feat: add system tray (StatusNotifierWatcher / SNI)

Implements org.kde.StatusNotifierWatcher as a D-Bus service so apps
like Nextcloud can register their tray icons. Icons are rendered from
SNI ARGB pixmaps (falling back to icon-name theme lookup), click calls
Activate(0,0), and NameOwnerChanged cleans up ghost icons when an app
exits. Styling follows the Bread Design System (4px tertiary radius,
xs/sm spacing, opacity transitions).

Also fixes a latent infinite-loop risk in osd.rs (.flatten → .map_while)
and syncs the notifications server version string to CARGO_PKG_VERSION.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Cargo.lock

@@ -89,7 +89,7 @@ dependencies = [
 
 [[package]]
 name = "breadbar"
-version = "0.1.1"
+version = "0.1.2"
 dependencies = [
  "bread-theme",
  "futures-lite",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "breadbar"
-version = "0.1.1"
+version = "0.1.2"
 edition = "2021"
 description = "Minimal status bar and notification daemon for Hyprland on Wayland"
 license = "MIT"

README.md

@@ -2,7 +2,7 @@
 
 Minimal status bar and notification daemon for [Hyprland](https://hyprland.org/) on Wayland.
 
-A single Rust binary that provides a full-width top bar and a standards-compliant D-Bus notification daemon, with no system tray, no launcher, and no wallpaper logic.
+A single Rust binary that provides a full-width top bar, a system tray, and a standards-compliant D-Bus notification daemon. No launcher, no wallpaper logic.
 
 ## Features
 
@@ -10,7 +10,7 @@ A single Rust binary that provides a full-width top bar and a standards-complian
 
 - Left: live workspace buttons sourced from Hyprland IPC, active workspace highlighted
 - Centre: clock (`HH:MM`, updates at the top of each minute)
-- Right: CPU%, RAM, power draw (W), battery level + AC indicator, Bluetooth state, WiFi SSID with signal strength
+- Right: CPU%, RAM, power draw (W), battery level + AC indicator, Bluetooth state, WiFi SSID with signal strength, system tray (SNI)
 
 **Notification daemon**:
 
@@ -105,6 +105,7 @@ Example — change the font size:
 | `src/bar/workspaces.rs` | Hyprland IPC event stream, workspace buttons |
 | `src/bar/clock.rs` | Minute-tick clock |
 | `src/bar/stats.rs` | Polling loop: CPU, RAM, power, battery, Bluetooth, WiFi |
+| `src/bar/tray.rs` | `org.kde.StatusNotifierWatcher` D-Bus service, SNI item rendering |
 | `src/notifications/mod.rs` | `org.freedesktop.Notifications` zbus service |
 | `src/notifications/popup.rs` | Layer-shell popup window and card stack |
 | `src/theme.rs` | pywal reader, GTK CSS provider injection |

src/bar/mod.rs

@@ -1,3 +1,4 @@
 pub mod clock;
 pub mod stats;
+pub mod tray;
 pub mod workspaces;

src/bar/tray.rs

@@ -0,0 +1,240 @@
+use crate::{App, AppInput};
+use futures_lite::StreamExt;
+use gtk4::prelude::Cast;
+use relm4::ComponentSender;
+use std::collections::HashMap;
+use std::sync::{Arc, Mutex};
+use zbus::{interface, object_server::SignalEmitter};
+
+#[derive(Debug)]
+pub enum TrayIconData {
+    Pixels { width: i32, height: i32, data: Vec<u8> },
+    Name(String),
+}
+
+#[derive(Debug)]
+pub enum TrayUpdate {
+    Add { id: String, icon: Option<TrayIconData>, title: String },
+    Remove { id: String },
+}
+
+struct WatcherState {
+    items: Vec<String>,
+}
+
+struct Watcher {
+    state: Arc<Mutex<WatcherState>>,
+    tx: tokio::sync::mpsc::UnboundedSender<(String, String)>,
+}
+
+#[interface(name = "org.kde.StatusNotifierWatcher")]
+impl Watcher {
+    async fn register_status_notifier_item(
+        &self,
+        service: String,
+        #[zbus(header)] header: zbus::message::Header<'_>,
+        #[zbus(signal_emitter)] ctx: SignalEmitter<'_>,
+    ) {
+        let sender_name = header.sender().map(|s| s.to_string()).unwrap_or_default();
+        let (bus, path) = parse_service(&service, &sender_name);
+        let full = format!("{}{}", bus, path);
+        {
+            let mut state = self.state.lock().unwrap();
+            if !state.items.contains(&full) {
+                state.items.push(full.clone());
+            }
+        }
+        let _ = Self::status_notifier_item_registered(&ctx, &full).await;
+        let _ = self.tx.send((bus, path));
+    }
+
+    async fn register_status_notifier_host(
+        &self,
+        _service: String,
+        #[zbus(signal_emitter)] ctx: SignalEmitter<'_>,
+    ) {
+        let _ = Self::status_notifier_host_registered(&ctx).await;
+    }
+
+    #[zbus(property)]
+    fn registered_status_notifier_items(&self) -> Vec<String> {
+        self.state.lock().unwrap().items.clone()
+    }
+
+    #[zbus(property)]
+    fn is_status_notifier_host_registered(&self) -> bool {
+        true
+    }
+
+    #[zbus(property)]
+    fn protocol_version(&self) -> i32 {
+        0
+    }
+
+    #[zbus(signal)]
+    async fn status_notifier_item_registered(
+        ctx: &SignalEmitter<'_>,
+        service: &str,
+    ) -> zbus::Result<()>;
+
+    #[zbus(signal)]
+    async fn status_notifier_item_unregistered(
+        ctx: &SignalEmitter<'_>,
+        service: &str,
+    ) -> zbus::Result<()>;
+
+    #[zbus(signal)]
+    async fn status_notifier_host_registered(ctx: &SignalEmitter<'_>) -> zbus::Result<()>;
+}
+
+fn parse_service(service: &str, sender: &str) -> (String, String) {
+    if service.starts_with('/') {
+        return (sender.to_string(), service.to_string());
+    }
+    match service.find('/') {
+        Some(slash) => (service[..slash].to_string(), service[slash..].to_string()),
+        None => (service.to_string(), "/StatusNotifierItem".to_string()),
+    }
+}
+
+async fn read_item(
+    conn: &zbus::Connection,
+    bus: &str,
+    path: &str,
+) -> (Option<TrayIconData>, String) {
+    let Ok(proxy) = zbus::Proxy::new(conn, bus, path, "org.kde.StatusNotifierItem").await else {
+        return (None, String::new());
+    };
+    let icon = read_icon(&proxy).await;
+    let title = proxy.get_property::<String>("Title").await.unwrap_or_default();
+    (icon, title)
+}
+
+async fn read_icon(proxy: &zbus::Proxy<'_>) -> Option<TrayIconData> {
+    let pixmaps: Vec<(i32, i32, Vec<u8>)> =
+        proxy.get_property("IconPixmap").await.unwrap_or_default();
+
+    if !pixmaps.is_empty() {
+        return pixmaps
+            .into_iter()
+            .filter(|(w, h, _)| *w > 0 && *h > 0)
+            .min_by_key(|(w, h, _)| (w.max(h) - 22).abs())
+            .map(|(width, height, data)| TrayIconData::Pixels { width, height, data });
+    }
+
+    let name: String = proxy.get_property("IconName").await.ok()?;
+    if name.is_empty() {
+        return None;
+    }
+    Some(TrayIconData::Name(name))
+}
+
+/// Call `Activate(0, 0)` on the SNI item identified by `id` (`{bus}{path}`).
+pub fn spawn_activate(id: String) {
+    relm4::spawn(async move {
+        let (bus, path) = match id.find('/') {
+            Some(slash) => (id[..slash].to_string(), id[slash..].to_string()),
+            None => (id, "/StatusNotifierItem".to_string()),
+        };
+        let Ok(conn) = zbus::Connection::session().await else { return };
+        let Ok(proxy) = zbus::Proxy::new(&conn, bus.as_str(), path.as_str(), "org.kde.StatusNotifierItem").await else { return };
+        let _ = proxy.call_method("Activate", &(0i32, 0i32)).await;
+    });
+}
+
+pub fn spawn_watcher(sender: ComponentSender<App>) {
+    let (tx, mut rx) = tokio::sync::mpsc::unbounded_channel::<(String, String)>();
+    // Maps bus name → item ids, shared between registration and cleanup tasks.
+    let bus_map: Arc<Mutex<HashMap<String, Vec<String>>>> = Arc::new(Mutex::new(HashMap::new()));
+    let bus_map_cleanup = bus_map.clone();
+    let sender_cleanup = sender.clone();
+
+    // Registration task — owns the watcher service and processes new items.
+    relm4::spawn(async move {
+        let watcher = Watcher {
+            state: Arc::new(Mutex::new(WatcherState { items: Vec::new() })),
+            tx,
+        };
+        // Builder steps fail only on invalid static strings — safe to unwrap.
+        let conn = zbus::connection::Builder::session()
+            .unwrap()
+            .name("org.kde.StatusNotifierWatcher")
+            .unwrap()
+            .serve_at("/StatusNotifierWatcher", watcher)
+            .unwrap()
+            .build()
+            .await
+            .expect("failed to register org.kde.StatusNotifierWatcher");
+
+        while let Some((bus, path)) = rx.recv().await {
+            let (icon, title) = read_item(&conn, &bus, &path).await;
+            let id = format!("{}{}", bus, path);
+            bus_map.lock().unwrap().entry(bus).or_default().push(id.clone());
+            sender.input(AppInput::TrayUpdate(TrayUpdate::Add { id, icon, title }));
+        }
+    });
+
+    // Cleanup task — watches NameOwnerChanged and removes items when their owner exits.
+    relm4::spawn(async move {
+        let Ok(conn) = zbus::Connection::session().await else { return };
+        let Ok(proxy) = zbus::fdo::DBusProxy::new(&conn).await else { return };
+        let Ok(mut stream) = proxy.receive_name_owner_changed().await else { return };
+        while let Some(signal) = stream.next().await {
+            let Ok(args) = signal.args() else { continue };
+            if args.new_owner().is_none() {
+                let gone = args.name().to_string();
+                if let Some(ids) = bus_map_cleanup.lock().unwrap().remove(&gone) {
+                    for id in ids {
+                        sender_cleanup.input(AppInput::TrayUpdate(TrayUpdate::Remove { id }));
+                    }
+                }
+            }
+        }
+    });
+}
+
+/// Convert SNI ARGB pixel data (network byte order) to a GTK4 `Image`.
+/// Falls back to an icon-name lookup or a placeholder on failure.
+pub fn make_tray_image(icon: Option<&TrayIconData>) -> gtk4::Image {
+    let img = match icon {
+        Some(TrayIconData::Pixels { width, height, data }) => pixels_to_image(*width, *height, data),
+        Some(TrayIconData::Name(name)) => {
+            let img = gtk4::Image::from_icon_name(name);
+            img.set_pixel_size(16);
+            Some(img)
+        }
+        None => None,
+    };
+    img.unwrap_or_else(|| {
+        let img = gtk4::Image::from_icon_name("image-missing");
+        img.set_pixel_size(16);
+        img
+    })
+}
+
+fn pixels_to_image(width: i32, height: i32, data: &[u8]) -> Option<gtk4::Image> {
+    if data.len() != (width * height * 4) as usize {
+        return None;
+    }
+    // SNI delivers ARGB big-endian: bytes are [A, R, G, B] per pixel.
+    // GTK4 R8g8b8a8 expects [R, G, B, A] per pixel.
+    let mut rgba = Vec::with_capacity(data.len());
+    for chunk in data.chunks_exact(4) {
+        rgba.push(chunk[1]);
+        rgba.push(chunk[2]);
+        rgba.push(chunk[3]);
+        rgba.push(chunk[0]);
+    }
+    let bytes = gtk4::glib::Bytes::from_owned(rgba);
+    let tex = gtk4::gdk::MemoryTexture::new(
+        width,
+        height,
+        gtk4::gdk::MemoryFormat::R8g8b8a8,
+        &bytes,
+        (width * 4) as usize,
+    );
+    let tex: gtk4::gdk::Texture = tex.upcast();
+    let img = gtk4::Image::from_paintable(Some(&tex));
+    img.set_pixel_size(16);
+    Some(img)
+}

src/main.rs

@@ -34,6 +34,8 @@ pub struct App {
     wifi_img: gtk4::Image,
     // Pre-loaded textures indexed by constant pointer values.
     wifi_textures: std::collections::HashMap<usize, gtk4::gdk::Texture>,
+    tray_box: gtk4::Box,
+    tray_items: std::collections::HashMap<String, gtk4::Button>,
 }
 
 #[derive(Debug)]
@@ -42,6 +44,7 @@ pub enum AppInput {
     ActiveWorkspace(WorkspaceId),
     ClockTick,
     StatsUpdate(bar::stats::Stats),
+    TrayUpdate(bar::tray::TrayUpdate),
 }
 
 #[relm4::component(pub)]
@@ -153,6 +156,8 @@ impl SimpleComponent for App {
             wifi_lbl: wifi_lbl.clone(),
             wifi_img: wifi_img.clone(),
             wifi_textures,
+            tray_box: gtk4::Box::new(gtk4::Orientation::Horizontal, 4),
+            tray_items: std::collections::HashMap::new(),
         };
         let widgets = view_output!();
         model.workspace_box = widgets.workspace_box.clone();
@@ -179,12 +184,15 @@ impl SimpleComponent for App {
         wifi_pair.append(&wifi_img);
         wifi_pair.append(&wifi_lbl);
         stats_box.append(&wifi_pair);
+        model.tray_box.add_css_class("tray-box");
+        stats_box.append(&model.tray_box);
         widgets.center_box.set_end_widget(Some(&stats_box));
 
         theme::apply();
         bar::workspaces::spawn_watcher(sender.clone());
         bar::clock::spawn_ticker(sender.clone());
-        bar::stats::spawn_poller(sender);
+        bar::stats::spawn_poller(sender.clone());
+        bar::tray::spawn_watcher(sender.clone());
         notifications::spawn();
         osd::spawn();
 
@@ -228,6 +236,26 @@ impl SimpleComponent for App {
                     self.wifi_img.set_paintable(Some(tex));
                 }
             }
+            AppInput::TrayUpdate(bar::tray::TrayUpdate::Add { id, icon, title }) => {
+                if self.tray_items.contains_key(&id) {
+                    return;
+                }
+                let btn = gtk4::Button::new();
+                btn.add_css_class("tray-btn");
+                btn.set_child(Some(&bar::tray::make_tray_image(icon.as_ref())));
+                if !title.is_empty() {
+                    btn.set_tooltip_text(Some(&title));
+                }
+                let id_click = id.clone();
+                btn.connect_clicked(move |_| bar::tray::spawn_activate(id_click.clone()));
+                self.tray_box.append(&btn);
+                self.tray_items.insert(id, btn);
+            }
+            AppInput::TrayUpdate(bar::tray::TrayUpdate::Remove { id }) => {
+                if let Some(btn) = self.tray_items.remove(&id) {
+                    self.tray_box.remove(&btn);
+                }
+            }
         }
     }
 }

src/notifications/mod.rs

@@ -70,7 +70,7 @@ impl NotifServer {
         (
             "breadbar".into(),
             "breadway".into(),
-            "0.1.0".into(),
+            env!("CARGO_PKG_VERSION").into(),
             "1.2".into(),
         )
     }

src/osd.rs

@@ -35,7 +35,7 @@ fn volume_watcher(tx: mpsc::Sender<OsdEvent>) {
     let stdout = child.stdout.take().unwrap();
     let reader = BufReader::new(stdout);
 
-    for line in reader.lines().flatten() {
+    for line in reader.lines().map_while(Result::ok) {
         if line.contains("'change' on sink") {
             if let Some(evt) = query_volume() {
                 let _ = tx.blocking_send(evt);