Cleanup combo timer only when affected keys are released.

app/src/combo.c

@@ -453,19 +453,55 @@ static int position_state_down(const zmk_event_t *ev, struct zmk_position_state_
     }
 }
 
+static bool is_key_part_of_candidate(int32_t position) {
+    for (int i = 0; i < CONFIG_ZMK_COMBO_MAX_COMBOS_PER_KEY; i++) {
+        struct combo_candidate *candidate = &candidates[i];
+        if (candidate->combo == NULL) {
+            continue;
+        }
+
+        for (int j = 0; j < candidate->combo->key_position_len; j++) {
+            if (candidate->combo->key_positions[j] == position) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+static bool is_key_part_of_active_combo(int32_t position) {
+    for (int i = 0; i < active_combo_count; i++) {
+        struct active_combo *active_combo = &active_combos[i];
+        for (int j = 0; j < active_combo->key_positions_pressed_count; j++) {
+            if (active_combo->key_positions_pressed[j].data.position == position) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+static bool is_key_part_of_any_combo(int32_t position) {
+    return is_key_part_of_candidate(position) || is_key_part_of_active_combo(position);
+}
+
 static int position_state_up(const zmk_event_t *ev, struct zmk_position_state_changed *data) {
-    int released_keys = cleanup();
-    if (release_combo_key(data->position, data->timestamp)) {
-        return ZMK_EV_EVENT_HANDLED;
-    }
-    if (released_keys > 1) {
-        // The second and further key down events are re-raised. To preserve
-        // correct order for e.g. hold-taps, reraise the key up event too.
-        struct zmk_position_state_changed_event dupe_ev =
-            copy_raised_zmk_position_state_changed(data);
-        ZMK_EVENT_RAISE(dupe_ev);
-        return ZMK_EV_EVENT_CAPTURED;
+    // Check if the released key is part of any combo candidate or active combo
+    if (is_key_part_of_any_combo(data->position)) {
+        int released_keys = cleanup();
+        if (release_combo_key(data->position, data->timestamp)) {
+            return ZMK_EV_EVENT_HANDLED;
+        }
+        if (released_keys > 1) {
+            // The second and further key down events are re-raised. To preserve
+            // correct order for e.g. hold-taps, reraise the key up event too.
+            struct zmk_position_state_changed_event dupe_ev =
+                copy_raised_zmk_position_state_changed(data);
+            ZMK_EVENT_RAISE(dupe_ev);
+            return ZMK_EV_EVENT_CAPTURED;
+        }
     }
+
     return ZMK_EV_EVENT_BUBBLE;
 }
 

app/tests/combo/other-key-release/native_posix_64.keymap

@@ -11,13 +11,20 @@
             key-positions = <0 1>;
             bindings = <&kp D>;
         };
+
+        // not actuated combo to test behavior
+        combo_g {
+            timeout-ms = <50>;
+            key-positions = <2 3>;
+            bindings = <&kp G>;
+        };
     };
 
     keymap {
         compatible = "zmk,keymap";
 
         default_layer {
-            bindings = <&kp A &kp B &kp C>;
+            bindings = <&kp A &kp B &kp C &kp D>;
         };
     };
 };