From a3e84c5c15ac9fa6595d63c36d6ec5daed2648a5 Mon Sep 17 00:00:00 2001
From: Brad Stein <Brad.Stein@gmail.com>
Date: Thu, 16 Apr 2026 15:32:15 -0300
Subject: [PATCH] lesavka: preserve quick modifier chords

---
 client/src/input/inputs.rs                    | 37 +++++++++++-----
 testing/tests/client_inputs_extra_contract.rs | 42 +++++++++++++++++++
 2 files changed, 68 insertions(+), 11 deletions(-)

diff --git a/client/src/input/inputs.rs b/client/src/input/inputs.rs
index 773ddac..c8a90dd 100644
--- a/client/src/input/inputs.rs
+++ b/client/src/input/inputs.rs
@@ -473,15 +473,32 @@ impl InputAggregator {
 
     fn process_keyboard_updates(&mut self) {
         for index in 0..self.keyboards.len() {
+            let mut keyboard_shadow: HashSet<KeyCode> = self.keyboards[index]
+                .pressed_keys_snapshot()
+                .into_iter()
+                .collect();
+            let other_pressed: HashSet<KeyCode> = self
+                .keyboards
+                .iter()
+                .enumerate()
+                .filter(|(other_index, _)| *other_index != index)
+                .flat_map(|(_, keyboard)| keyboard.pressed_keys_snapshot())
+                .collect();
             let updates = {
                 let keyboard = &mut self.keyboards[index];
                 keyboard.drain_key_updates()
             };
             for update in updates {
+                update_shadow_pressed_keys(&mut keyboard_shadow, update.code, update.value);
                 if update.swallowed || !self.keyboard_capture_enabled() {
                     continue;
                 }
-                let report = self.build_combined_keyboard_report();
+                let report = build_keyboard_report(
+                    other_pressed
+                        .iter()
+                        .copied()
+                        .chain(keyboard_shadow.iter().copied()),
+                );
                 if report == self.last_keyboard_report {
                     continue;
                 }
@@ -497,16 +514,6 @@ impl InputAggregator {
             .any(KeyboardAggregator::sending_enabled)
     }
 
-    fn build_combined_keyboard_report(&self) -> [u8; 8] {
-        let mut pressed = HashSet::new();
-        for keyboard in &self.keyboards {
-            for key in keyboard.pressed_keys_snapshot() {
-                pressed.insert(key);
-            }
-        }
-        build_keyboard_report(pressed.into_iter())
-    }
-
     fn quick_toggle_active(&mut self) -> bool {
         self.quick_toggle_key.is_some_and(|key| {
             self.keyboards
@@ -696,6 +703,14 @@ fn should_ignore_keyboard_device(dev: &Device) -> bool {
         || name.contains("codex-persistent-kbd")
 }
 
+fn update_shadow_pressed_keys(pressed_keys: &mut HashSet<KeyCode>, code: KeyCode, value: i32) {
+    if value == 0 {
+        pressed_keys.remove(&code);
+    } else if value > 0 {
+        pressed_keys.insert(code);
+    }
+}
+
 /// Resolves the quick-toggle key from env, defaulting to Pause/Break.
 fn quick_toggle_key_from_env() -> Option<KeyCode> {
     match std::env::var("LESAVKA_INPUT_TOGGLE_KEY") {
diff --git a/testing/tests/client_inputs_extra_contract.rs b/testing/tests/client_inputs_extra_contract.rs
index 0a81368..722a232 100644
--- a/testing/tests/client_inputs_extra_contract.rs
+++ b/testing/tests/client_inputs_extra_contract.rs
@@ -153,6 +153,48 @@ mod inputs_contract_extra {
         );
     }
 
+    #[test]
+    #[serial]
+    fn process_keyboard_updates_keeps_quick_shift_chord_when_full_tap_lands_in_one_poll_cycle() {
+        let Some((mut vdev, dev)) = build_keyboard_pair_with_keys(
+            "lesavka-input-shift-batch",
+            &[evdev::KeyCode::KEY_LEFTSHIFT, evdev::KeyCode::KEY_A],
+        ) else {
+            return;
+        };
+
+        let (kbd_tx, mut rx) = tokio::sync::broadcast::channel(32);
+        let (mou_tx, _) = tokio::sync::broadcast::channel(16);
+        let keyboard = KeyboardAggregator::new(dev, false, kbd_tx.clone(), None);
+
+        let mut agg = InputAggregator::new(false, kbd_tx, mou_tx, None);
+        agg.keyboards.push(keyboard);
+
+        vdev.emit(&[
+            evdev::InputEvent::new(evdev::EventType::KEY.0, evdev::KeyCode::KEY_LEFTSHIFT.0, 1),
+            evdev::InputEvent::new(evdev::EventType::KEY.0, evdev::KeyCode::KEY_A.0, 1),
+            evdev::InputEvent::new(evdev::EventType::KEY.0, evdev::KeyCode::KEY_A.0, 0),
+            evdev::InputEvent::new(evdev::EventType::KEY.0, evdev::KeyCode::KEY_LEFTSHIFT.0, 0),
+        ])
+        .expect("emit quick shifted tap");
+        thread::sleep(std::time::Duration::from_millis(25));
+
+        temp_env::with_var("LESAVKA_LIVE_MODIFIER_DELAY_MS", Some("0"), || {
+            agg.process_keyboard_updates();
+        });
+
+        let reports: Vec<Vec<u8>> =
+            std::iter::from_fn(|| rx.try_recv().ok().map(|pkt| pkt.data)).collect();
+        assert!(
+            reports.contains(&vec![0x02, 0, 0x04, 0, 0, 0, 0, 0]),
+            "expected shifted A report from one-batch chord, got {reports:?}"
+        );
+        assert!(
+            reports.contains(&vec![0; 8]),
+            "expected final empty report after one-batch chord, got {reports:?}"
+        );
+    }
+
     #[test]
     #[serial]
     fn process_keyboard_updates_keeps_overlapping_plain_keys_from_sticking_across_keyboards() {