1 files changed, 98 insertions, 8 deletions

diff --git a/src/terminal_modes.rs b/src/terminal_modes.rs
index c9f08ceb..b38d251b 100644
--- a/src/terminal_modes.rs
+++ b/src/terminal_modes.rs
@@ -1,7 +1,5 @@
 use std::io::{self, Write};
 
-#[cfg(not(windows))]
-use crossterm::event::{PopKeyboardEnhancementFlags, PushKeyboardEnhancementFlags};
 #[cfg(any(not(windows), test))]
 const DISABLE_HOST_MOUSE_REPORTING_SEQUENCE: &[u8] =
     b"\x1b[?1006l\x1b[?1016l\x1b[?1015l\x1b[?1005l\x1b[?1003l\x1b[?1002l\x1b[?1000l";
@@ -53,18 +51,14 @@ pub(crate) fn set_host_kitty_keyboard_report_all<W: Write>(
     let mut flags = crate::input::ime_compatible_keyboard_enhancement_flags();
     if report_all_keys {
         flags |= crossterm::event::KeyboardEnhancementFlags::REPORT_ALL_KEYS_AS_ESCAPE_CODES;
-        // Report-all turns IME commits into CSI-u key events in terminals such
-        // as Ghostty. Ask the terminal to carry the committed text with them.
         flags = crossterm::event::KeyboardEnhancementFlags::from_bits_retain(
             flags.bits() | 0b0001_0000,
         );
     }
-    // Older iTerm2 releases clear the keyboard stack on SET, so a later pop
-    // cannot restore the host state. Replace only Herdr's top entry instead.
     crossterm::execute!(
         writer,
-        PopKeyboardEnhancementFlags,
-        PushKeyboardEnhancementFlags(flags)
+        crossterm::event::PopKeyboardEnhancementFlags,
+        crossterm::event::PushKeyboardEnhancementFlags(flags)
     )
 }
 
@@ -76,10 +70,64 @@ pub(crate) fn set_host_kitty_keyboard_report_all<W: Write>(
     Ok(())
 }
 
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
+pub(crate) struct DirectHostKeyboardState {
+    kitty_flags: Option<u16>,
+    modify_other_keys_level: u8,
+}
+
+#[cfg(not(windows))]
+pub(crate) fn set_direct_host_keyboard_protocol<W: Write>(
+    writer: &mut W,
+    active: &mut DirectHostKeyboardState,
+    next_flags: u16,
+    next_modify_other_keys_level: u8,
+) -> io::Result<()> {
+    let next_kitty_flags = (next_flags != 0).then_some(next_flags);
+    if active.kitty_flags == next_kitty_flags
+        && active.modify_other_keys_level == next_modify_other_keys_level
+    {
+        return Ok(());
+    }
+
+    if active.kitty_flags != next_kitty_flags {
+        if active.kitty_flags.is_some() {
+            writer.write_all(b"\x1b[<1u")?;
+        }
+        if next_flags != 0 {
+            write!(writer, "\x1b[>{next_flags}u")?;
+        }
+    }
+    if active.modify_other_keys_level != next_modify_other_keys_level {
+        write!(writer, "\x1b[>4;{next_modify_other_keys_level}m")?;
+    }
+    writer.flush()?;
+    *active = DirectHostKeyboardState {
+        kitty_flags: next_kitty_flags,
+        modify_other_keys_level: next_modify_other_keys_level,
+    };
+    Ok(())
+}
+
+#[cfg(windows)]
+pub(crate) fn set_direct_host_keyboard_protocol<W: Write>(
+    _writer: &mut W,
+    active: &mut DirectHostKeyboardState,
+    next_flags: u16,
+    next_modify_other_keys_level: u8,
+) -> io::Result<()> {
+    *active = DirectHostKeyboardState {
+        kitty_flags: (next_flags != 0).then_some(next_flags),
+        modify_other_keys_level: next_modify_other_keys_level,
+    };
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    #[cfg(not(windows))]
     #[test]
     fn host_keyboard_report_all_replaces_the_current_herdr_stack_entry() {
         let mut output = Vec::new();
@@ -90,6 +138,48 @@ mod tests {
         assert_eq!(output, b"\x1b[<1u\x1b[>31u\x1b[<1u\x1b[>7u");
     }
 
+    #[cfg(not(windows))]
+    #[test]
+    fn direct_keyboard_protocol_owns_exactly_one_stack_entry_and_modify_other_keys() {
+        let mut output = Vec::new();
+        let mut active = DirectHostKeyboardState::default();
+
+        set_direct_host_keyboard_protocol(&mut output, &mut active, 3, 0).unwrap();
+        set_direct_host_keyboard_protocol(&mut output, &mut active, 15, 2).unwrap();
+        set_direct_host_keyboard_protocol(&mut output, &mut active, 0, 0).unwrap();
+
+        assert_eq!(
+            output,
+            b"\x1b[>3u\x1b[<1u\x1b[>15u\x1b[>4;2m\x1b[<1u\x1b[>4;0m"
+        );
+        assert_eq!(active, DirectHostKeyboardState::default());
+    }
+
+    #[cfg(not(windows))]
+    #[test]
+    fn direct_modify_other_keys_works_without_kitty_flags() {
+        let mut output = Vec::new();
+        let mut active = DirectHostKeyboardState::default();
+
+        set_direct_host_keyboard_protocol(&mut output, &mut active, 0, 1).unwrap();
+        set_direct_host_keyboard_protocol(&mut output, &mut active, 0, 2).unwrap();
+        set_direct_host_keyboard_protocol(&mut output, &mut active, 0, 0).unwrap();
+
+        assert_eq!(output, b"\x1b[>4;1m\x1b[>4;2m\x1b[>4;0m");
+        assert_eq!(active, DirectHostKeyboardState::default());
+    }
+
+    #[test]
+    fn direct_legacy_keyboard_mode_does_not_pop_the_host_stack() {
+        let mut output = Vec::new();
+        let mut active = DirectHostKeyboardState::default();
+
+        set_direct_host_keyboard_protocol(&mut output, &mut active, 0, 0).unwrap();
+
+        assert!(output.is_empty());
+        assert_eq!(active, DirectHostKeyboardState::default());
+    }
+
     #[test]
     fn clears_all_known_host_mouse_modes() {
         let sequence = std::str::from_utf8(DISABLE_HOST_MOUSE_REPORTING_SEQUENCE).unwrap();