feat(gui): expose host_switch_targets in the device Device tab

crates/openlogi-core/src/config.rs

@@ -767,6 +767,26 @@ impl Config {
             .dpi_presets = presets;
     }
 
+    /// The pointing-device config keys that follow `device_key`'s (a
+    /// keyboard's) host-switch channel, or an empty `Vec` if none are
+    /// configured yet.
+    #[must_use]
+    pub fn host_switch_targets(&self, device_key: &str) -> Vec<String> {
+        self.devices
+            .get(device_key)
+            .map(|d| d.host_switch_targets.clone())
+            .unwrap_or_default()
+    }
+
+    /// Replace the set of pointing devices that follow `device_key`'s host
+    /// switch. Pass an empty `Vec` to clear.
+    pub fn set_host_switch_targets(&mut self, device_key: &str, targets: Vec<String>) {
+        self.devices
+            .entry(device_key.to_string())
+            .or_default()
+            .host_switch_targets = targets;
+    }
+
     /// The last-known [`DeviceIdentity`] for `device_key`, or `None` if the
     /// device has never been seen online (or was configured before identities
     /// were recorded).

crates/openlogi-core/src/config/tests.rs

@@ -586,6 +586,8 @@ fn device_identity_roundtrips_and_is_iterable() {
             haptic_feedback: false,
             haptic_panel: false,
             dpi_gestures: true,
+            host_switch_target: false,
+            host_switch_source: false,
         },
         light_capabilities: None,
         driver_id: None,

crates/openlogi-core/src/device.rs

@@ -132,6 +132,17 @@ pub struct Capabilities {
     /// both diversion and raw-XY reporting for hold-and-swipe gestures.
     #[serde(default)]
     pub dpi_gestures: bool,
+    /// This device can be switched to by another device's Easy-Switch host
+    /// change — HID++ `0x1814`/`0x1815 ChangeHost`. A pointing device needs
+    /// this to be a host-switch link's *target*.
+    #[serde(default)]
+    pub host_switch_target: bool,
+    /// A host-switch-channel control in the device's `0x1b04` control table
+    /// is divertable or reports analytics key events, so pressing it can be
+    /// detected and used to trigger a linked device's host change. A
+    /// keyboard needs this to be a host-switch link's *source*.
+    #[serde(default)]
+    pub host_switch_source: bool,
 }
 
 impl Capabilities {
@@ -144,6 +155,7 @@ impl Capabilities {
         // Every family here is driven by `set_keyboard_color`, which tries
         // effect engines before per-zone paths. Backlight (0x198x) stays out.
         const LIGHTING: [u16; 4] = [0x8070, 0x8071, 0x8081, 0x8080];
+        const CHANGE_HOST: [u16; 2] = [0x1814, 0x1815];
         let has = |family: &[u16]| ids.iter().any(|id| family.contains(id));
         Self {
             buttons: has(&BUTTONS),
@@ -155,6 +167,8 @@ impl Capabilities {
             haptic_feedback: ids.contains(&0x19b0),
             haptic_panel: false,
             dpi_gestures: false,
+            host_switch_target: has(&CHANGE_HOST),
+            host_switch_source: false,
         }
     }
 
@@ -176,6 +190,8 @@ impl Capabilities {
                 haptic_feedback: false,
                 haptic_panel: false,
                 dpi_gestures: false,
+                host_switch_target: false,
+                host_switch_source: false,
             },
             DeviceKind::Keyboard => Self {
                 lighting: true,
@@ -482,6 +498,8 @@ mod tests {
                     haptic_feedback: false,
                     haptic_panel: false,
                     dpi_gestures: false,
+                    host_switch_target: false,
+                    host_switch_source: false,
                 }),
             }],
         }
@@ -553,6 +571,8 @@ mod tests {
                 haptic_feedback: false,
                 haptic_panel: false,
                 dpi_gestures: false,
+                host_switch_target: false,
+                host_switch_source: false,
             }
         );
         assert!(!Capabilities::from_feature_ids(&[0x0003, 0x1b04]).thumbwheel);
@@ -570,6 +590,8 @@ mod tests {
                 haptic_feedback: false,
                 haptic_panel: false,
                 dpi_gestures: false,
+                host_switch_target: false,
+                host_switch_source: false,
             }
         );
         // No driving features → nothing offered.

crates/openlogi-core/src/diagnostics.rs

@@ -598,6 +598,8 @@ mod tests {
                         haptic_feedback: false,
                         haptic_panel: false,
                         dpi_gestures: false,
+                        host_switch_target: false,
+                        host_switch_source: false,
                     }),
                     dpi: Some("1600 dpi (range 200–8000, 5 steps)".to_string()),
                     config_key: "4082d".to_string(),

crates/openlogi-desktop/src/app/detail.rs

@@ -35,7 +35,7 @@ use crate::features::pointer::smartshift::SmartShiftPanel;
 use crate::features::profiles::{
     AppCatalogPicker, ProfileIconCache, action_ring_profile_scope_bar, button_profile_scope_bar,
 };
-use crate::state::{AppState, DeviceRecord, StateEvent};
+use crate::state::{AppState, DeviceRecord, HostSwitchCandidate, StateEvent};
 use crate::ui::battery::BatteryIndicator;
 use crate::ui::components::{PanelCard, Toggle};
 use crate::ui::theme::{
@@ -635,13 +635,59 @@ fn light_tab(
 /// Device tab: device details and configuration cards stacked.
 fn device_tab(cx: &mut Context<AppView>) -> impl IntoElement {
     let pal = theme::palette(cx);
+    let host_switch_candidates = AppState::try_read(cx)
+        .map(AppState::host_switch_candidates)
+        .unwrap_or_default();
     tab_body(
         ContentWidth::Small,
         v_flex()
             .w_full()
             .gap_3()
             .child(device_details_card(pal, cx))
-            .child(configuration_card(pal, cx)),
+            .child(configuration_card(pal, cx))
+            .when(!host_switch_candidates.is_empty(), |content| {
+                content.child(host_switch_card(host_switch_candidates))
+            }),
+    )
+}
+
+/// "Follow host switches from:" — a checkbox per other configured keyboard,
+/// letting this pointing device be added to that keyboard's
+/// `host_switch_targets` so it follows when the keyboard's Easy-Switch key
+/// changes host. Shown only for a persistent mouse/trackball with at least
+/// one other configured keyboard to follow.
+fn host_switch_card(candidates: Vec<HostSwitchCandidate>) -> impl IntoElement {
+    let content = v_flex().gap_2().children(candidates.into_iter().map(
+        |HostSwitchCandidate {
+             config_key,
+             display_name,
+             following,
+         }| {
+            h_flex()
+                .justify_between()
+                .items_center()
+                .child(div().text_body().child(display_name))
+                .child(
+                    Switch::new(gpui::ElementId::Name(
+                        format!("host-switch-follow-{config_key}").into(),
+                    ))
+                    .checked(following)
+                    .on_click(move |checked, _window, cx| {
+                        let checked = *checked;
+                        let keyboard_key = config_key.clone();
+                        AppState::update(cx, |state, cx| {
+                            state.set_host_switch_follow(&keyboard_key, checked);
+                            cx.emit(StateEvent::DeviceConfigChanged(keyboard_key.into()));
+                        });
+                    }),
+                )
+        },
+    ));
+
+    PanelCard::new(
+        tr!("device.host_switch_targets"),
+        Icon::empty().path("action-icons/keyboard.svg"),
+        content,
     )
 }
 

crates/openlogi-desktop/src/app/tests.rs

@@ -188,6 +188,8 @@ fn tabs_follow_capabilities_not_kind() {
         haptic_feedback: false,
         haptic_panel: false,
         dpi_gestures: false,
+        host_switch_target: false,
+        host_switch_source: false,
     });
     // After 0x0005 kind-correction the record has kind=Mouse, not Keyboard.
     let tabs = DetailTab::tabs_for(&record(DeviceKind::Mouse, caps));
@@ -211,6 +213,8 @@ fn keyboard_without_asset_hides_buttons_tab() {
         haptic_feedback: false,
         haptic_panel: false,
         dpi_gestures: false,
+        host_switch_target: false,
+        host_switch_source: false,
     });
     let tabs = DetailTab::tabs_for(&record(DeviceKind::Keyboard, caps));
     assert!(
@@ -232,6 +236,8 @@ fn keyboard_with_buttons_shows_keys_tab() {
         haptic_feedback: false,
         haptic_panel: false,
         dpi_gestures: false,
+        host_switch_target: false,
+        host_switch_source: false,
     });
     let tabs = DetailTab::tabs_for(&record(DeviceKind::Keyboard, caps));
     assert!(tabs.contains(&DetailTab::Keys));

crates/openlogi-desktop/src/state.rs

@@ -22,6 +22,7 @@ use tracing::warn;
 pub use config::ConfigPersistence;
 pub(crate) use device_key::DeviceKey;
 pub use devices::DeviceRecord;
+pub use host_switch::HostSwitchCandidate;
 pub use light::LightCommandStatus;
 pub(crate) use load::Load;
 pub use load::{DpiStatus, SmartShiftLoad};
@@ -64,6 +65,7 @@ mod device_runtime;
 mod device_store;
 mod devices;
 mod dpi;
+mod host_switch;
 mod inventory;
 mod light;
 mod lighting;

crates/openlogi-desktop/src/state/devices/tests.rs

@@ -268,6 +268,8 @@ fn mouse_identity(name: &str) -> DeviceIdentity {
             haptic_feedback: false,
             haptic_panel: false,
             dpi_gestures: false,
+            host_switch_target: false,
+            host_switch_source: false,
         },
         light_capabilities: None,
         model_info: None,