refactor: split terminal keyboard protocol module

5 files changed, 1211 insertions, 0 deletions

diff --git a/src/input/encode.rs b/src/input/encode.rs
new file mode 100644
index 00000000..657fab80
--- /dev/null
+++ b/src/input/encode.rs
@@ -0,0 +1,285 @@
+use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
+
+use super::{KeyboardProtocol, TerminalKey};
+
+const KITTY_FLAG_REPORT_EVENT_TYPES: u16 = 0b0000_0010;
+const KITTY_FLAG_REPORT_ALTERNATE_KEYS: u16 = 0b0000_0100;
+
+/// Encode a key event for a PTY child using the pane's negotiated keyboard protocol.
+pub fn encode_key(key: KeyEvent, protocol: KeyboardProtocol) -> Vec<u8> {
+    encode_terminal_key(key.into(), protocol)
+}
+
+pub fn encode_terminal_key(key: TerminalKey, protocol: KeyboardProtocol) -> Vec<u8> {
+    if let KeyboardProtocol::Kitty { flags } = protocol {
+        if let Some(bytes) = try_encode_csi_u(&key, flags) {
+            return bytes;
+        }
+    }
+    encode_legacy(key.as_key_event())
+}
+
+/// 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: &TerminalKey, flags: u16) -> 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, alternate_shifted) = match key.code {
+        KeyCode::Char(c) => {
+            let base = canonical_kitty_char(c, mods);
+            let shifted = alternate_shifted_codepoint(key, flags);
+            (base as u32, shifted)
+        }
+        KeyCode::Enter => (13, None),
+        KeyCode::Tab => (9, None),
+        KeyCode::Backspace => (127, None),
+        KeyCode::Esc => (27, None),
+        _ => return None, // fall back to legacy for unhandled keys
+    };
+
+    let modifier = kitty_modifier(mods);
+    let event_suffix = kitty_event_suffix(key, flags);
+
+    let sequence = match (alternate_shifted, event_suffix) {
+        (Some(shifted), Some(event)) => format!("\x1b[{codepoint}:{shifted};{modifier}:{event}u"),
+        (Some(shifted), None) => format!("\x1b[{codepoint}:{shifted};{modifier}u"),
+        (None, Some(event)) => format!("\x1b[{codepoint};{modifier}:{event}u"),
+        (None, None) => format!("\x1b[{codepoint};{modifier}u"),
+    };
+
+    Some(sequence.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 canonical_kitty_char(ch: char, mods: KeyModifiers) -> char {
+    if mods.contains(KeyModifiers::SHIFT) && ch.is_ascii_uppercase() {
+        ch.to_ascii_lowercase()
+    } else {
+        ch
+    }
+}
+
+fn alternate_shifted_codepoint(key: &TerminalKey, flags: u16) -> Option<u32> {
+    if flags & KITTY_FLAG_REPORT_ALTERNATE_KEYS == 0 {
+        return None;
+    }
+
+    if let Some(shifted) = key.shifted_codepoint {
+        return Some(shifted);
+    }
+
+    match key.code {
+        KeyCode::Char(ch)
+            if key.modifiers.contains(KeyModifiers::SHIFT) && ch.is_ascii_uppercase() =>
+        {
+            Some(ch as u32)
+        }
+        _ => None,
+    }
+}
+
+fn kitty_event_suffix(key: &TerminalKey, flags: u16) -> Option<u8> {
+    if flags & KITTY_FLAG_REPORT_EVENT_TYPES == 0 {
+        return None;
+    }
+
+    Some(match key.kind {
+        crossterm::event::KeyEventKind::Press => 1,
+        crossterm::event::KeyEventKind::Repeat => 2,
+        crossterm::event::KeyEventKind::Release => 3,
+    })
+}
+
+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![],
+    }
+}
diff --git a/src/input/mod.rs b/src/input/mod.rs
new file mode 100644
index 00000000..de4330a4
--- /dev/null
+++ b/src/input/mod.rs
@@ -0,0 +1,10 @@
+mod encode;
+mod model;
+mod parse;
+
+pub use encode::{encode_key, encode_terminal_key};
+pub use model::{KeyboardProtocol, TerminalKey};
+pub use parse::parse_terminal_key_sequence;
+
+#[cfg(test)]
+mod tests;
diff --git a/src/input/model.rs b/src/input/model.rs
new file mode 100644
index 00000000..31c521e8
--- /dev/null
+++ b/src/input/model.rs
@@ -0,0 +1,57 @@
+use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct TerminalKey {
+    pub code: KeyCode,
+    pub modifiers: KeyModifiers,
+    pub kind: crossterm::event::KeyEventKind,
+    pub shifted_codepoint: Option<u32>,
+}
+
+impl TerminalKey {
+    pub fn new(code: KeyCode, modifiers: KeyModifiers) -> Self {
+        Self {
+            code,
+            modifiers,
+            kind: crossterm::event::KeyEventKind::Press,
+            shifted_codepoint: None,
+        }
+    }
+
+    pub fn with_kind(mut self, kind: crossterm::event::KeyEventKind) -> Self {
+        self.kind = kind;
+        self
+    }
+
+    #[allow(dead_code)] // Reserved for the upcoming raw input parser to preserve shifted/base key pairs.
+    pub fn with_shifted_codepoint(mut self, shifted_codepoint: u32) -> Self {
+        self.shifted_codepoint = Some(shifted_codepoint);
+        self
+    }
+
+    pub fn as_key_event(self) -> KeyEvent {
+        KeyEvent::new_with_kind(self.code, self.modifiers, self.kind)
+    }
+}
+
+impl From<KeyEvent> for TerminalKey {
+    fn from(value: KeyEvent) -> Self {
+        Self::new(value.code, value.modifiers).with_kind(value.kind)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum KeyboardProtocol {
+    Legacy,
+    Kitty { flags: u16 },
+}
+
+impl KeyboardProtocol {
+    pub fn from_kitty_flags(flags: u16) -> Self {
+        if flags == 0 {
+            Self::Legacy
+        } else {
+            Self::Kitty { flags }
+        }
+    }
+}
diff --git a/src/input/parse.rs b/src/input/parse.rs
new file mode 100644
index 00000000..1662d9ff
--- /dev/null
+++ b/src/input/parse.rs
@@ -0,0 +1,225 @@
+use crossterm::event::{KeyCode, KeyModifiers};
+
+use super::TerminalKey;
+
+#[allow(dead_code)] // Next step: raw stdin parser will feed TerminalKey directly through this path.
+pub fn parse_terminal_key_sequence(data: &str) -> Option<TerminalKey> {
+    parse_kitty_key_sequence(data)
+        .or_else(|| parse_modify_other_keys_sequence(data))
+        .or_else(|| parse_legacy_key_sequence(data))
+}
+
+#[allow(dead_code)] // Reserved for the upcoming raw stdin parser.
+fn parse_kitty_key_sequence(data: &str) -> Option<TerminalKey> {
+    let body = data.strip_prefix("\x1b[")?.strip_suffix('u')?;
+
+    let (main, event_type) = match body.rsplit_once(':') {
+        Some((head, tail)) if tail.chars().all(|ch| ch.is_ascii_digit()) && head.contains(';') => {
+            (head, Some(tail))
+        }
+        _ => (body, None),
+    };
+
+    let (key_part, modifier_part) = main.rsplit_once(';').unwrap_or((main, "1"));
+    let modifier = modifier_part.parse::<u8>().ok()?.checked_sub(1)?;
+
+    let mut key_fields = key_part.split(':');
+    let codepoint = key_fields.next()?.parse::<u32>().ok()?;
+    let shifted_codepoint = key_fields
+        .next()
+        .filter(|field| !field.is_empty())
+        .and_then(|field| field.parse::<u32>().ok());
+
+    let code = kitty_codepoint_to_keycode(codepoint)?;
+    let kind = parse_kitty_event_type(event_type)?;
+
+    Some(TerminalKey {
+        code,
+        modifiers: key_modifiers_from_u8(modifier),
+        kind,
+        shifted_codepoint,
+    })
+}
+
+#[allow(dead_code)] // Reserved for the upcoming raw stdin parser.
+fn parse_modify_other_keys_sequence(data: &str) -> Option<TerminalKey> {
+    let body = data.strip_prefix("\x1b[27;")?.strip_suffix('~')?;
+    let (modifier_part, codepoint_part) = body.split_once(';')?;
+    let modifier = modifier_part.parse::<u8>().ok()?.checked_sub(1)?;
+    let codepoint = codepoint_part.parse::<u32>().ok()?;
+
+    Some(TerminalKey::new(
+        kitty_codepoint_to_keycode(codepoint)?,
+        key_modifiers_from_u8(modifier),
+    ))
+}
+
+#[allow(dead_code)] // Reserved for the upcoming raw stdin parser.
+fn parse_legacy_key_sequence(data: &str) -> Option<TerminalKey> {
+    if let Some(key) = parse_legacy_special_sequence(data) {
+        return Some(key);
+    }
+
+    match data {
+        "\r" | "\n" => Some(TerminalKey::new(KeyCode::Enter, KeyModifiers::empty())),
+        "\t" => Some(TerminalKey::new(KeyCode::Tab, KeyModifiers::empty())),
+        "\x1b" => Some(TerminalKey::new(KeyCode::Esc, KeyModifiers::empty())),
+        "\x7f" => Some(TerminalKey::new(KeyCode::Backspace, KeyModifiers::empty())),
+        _ if data.starts_with('\x1b') => {
+            let rest = data.strip_prefix('\x1b')?;
+            if rest.chars().count() == 1 {
+                let ch = rest.chars().next()?;
+                Some(TerminalKey::new(KeyCode::Char(ch), KeyModifiers::ALT))
+            } else {
+                None
+            }
+        }
+        _ if data.chars().count() == 1 => {
+            let ch = data.chars().next()?;
+
+            if let Some(ctrl_key) = parse_legacy_ctrl_char(ch) {
+                return Some(ctrl_key);
+            }
+
+            let mut modifiers = KeyModifiers::empty();
+            let code = if ch.is_ascii_uppercase() {
+                modifiers |= KeyModifiers::SHIFT;
+                KeyCode::Char(ch)
+            } else {
+                KeyCode::Char(ch)
+            };
+            Some(TerminalKey::new(code, modifiers))
+        }
+        _ => None,
+    }
+}
+
+fn parse_legacy_ctrl_char(ch: char) -> Option<TerminalKey> {
+    match ch as u32 {
+        0 => Some(TerminalKey::new(KeyCode::Char(' '), KeyModifiers::CONTROL)),
+        1..=26 => Some(TerminalKey::new(
+            KeyCode::Char(char::from_u32((ch as u32) + 96)?),
+            KeyModifiers::CONTROL,
+        )),
+        27 => Some(TerminalKey::new(KeyCode::Char('['), KeyModifiers::CONTROL)),
+        28 => Some(TerminalKey::new(KeyCode::Char('\\'), KeyModifiers::CONTROL)),
+        29 => Some(TerminalKey::new(KeyCode::Char(']'), KeyModifiers::CONTROL)),
+        30 => Some(TerminalKey::new(KeyCode::Char('^'), KeyModifiers::CONTROL)),
+        31 => Some(TerminalKey::new(KeyCode::Char('-'), KeyModifiers::CONTROL)),
+        _ => None,
+    }
+}
+
+fn parse_legacy_special_sequence(data: &str) -> Option<TerminalKey> {
+    match data {
+        "\x1b\x1b[A" => Some(TerminalKey::new(KeyCode::Up, KeyModifiers::ALT)),
+        "\x1b\x1b[B" => Some(TerminalKey::new(KeyCode::Down, KeyModifiers::ALT)),
+        "\x1b\x1b[C" => Some(TerminalKey::new(KeyCode::Right, KeyModifiers::ALT)),
+        "\x1b\x1b[D" => Some(TerminalKey::new(KeyCode::Left, KeyModifiers::ALT)),
+        "\x1b[A" => Some(TerminalKey::new(KeyCode::Up, KeyModifiers::empty())),
+        "\x1b[B" => Some(TerminalKey::new(KeyCode::Down, KeyModifiers::empty())),
+        "\x1b[C" => Some(TerminalKey::new(KeyCode::Right, KeyModifiers::empty())),
+        "\x1b[D" => Some(TerminalKey::new(KeyCode::Left, KeyModifiers::empty())),
+        "\x1b[H" | "\x1bOH" | "\x1b[1~" | "\x1b[7~" => {
+            Some(TerminalKey::new(KeyCode::Home, KeyModifiers::empty()))
+        }
+        "\x1b[F" | "\x1bOF" | "\x1b[4~" | "\x1b[8~" => {
+            Some(TerminalKey::new(KeyCode::End, KeyModifiers::empty()))
+        }
+        "\x1b[5~" => Some(TerminalKey::new(KeyCode::PageUp, KeyModifiers::empty())),
+        "\x1b[6~" => Some(TerminalKey::new(KeyCode::PageDown, KeyModifiers::empty())),
+        "\x1b[2~" => Some(TerminalKey::new(KeyCode::Insert, KeyModifiers::empty())),
+        "\x1b[3~" => Some(TerminalKey::new(KeyCode::Delete, KeyModifiers::empty())),
+        "\x1b[Z" => Some(TerminalKey::new(KeyCode::BackTab, KeyModifiers::SHIFT)),
+        _ => parse_xterm_modified_special_sequence(data),
+    }
+}
+
+fn parse_xterm_modified_special_sequence(data: &str) -> Option<TerminalKey> {
+    let body = data.strip_prefix("\x1b[")?;
+
+    if let Some(body) = body.strip_prefix("1;") {
+        let suffix_char = body.chars().last()?;
+        if suffix_char.is_ascii_alphabetic() {
+            let modifier = body.strip_suffix(suffix_char)?;
+            let mod_value = modifier.parse::<u8>().ok()?.checked_sub(1)?;
+            let code = match suffix_char {
+                'A' => KeyCode::Up,
+                'B' => KeyCode::Down,
+                'C' => KeyCode::Right,
+                'D' => KeyCode::Left,
+                'H' => KeyCode::Home,
+                'F' => KeyCode::End,
+                _ => return None,
+            };
+            return Some(TerminalKey::new(code, key_modifiers_from_u8(mod_value)));
+        }
+    }
+
+    let tilde_body = body.strip_suffix('~')?;
+    let (code_part, modifier_part) = tilde_body.split_once(';')?;
+    let mod_value = modifier_part.parse::<u8>().ok()?.checked_sub(1)?;
+    let code = match code_part {
+        "2" => KeyCode::Insert,
+        "3" => KeyCode::Delete,
+        "5" => KeyCode::PageUp,
+        "6" => KeyCode::PageDown,
+        _ => return None,
+    };
+    Some(TerminalKey::new(code, key_modifiers_from_u8(mod_value)))
+}
+
+#[allow(dead_code)] // Reserved for the upcoming raw stdin parser.
+fn parse_kitty_event_type(value: Option<&str>) -> Option<crossterm::event::KeyEventKind> {
+    match value.unwrap_or("1") {
+        "1" => Some(crossterm::event::KeyEventKind::Press),
+        "2" => Some(crossterm::event::KeyEventKind::Repeat),
+        "3" => Some(crossterm::event::KeyEventKind::Release),
+        _ => None,
+    }
+}
+
+#[allow(dead_code)] // Reserved for the upcoming raw stdin parser.
+fn kitty_codepoint_to_keycode(codepoint: u32) -> Option<KeyCode> {
+    match codepoint {
+        8 | 127 => Some(KeyCode::Backspace),
+        9 => Some(KeyCode::Tab),
+        13 | 57414 => Some(KeyCode::Enter),
+        27 => Some(KeyCode::Esc),
+        57417 => Some(KeyCode::Left),
+        57418 => Some(KeyCode::Right),
+        57419 => Some(KeyCode::Up),
+        57420 => Some(KeyCode::Down),
+        57421 => Some(KeyCode::PageUp),
+        57422 => Some(KeyCode::PageDown),
+        57423 => Some(KeyCode::Home),
+        57424 => Some(KeyCode::End),
+        57425 => Some(KeyCode::Insert),
+        57426 => Some(KeyCode::Delete),
+        value => char::from_u32(value).map(KeyCode::Char),
+    }
+}
+
+#[allow(dead_code)] // Reserved for the upcoming raw stdin parser.
+fn key_modifiers_from_u8(modifier: u8) -> KeyModifiers {
+    let mut mods = KeyModifiers::empty();
+    if modifier & 0b0000_0001 != 0 {
+        mods |= KeyModifiers::SHIFT;
+    }
+    if modifier & 0b0000_0010 != 0 {
+        mods |= KeyModifiers::ALT;
+    }
+    if modifier & 0b0000_0100 != 0 {
+        mods |= KeyModifiers::CONTROL;
+    }
+    if modifier & 0b0000_1000 != 0 {
+        mods |= KeyModifiers::SUPER;
+    }
+    if modifier & 0b0001_0000 != 0 {
+        mods |= KeyModifiers::HYPER;
+    }
+    if modifier & 0b0010_0000 != 0 {
+        mods |= KeyModifiers::META;
+    }
+    mods
+}
diff --git a/src/input/tests.rs b/src/input/tests.rs
new file mode 100644
index 00000000..ec8fdf63
--- /dev/null
+++ b/src/input/tests.rs
@@ -0,0 +1,634 @@
+use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
+
+use super::{
+    encode_key, encode_terminal_key, parse_terminal_key_sequence, KeyboardProtocol, TerminalKey,
+};
+
+fn assert_terminal_key_eq(
+    actual: TerminalKey,
+    code: KeyCode,
+    modifiers: KeyModifiers,
+    kind: crossterm::event::KeyEventKind,
+    shifted_codepoint: Option<u32>,
+) {
+    assert_eq!(actual.code, code);
+    assert_eq!(actual.modifiers, modifiers);
+    assert_eq!(actual.kind, kind);
+    assert_eq!(actual.shifted_codepoint, shifted_codepoint);
+}
+
+fn decode_hex(hex: &str) -> Vec<u8> {
+    let hex = hex.trim();
+    assert_eq!(hex.len() % 2, 0, "hex string must have even length");
+    (0..hex.len())
+        .step_by(2)
+        .map(|idx| u8::from_str_radix(&hex[idx..idx + 2], 16).unwrap())
+        .collect()
+}
+
+fn parse_fixture_key_code(value: &str) -> KeyCode {
+    match value {
+        "enter" => KeyCode::Enter,
+        "tab" => KeyCode::Tab,
+        "backspace" => KeyCode::Backspace,
+        "esc" => KeyCode::Esc,
+        "up" => KeyCode::Up,
+        "down" => KeyCode::Down,
+        "left" => KeyCode::Left,
+        "right" => KeyCode::Right,
+        "home" => KeyCode::Home,
+        "end" => KeyCode::End,
+        "pageup" => KeyCode::PageUp,
+        "pagedown" => KeyCode::PageDown,
+        "insert" => KeyCode::Insert,
+        "delete" => KeyCode::Delete,
+        value if value.starts_with("char:") => {
+            KeyCode::Char(value.trim_start_matches("char:").chars().next().unwrap())
+        }
+        other => panic!("unsupported fixture key code: {other}"),
+    }
+}
+
+fn parse_fixture_modifiers(value: &str) -> KeyModifiers {
+    if value == "-" || value.is_empty() {
+        return KeyModifiers::empty();
+    }
+
+    let mut modifiers = KeyModifiers::empty();
+    for part in value.split('+') {
+        match part {
+            "shift" => modifiers |= KeyModifiers::SHIFT,
+            "alt" => modifiers |= KeyModifiers::ALT,
+            "control" => modifiers |= KeyModifiers::CONTROL,
+            "super" => modifiers |= KeyModifiers::SUPER,
+            "hyper" => modifiers |= KeyModifiers::HYPER,
+            "meta" => modifiers |= KeyModifiers::META,
+            other => panic!("unsupported fixture modifier: {other}"),
+        }
+    }
+    modifiers
+}
+
+fn parse_fixture_kind(value: &str) -> crossterm::event::KeyEventKind {
+    match value {
+        "press" => crossterm::event::KeyEventKind::Press,
+        "repeat" => crossterm::event::KeyEventKind::Repeat,
+        "release" => crossterm::event::KeyEventKind::Release,
+        other => panic!("unsupported fixture kind: {other}"),
+    }
+}
+
+#[test]
+fn legacy_enter() {
+    let key = KeyEvent::new(KeyCode::Enter, KeyModifiers::empty());
+    assert_eq!(encode_key(key, KeyboardProtocol::Legacy), vec![b'\r']);
+}
+
+#[test]
+fn legacy_ctrl_c() {
+    let key = KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL);
+    assert_eq!(encode_key(key, KeyboardProtocol::Legacy), 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, KeyboardProtocol::Legacy), 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, KeyboardProtocol::Legacy), b"\x1b[1;3A");
+}
+
+#[test]
+fn legacy_shift_right() {
+    let key = KeyEvent::new(KeyCode::Right, KeyModifiers::SHIFT);
+    assert_eq!(encode_key(key, KeyboardProtocol::Legacy), b"\x1b[1;2C");
+}
+
+#[test]
+fn legacy_ctrl_left() {
+    let key = KeyEvent::new(KeyCode::Left, KeyModifiers::CONTROL);
+    assert_eq!(encode_key(key, KeyboardProtocol::Legacy), 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, KeyboardProtocol::Legacy), b"\x1b[1;6F");
+}
+
+#[test]
+fn legacy_alt_delete() {
+    let key = KeyEvent::new(KeyCode::Delete, KeyModifiers::ALT);
+    assert_eq!(encode_key(key, KeyboardProtocol::Legacy), b"\x1b[3;3~");
+}
+
+#[test]
+fn legacy_shift_f5() {
+    let key = KeyEvent::new(KeyCode::F(5), KeyModifiers::SHIFT);
+    assert_eq!(encode_key(key, KeyboardProtocol::Legacy), 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, KeyboardProtocol::Legacy), b"\x1ba");
+}
+
+#[test]
+fn kitty_shift_enter() {
+    let key = KeyEvent::new(KeyCode::Enter, KeyModifiers::SHIFT);
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 1 }),
+        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, KeyboardProtocol::Kitty { flags: 1 }),
+        b"\x1b[97;6u"
+    );
+}
+
+#[test]
+fn kitty_shift_uppercase_letter_uses_base_codepoint() {
+    let key = KeyEvent::new(KeyCode::Char('L'), KeyModifiers::SHIFT);
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 1 }),
+        b"\x1b[108;2u"
+    );
+}
+
+#[test]
+fn kitty_shift_uppercase_letter_with_alternate_keys_reports_shifted_codepoint() {
+    let key = KeyEvent::new(KeyCode::Char('L'), KeyModifiers::SHIFT);
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 7 }),
+        b"\x1b[108:76;2:1u"
+    );
+}
+
+#[test]
+fn kitty_shift_lowercase_letter_normalizes_to_base_codepoint() {
+    let key = KeyEvent::new(KeyCode::Char('l'), KeyModifiers::SHIFT);
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 1 }),
+        b"\x1b[108;2u"
+    );
+}
+
+#[test]
+fn kitty_alt_shift_uppercase_letter_uses_base_codepoint() {
+    let key = KeyEvent::new(KeyCode::Char('L'), KeyModifiers::ALT | KeyModifiers::SHIFT);
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 1 }),
+        b"\x1b[108;4u"
+    );
+}
+
+#[test]
+fn kitty_ctrl_shift_uppercase_letter_uses_base_codepoint() {
+    let key = KeyEvent::new(
+        KeyCode::Char('L'),
+        KeyModifiers::CONTROL | KeyModifiers::SHIFT,
+    );
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 1 }),
+        b"\x1b[108;6u"
+    );
+}
+
+#[test]
+fn legacy_shift_uppercase_letter_stays_uppercase() {
+    let key = KeyEvent::new(KeyCode::Char('L'), KeyModifiers::SHIFT);
+    assert_eq!(encode_key(key, KeyboardProtocol::Legacy), b"L");
+}
+
+#[test]
+fn kitty_alt_enter() {
+    let key = KeyEvent::new(KeyCode::Enter, KeyModifiers::ALT);
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 1 }),
+        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, KeyboardProtocol::Kitty { flags: 1 }),
+        vec![3]
+    );
+}
+
+#[test]
+fn kitty_unmodified_uses_legacy() {
+    let key = KeyEvent::new(KeyCode::Char('a'), KeyModifiers::empty());
+    assert_eq!(encode_key(key, KeyboardProtocol::Kitty { flags: 1 }), b"a");
+}
+
+#[test]
+fn kitty_shift_tab() {
+    let key = KeyEvent::new(KeyCode::Tab, KeyModifiers::SHIFT);
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 1 }),
+        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, KeyboardProtocol::Kitty { flags: 1 }),
+        b"\x1b[13;6u"
+    );
+}
+
+#[test]
+fn kitty_repeat_event_type_is_encoded_when_requested() {
+    let key = KeyEvent::new_with_kind(
+        KeyCode::Enter,
+        KeyModifiers::SHIFT,
+        crossterm::event::KeyEventKind::Repeat,
+    );
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 3 }),
+        b"\x1b[13;2:2u"
+    );
+}
+
+#[test]
+fn kitty_release_event_type_and_alternate_keys_are_encoded_together() {
+    let key = KeyEvent::new_with_kind(
+        KeyCode::Char('L'),
+        KeyModifiers::SHIFT,
+        crossterm::event::KeyEventKind::Release,
+    );
+    assert_eq!(
+        encode_key(key, KeyboardProtocol::Kitty { flags: 7 }),
+        b"\x1b[108:76;2:3u"
+    );
+}
+
+#[test]
+fn kitty_rich_key_data_can_preserve_shifted_symbol_pairs() {
+    let key = TerminalKey::new(KeyCode::Char('1'), KeyModifiers::SHIFT)
+        .with_shifted_codepoint('!' as u32);
+    assert_eq!(
+        encode_terminal_key(key, KeyboardProtocol::Kitty { flags: 7 }),
+        b"\x1b[49:33;2:1u"
+    );
+}
+
+#[test]
+fn parse_kitty_sequence_preserves_shifted_symbol_pair() {
+    let key = parse_terminal_key_sequence("\x1b[49:33;2:1u").unwrap();
+    assert_eq!(key.code, KeyCode::Char('1'));
+    assert_eq!(key.modifiers, KeyModifiers::SHIFT);
+    assert_eq!(key.kind, crossterm::event::KeyEventKind::Press);
+    assert_eq!(key.shifted_codepoint, Some('!' as u32));
+}
+
+#[test]
+fn parse_kitty_sequence_preserves_shifted_letter_pair_and_release() {
+    let key = parse_terminal_key_sequence("\x1b[108:76;2:3u").unwrap();
+    assert_eq!(key.code, KeyCode::Char('l'));
+    assert_eq!(key.modifiers, KeyModifiers::SHIFT);
+    assert_eq!(key.kind, crossterm::event::KeyEventKind::Release);
+    assert_eq!(key.shifted_codepoint, Some('L' as u32));
+}
+
+#[test]
+fn parse_modify_other_keys_sequence() {
+    let key = parse_terminal_key_sequence("\x1b[27;6;108~").unwrap();
+    assert_eq!(key.code, KeyCode::Char('l'));
+    assert_eq!(key.modifiers, KeyModifiers::CONTROL | KeyModifiers::SHIFT);
+    assert_eq!(key.kind, crossterm::event::KeyEventKind::Press);
+    assert_eq!(key.shifted_codepoint, None);
+}
+
+#[test]
+fn parse_legacy_uppercase_letter_as_shifted_char() {
+    let key = parse_terminal_key_sequence("L").unwrap();
+    assert_eq!(key.code, KeyCode::Char('L'));
+    assert_eq!(key.modifiers, KeyModifiers::SHIFT);
+}
+
+#[test]
+fn parse_legacy_up_arrow_sequence() {
+    let key = parse_terminal_key_sequence("\x1b[A").unwrap();
+    assert_eq!(key.code, KeyCode::Up);
+    assert_eq!(key.modifiers, KeyModifiers::empty());
+}
+
+#[test]
+fn parse_xterm_alt_up_arrow_sequence() {
+    let key = parse_terminal_key_sequence("\x1b[1;3A").unwrap();
+    assert_eq!(key.code, KeyCode::Up);
+    assert_eq!(key.modifiers, KeyModifiers::ALT);
+}
+
+#[test]
+fn parse_xterm_alt_down_arrow_sequence() {
+    let key = parse_terminal_key_sequence("\x1b[1;3B").unwrap();
+    assert_eq!(key.code, KeyCode::Down);
+    assert_eq!(key.modifiers, KeyModifiers::ALT);
+}
+
+#[test]
+fn parse_kitty_functional_up_arrow_sequence() {
+    let key = parse_terminal_key_sequence("\x1b[57419;1u").unwrap();
+    assert_eq!(key.code, KeyCode::Up);
+    assert_eq!(key.modifiers, KeyModifiers::empty());
+}
+
+#[test]
+fn parse_legacy_ctrl_b_sequence() {
+    let key = parse_terminal_key_sequence("\x02").unwrap();
+    assert_eq!(key.code, KeyCode::Char('b'));
+    assert_eq!(key.modifiers, KeyModifiers::CONTROL);
+}
+
+#[test]
+fn parse_legacy_ctrl_c_sequence() {
+    let key = parse_terminal_key_sequence("\x03").unwrap();
+    assert_eq!(key.code, KeyCode::Char('c'));
+    assert_eq!(key.modifiers, KeyModifiers::CONTROL);
+}
+
+#[test]
+fn legacy_ctrl_byte_matrix_is_covered() {
+    for (byte, expected) in [
+        (b'\x01', 'a'),
+        (b'\x02', 'b'),
+        (b'\x03', 'c'),
+        (b'\x1a', 'z'),
+    ] {
+        let key = parse_terminal_key_sequence(std::str::from_utf8(&[byte]).unwrap()).unwrap();
+        assert_terminal_key_eq(
+            key,
+            KeyCode::Char(expected),
+            KeyModifiers::CONTROL,
+            crossterm::event::KeyEventKind::Press,
+            None,
+        );
+    }
+
+    // Ctrl+[ is byte-identical to Escape in legacy terminals, so the parser
+    // intentionally treats 0x1b as Escape and only disambiguates the other
+    // legacy control-symbol bytes here.
+    for (byte, expected) in [
+        (b'\x1c', '\\'),
+        (b'\x1d', ']'),
+        (b'\x1e', '^'),
+        (b'\x1f', '-'),
+    ] {
+        let key = parse_terminal_key_sequence(std::str::from_utf8(&[byte]).unwrap()).unwrap();
+        assert_terminal_key_eq(
+            key,
+            KeyCode::Char(expected),
+            KeyModifiers::CONTROL,
+            crossterm::event::KeyEventKind::Press,
+            None,
+        );
+    }
+}
+
+#[test]
+fn legacy_modified_special_roundtrip_matrix() {
+    let cases = [
+        KeyEvent::new(KeyCode::Up, KeyModifiers::ALT),
+        KeyEvent::new(KeyCode::Down, KeyModifiers::ALT),
+        KeyEvent::new(KeyCode::Right, KeyModifiers::SHIFT),
+        KeyEvent::new(KeyCode::Left, KeyModifiers::CONTROL),
+        KeyEvent::new(KeyCode::Home, KeyModifiers::CONTROL),
+        KeyEvent::new(KeyCode::End, KeyModifiers::CONTROL | KeyModifiers::SHIFT),
+        KeyEvent::new(KeyCode::PageUp, KeyModifiers::ALT),
+        KeyEvent::new(KeyCode::PageDown, KeyModifiers::CONTROL),
+        KeyEvent::new(KeyCode::Insert, KeyModifiers::SHIFT),
+        KeyEvent::new(KeyCode::Delete, KeyModifiers::ALT),
+    ];
+
+    for key in cases {
+        let encoded = encode_key(key, KeyboardProtocol::Legacy);
+        let parsed = parse_terminal_key_sequence(std::str::from_utf8(&encoded).unwrap()).unwrap();
+        assert_terminal_key_eq(parsed, key.code, key.modifiers, key.kind, None);
+    }
+}
+
+#[test]
+fn kitty_shifted_symbol_roundtrip_preserves_alternate_key() {
+    let key = TerminalKey::new(KeyCode::Char('1'), KeyModifiers::SHIFT)
+        .with_shifted_codepoint('!' as u32);
+    let encoded = encode_terminal_key(key, KeyboardProtocol::Kitty { flags: 7 });
+    let parsed = parse_terminal_key_sequence(std::str::from_utf8(&encoded).unwrap()).unwrap();
+    assert_terminal_key_eq(
+        parsed,
+        KeyCode::Char('1'),
+        KeyModifiers::SHIFT,
+        crossterm::event::KeyEventKind::Press,
+        Some('!' as u32),
+    );
+}
+
+#[test]
+fn legacy_basic_special_roundtrip_matrix() {
+    let cases = [
+        KeyEvent::new(KeyCode::Enter, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Tab, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Backspace, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Esc, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Up, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Down, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Left, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Right, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Home, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::End, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::PageUp, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::PageDown, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Insert, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Delete, KeyModifiers::empty()),
+    ];
+
+    for key in cases {
+        let encoded = encode_key(key, KeyboardProtocol::Legacy);
+        let parsed = parse_terminal_key_sequence(std::str::from_utf8(&encoded).unwrap()).unwrap();
+        assert_terminal_key_eq(parsed, key.code, key.modifiers, key.kind, None);
+    }
+}
+
+#[test]
+fn kitty_functional_key_matrix_is_covered() {
+    let cases = [
+        ("\x1b[57417;1u", KeyCode::Left),
+        ("\x1b[57418;1u", KeyCode::Right),
+        ("\x1b[57419;1u", KeyCode::Up),
+        ("\x1b[57420;1u", KeyCode::Down),
+        ("\x1b[57421;1u", KeyCode::PageUp),
+        ("\x1b[57422;1u", KeyCode::PageDown),
+        ("\x1b[57423;1u", KeyCode::Home),
+        ("\x1b[57424;1u", KeyCode::End),
+        ("\x1b[57425;1u", KeyCode::Insert),
+        ("\x1b[57426;1u", KeyCode::Delete),
+    ];
+
+    for (sequence, code) in cases {
+        let parsed = parse_terminal_key_sequence(sequence).unwrap();
+        assert_terminal_key_eq(
+            parsed,
+            code,
+            KeyModifiers::empty(),
+            crossterm::event::KeyEventKind::Press,
+            None,
+        );
+    }
+}
+
+#[test]
+fn kitty_shifted_symbol_pair_matrix_is_covered() {
+    let cases = [('1', '!'), ('/', '?'), ('[', '{')];
+
+    for (base, shifted) in cases {
+        let key = TerminalKey::new(KeyCode::Char(base), KeyModifiers::SHIFT)
+            .with_shifted_codepoint(shifted as u32);
+        let encoded = encode_terminal_key(key, KeyboardProtocol::Kitty { flags: 7 });
+        let parsed = parse_terminal_key_sequence(std::str::from_utf8(&encoded).unwrap()).unwrap();
+        assert_terminal_key_eq(
+            parsed,
+            KeyCode::Char(base),
+            KeyModifiers::SHIFT,
+            crossterm::event::KeyEventKind::Press,
+            Some(shifted as u32),
+        );
+    }
+}
+
+fn assert_fixture_corpus_parses(corpus: &str) {
+    for line in corpus.lines() {
+        let line = line.trim();
+        if line.is_empty() || line.starts_with('#') {
+            continue;
+        }
+
+        let mut columns: Vec<_> = line.split('\t').collect();
+        if columns.len() == 5 {
+            columns.push("");
+        }
+
+        let (family, bytes_hex, code, modifiers, kind, shifted) = match columns.len() {
+            6 => {
+                if columns[1].chars().all(|ch| ch.is_ascii_hexdigit()) {
+                    (
+                        columns[0], columns[1], columns[2], columns[3], columns[4], columns[5],
+                    )
+                } else {
+                    (
+                        columns[0], columns[2], columns[3], columns[4], columns[5], "",
+                    )
+                }
+            }
+            7 => (
+                columns[0], columns[2], columns[3], columns[4], columns[5], columns[6],
+            ),
+            _ => panic!("fixture row must have 6 or 7 columns: {line}"),
+        };
+
+        assert!(
+            bytes_hex.chars().all(|ch| ch.is_ascii_hexdigit()),
+            "non-hex fixture bytes for {family}: {bytes_hex}"
+        );
+        let bytes = decode_hex(bytes_hex);
+        let text = std::str::from_utf8(&bytes).unwrap();
+        let parsed = parse_terminal_key_sequence(text)
+            .unwrap_or_else(|| panic!("fixture failed to parse: {family}"));
+
+        assert_terminal_key_eq(
+            parsed,
+            parse_fixture_key_code(code),
+            parse_fixture_modifiers(modifiers),
+            parse_fixture_kind(kind),
+            if shifted.is_empty() {
+                None
+            } else {
+                Some(shifted.parse::<u32>().unwrap())
+            },
+        );
+    }
+}
+
+#[test]
+fn keyboard_protocol_corpus_fixture_parses() {
+    let corpus = include_str!("../../tests/fixtures/keyboard_protocol_corpus.tsv");
+    assert_fixture_corpus_parses(corpus);
+}
+
+#[test]
+fn macos_terminal_variants_fixture_parses() {
+    let corpus = include_str!("../../tests/fixtures/macos_terminal_variants.tsv");
+    for line in corpus.lines() {
+        let line = line.trim();
+        if line.is_empty() || line.starts_with('#') {
+            continue;
+        }
+
+        let mut columns: Vec<_> = line.split('\t').collect();
+        if columns.len() == 6 {
+            columns.push("");
+        }
+        assert_eq!(
+            columns.len(),
+            7,
+            "macOS fixture row must have 7 columns: {line}"
+        );
+
+        let source = format!("{}:{}", columns[0], columns[1]);
+        let transformed = [
+            source.as_str(),
+            columns[2],
+            columns[3],
+            columns[4],
+            columns[5],
+            columns[6],
+        ]
+        .join("\t");
+        assert_fixture_corpus_parses(&transformed);
+    }
+}
+
+#[test]
+fn linux_terminal_variants_fixture_parses() {
+    let corpus = include_str!("../../tests/fixtures/linux_terminal_variants.tsv");
+    assert_fixture_corpus_parses(corpus);
+}
+
+#[test]
+fn protocol_from_zero_flags_is_legacy() {
+    assert_eq!(
+        KeyboardProtocol::from_kitty_flags(0),
+        KeyboardProtocol::Legacy
+    );
+}
+
+#[test]
+fn protocol_from_nonzero_flags_is_kitty() {
+    assert_eq!(
+        KeyboardProtocol::from_kitty_flags(7),
+        KeyboardProtocol::Kitty { flags: 7 }
+    );
+}