feat: add tap-hold-release-order action

cfg_samples/kanata.kbd

@@ -570,6 +570,10 @@ If you need help, please feel welcome to ask in the GitHub discussions.
   ;; This is useful for home row mods where fast typing should not trigger modifiers.
   utk (tap-hold-tap-keys 200 200 u @msc (a o e))
 
+  ;; tap-hold-order resolves by release order instead of timeout.
+  ;; tap: a    hold: lctl    buffer: 50ms (fast typing grace period)
+  aor (tap-hold-order 200 50 a lctl)
+
   ;; tap for capslk, hold for lctl
   cap (tap-hold 200 200 caps lctl)
 

docs/config.adoc

@@ -2018,6 +2018,7 @@ results in `$tap-action` activating.
 (tap-hold-except-keys $tap-repress-timeout $hold-timeout $tap-action $hold-action $tap-keys)
 (tap-hold-tap-keys $tap-repress-timeout $hold-timeout $tap-action $hold-action $tap-keys)
 (tap-hold-opposite-hand $timeout $tap-action $hold-action [options...])
+(tap-hold-order $tap-repress-timeout $buffer-ms $tap-action $hold-action [options...])
 ----
 
 [cols="1,2"]
@@ -2073,6 +2074,18 @@ This is useful for home row mods where fast typing should not trigger modifiers.
 | Resolves to `$hold-action` when a key from the opposite hand (per `defhands`) is pressed.
 Requires a `defhands` directive. Supports list-form options for fine-grained control.
 See <<defhands and tap-hold-opposite-hand>> below.
+
+| `tap-hold-order`
+| Resolves purely by key release order, with no timeout.
+If the tap-hold key is released before the other key, activates `$tap-action`;
+if the other key is released first (while the tap-hold key is still held), activates `$hold-action`.
+`$buffer-ms` is a grace period after the tap-hold key is pressed during which
+release-order logic is ignored so that fast typing resolves as tap.
+Optionally, `(require-prior-idle <ms>)` can short-circuit to tap when a different key
+was pressed within that many milliseconds before the tap-hold key;
+`require-prior-idle` checks prior typing activity before release-order logic begins,
+whereas `buffer-ms` creates an unconditional tap-only window after the key is pressed.
+This option is available on all tap-hold variants; see <<tap-hold-require-prior-idle>>.
 |===
 
 All `tap-hold` variants support an optional trailing `(require-prior-idle <ms>)` option

keyberon/src/action.rs

@@ -61,6 +61,13 @@ pub enum HoldTapConfig<'a> {
     /// not used in the flow of typing, like escape for example. If
     /// you are annoyed by accidental tap, you can try this behavior.
     HoldOnOtherKeyPress,
+    /// Resolves based on release order after both keys are down.
+    /// If the other key releases first (modifier still held) → Hold.
+    /// If the modifier releases first (other key still held) → Tap.
+    /// The buffer field specifies a grace period in ticks (ms) after the
+    /// initial press during which release-order logic is ignored and fast
+    /// typing will resolve as Tap.
+    Order { buffer: u16 },
     /// If there is a press and release of another key, the hold
     /// action is activated.
     ///
@@ -100,6 +107,7 @@ impl Debug for HoldTapConfig<'_> {
         match self {
             HoldTapConfig::Default => f.write_str("Default"),
             HoldTapConfig::HoldOnOtherKeyPress => f.write_str("HoldOnOtherKeyPress"),
+            HoldTapConfig::Order { .. } => f.write_str("Order"),
             HoldTapConfig::PermissiveHold => f.write_str("PermissiveHold"),
             HoldTapConfig::Custom(_) => f.write_str("Custom"),
         }
@@ -113,6 +121,7 @@ impl PartialEq for HoldTapConfig<'_> {
             (HoldTapConfig::Default, HoldTapConfig::Default)
             | (HoldTapConfig::HoldOnOtherKeyPress, HoldTapConfig::HoldOnOtherKeyPress)
             | (HoldTapConfig::PermissiveHold, HoldTapConfig::PermissiveHold) => true,
+            (HoldTapConfig::Order { .. }, HoldTapConfig::Order { .. }) => true,
             _ => false,
         }
     }

keyberon/src/layout.rs

@@ -544,6 +544,30 @@ impl<'a, T: std::fmt::Debug> WaitingState<'a, T> {
                     return Some(WaitingAction::Hold);
                 }
             }
+            HoldTapConfig::Order { buffer, .. } => {
+                // Like PermissiveHold: if another key was pressed AND released
+                // (while modifier is still held), resolve as Hold.
+                // If modifier is released first, the fallthrough below handles Tap.
+                //
+                // Buffer: key presses that occurred within `buffer` ticks of the
+                // hold-tap key press are ignored by release-order logic, allowing
+                // fast typing to resolve as Tap regardless of release order.
+                let mut queued = queued.iter();
+                while let Some(q) = queued.next() {
+                    if q.event.is_press() {
+                        // Elapsed ticks since this key entered the queue, compared against buffer window.
+                        let press_tick = self.ticks.saturating_sub(q.since);
+                        if press_tick < buffer {
+                            continue;
+                        }
+                        let (i, j) = q.event.coord();
+                        let target = Event::Release(i, j);
+                        if queued.clone().any(|q| q.event == target) {
+                            return Some(WaitingAction::Hold);
+                        }
+                    }
+                }
+            }
             HoldTapConfig::PermissiveHold => {
                 let mut queued = queued.iter();
                 while let Some(q) = queued.next() {
@@ -2518,6 +2542,161 @@ mod test {
         assert_keys(&[], layout.keycodes());
     }
 
+    #[test]
+    fn order_clean_tap() {
+        // Press and release modifier with no other keys → Tap.
+        static LAYERS: Layers<2, 1> = &[[[
+            HoldTap(&HoldTapAction {
+                on_press_reset_timeout_to: None,
+                timeout: u16::MAX,
+                hold: k(LAlt),
+                timeout_action: k(Space),
+                tap: k(Space),
+                config: HoldTapConfig::Order { buffer: 0 },
+                tap_hold_interval: 0,
+                require_prior_idle: None,
+            }),
+            k(Enter),
+        ]]];
+        let mut layout = Layout::new(LAYERS);
+
+        layout.event(Press(0, 0));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+        for _ in 0..50 {
+            assert_eq!(CustomEvent::NoEvent, layout.tick());
+            assert_keys(&[], layout.keycodes());
+        }
+        layout.event(Release(0, 0));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[Space], layout.keycodes());
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+    }
+
+    #[test]
+    fn order_hold() {
+        // Modifier down → other down → other up first → Hold.
+        static LAYERS: Layers<2, 1> = &[[[
+            HoldTap(&HoldTapAction {
+                on_press_reset_timeout_to: None,
+                timeout: u16::MAX,
+                hold: k(LAlt),
+                timeout_action: k(Space),
+                tap: k(Space),
+                config: HoldTapConfig::Order { buffer: 0 },
+                tap_hold_interval: 0,
+                require_prior_idle: None,
+            }),
+            k(Enter),
+        ]]];
+        let mut layout = Layout::new(LAYERS);
+
+        layout.event(Press(0, 0));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+        layout.event(Press(0, 1));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+        // Other key releases first → Hold
+        layout.event(Release(0, 1));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[LAlt], layout.keycodes());
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[LAlt, Enter], layout.keycodes());
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[LAlt], layout.keycodes());
+        // Release modifier
+        layout.event(Release(0, 0));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+    }
+
+    #[test]
+    fn order_tap() {
+        // Modifier down → other down → modifier up first → Tap.
+        static LAYERS: Layers<2, 1> = &[[[
+            HoldTap(&HoldTapAction {
+                on_press_reset_timeout_to: None,
+                timeout: u16::MAX,
+                hold: k(LAlt),
+                timeout_action: k(Space),
+                tap: k(Space),
+                config: HoldTapConfig::Order { buffer: 0 },
+                tap_hold_interval: 0,
+                require_prior_idle: None,
+            }),
+            k(Enter),
+        ]]];
+        let mut layout = Layout::new(LAYERS);
+
+        layout.event(Press(0, 0));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+        layout.event(Press(0, 1));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+        // Modifier releases first → Tap
+        layout.event(Release(0, 0));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[Space], layout.keycodes());
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[Space, Enter], layout.keycodes());
+    }
+
+    #[test]
+    fn order_multi_key_hold() {
+        // TH down → A down → B down → A up (while B still held) → TH up.
+        // A's press+release cycle completes while TH is held → Hold.
+        static LAYERS: Layers<3, 1> = &[[[
+            HoldTap(&HoldTapAction {
+                on_press_reset_timeout_to: None,
+                timeout: u16::MAX,
+                hold: k(LAlt),
+                timeout_action: k(Space),
+                tap: k(Space),
+                config: HoldTapConfig::Order { buffer: 0 },
+                tap_hold_interval: 0,
+                require_prior_idle: None,
+            }),
+            k(Enter),
+            k(Tab),
+        ]]];
+        let mut layout = Layout::new(LAYERS);
+
+        // TH down
+        layout.event(Press(0, 0));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+        // A down
+        layout.event(Press(0, 1));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+        // B down
+        layout.event(Press(0, 2));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+        // A up — A's press+release cycle is complete → Hold resolves
+        layout.event(Release(0, 1));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[LAlt], layout.keycodes());
+        // Queued keys replay: Enter press, Tab press, Enter release
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[LAlt, Enter], layout.keycodes());
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[LAlt, Enter, Tab], layout.keycodes());
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[LAlt, Tab], layout.keycodes());
+        // Release B
+        layout.event(Release(0, 2));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[LAlt], layout.keycodes());
+        // Release TH
+        layout.event(Release(0, 0));
+        assert_eq!(CustomEvent::NoEvent, layout.tick());
+        assert_keys(&[], layout.keycodes());
+    }
+
     #[test]
     fn permissive_hold() {
         static LAYERS: Layers<2, 1> = &[[[

parser/src/cfg/list_actions.rs

@@ -136,6 +136,7 @@ pub const CLIPBOARD_RESTORE: &str = "clipboard-restore";
 pub const CLIPBOARD_SAVE_SET: &str = "clipboard-save-set";
 pub const CLIPBOARD_SAVE_CMD_SET: &str = "clipboard-save-cmd-set";
 pub const CLIPBOARD_SAVE_SWAP: &str = "clipboard-save-swap";
+pub const TAP_HOLD_ORDER: &str = "tap-hold-order";
 pub const TAP_HOLD_OPPOSITE_HAND: &str = "tap-hold-opposite-hand";
 
 pub fn is_list_action(ac: &str) -> bool {
@@ -272,6 +273,7 @@ pub fn is_list_action(ac: &str) -> bool {
         CLIPBOARD_SAVE_SET,
         CLIPBOARD_SAVE_CMD_SET,
         CLIPBOARD_SAVE_SWAP,
+        TAP_HOLD_ORDER,
         TAP_HOLD_OPPOSITE_HAND,
     ];
     LIST_ACTIONS.contains(&ac)

parser/src/cfg/mod.rs

@@ -1508,6 +1508,7 @@ fn parse_action_list(ac: &[SExpr], s: &ParserState) -> Result<&'static KanataAct
         TAP_HOLD_PRESS | TAP_HOLD_PRESS_A => {
             parse_tap_hold(&ac[1..], s, HoldTapConfig::HoldOnOtherKeyPress)
         }
+        TAP_HOLD_ORDER => parse_tap_hold_order(&ac[1..], s),
         TAP_HOLD_RELEASE | TAP_HOLD_RELEASE_A => {
             parse_tap_hold(&ac[1..], s, HoldTapConfig::PermissiveHold)
         }

parser/src/cfg/tap_hold.rs

@@ -188,6 +188,40 @@ pub(crate) fn parse_tap_hold_timeout(
     }))))
 }
 
+pub(crate) fn parse_tap_hold_order(
+    ac_params: &[SExpr],
+    s: &ParserState,
+) -> Result<&'static KanataAction> {
+    let n_opts = count_trailing_options(ac_params, s);
+    let n_positional = ac_params.len() - n_opts;
+    if n_positional != 4 {
+        bail!(
+            r"tap-hold-order expects 4 items after it, got {}.
+Params in order:
+<tap-repress-timeout> <buffer-ms> <tap-action> <hold-action>",
+            n_positional,
+        )
+    }
+    let tap_repress_timeout = parse_u16(&ac_params[0], s, "tap repress timeout")?;
+    let buffer = parse_u16(&ac_params[1], s, "buffer")?;
+    let tap_action = parse_action(&ac_params[2], s)?;
+    let hold_action = parse_action(&ac_params[3], s)?;
+    if matches!(tap_action, Action::HoldTap { .. }) {
+        bail!("tap-hold does not work in the tap-action of tap-hold")
+    }
+    let opts = parse_tap_hold_options(&ac_params[n_positional..], s)?;
+    Ok(s.a.sref(Action::HoldTap(s.a.sref(HoldTapAction {
+        config: HoldTapConfig::Order { buffer },
+        tap_hold_interval: tap_repress_timeout,
+        timeout: u16::MAX, // Resolution is purely event-driven, not timeout-based.
+        tap: *tap_action,
+        hold: *hold_action,
+        timeout_action: *tap_action,
+        on_press_reset_timeout_to: None,
+        require_prior_idle: opts.require_prior_idle,
+    }))))
+}
+
 pub(crate) fn parse_tap_hold_keys(
     ac_params: &[SExpr],
     s: &ParserState,