feature(split): behavior locality support.

* GATT characteristic allowing passng data + behavior
  label to invoke the behavior on the peripheral side.
* Behaviors have a locality setting to specify where they run.
* Build reset/power/RGB on peripheral.

17 files changed, 247 insertions, 20 deletions

diff --git a/app/CMakeLists.txt b/app/CMakeLists.txt
index c5b74aa..1e153fb 100644
--- a/app/CMakeLists.txt
+++ b/app/CMakeLists.txt
@@ -42,9 +42,10 @@ target_sources_ifdef(CONFIG_ZMK_WPM app PRIVATE src/events/wpm_state_changed.c)
 target_sources_ifdef(CONFIG_ZMK_BLE app PRIVATE src/events/ble_active_profile_changed.c)
 target_sources_ifdef(CONFIG_ZMK_BLE app PRIVATE src/events/battery_state_changed.c)
 target_sources_ifdef(CONFIG_USB app PRIVATE src/events/usb_conn_state_changed.c)
+target_sources(app PRIVATE src/behaviors/behavior_reset.c)
+target_sources_ifdef(CONFIG_ZMK_EXT_POWER app PRIVATE src/behaviors/behavior_ext_power.c)
 if ((NOT CONFIG_ZMK_SPLIT) OR CONFIG_ZMK_SPLIT_BLE_ROLE_CENTRAL)
   target_sources(app PRIVATE src/behaviors/behavior_key_press.c)
-  target_sources(app PRIVATE src/behaviors/behavior_reset.c)
   target_sources(app PRIVATE src/behaviors/behavior_hold_tap.c)
   target_sources(app PRIVATE src/behaviors/behavior_sticky_key.c)
   target_sources(app PRIVATE src/behaviors/behavior_caps_word.c)
@@ -57,7 +58,6 @@ if ((NOT CONFIG_ZMK_SPLIT) OR CONFIG_ZMK_SPLIT_BLE_ROLE_CENTRAL)
   target_sources(app PRIVATE src/behaviors/behavior_transparent.c)
   target_sources(app PRIVATE src/behaviors/behavior_none.c)
   target_sources(app PRIVATE src/behaviors/behavior_sensor_rotate_key_press.c)
-  target_sources_ifdef(CONFIG_ZMK_EXT_POWER app PRIVATE src/behaviors/behavior_ext_power.c)
   target_sources(app PRIVATE src/combo.c)
   target_sources(app PRIVATE src/conditional_layer.c)
   target_sources(app PRIVATE src/keymap.c)
diff --git a/app/dts/behaviors/ext_power.dtsi b/app/dts/behaviors/ext_power.dtsi
index 742e33a..abb7f2f 100644
--- a/app/dts/behaviors/ext_power.dtsi
+++ b/app/dts/behaviors/ext_power.dtsi
@@ -8,7 +8,7 @@
 	behaviors {
 		/omit-if-no-ref/ ext_power: behavior_ext_power {
 			compatible = "zmk,behavior-ext-power";
-			label = "EXT_POWER_BEHAVIOR";
+			label = "EXTPOWER";
 			#binding-cells = <1>;
 		};
 	};
diff --git a/app/dts/behaviors/reset.dtsi b/app/dts/behaviors/reset.dtsi
index c720bc8..e4ba565 100644
--- a/app/dts/behaviors/reset.dtsi
+++ b/app/dts/behaviors/reset.dtsi
@@ -16,7 +16,7 @@
 
 		/omit-if-no-ref/ bootloader: behavior_reset_dfu {
 			compatible = "zmk,behavior-reset";
-			label = "BOOTLOADER_RESET";
+			label = "BOOTLOAD";
 			type = <RST_UF2>;
 			#binding-cells = <0>;
 		};
diff --git a/app/dts/behaviors/rgb_underglow.dtsi b/app/dts/behaviors/rgb_underglow.dtsi
index 60bdb3a..265a1a5 100644
--- a/app/dts/behaviors/rgb_underglow.dtsi
+++ b/app/dts/behaviors/rgb_underglow.dtsi
@@ -8,7 +8,7 @@
 	behaviors {
 		/omit-if-no-ref/ rgb_ug: behavior_rgb_underglow {
 			compatible = "zmk,behavior-rgb-underglow";
-			label = "RGB_UNDERGLOW";
+			label = "RGB_UG";
 			#binding-cells = <2>;
 		};
 	};
diff --git a/app/include/drivers/behavior.h b/app/include/drivers/behavior.h
index 2bdffea..fcb24f6 100644
--- a/app/include/drivers/behavior.h
+++ b/app/include/drivers/behavior.h
@@ -8,6 +8,8 @@
 
 #include <zephyr/types.h>
 #include <stddef.h>
+#include <sys/util.h>
+#include <string.h>
 #include <device.h>
 #include <zmk/keys.h>
 #include <zmk/behavior.h>
@@ -26,7 +28,14 @@ typedef int (*behavior_sensor_keymap_binding_callback_t)(struct zmk_behavior_bin
                                                          const struct device *sensor,
                                                          int64_t timestamp);
 
+enum behavior_locality {
+    BEHAVIOR_LOCALITY_CENTRAL,
+    BEHAVIOR_LOCALITY_EVENT_SOURCE,
+    BEHAVIOR_LOCALITY_GLOBAL
+};
+
 __subsystem struct behavior_driver_api {
+    enum behavior_locality locality;
     behavior_keymap_binding_callback_t binding_convert_central_state_dependent_params;
     behavior_keymap_binding_callback_t binding_pressed;
     behavior_keymap_binding_callback_t binding_released;
@@ -61,6 +70,28 @@ static inline int z_impl_behavior_keymap_binding_convert_central_state_dependent
 }
 
 /**
+ * @brief Determine where the behavior should be run
+ * @param behavior Pointer to the device structure for the driver instance.
+ *
+ * @retval Zero if successful.
+ * @retval Negative errno code if failure.
+ */
+__syscall int behavior_get_locality(const struct device *behavior,
+                                    enum behavior_locality *locality);
+
+static inline int z_impl_behavior_get_locality(const struct device *behavior,
+                                               enum behavior_locality *locality) {
+    if (behavior == NULL) {
+        return -EINVAL;
+    }
+
+    const struct behavior_driver_api *api = (const struct behavior_driver_api *)behavior->api;
+    *locality = api->locality;
+
+    return 0;
+}
+
+/**
  * @brief Handle the keymap binding being pressed
  * @param dev Pointer to the device structure for the driver instance.
  * @param param1 User parameter specified at time of behavior binding.
@@ -75,6 +106,11 @@ __syscall int behavior_keymap_binding_pressed(struct zmk_behavior_binding *bindi
 static inline int z_impl_behavior_keymap_binding_pressed(struct zmk_behavior_binding *binding,
                                                          struct zmk_behavior_binding_event event) {
     const struct device *dev = device_get_binding(binding->behavior_dev);
+
+    if (dev == NULL) {
+        return -EINVAL;
+    }
+
     const struct behavior_driver_api *api = (const struct behavior_driver_api *)dev->api;
 
     if (api->binding_pressed == NULL) {
@@ -98,6 +134,11 @@ __syscall int behavior_keymap_binding_released(struct zmk_behavior_binding *bind
 static inline int z_impl_behavior_keymap_binding_released(struct zmk_behavior_binding *binding,
                                                           struct zmk_behavior_binding_event event) {
     const struct device *dev = device_get_binding(binding->behavior_dev);
+
+    if (dev == NULL) {
+        return -EINVAL;
+    }
+
     const struct behavior_driver_api *api = (const struct behavior_driver_api *)dev->api;
 
     if (api->binding_released == NULL) {
@@ -125,6 +166,11 @@ static inline int
 z_impl_behavior_sensor_keymap_binding_triggered(struct zmk_behavior_binding *binding,
                                                 const struct device *sensor, int64_t timestamp) {
     const struct device *dev = device_get_binding(binding->behavior_dev);
+
+    if (dev == NULL) {
+        return -EINVAL;
+    }
+
     const struct behavior_driver_api *api = (const struct behavior_driver_api *)dev->api;
 
     if (api->sensor_binding_triggered == NULL) {
diff --git a/app/include/zmk/events/position_state_changed.h b/app/include/zmk/events/position_state_changed.h
index e2f6872..59619db 100644
--- a/app/include/zmk/events/position_state_changed.h
+++ b/app/include/zmk/events/position_state_changed.h
@@ -8,10 +8,19 @@
 
 #include <zephyr.h>
 #include <zmk/event_manager.h>
+#include <bluetooth/addr.h>
+
+#if IS_ENABLED(CONFIG_ZMK_BLE)
+typedef const bt_addr_le_t *zmk_position_state_changed_source_t;
+#else
+typedef void *zmk_position_state_changed_source_t;
+#endif
+
 struct zmk_position_state_changed {
+    zmk_position_state_changed_source_t source;
     uint32_t position;
     bool state;
     int64_t timestamp;
 };
 
-ZMK_EVENT_DECLARE(zmk_position_state_changed);
\ No newline at end of file
+ZMK_EVENT_DECLARE(zmk_position_state_changed);
diff --git a/app/include/zmk/keymap.h b/app/include/zmk/keymap.h
index 7151930..0771542 100644
--- a/app/include/zmk/keymap.h
+++ b/app/include/zmk/keymap.h
@@ -6,6 +6,8 @@
 
 #pragma once
 
+#include <zmk/events/position_state_changed.h>
+
 typedef uint32_t zmk_keymap_layers_state_t;
 
 uint8_t zmk_keymap_layer_default();
@@ -18,7 +20,8 @@ int zmk_keymap_layer_toggle(uint8_t layer);
 int zmk_keymap_layer_to(uint8_t layer);
 const char *zmk_keymap_layer_label(uint8_t layer);
 
-int zmk_keymap_position_state_changed(uint32_t position, bool pressed, int64_t timestamp);
+int zmk_keymap_position_state_changed(zmk_position_state_changed_source_t source, uint32_t position,
+                                      bool pressed, int64_t timestamp);
 
 #define ZMK_KEYMAP_EXTRACT_BINDING(idx, drv_inst)                                                  \
     {                                                                                              \
diff --git a/app/include/zmk/split/bluetooth/central.h b/app/include/zmk/split/bluetooth/central.h
new file mode 100644
index 0000000..ab46a8f
--- /dev/null
+++ b/app/include/zmk/split/bluetooth/central.h
@@ -0,0 +1,8 @@
+
+#pragma once
+
+#include <bluetooth/addr.h>
+#include <zmk/behavior.h>
+
+int zmk_split_bt_invoke_behavior(const bt_addr_le_t *source, struct zmk_behavior_binding *binding,
+                                 struct zmk_behavior_binding_event event, bool state);
\ No newline at end of file
diff --git a/app/include/zmk/split/bluetooth/service.h b/app/include/zmk/split/bluetooth/service.h
index b9f9fc3..f0c1d79 100644
--- a/app/include/zmk/split/bluetooth/service.h
+++ b/app/include/zmk/split/bluetooth/service.h
@@ -6,5 +6,19 @@
 
 #pragma once
 
+#define ZMK_SPLIT_RUN_BEHAVIOR_DEV_LEN 9
+
+struct zmk_split_run_behavior_data {
+    uint8_t position;
+    uint8_t state;
+    uint32_t param1;
+    uint32_t param2;
+} __packed;
+
+struct zmk_split_run_behavior_payload {
+    struct zmk_split_run_behavior_data data;
+    char behavior_dev[ZMK_SPLIT_RUN_BEHAVIOR_DEV_LEN];
+} __packed;
+
 int zmk_split_bt_position_pressed(uint8_t position);
 int zmk_split_bt_position_released(uint8_t position);
\ No newline at end of file
diff --git a/app/include/zmk/split/bluetooth/uuid.h b/app/include/zmk/split/bluetooth/uuid.h
index a31884d..735f575 100644
--- a/app/include/zmk/split/bluetooth/uuid.h
+++ b/app/include/zmk/split/bluetooth/uuid.h
@@ -15,3 +15,4 @@
 #define ZMK_BT_SPLIT_UUID(num) BT_UUID_128_ENCODE(num, 0x0096, 0x7107, 0xc967, 0xc5cfb1c2482a)
 #define ZMK_SPLIT_BT_SERVICE_UUID ZMK_BT_SPLIT_UUID(0x00000000)
 #define ZMK_SPLIT_BT_CHAR_POSITION_STATE_UUID ZMK_BT_SPLIT_UUID(0x00000001)
+#define ZMK_SPLIT_BT_CHAR_RUN_BEHAVIOR_UUID ZMK_BT_SPLIT_UUID(0x00000002)
diff --git a/app/src/behaviors/behavior_ext_power.c b/app/src/behaviors/behavior_ext_power.c
index fdd890c..2779331 100644
--- a/app/src/behaviors/behavior_ext_power.c
+++ b/app/src/behaviors/behavior_ext_power.c
@@ -71,6 +71,7 @@ static const struct behavior_driver_api behavior_ext_power_driver_api = {
         on_keymap_binding_convert_central_state_dependent_params,
     .binding_pressed = on_keymap_binding_pressed,
     .binding_released = on_keymap_binding_released,
+    .locality = BEHAVIOR_LOCALITY_GLOBAL,
 };
 
 DEVICE_DT_INST_DEFINE(0, behavior_ext_power_init, device_pm_control_nop, NULL, NULL, APPLICATION,
diff --git a/app/src/behaviors/behavior_reset.c b/app/src/behaviors/behavior_reset.c
index e19cf32..eb0477d 100644
--- a/app/src/behaviors/behavior_reset.c
+++ b/app/src/behaviors/behavior_reset.c
@@ -36,6 +36,7 @@ static int on_keymap_binding_pressed(struct zmk_behavior_binding *binding,
 
 static const struct behavior_driver_api behavior_reset_driver_api = {
     .binding_pressed = on_keymap_binding_pressed,
+    .locality = BEHAVIOR_LOCALITY_EVENT_SOURCE,
 };
 
 #define RST_INST(n)                                                                                \
diff --git a/app/src/behaviors/behavior_rgb_underglow.c b/app/src/behaviors/behavior_rgb_underglow.c
index 0243b54..33af655 100644
--- a/app/src/behaviors/behavior_rgb_underglow.c
+++ b/app/src/behaviors/behavior_rgb_underglow.c
@@ -134,6 +134,7 @@ static const struct behavior_driver_api behavior_rgb_underglow_driver_api = {
         on_keymap_binding_convert_central_state_dependent_params,
     .binding_pressed = on_keymap_binding_pressed,
     .binding_released = on_keymap_binding_released,
+    .locality = BEHAVIOR_LOCALITY_GLOBAL,
 };
 
 DEVICE_DT_INST_DEFINE(0, behavior_rgb_underglow_init, device_pm_control_nop, NULL, NULL,
diff --git a/app/src/keymap.c b/app/src/keymap.c
index 1643f64..16ec316 100644
--- a/app/src/keymap.c
+++ b/app/src/keymap.c
@@ -4,7 +4,12 @@
  * SPDX-License-Identifier: MIT
  */
 
+#define IS_BLE_CENTRAL                                                                             \
+    (IS_ENABLED(CONFIG_ZMK_SPLIT) && IS_ENABLED(CONFIG_ZMK_BLE) &&                                 \
+     IS_ENABLED(CONFIG_ZMK_SPLIT_BLE_ROLE_CENTRAL))
+
 #include <sys/util.h>
+#include <bluetooth/bluetooth.h>
 #include <logging/log.h>
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
@@ -14,6 +19,10 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 #include <drivers/behavior.h>
 #include <zmk/behavior.h>
 
+#if IS_BLE_CENTRAL
+#include <zmk/split/bluetooth/central.h>
+#endif
+
 #include <zmk/event_manager.h>
 #include <zmk/events/position_state_changed.h>
 #include <zmk/events/layer_state_changed.h>
@@ -152,7 +161,17 @@ const char *zmk_keymap_layer_label(uint8_t layer) {
     return zmk_keymap_layer_names[layer];
 }
 
-int zmk_keymap_apply_position_state(int layer, uint32_t position, bool pressed, int64_t timestamp) {
+int invoke_locally(struct zmk_behavior_binding *binding, struct zmk_behavior_binding_event event,
+                   bool pressed) {
+    if (pressed) {
+        return behavior_keymap_binding_pressed(binding, event);
+    } else {
+        return behavior_keymap_binding_released(binding, event);
+    }
+}
+
+int zmk_keymap_apply_position_state(zmk_position_state_changed_source_t source, int layer,
+                                    uint32_t position, bool pressed, int64_t timestamp) {
     // We want to make a copy of this, since it may be converted from
     // relative to absolute before being invoked
     struct zmk_behavior_binding binding = zmk_keymap[layer][position];
@@ -169,7 +188,7 @@ int zmk_keymap_apply_position_state(int layer, uint32_t position, bool pressed,
     behavior = device_get_binding(binding.behavior_dev);
 
     if (!behavior) {
-        LOG_DBG("No behavior assigned to %d on layer %d", position, layer);
+        LOG_WRN("No behavior assigned to %d on layer %d", position, layer);
         return 1;
     }
 
@@ -179,20 +198,44 @@ int zmk_keymap_apply_position_state(int layer, uint32_t position, bool pressed,
         return err;
     }
 
-    if (pressed) {
-        return behavior_keymap_binding_pressed(&binding, event);
-    } else {
-        return behavior_keymap_binding_released(&binding, event);
+    enum behavior_locality locality = BEHAVIOR_LOCALITY_CENTRAL;
+    err = behavior_get_locality(behavior, &locality);
+    if (err) {
+        LOG_ERR("Failed to get behavior locality %d", err);
+        return err;
+    }
+
+    switch (locality) {
+    case BEHAVIOR_LOCALITY_CENTRAL:
+        return invoke_locally(&binding, event, pressed);
+    case BEHAVIOR_LOCALITY_EVENT_SOURCE:
+#if IS_BLE_CENTRAL
+        if (!bt_addr_le_cmp(source, BT_ADDR_LE_NONE)) {
+            return invoke_locally(&binding, event, pressed);
+        } else {
+            return zmk_split_bt_invoke_behavior(source, &binding, event, pressed);
+        }
+#else
+        return invoke_locally(&binding, event, pressed);
+#endif
+    case BEHAVIOR_LOCALITY_GLOBAL:
+#if IS_BLE_CENTRAL
+        zmk_split_bt_invoke_behavior(BT_ADDR_LE_ANY, &binding, event, pressed);
+#endif
+        return invoke_locally(&binding, event, pressed);
     }
+
+    return -ENOTSUP;
 }
 
-int zmk_keymap_position_state_changed(uint32_t position, bool pressed, int64_t timestamp) {
+int zmk_keymap_position_state_changed(zmk_position_state_changed_source_t source, uint32_t position,
+                                      bool pressed, int64_t timestamp) {
     if (pressed) {
         zmk_keymap_active_behavior_layer[position] = _zmk_keymap_layer_state;
     }
     for (int layer = ZMK_KEYMAP_LAYERS_LEN - 1; layer >= _zmk_keymap_layer_default; layer--) {
         if (zmk_keymap_layer_active_with_state(layer, zmk_keymap_active_behavior_layer[position])) {
-            int ret = zmk_keymap_apply_position_state(layer, position, pressed, timestamp);
+            int ret = zmk_keymap_apply_position_state(source, layer, position, pressed, timestamp);
             if (ret > 0) {
                 LOG_DBG("behavior processing to continue to next layer");
                 continue;
@@ -249,7 +292,7 @@ int zmk_keymap_sensor_triggered(uint8_t sensor_number, const struct device *sens
 int keymap_listener(const zmk_event_t *eh) {
     const struct zmk_position_state_changed *pos_ev;
     if ((pos_ev = as_zmk_position_state_changed(eh)) != NULL) {
-        return zmk_keymap_position_state_changed(pos_ev->position, pos_ev->state,
+        return zmk_keymap_position_state_changed(pos_ev->source, pos_ev->position, pos_ev->state,
                                                  pos_ev->timestamp);
     }
 
diff --git a/app/src/kscan.c b/app/src/kscan.c
index 3c9c201..13ad2cc 100644
--- a/app/src/kscan.c
+++ b/app/src/kscan.c
@@ -6,6 +6,7 @@
 
 #include <zephyr.h>
 #include <device.h>
+#include <bluetooth/addr.h>
 #include <drivers/kscan.h>
 #include <logging/log.h>
 
@@ -49,8 +50,12 @@ void zmk_kscan_process_msgq(struct k_work *item) {
         uint32_t position = zmk_matrix_transform_row_column_to_position(ev.row, ev.column);
         LOG_DBG("Row: %d, col: %d, position: %d, pressed: %s", ev.row, ev.column, position,
                 (pressed ? "true" : "false"));
-        ZMK_EVENT_RAISE(new_zmk_position_state_changed((struct zmk_position_state_changed){
-            .state = pressed, .position = position, .timestamp = k_uptime_get()}));
+        ZMK_EVENT_RAISE(new_zmk_position_state_changed((struct zmk_position_state_changed) {
+#if IS_ENABLED(CONFIG_ZMK_BLE)
+            .source = BT_ADDR_LE_NONE,
+#endif
+            .state = pressed, .position = position, .timestamp = k_uptime_get()
+        }));
     }
 }
 
diff --git a/app/src/split/bluetooth/central.c b/app/src/split/bluetooth/central.c
index 9a7f01b..5ac4f83 100644
--- a/app/src/split/bluetooth/central.c
+++ b/app/src/split/bluetooth/central.c
@@ -18,7 +18,9 @@
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
 #include <zmk/ble.h>
+#include <zmk/behavior.h>
 #include <zmk/split/bluetooth/uuid.h>
+#include <zmk/split/bluetooth/service.h>
 #include <zmk/event_manager.h>
 #include <zmk/events/position_state_changed.h>
 #include <init.h>
@@ -33,6 +35,7 @@ static const struct bt_uuid_128 split_service_uuid = BT_UUID_INIT_128(ZMK_SPLIT_
 static struct bt_gatt_discover_params discover_params;
 static struct bt_gatt_subscribe_params subscribe_params;
 static struct bt_gatt_discover_params sub_discover_params;
+static uint16_t run_behavior_handle;
 
 K_MSGQ_DEFINE(peripheral_event_msgq, sizeof(struct zmk_position_state_changed),
               CONFIG_ZMK_SPLIT_BLE_CENTRAL_POSITION_QUEUE_SIZE, 4);
@@ -72,8 +75,10 @@ static uint8_t split_central_notify_func(struct bt_conn *conn,
             if (changed_positions[i] & BIT(j)) {
                 uint32_t position = (i * 8) + j;
                 bool pressed = position_state[i] & BIT(j);
-                struct zmk_position_state_changed ev = {
-                    .position = position, .state = pressed, .timestamp = k_uptime_get()};
+                struct zmk_position_state_changed ev = {.source = bt_conn_get_dst(conn),
+                                                        .position = position,
+                                                        .state = pressed,
+                                                        .timestamp = k_uptime_get()};
 
                 k_msgq_put(&peripheral_event_msgq, &ev, K_NO_WAIT);
                 k_work_submit(&peripheral_event_work);
@@ -124,9 +129,28 @@ static uint8_t split_central_chrc_discovery_func(struct bt_conn *conn,
         subscribe_params.disc_params = &sub_discover_params;
         subscribe_params.end_handle = discover_params.end_handle;
         subscribe_params.value_handle = bt_gatt_attr_value_handle(attr);
+
+        err = bt_gatt_discover(conn, &discover_params);
+        if (err) {
+            LOG_ERR("Discover failed (err %d)", err);
+        }
+    } else if (!bt_uuid_cmp(discover_params.uuid,
+                            BT_UUID_DECLARE_128(ZMK_SPLIT_BT_CHAR_RUN_BEHAVIOR_UUID))) {
+        run_behavior_handle = bt_gatt_attr_value_handle(attr);
+    } else {
         subscribe_params.notify = split_central_notify_func;
         subscribe_params.value = BT_GATT_CCC_NOTIFY;
         split_central_subscribe(conn);
+
+        memcpy(&uuid, BT_UUID_DECLARE_128(ZMK_SPLIT_BT_CHAR_RUN_BEHAVIOR_UUID), sizeof(uuid));
+        discover_params.uuid = &uuid.uuid;
+        discover_params.start_handle = attr->handle + 1;
+        discover_params.type = BT_GATT_DISCOVER_CHARACTERISTIC;
+
+        err = bt_gatt_discover(conn, &discover_params);
+        if (err) {
+            LOG_ERR("Discover failed (err %d)", err);
+        }
     }
 
     return subscribe_params.value_handle ? BT_GATT_ITER_STOP : BT_GATT_ITER_CONTINUE;
@@ -340,6 +364,27 @@ static struct bt_conn_cb conn_callbacks = {
     .disconnected = split_central_disconnected,
 };
 
+int zmk_split_bt_invoke_behavior(const bt_addr_le_t *source, struct zmk_behavior_binding *binding,
+                                 struct zmk_behavior_binding_event event, bool state) {
+    struct zmk_split_run_behavior_payload payload = {.data = {
+                                                         .param1 = binding->param1,
+                                                         .param2 = binding->param2,
+                                                         .position = event.position,
+                                                         .state = state,
+                                                     }};
+    strncpy(payload.behavior_dev, binding->behavior_dev, ZMK_SPLIT_RUN_BEHAVIOR_DEV_LEN - 1);
+    payload.behavior_dev[ZMK_SPLIT_RUN_BEHAVIOR_DEV_LEN - 1] = '\0';
+
+    int err = bt_gatt_write_without_response(default_conn, run_behavior_handle, &payload,
+                                             sizeof(struct zmk_split_run_behavior_payload), true);
+
+    if (err) {
+        LOG_ERR("Failed to write the behavior characteristic (err %d)", err);
+    }
+
+    return err;
+};
+
 int zmk_split_bt_central_init(const struct device *_arg) {
     bt_conn_cb_register(&conn_callbacks);
 
diff --git a/app/src/split/bluetooth/service.c b/app/src/split/bluetooth/service.c
index fbac644..bb0202c 100644
--- a/app/src/split/bluetooth/service.c
+++ b/app/src/split/bluetooth/service.c
@@ -15,6 +15,8 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 #include <bluetooth/gatt.h>
 #include <bluetooth/uuid.h>
 
+#include <drivers/behavior.h>
+#include <zmk/behavior.h>
 #include <zmk/matrix.h>
 #include <zmk/split/bluetooth/uuid.h>
 #include <zmk/split/bluetooth/service.h>
@@ -24,12 +26,57 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 static uint8_t num_of_positions = ZMK_KEYMAP_LEN;
 static uint8_t position_state[POS_STATE_LEN];
 
+static struct zmk_split_run_behavior_payload behavior_run_payload;
+
 static ssize_t split_svc_pos_state(struct bt_conn *conn, const struct bt_gatt_attr *attrs,
                                    void *buf, uint16_t len, uint16_t offset) {
     return bt_gatt_attr_read(conn, attrs, buf, len, offset, &position_state,
                              sizeof(position_state));
 }
 
+static ssize_t split_svc_run_behavior(struct bt_conn *conn, const struct bt_gatt_attr *attrs,
+                                      const void *buf, uint16_t len, uint16_t offset,
+                                      uint8_t flags) {
+    struct zmk_split_run_behavior_payload *payload = attrs->user_data;
+    uint16_t end_addr = offset + len;
+
+    LOG_DBG("offset %d len %d", offset, len);
+
+    if (end_addr > sizeof(struct zmk_split_run_behavior_payload)) {
+        return BT_GATT_ERR(BT_ATT_ERR_INVALID_OFFSET);
+    }
+
+    memcpy(payload + offset, buf, len);
+
+    // We run if:
+    // 1: We've gotten all the position/state/param data.
+    // 2: We have a null terminated string for the behavior device label.
+    if ((end_addr > sizeof(struct zmk_split_run_behavior_data)) &&
+        payload->behavior_dev[end_addr - sizeof(struct zmk_split_run_behavior_data)] == '\0') {
+        struct zmk_behavior_binding binding = {
+            .param1 = payload->data.param1,
+            .param2 = payload->data.param2,
+            .behavior_dev = payload->behavior_dev,
+        };
+        LOG_DBG("INVOKE THE BEHAVIOR: %s with params %d %d", log_strdup(binding.behavior_dev),
+                binding.param1, binding.param2);
+        struct zmk_behavior_binding_event event = {.position = payload->data.position,
+                                                   .timestamp = k_uptime_get()};
+        int err;
+        if (payload->data.state > 0) {
+            err = behavior_keymap_binding_pressed(&binding, event);
+        } else {
+            err = behavior_keymap_binding_released(&binding, event);
+        }
+
+        if (err) {
+            LOG_ERR("Failed to invoke behavior %s: %d", log_strdup(binding.behavior_dev), err);
+        }
+    }
+
+    return len;
+}
+
 static ssize_t split_svc_num_of_positions(struct bt_conn *conn, const struct bt_gatt_attr *attrs,
                                           void *buf, uint16_t len, uint16_t offset) {
     return bt_gatt_attr_read(conn, attrs, buf, len, offset, attrs->user_data, sizeof(uint8_t));
@@ -45,6 +92,9 @@ BT_GATT_SERVICE_DEFINE(
                            BT_GATT_CHRC_READ | BT_GATT_CHRC_NOTIFY, BT_GATT_PERM_READ_ENCRYPT,
                            split_svc_pos_state, NULL, &position_state),
     BT_GATT_CCC(split_svc_pos_state_ccc, BT_GATT_PERM_READ_ENCRYPT | BT_GATT_PERM_WRITE_ENCRYPT),
+    BT_GATT_CHARACTERISTIC(BT_UUID_DECLARE_128(ZMK_SPLIT_BT_CHAR_RUN_BEHAVIOR_UUID),
+                           BT_GATT_CHRC_WRITE_WITHOUT_RESP, BT_GATT_PERM_WRITE_ENCRYPT, NULL,
+                           split_svc_run_behavior, &behavior_run_payload),
     BT_GATT_DESCRIPTOR(BT_UUID_NUM_OF_DIGITALS, BT_GATT_PERM_READ, split_svc_num_of_positions, NULL,
                        &num_of_positions), );