initial release

terminal workspace manager for AI coding agents.
single rust binary, runs inside your existing terminal.
workspaces, tiled panes, intelligent agent state detection.

https://herdr.dev

1 files changed, 339 insertions, 0 deletions

diff --git a/src/input.rs b/src/input.rs
new file mode 100644
index 00000000..dbbf65df
--- /dev/null
+++ b/src/input.rs
@@ -0,0 +1,339 @@
+use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
+
+/// Encode a key event for a PTY child.
+/// If `kitty_mode` is true, modified keys use CSI u format.
+pub fn encode_key(key: KeyEvent, kitty_mode: bool) -> Vec<u8> {
+    if kitty_mode {
+        if let Some(bytes) = try_encode_csi_u(&key) {
+            return bytes;
+        }
+    }
+    encode_legacy(key)
+}
+
+/// CSI u encoding: \e[{codepoint};{modifiers}u
+/// Used when the child has pushed Kitty keyboard enhancement.
+/// Returns None if the key doesn't need CSI u (unmodified basic keys).
+fn try_encode_csi_u(key: &KeyEvent) -> Option<Vec<u8>> {
+    let mods = key.modifiers;
+
+    // Unmodified keys use legacy encoding (more compatible)
+    if mods.is_empty() {
+        return None;
+    }
+
+    // Plain Ctrl+letter is well-represented in legacy (bytes 1-26)
+    if mods == KeyModifiers::CONTROL {
+        if let KeyCode::Char(c) = key.code {
+            if c.is_ascii_alphabetic() {
+                return None; // let legacy handle it
+            }
+        }
+    }
+
+    // Special keys (arrows, F-keys, etc.) have well-established legacy
+    // xterm modified formats (\x1b[1;3A for Alt+Up, etc.) that are universally
+    // understood. Even Ghostty sends these in legacy format with kitty mode on.
+    // Only use CSI u for character keys and keys without legacy representations.
+    match key.code {
+        KeyCode::Up | KeyCode::Down | KeyCode::Left | KeyCode::Right
+        | KeyCode::Home | KeyCode::End | KeyCode::PageUp | KeyCode::PageDown
+        | KeyCode::Insert | KeyCode::Delete | KeyCode::F(_) => {
+            return None; // let legacy handle these
+        }
+        _ => {}
+    }
+
+    let codepoint = match key.code {
+        KeyCode::Char(c) => c as u32,
+        KeyCode::Enter => 13,
+        KeyCode::Tab => 9,
+        KeyCode::Backspace => 127,
+        KeyCode::Esc => 27,
+        _ => return None, // fall back to legacy for unhandled keys
+    };
+
+    let modifier = kitty_modifier(mods);
+
+    Some(format!("\x1b[{codepoint};{modifier}u").into_bytes())
+}
+
+/// Legacy terminal encoding (standard escape sequences).
+fn encode_legacy(key: KeyEvent) -> Vec<u8> {
+    let mods = key.modifiers;
+
+    // Modified special keys (arrows, home, end, etc.) use xterm format:
+    //   \x1b[1;{modifier}A  for arrows/home/end
+    //   \x1b[{n};{modifier}~ for insert/delete/pgup/pgdn
+    // The ESC-prefix hack doesn't work for these since they're already escape sequences.
+    if !mods.is_empty() {
+        if let Some(bytes) = encode_modified_special(key.code, mods) {
+            return bytes;
+        }
+    }
+
+    // Alt modifier on character keys: prefix with ESC
+    if mods.contains(KeyModifiers::ALT) {
+        let inner = KeyEvent::new(key.code, mods.difference(KeyModifiers::ALT));
+        let mut bytes = vec![0x1b];
+        bytes.extend(encode_legacy_inner(inner));
+        return bytes;
+    }
+    encode_legacy_inner(key)
+}
+
+/// xterm-style encoding for modified special keys.
+/// Modifier value: 1 + (shift?1:0) + (alt?2:0) + (ctrl?4:0)
+fn encode_modified_special(code: KeyCode, mods: KeyModifiers) -> Option<Vec<u8>> {
+    let modifier = xterm_modifier(mods);
+    if modifier <= 1 {
+        return None; // no modifiers to encode
+    }
+
+    match code {
+        // CSI 1;{mod}{letter} format
+        KeyCode::Up => Some(format!("\x1b[1;{modifier}A").into_bytes()),
+        KeyCode::Down => Some(format!("\x1b[1;{modifier}B").into_bytes()),
+        KeyCode::Right => Some(format!("\x1b[1;{modifier}C").into_bytes()),
+        KeyCode::Left => Some(format!("\x1b[1;{modifier}D").into_bytes()),
+        KeyCode::Home => Some(format!("\x1b[1;{modifier}H").into_bytes()),
+        KeyCode::End => Some(format!("\x1b[1;{modifier}F").into_bytes()),
+        // CSI {n};{mod}~ format
+        KeyCode::Insert => Some(format!("\x1b[2;{modifier}~").into_bytes()),
+        KeyCode::Delete => Some(format!("\x1b[3;{modifier}~").into_bytes()),
+        KeyCode::PageUp => Some(format!("\x1b[5;{modifier}~").into_bytes()),
+        KeyCode::PageDown => Some(format!("\x1b[6;{modifier}~").into_bytes()),
+        // F1-F4: CSI 1;{mod}{P-S}
+        KeyCode::F(1) => Some(format!("\x1b[1;{modifier}P").into_bytes()),
+        KeyCode::F(2) => Some(format!("\x1b[1;{modifier}Q").into_bytes()),
+        KeyCode::F(3) => Some(format!("\x1b[1;{modifier}R").into_bytes()),
+        KeyCode::F(4) => Some(format!("\x1b[1;{modifier}S").into_bytes()),
+        // F5-F12: CSI {n};{mod}~
+        KeyCode::F(n @ 5..=12) => {
+            let code = match n {
+                5 => 15,
+                6 => 17,
+                7 => 18,
+                8 => 19,
+                9 => 20,
+                10 => 21,
+                11 => 23,
+                12 => 24,
+                _ => unreachable!(),
+            };
+            Some(format!("\x1b[{code};{modifier}~").into_bytes())
+        }
+        _ => None,
+    }
+}
+
+/// xterm modifier encoding: 1 + shift(1) + alt(2) + ctrl(4)
+/// Used for legacy modified special keys (arrows, function keys, etc.)
+fn xterm_modifier(mods: KeyModifiers) -> u32 {
+    let mut m = 1u32;
+    if mods.contains(KeyModifiers::SHIFT) {
+        m += 1;
+    }
+    if mods.contains(KeyModifiers::ALT) {
+        m += 2;
+    }
+    if mods.contains(KeyModifiers::CONTROL) {
+        m += 4;
+    }
+    m
+}
+
+/// Kitty protocol modifier encoding: 1 + shift(1) + alt(2) + ctrl(4) + super(8) + hyper(16) + meta(32)
+/// Superset of xterm — adds Super/Hyper/Meta bits.
+fn kitty_modifier(mods: KeyModifiers) -> u32 {
+    let mut m = xterm_modifier(mods);
+    if mods.contains(KeyModifiers::SUPER) {
+        m += 8;
+    }
+    if mods.contains(KeyModifiers::HYPER) {
+        m += 16;
+    }
+    if mods.contains(KeyModifiers::META) {
+        m += 32;
+    }
+    m
+}
+
+fn encode_legacy_inner(key: KeyEvent) -> Vec<u8> {
+    match key.code {
+        KeyCode::Char(ch) => {
+            if key.modifiers.contains(KeyModifiers::CONTROL) {
+                let upper = ch.to_ascii_uppercase();
+                match upper {
+                    'A'..='Z' => vec![upper as u8 - 64],
+                    ' ' | '@' | '2' => vec![0],
+                    '[' | '3' => vec![27],
+                    '\\' | '4' => vec![28],
+                    ']' | '5' => vec![29],
+                    '^' | '6' => vec![30],
+                    '_' | '7' | '-' => vec![31],
+                    _ => vec![ch as u8],
+                }
+            } else {
+                let mut buf = [0u8; 4];
+                ch.encode_utf8(&mut buf).as_bytes().to_vec()
+            }
+        }
+        KeyCode::Enter => vec![b'\r'],
+        KeyCode::Backspace => vec![127],
+        KeyCode::Tab => vec![9],
+        KeyCode::BackTab => vec![27, 91, 90],
+        KeyCode::Esc => vec![27],
+        KeyCode::Left => vec![27, 91, 68],
+        KeyCode::Right => vec![27, 91, 67],
+        KeyCode::Up => vec![27, 91, 65],
+        KeyCode::Down => vec![27, 91, 66],
+        KeyCode::Home => vec![27, 91, 72],
+        KeyCode::End => vec![27, 91, 70],
+        KeyCode::PageUp => vec![27, 91, 53, 126],
+        KeyCode::PageDown => vec![27, 91, 54, 126],
+        KeyCode::Delete => vec![27, 91, 51, 126],
+        KeyCode::Insert => vec![27, 91, 50, 126],
+        KeyCode::F(n) => encode_f_key(n),
+        _ => vec![],
+    }
+}
+
+fn encode_f_key(n: u8) -> Vec<u8> {
+    match n {
+        1 => vec![27, 79, 80],
+        2 => vec![27, 79, 81],
+        3 => vec![27, 79, 82],
+        4 => vec![27, 79, 83],
+        5 => vec![27, 91, 49, 53, 126],
+        6 => vec![27, 91, 49, 55, 126],
+        7 => vec![27, 91, 49, 56, 126],
+        8 => vec![27, 91, 49, 57, 126],
+        9 => vec![27, 91, 50, 48, 126],
+        10 => vec![27, 91, 50, 49, 126],
+        11 => vec![27, 91, 50, 51, 126],
+        12 => vec![27, 91, 50, 52, 126],
+        _ => vec![],
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn legacy_enter() {
+        let key = KeyEvent::new(KeyCode::Enter, KeyModifiers::empty());
+        assert_eq!(encode_key(key, false), vec![b'\r']);
+    }
+
+    #[test]
+    fn legacy_ctrl_c() {
+        let key = KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL);
+        assert_eq!(encode_key(key, false), vec![3]);
+    }
+
+    #[test]
+    fn legacy_shift_enter_is_just_cr() {
+        let key = KeyEvent::new(KeyCode::Enter, KeyModifiers::SHIFT);
+        // Enter/Tab/Backspace/Esc aren't special keys with xterm modifier encoding,
+        // so Shift+Enter falls through to legacy which just sends CR
+        assert_eq!(encode_key(key, false), vec![b'\r']);
+    }
+
+    #[test]
+    fn legacy_alt_up() {
+        let key = KeyEvent::new(KeyCode::Up, KeyModifiers::ALT);
+        // xterm modified key format: CSI 1;3A (3 = 1 + Alt)
+        assert_eq!(encode_key(key, false), b"\x1b[1;3A");
+    }
+
+    #[test]
+    fn legacy_shift_right() {
+        let key = KeyEvent::new(KeyCode::Right, KeyModifiers::SHIFT);
+        assert_eq!(encode_key(key, false), b"\x1b[1;2C");
+    }
+
+    #[test]
+    fn legacy_ctrl_left() {
+        let key = KeyEvent::new(KeyCode::Left, KeyModifiers::CONTROL);
+        assert_eq!(encode_key(key, false), b"\x1b[1;5D");
+    }
+
+    #[test]
+    fn legacy_ctrl_shift_end() {
+        let key = KeyEvent::new(
+            KeyCode::End,
+            KeyModifiers::CONTROL | KeyModifiers::SHIFT,
+        );
+        assert_eq!(encode_key(key, false), b"\x1b[1;6F");
+    }
+
+    #[test]
+    fn legacy_alt_delete() {
+        let key = KeyEvent::new(KeyCode::Delete, KeyModifiers::ALT);
+        assert_eq!(encode_key(key, false), b"\x1b[3;3~");
+    }
+
+    #[test]
+    fn legacy_shift_f5() {
+        let key = KeyEvent::new(KeyCode::F(5), KeyModifiers::SHIFT);
+        assert_eq!(encode_key(key, false), b"\x1b[15;2~");
+    }
+
+    #[test]
+    fn legacy_alt_char_still_esc_prefix() {
+        // Alt+a on character keys still uses ESC prefix (not xterm modified)
+        let key = KeyEvent::new(KeyCode::Char('a'), KeyModifiers::ALT);
+        assert_eq!(encode_key(key, false), b"\x1ba");
+    }
+
+    #[test]
+    fn kitty_shift_enter() {
+        let key = KeyEvent::new(KeyCode::Enter, KeyModifiers::SHIFT);
+        assert_eq!(encode_key(key, true), b"\x1b[13;2u");
+    }
+
+    #[test]
+    fn kitty_ctrl_shift_a() {
+        let key = KeyEvent::new(
+            KeyCode::Char('a'),
+            KeyModifiers::CONTROL | KeyModifiers::SHIFT,
+        );
+        assert_eq!(encode_key(key, true), b"\x1b[97;6u");
+    }
+
+    #[test]
+    fn kitty_alt_enter() {
+        let key = KeyEvent::new(KeyCode::Enter, KeyModifiers::ALT);
+        assert_eq!(encode_key(key, true), b"\x1b[13;3u");
+    }
+
+    #[test]
+    fn kitty_plain_ctrl_c_uses_legacy() {
+        // Plain Ctrl+letter is well-represented in legacy
+        let key = KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL);
+        assert_eq!(encode_key(key, true), vec![3]);
+    }
+
+    #[test]
+    fn kitty_unmodified_uses_legacy() {
+        let key = KeyEvent::new(KeyCode::Char('a'), KeyModifiers::empty());
+        assert_eq!(encode_key(key, true), b"a");
+    }
+
+    #[test]
+    fn kitty_shift_tab() {
+        let key = KeyEvent::new(KeyCode::Tab, KeyModifiers::SHIFT);
+        assert_eq!(encode_key(key, true), b"\x1b[9;2u");
+    }
+
+    #[test]
+    fn kitty_ctrl_shift_enter() {
+        let key = KeyEvent::new(
+            KeyCode::Enter,
+            KeyModifiers::CONTROL | KeyModifiers::SHIFT,
+        );
+        assert_eq!(encode_key(key, true), b"\x1b[13;6u");
+    }
+}