+
+    std::str::from_utf8(bytes)
+        .ok()
+        .and_then(crate::input::parse_terminal_key_sequence)
+        .is_some_and(|parsed| {
+            parsed.code == key.code && parsed.modifiers == key.modifiers && parsed.kind == key.kind
+        })
+}
+
 fn cursor_position_settle_pending(core: &GhosttyPaneCore) -> bool {
     core.cursor_settle_state.pending()
 }
@@ -2433,6 +2454,60 @@ mod tests {
     }
 
     #[test]
+    fn ghostty_enter_backspace_release_in_legacy_pane_emits_nothing() {
+        let (tx, _rx) = mpsc::channel(4);
+        let terminal = crate::ghostty::Terminal::new(80, 24, 0).unwrap();
+        let pane = GhosttyPaneTerminal::new(terminal, tx).unwrap();
+
+        for code in [
+            crossterm::event::KeyCode::Enter,
+            crossterm::event::KeyCode::Backspace,
+        ] {
+            let press = pane.encode_terminal_key(
+                crate::input::TerminalKey::new(code, crossterm::event::KeyModifiers::empty()),
+                crate::input::KeyboardProtocol::Legacy,
+            );
+            let release = pane.encode_terminal_key(
+                crate::input::TerminalKey::new(code, crossterm::event::KeyModifiers::empty())
+                    .with_kind(crossterm::event::KeyEventKind::Release),
+                crate::input::KeyboardProtocol::Legacy,
+            );
+            assert!(!press.is_empty(), "{code:?} press should emit bytes");
+            assert!(
+                release.is_empty(),
+                "{code:?} release should emit nothing in a legacy pane, got {release:?}"
+            );
+        }
+    }
+
+    #[test]
+    fn ghostty_release_still_encoded_for_report_event_pane() {
+        let (tx, _rx) = mpsc::channel(4);
+        // Push kitty flags including REPORT_EVENT_TYPES (0b10) + DISAMBIGUATE (0b1).
+        let mut terminal = crate::ghostty::Terminal::new(80, 24, 0).unwrap();
+        terminal.write(b"\x1b[>3u");
+        let pane = GhosttyPaneTerminal::new(terminal, tx).unwrap();
+
+        let release = pane.encode_terminal_key(
+            crate::input::TerminalKey::new(
+                crossterm::event::KeyCode::Enter,
+                crossterm::event::KeyModifiers::empty(),
+            )
+            .with_kind(crossterm::event::KeyEventKind::Release),
+            pane.keyboard_protocol().unwrap(),
+        );
+        let parsed =
+            crate::input::parse_terminal_key_sequence(std::str::from_utf8(&release).unwrap())
+                .unwrap();
+        assert_eq!(parsed.code, crossterm::event::KeyCode::Enter);
+        assert_eq!(
+            parsed.kind,
+            crossterm::event::KeyEventKind::Release,
+            "report-event pane should encode a release, got {release:?}"
+        );
+    }
+
+    #[test]
     fn ghostty_char_keys_still_use_herdr_encoding() {
         let (tx, _rx) = mpsc::channel(4);
         let mut terminal = crate::ghostty::Terminal::new(80, 24, 0).unwrap();