feature(stream) added json streams to daemon

Cargo.lock

@@ -572,7 +572,7 @@ checksum = "1d674e81391d1e1ab681a28d99df07927c6d4aa5b027d7da16ba32d1d21ecd99"
 
 [[package]]
 name = "fluxo-rs"
-version = "0.5.4"
+version = "0.6.0"
 dependencies = [
  "anyhow",
  "bluer",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fluxo-rs"
-version = "0.5.4"
+version = "0.6.0"
 edition = "2024"
 
 [[bin]]

README.md

@@ -1,12 +1,18 @@
 # fluxo
 
-`fluxo` is a high-performance system metrics daemon and client designed specifically for Waybar. It entirely replaces standard shell scripts with a compiled Rust binary that collects data via a background polling loop and serves it over a Unix socket. 
+`fluxo` is a high-performance system metrics daemon and client for status bars. It entirely replaces standard shell scripts with a compiled Rust binary that collects data via a background polling loop and serves it over a Unix socket.
 
-With its **100% Native, Content-Based Event-Driven Architecture**, it consumes effectively 0% CPU while idle and signals Waybar to redraw *only* when the rendered UI text or icons physically change.
+With its **100% Native, Content-Based Event-Driven Architecture**, it consumes effectively 0% CPU while idle and pushes updates *only* when the rendered UI text or icons physically change.
+
+It speaks two dialects, both driven by that same change detection:
+
+- **Waybar** — the daemon sends `SIGRTMIN+N` and the bar re-runs `fluxo <module>`. See [Waybar Configuration](#waybar-configuration).
+- **Any other bar** (Quickshell, ags, eww, …) — hold one `fluxo stream <modules...>` child open and read newline-delimited JSON from its stdout. See [Streaming](#streaming).
 
 ## Key Features
 
 - **100% Native Architecture**: Zero shell-outs or subprocesses. Uses `bluer` for Bluetooth, `libpulse-binding` for audio, `zbus` for MPRIS/DND, and `notify` for backlight.
+- **Push-Based for Any Bar**: `fluxo stream` turns the daemon into a push source, so bars that keep long-lived child processes never have to poll or re-exec a client.
 - **Content-Based Event Signaling**: `fluxo` evaluates your custom configuration formats internally. It only sends a `SIGRTMIN+X` signal to Waybar if the resulting string or CSS class has actually changed, eliminating pointless re-renders from raw polling fluctuations.
 - **Zero-Latency Interactions**: Direct library bindings mean that when you change your volume or connect a Bluetooth device via the CLI, the daemon updates instantly.
 - **Circuit Breaker (Failsafe)**: Automatically detects failing modules and enters a "Cool down" state, preventing resource waste and log spam. Fallback caching keeps your bar looking clean even during brief failures.
@@ -115,6 +121,58 @@ To achieve zero-latency updates and zero-polling CPU usage, set `interval: 0` on
 }
 ```
 
+## Streaming
+
+Waybar's model is *signal the bar, the bar re-runs a command*, which is why the
+one-shot client exists. Other bars have no equivalent of a signal, so they end up
+emulating one by polling — spawning a `fluxo <module>` client per module per
+interval, which means an exec and a dynamic link per reading, and values that are
+still up to one interval stale.
+
+`fluxo stream` is the push-based path for those bars. Subscribe once, and the
+daemon writes a JSON line whenever a module's rendered output actually changes:
+
+```console
+$ fluxo stream cpu mem net
+{"module":"cpu","text":"7.4|41.0","tooltip":"AMD Ryzen 7 PRO 3700U","class":"normal","percentage":7}
+{"module":"mem","text":"9.41|15.49","class":"normal","percentage":60}
+{"module":"cpu","text":"6.9|40.5","tooltip":"AMD Ryzen 7 PRO 3700U","class":"normal","percentage":6}
+```
+
+Each line is one complete JSON object: a `module` key naming the source, plus the
+module's usual `text` and — when set — `tooltip`, `class` and `percentage`. A full
+snapshot of every subscribed module is sent immediately on connect, so a bar
+renders correctly the moment it attaches rather than after the first change.
+
+Two deliberate differences from the one-shot client:
+
+- `text` is **not** padded with figure-spaces and zero-width spaces. That padding
+  exists to stop Waybar's proportional font from reflowing, and is noise to a
+  consumer doing its own layout.
+- Modules without a watch channel (`power`, `game`, `pool`) are re-evaluated on a
+  5 second sweep rather than event-driven. Unchanged output is never written, so a
+  quiet sweep costs nothing on the wire.
+
+Quickshell, for example, needs one `Process` for the whole bar:
+
+```qml
+Process {
+    running: true
+    command: ["fluxo", "stream", "cpu", "mem", "gpu", "net", "sys"]
+    stdout: SplitParser {
+        onRead: line => {
+            const ev = JSON.parse(line);
+            // dispatch on ev.module
+        }
+    }
+    onExited: reconnectTimer.restart()
+}
+```
+
+The connection dies when the daemon restarts, so drive `running` back to `true`
+from a timer — that is a reconnect, not a poll, and only ever fires while the
+stream is actually down.
+
 ## Debugging
 
 Use `--loglevel` to control log verbosity (trace, debug, info, warn, error):

example.config.toml

@@ -37,6 +37,10 @@ format = "{interface} ({ip}):  {rx:^4.1} MB/s   {tx:^4.1} MB/s"
 # enabled = false  # set to false to disable this module at runtime
 # tokens: {usage}, {temp}, {model}
 format = "CPU: {usage:^4.1}% {temp:^4.1}C"
+# Force a temperature sensor instead of auto-detecting it. Case-insensitive
+# substring of the label shown by `sensors` (e.g. "Tctl", "Package id 0",
+# "thinkpad CPU").
+# temp_sensor = "Tctl"
 
 [memory]
 # enabled = false  # set to false to disable this module at runtime

src/config.rs

@@ -125,6 +125,10 @@ pub struct CpuConfig {
     #[serde(default = "default_true")]
     pub enabled: bool,
     pub format: String,
+    /// Case-insensitive substring of the sensor label to force (e.g. `"Tctl"`,
+    /// `"Package id 0"`). Empty means auto-detect.
+    #[serde(default)]
+    pub temp_sensor: String,
 }
 
 impl Default for CpuConfig {
@@ -132,6 +136,7 @@ impl Default for CpuConfig {
         Self {
             enabled: true,
             format: "CPU: {usage:>4.1}% {temp:>4.1}C".to_string(),
+            temp_sensor: String::new(),
         }
     }
 }

src/daemon.rs

@@ -254,9 +254,10 @@ pub async fn run_daemon(config_path: Option<PathBuf>) -> Result<()> {
     {
         let cfg = config.read().await;
         let fast_enabled = cfg.cpu.enabled || cfg.memory.enabled || cfg.sys.enabled;
+        let temp_sensor = cfg.cpu.temp_sensor.clone();
         drop(cfg);
         if fast_enabled {
-            let mut daemon = HardwareDaemon::new();
+            let mut daemon = HardwareDaemon::new(temp_sensor);
             let token = cancel_token.clone();
             spawn_poll_loop_simple!(
                 "fast_hw",
@@ -274,7 +275,8 @@ pub async fn run_daemon(config_path: Option<PathBuf>) -> Result<()> {
         let slow_enabled = cfg.gpu.enabled || cfg.disk.enabled;
         drop(cfg);
         if slow_enabled {
-            let mut daemon = HardwareDaemon::new();
+            // Slow path never samples CPU temperature, so the override is moot.
+            let mut daemon = HardwareDaemon::new(String::new());
             let token = cancel_token.clone();
             spawn_poll_loop_simple!(
                 "slow_hw",
@@ -456,6 +458,21 @@ async fn run_ipc_loop(
                                     return;
                                 }
 
+                                // `stream` holds the connection open and pushes a
+                                // line per change instead of answering once.
+                                if *module_name == "stream" {
+                                    let requested: Vec<String> =
+                                        parts[1..].iter().map(|s| s.to_string()).collect();
+                                    crate::stream::run_stream(
+                                        writer,
+                                        requested,
+                                        state_clone,
+                                        config_clone,
+                                    )
+                                    .await;
+                                    return;
+                                }
+
                                 debug!(module = module_name, args = ?&parts[1..], "Handling IPC request");
                                 let response =
                                     handle_request(module_name, &parts[1..], &state_clone, &config_clone).await;

src/help.rs

@@ -365,8 +365,16 @@ fn print_overview() {
     println!("    fluxo daemon [--config <path>]    Start the background daemon");
     println!("    fluxo reload                      Hot-reload the daemon config");
     println!("    fluxo <module> [args...]           Query or control a module");
+    println!("    fluxo stream <module>...           Follow modules as JSON lines");
     println!("    fluxo help [module]                Show this help or module details\n");
 
+    println!("\x1b[1mBARS:\x1b[0m");
+    println!("    Waybar        set `signal = N` per module and let the daemon poke it;");
+    println!("                  `fluxo <module>` is re-run by the bar on each signal.");
+    println!("    Everything    keep one `fluxo stream cpu mem net ...` child running and");
+    println!("    else          read its stdout — one JSON line per actual change, so");
+    println!("                  there is no polling, no re-exec, and no interval lag.\n");
+
     println!("\x1b[1mCONFIGURATION:\x1b[0m");
     println!("    Config file:  $XDG_CONFIG_HOME/fluxo/config.toml");
     println!("    Format tokens in config strings use {{token}} syntax.");

src/ipc.rs

@@ -44,3 +44,37 @@ pub fn request_data(module: &str, args: &[&str]) -> anyhow::Result<String> {
 
     Ok(response)
 }
+
+/// Subscribe to `modules` and copy the daemon's push stream to stdout.
+///
+/// Blocks until the daemon closes the connection or the process is killed —
+/// this is the long-lived counterpart to [`request_data`], so no read timeout
+/// is set. Each line is flushed immediately, otherwise a consumer reading our
+/// stdout through a pipe would see updates only once a block's worth had
+/// accumulated.
+pub fn stream_modules(modules: &[String]) -> anyhow::Result<()> {
+    use std::io::{BufRead, BufReader};
+
+    let sock = socket_path();
+    debug!(?modules, "Opening stream to daemon socket: {}", sock);
+    let mut stream = UnixStream::connect(&sock)?;
+
+    let mut request = String::from("stream");
+    for module in modules {
+        request.push(' ');
+        request.push_str(module);
+    }
+    request.push('\n');
+    stream.write_all(request.as_bytes())?;
+
+    let reader = BufReader::new(stream);
+    let mut stdout = std::io::stdout();
+    for line in reader.lines() {
+        let line = line?;
+        stdout.write_all(line.as_bytes())?;
+        stdout.write_all(b"\n")?;
+        stdout.flush()?;
+    }
+
+    Ok(())
+}

src/main.rs

@@ -28,6 +28,7 @@ mod output;
 mod registry;
 mod signaler;
 mod state;
+mod stream;
 mod utils;
 
 use clap::{Parser, Subcommand, ValueEnum};
@@ -91,6 +92,17 @@ enum Commands {
     },
     /// Reload the daemon configuration
     Reload,
+    /// Stream module updates as newline-delimited JSON until interrupted
+    ///
+    /// Push-based alternative to polling `fluxo <module>` on a timer: one
+    /// connection, one line per actual change. Intended for bars that keep a
+    /// long-lived child process (Quickshell, ags, eww) rather than re-running a
+    /// command on a signal the way Waybar does.
+    Stream {
+        /// Modules to subscribe to (e.g. `cpu mem gpu net sys`)
+        #[arg(required = true)]
+        modules: Vec<String>,
+    },
     /// Show detailed help for all modules or a specific module
     Help {
         /// Optional module name to show detailed help for
@@ -142,6 +154,12 @@ fn main() {
                     process::exit(1);
                 }
             },
+            Commands::Stream { modules } => {
+                if let Err(e) = ipc::stream_modules(modules) {
+                    error!("Stream ended: {}", e);
+                    process::exit(1);
+                }
+            }
             Commands::Help { module } => {
                 help::print_help(module.as_deref());
             }

src/modules/backlight.rs

@@ -1,6 +1,7 @@
-//! Screen backlight indicator, driven by `inotify` on
+//! Screen backlight indicator, driven by `poll(2)` on
-//! `/sys/class/backlight/*/actual_brightness`. Falls back to a 5 s poll loop
+//! `/sys/class/backlight/*/actual_brightness`. The kernel backlight class calls
-//! to catch any missed events.
+//! `sysfs_notify` on that attribute, so it wakes on `POLLPRI`; inotify does not
+//! work on sysfs. Falls back to a 5 s timeout to catch any missed wakeups.
 
 use crate::config::Config;
 use crate::error::Result;
@@ -8,9 +9,9 @@ use crate::modules::WaybarModule;
 use crate::output::WaybarOutput;
 use crate::state::{AppReceivers, BacklightState};
 use crate::utils::{TokenValue, format_template};
-use notify::{Config as NotifyConfig, Event, RecommendedWatcher, RecursiveMode, Watcher};
+use std::io::{Read, Seek, SeekFrom};
+use std::os::fd::AsRawFd;
 use std::path::PathBuf;
-use std::sync::mpsc;
 use std::time::Duration;
 use tokio::sync::watch;
 use tracing::{error, info};
@@ -85,13 +86,16 @@ impl BacklightDaemon {
             info!("Monitoring backlight device: {:?}", dir);
 
             let max_brightness_path = dir.join("max_brightness");
-            let brightness_path = dir.join("actual_brightness");
+            let actual_path = dir.join("actual_brightness");
-            let brightness_path_fallback = dir.join("brightness");
+            let set_path = dir.join("brightness");
 
-            let target_file = if brightness_path.exists() {
+            // `brightness` is the requested level; `actual_brightness` is a
-                brightness_path
+            // hardware readback that can settle a few steps below it (amdgpu
+            // reports 64265/64764 at full), which would render as 99 %.
+            let level_file = if set_path.exists() {
+                set_path
             } else {
-                brightness_path_fallback
+                actual_path.clone()
             };
 
             let get_percentage = || -> u8 {
@@ -100,7 +104,7 @@ impl BacklightDaemon {
                     .trim()
                     .parse()
                     .unwrap_or(100.0);
-                let current: f64 = std::fs::read_to_string(&target_file)
+                let current: f64 = std::fs::read_to_string(&level_file)
                     .unwrap_or_default()
                     .trim()
                     .parse()
@@ -117,29 +121,51 @@ impl BacklightDaemon {
                 percentage: get_percentage(),
             });
 
-            let (ev_tx, ev_rx) = mpsc::channel();
+            // Watch the attribute the kernel actually notifies on, even when the
-            let mut watcher = RecommendedWatcher::new(
+            // percentage is read from `brightness`.
-                move |res: notify::Result<Event>| {
+            let watch_path = if actual_path.exists() {
-                    if let Ok(event) = res
+                actual_path
-                        && event.kind.is_modify()
+            } else {
-                    {
+                dir.join("brightness")
-                        let _ = ev_tx.send(());
+            };
-                    }
-                },
-                NotifyConfig::default(),
-            )
-            .unwrap();
 
-            if let Err(e) = watcher.watch(&target_file, RecursiveMode::NonRecursive) {
+            let Ok(mut file) = std::fs::File::open(&watch_path) else {
-                error!("Failed to watch backlight file: {}", e);
+                error!("Failed to open backlight file: {:?}", watch_path);
                 return;
-            }
+            };
+
+            // A sysfs poll event stays raised until the attribute is re-read, so
+            // every wakeup must drain the fd or poll() spins.
+            let mut scratch = String::new();
+            let mut drain = |file: &mut std::fs::File| {
+                scratch.clear();
+                let _ = file.seek(SeekFrom::Start(0));
+                let _ = file.read_to_string(&mut scratch);
+            };
+            drain(&mut file);
 
             loop {
-                if ev_rx.recv_timeout(Duration::from_secs(5)).is_ok() {
+                let mut pfd = libc::pollfd {
+                    fd: file.as_raw_fd(),
+                    events: libc::POLLPRI | libc::POLLERR,
+                    revents: 0,
+                };
+                let rc = unsafe { libc::poll(&mut pfd, 1, 5_000) };
+
+                if rc < 0 {
+                    let err = std::io::Error::last_os_error();
+                    if err.kind() == std::io::ErrorKind::Interrupted {
+                        continue;
+                    }
+                    error!("poll() on backlight failed: {}", err);
+                    return;
+                }
+
+                if rc > 0 {
+                    drain(&mut file);
                     // Debounce bursts from scroll-driven brightness changes.
                     std::thread::sleep(Duration::from_millis(50));
-                    while ev_rx.try_recv().is_ok() {}
+                    drain(&mut file);
 
                     let _ = tx.send(BacklightState {
                         percentage: get_percentage(),

src/modules/bt/mod.rs

@@ -55,60 +55,21 @@ impl BtDaemon {
             self.session = Some(bluer::Session::new().await?);
         }
         let session = self.session.as_ref().unwrap();
-        let adapter = session.default_adapter().await?;
+
+        let adapter = match session.default_adapter().await {
+            Ok(adapter) => adapter,
+            Err(e) if is_gone(&e) => return Ok(publish_powered_off(tx)),
+            Err(e) => return Err(e.into()),
+        };
         let adapter_powered = adapter.is_powered().await.unwrap_or(false);
 
         let mut connected_devices = Vec::new();
 
         if adapter_powered {
-            let mut addresses = adapter.device_addresses().await?;
+            match collect_devices(&adapter, state, config).await {
-            addresses.sort();
+                Ok(devices) => connected_devices = devices,
-            let audio_sink_uuid = bluer::Uuid::from_u128(0x0000110b_0000_1000_8000_00805f9b34fb);
+                Err(e) if is_gone(&e) => return Ok(publish_powered_off(tx)),
-
+                Err(e) => return Err(e.into()),
-            for addr in addresses {
-                let device = adapter.device(addr)?;
-                if !device.is_connected().await.unwrap_or(false) {
-                    continue;
-                }
-                let uuids = device.uuids().await?.unwrap_or_default();
-                if !uuids.contains(&audio_sink_uuid) {
-                    continue;
-                }
-
-                let mut dev_info = BtDeviceInfo {
-                    device_address: addr.to_string(),
-                    device_alias: device.alias().await.unwrap_or_else(|_| addr.to_string()),
-                    battery_percentage: device.battery_percentage().await.unwrap_or(None),
-                    plugin_data: vec![],
-                };
-
-                for p in PLUGINS.iter() {
-                    if p.can_handle(&dev_info.device_alias, &dev_info.device_address) {
-                        match p.get_data(config, state, &dev_info.device_address).await {
-                            Ok(data) => {
-                                dev_info.plugin_data = data
-                                    .into_iter()
-                                    .map(|(k, v)| {
-                                        let val_str = match v {
-                                            TokenValue::String(s) => s,
-                                            TokenValue::Int(i) => i.to_string(),
-                                            TokenValue::Float(f) => format!("{:.1}", f),
-                                        };
-                                        (k, val_str)
-                                    })
-                                    .collect();
-                            }
-                            Err(e) => {
-                                warn!("Plugin {} failed for {}: {}", p.name(), addr, e);
-                                dev_info
-                                    .plugin_data
-                                    .push(("plugin_error".to_string(), e.to_string()));
-                            }
-                        }
-                        break;
-                    }
-                }
-                connected_devices.push(dev_info);
             }
         }
 
@@ -121,6 +82,90 @@ impl BtDaemon {
     }
 }
 
+/// BlueZ tears down its adapter and device objects when the radio is switched
+/// off, so calls racing with that return `NotFound`. That is a normal
+/// bluetooth-off transition, not a failure.
+fn is_gone(err: &bluer::Error) -> bool {
+    err.kind == bluer::ErrorKind::NotFound
+}
+
+fn publish_powered_off(tx: &watch::Sender<BtState>) {
+    let _ = tx.send(BtState {
+        adapter_powered: false,
+        devices: vec![],
+    });
+}
+
+/// Collect paired+connected audio-sink devices, enriched by their plugins.
+async fn collect_devices(
+    adapter: &bluer::Adapter,
+    state: &AppReceivers,
+    config: &Config,
+) -> bluer::Result<Vec<BtDeviceInfo>> {
+    let mut addresses = adapter.device_addresses().await?;
+    addresses.sort();
+    let audio_sink_uuid = bluer::Uuid::from_u128(0x0000110b_0000_1000_8000_00805f9b34fb);
+
+    let mut connected_devices = Vec::new();
+
+    for addr in addresses {
+        let device = match adapter.device(addr) {
+            Ok(device) => device,
+            Err(e) if is_gone(&e) => continue,
+            Err(e) => return Err(e),
+        };
+        if !device.is_connected().await.unwrap_or(false) {
+            continue;
+        }
+        let uuids = match device.uuids().await {
+            Ok(uuids) => uuids.unwrap_or_default(),
+            // Device disappeared between enumeration and query.
+            Err(e) if is_gone(&e) => continue,
+            Err(e) => return Err(e),
+        };
+        if !uuids.contains(&audio_sink_uuid) {
+            continue;
+        }
+
+        let mut dev_info = BtDeviceInfo {
+            device_address: addr.to_string(),
+            device_alias: device.alias().await.unwrap_or_else(|_| addr.to_string()),
+            battery_percentage: device.battery_percentage().await.unwrap_or(None),
+            plugin_data: vec![],
+        };
+
+        for p in PLUGINS.iter() {
+            if p.can_handle(&dev_info.device_alias, &dev_info.device_address) {
+                match p.get_data(config, state, &dev_info.device_address).await {
+                    Ok(data) => {
+                        dev_info.plugin_data = data
+                            .into_iter()
+                            .map(|(k, v)| {
+                                let val_str = match v {
+                                    TokenValue::String(s) => s,
+                                    TokenValue::Int(i) => i.to_string(),
+                                    TokenValue::Float(f) => format!("{:.1}", f),
+                                };
+                                (k, val_str)
+                            })
+                            .collect();
+                    }
+                    Err(e) => {
+                        warn!("Plugin {} failed for {}: {}", p.name(), addr, e);
+                        dev_info
+                            .plugin_data
+                            .push(("plugin_error".to_string(), e.to_string()));
+                    }
+                }
+                break;
+            }
+        }
+        connected_devices.push(dev_info);
+    }
+
+    Ok(connected_devices)
+}
+
 static PLUGINS: LazyLock<Vec<Box<dyn BtPlugin>>> =
     LazyLock::new(|| vec![Box::new(PixelBudsPlugin)]);
 

src/modules/dnd.rs

@@ -20,6 +20,21 @@ use zbus::{Connection, fdo::PropertiesProxy};
 /// Renders + toggles DND state. Args: `["show"]` (default) or `["toggle"]`.
 pub struct DndModule;
 
+const SWAYNC_SERVICE: &str = "org.erikreider.swaync.control";
+
+/// Build a SwayNC proxy, but only if the service is actually on the bus.
+///
+/// Constructing the proxy unconditionally makes zbus spawn a property-caching
+/// task that logs a `ServiceUnknown` warning when SwayNC isn't running.
+async fn swaync_proxy(connection: &Connection) -> Option<SwayncControlProxy<'_>> {
+    let dbus = zbus::fdo::DBusProxy::new(connection).await.ok()?;
+    let name = zbus::names::BusName::try_from(SWAYNC_SERVICE).ok()?;
+    if !dbus.name_has_owner(name).await.unwrap_or(false) {
+        return None;
+    }
+    SwayncControlProxy::new(connection).await.ok()
+}
+
 /// Read dunst's `paused` property via raw D-Bus call.
 async fn dunst_get_paused(connection: &Connection) -> anyhow::Result<bool> {
     let reply = connection
@@ -68,7 +83,7 @@ impl WaybarModule for DndModule {
                         message: format!("DBus connection failed: {}", e),
                     })?;
 
-            if let Ok(proxy) = SwayncControlProxy::new(&connection).await
+            if let Some(proxy) = swaync_proxy(&connection).await
                 && let Ok(is_dnd) = proxy.dnd().await
             {
                 let _ = proxy.set_dnd(!is_dnd).await;
@@ -145,14 +160,14 @@ impl DndDaemon {
 
         info!("Connected to D-Bus for DND monitoring");
 
-        if let Ok(proxy) = SwayncControlProxy::new(&connection).await
+        if let Some(proxy) = swaync_proxy(&connection).await
             && let Ok(is_dnd) = proxy.dnd().await
         {
             debug!("Found SwayNC, using signal-based DND monitoring");
             let _ = tx.send(DndState { is_dnd });
 
             if let Ok(props_proxy) = PropertiesProxy::builder(&connection)
-                .destination("org.erikreider.swaync.control")?
+                .destination(SWAYNC_SERVICE)?
                 .path("/org/erikreider/swaync/control")?
                 .build()
                 .await

src/modules/hardware.rs

@@ -14,14 +14,48 @@ use tokio::sync::watch;
 pub struct HardwareDaemon {
     sys: System,
     components: Components,
+    /// User-forced CPU sensor label substring; empty means auto-detect.
+    temp_sensor: String,
     gpu_vendor: Option<String>,
     gpu_poll_counter: u8,
     disk_poll_counter: u8,
 }
 
+/// Sensors that are never the CPU but whose labels can look like one. Unlabeled
+/// hwmon channels reach us as `"<driver> temp1"`, so a bare `temp1` match would
+/// happily pick up the WiFi card or the NVMe drive.
+const NON_CPU_SENSORS: &[&str] = &[
+    "iwlwifi", "wifi", "nvme", "amdgpu", "nouveau", "gpu", "bat", "acpi ac", "composite", "edge",
+    "junction", "mem",
+];
+
+/// Score a component label for "is this the CPU package temperature".
+/// Higher wins; 0 means unusable.
+fn cpu_sensor_rank(label: &str) -> u8 {
+    if NON_CPU_SENSORS.iter().any(|s| label.contains(s)) {
+        return 0;
+    }
+    // AMD (k10temp) and Intel (coretemp) package sensors are the canonical ones.
+    if label.contains("tctl") || label.contains("tdie") || label.contains("package") {
+        100
+    } else if label.contains("core ") {
+        80
+    } else if label.contains("cpu") {
+        // e.g. thinkpad_acpi's "thinkpad CPU" — right sensor, coarser reading.
+        70
+    } else if label.contains("k10temp") || label.contains("coretemp") {
+        60
+    } else if label.contains("acpitz") {
+        20
+    } else {
+        0
+    }
+}
+
 impl HardwareDaemon {
-    /// Build a new daemon with an initial `sysinfo` snapshot.
+    /// Build a new daemon with an initial `sysinfo` snapshot. `temp_sensor` is
-    pub fn new() -> Self {
+    /// the configured CPU sensor override (empty to auto-detect).
+    pub fn new(temp_sensor: String) -> Self {
         let mut sys = System::new();
         sys.refresh_cpu_usage();
         sys.refresh_memory();
@@ -29,6 +63,7 @@ impl HardwareDaemon {
         Self {
             sys,
             components,
+            temp_sensor: temp_sensor.to_lowercase(),
             gpu_vendor: None,
             gpu_poll_counter: 0,
             // Start at 9 so (counter + 1) % 10 == 0 on the first tick.
@@ -57,18 +92,24 @@ impl HardwareDaemon {
             .unwrap_or_else(|| "Unknown".to_string());
 
         let mut cpu_temp = 0.0;
+        let mut best_rank = 0;
         for component in &self.components {
             let label = component.label().to_lowercase();
-            if (label.contains("tctl")
+
-                || label.contains("cpu")
+            let rank = if self.temp_sensor.is_empty() {
-                || label.contains("package")
+                cpu_sensor_rank(&label)
-                || label.contains("temp1"))
+            } else if label.contains(&self.temp_sensor) {
+                u8::MAX
+            } else {
+                0
+            };
+
+            if rank > best_rank
                 && let Some(temp) = component.temperature()
+                && temp > 0.0
             {
                 cpu_temp = temp as f64;
-                if cpu_temp > 0.0 {
+                best_rank = rank;
-                    break;
-                }
             }
         }
 

src/modules/network.rs

@@ -207,6 +207,11 @@ fn get_primary_interface() -> Result<String> {
             let mask = u32::from_str_radix(parts[7], 16).unwrap_or(0);
 
             if dest == "00000000" {
+                // Skip ProtonVPN kill-switch interfaces — they exist
+                // only for leak protection and don't carry real traffic.
+                if iface.starts_with("pvpnksintrf") {
+                    continue;
+                }
                 defaults.push((mask, metric, iface.to_string()));
             }
         }

src/signaler.rs

@@ -5,24 +5,42 @@
 //! `watch::Receiver`, evaluates the module when its channel fires, and only
 //! signals Waybar when the rendered output actually changed. A 50 ms per-signal
 //! debounce prevents storms during rapid state churn.
+//!
+//! Waybar is optional: a bar that reads the daemon over `fluxo stream` (see
+//! [`crate::stream`]) never wants a signal at all. Discovery is therefore
+//! written to be cheap *and* to stay cheap when Waybar is simply not installed —
+//! see [`WaybarSignaler::send_signal`].
 
 use crate::config::Config;
 use crate::state::AppReceivers;
 use std::collections::HashMap;
 use std::sync::Arc;
-use sysinfo::{ProcessesToUpdate, System};
 use tokio::sync::RwLock;
 use tokio::time::{Duration, Instant, sleep};
 use tracing::{debug, warn};
 
+/// Shortest gap between two signals with the same number.
+const SIGNAL_DEBOUNCE: Duration = Duration::from_millis(50);
+
+/// First cooldown applied after a failed Waybar lookup.
+const DISCOVERY_BACKOFF_MIN: Duration = Duration::from_secs(2);
+
+/// Ceiling for the discovery cooldown. A Waybar started later is still picked
+/// up within this long, which is well inside "I just launched my bar" latency.
+const DISCOVERY_BACKOFF_MAX: Duration = Duration::from_secs(60);
+
 /// Sends real-time signals to the Waybar process.
 ///
 /// Resolves Waybar's PID lazily and caches it — the PID is invalidated on
-/// signal failure (e.g. Waybar was restarted) and rediscovered via `sysinfo`.
+/// signal failure (e.g. Waybar was restarted) and rediscovered by scanning
+/// `/proc`. Failed lookups are cached too, under an exponential cooldown.
 pub struct WaybarSignaler {
     cached_pid: Option<i32>,
-    sys: System,
     last_signal_sent: HashMap<i32, Instant>,
+    /// When set, no rescan of `/proc` happens before this instant.
+    discovery_blocked_until: Option<Instant>,
+    /// Current cooldown length, doubling on each consecutive failed lookup.
+    discovery_backoff: Duration,
 }
 
 impl WaybarSignaler {
@@ -30,50 +48,97 @@ impl WaybarSignaler {
     pub fn new() -> Self {
         Self {
             cached_pid: None,
-            sys: System::new(),
             last_signal_sent: HashMap::new(),
+            discovery_blocked_until: None,
+            discovery_backoff: DISCOVERY_BACKOFF_MIN,
         }
     }
 
-    fn find_waybar_pid(&mut self) -> Option<i32> {
+    /// Scan `/proc` for a process named `waybar`.
-        self.sys.refresh_processes(ProcessesToUpdate::All, true);
+    ///
-        for (pid, process) in self.sys.processes() {
+    /// Reads only `/proc/<pid>/comm`, one short line per process. The previous
-            if process.name() == "waybar" {
+    /// implementation called `sysinfo`'s `refresh_processes(All, true)`, which
-                return Some(pid.as_u32() as i32);
+    /// walks every thread of every process and parses `stat`, `status` and
+    /// `cmdline` for each — thousands of file reads per call with a browser
+    /// open, and it ran on *every* signal (see `send_signal`).
+    fn find_waybar_pid() -> Option<i32> {
+        let dir = std::fs::read_dir("/proc").ok()?;
+        for entry in dir.flatten() {
+            let file_name = entry.file_name();
+            let Some(pid) = file_name.to_str().and_then(|s| s.parse::<i32>().ok()) else {
+                continue;
+            };
+            // `comm` is truncated to 15 bytes by the kernel, which "waybar"
+            // comfortably fits inside.
+            if let Ok(comm) = std::fs::read_to_string(format!("/proc/{}/comm", pid))
+                && comm.trim_end() == "waybar"
+            {
+                return Some(pid);
             }
         }
         None
     }
 
-    fn send_signal(&mut self, signal_num: i32) {
+    /// Resolve Waybar's PID, honouring the failed-lookup cooldown.
-        if let Some(last) = self.last_signal_sent.get(&signal_num)
+    fn resolve_pid(&mut self) -> Option<i32> {
-            && last.elapsed() < Duration::from_millis(50)
-        {
-            return;
-        }
-
-        let mut valid_pid = false;
         if let Some(pid) = self.cached_pid
             && unsafe { libc::kill(pid, 0) } == 0
         {
-            valid_pid = true;
+            return Some(pid);
+        }
+        self.cached_pid = None;
+
+        if let Some(until) = self.discovery_blocked_until
+            && Instant::now() < until
+        {
+            return None;
         }
 
-        if !valid_pid {
+        match Self::find_waybar_pid() {
-            self.cached_pid = self.find_waybar_pid();
+            Some(pid) => {
-        }
+                debug!("Discovered waybar at PID {}", pid);
-
+                self.cached_pid = Some(pid);
-        if let Some(pid) = self.cached_pid {
+                self.discovery_blocked_until = None;
-            let sig = libc::SIGRTMIN() + signal_num;
+                self.discovery_backoff = DISCOVERY_BACKOFF_MIN;
-            if unsafe { libc::kill(pid, sig) } == 0 {
+                Some(pid)
-                debug!("Sent SIGRTMIN+{} to waybar (PID: {})", signal_num, pid);
-                self.last_signal_sent.insert(signal_num, Instant::now());
-            } else {
-                warn!("Failed to send SIGRTMIN+{} to waybar", signal_num);
-                self.cached_pid = None;
             }
+            None => {
+                // Nothing to signal. Without this cooldown every state change
+                // rescanned /proc, which on a Waybar-less setup meant a full
+                // process walk several times a second, forever.
+                self.discovery_blocked_until = Some(Instant::now() + self.discovery_backoff);
+                self.discovery_backoff =
+                    (self.discovery_backoff * 2).min(DISCOVERY_BACKOFF_MAX);
+                debug!(
+                    "No waybar process; pausing discovery for {:?}",
+                    self.discovery_backoff
+                );
+                None
+            }
+        }
+    }
+
+    fn send_signal(&mut self, signal_num: i32) {
+        // Debounce on attempt, not on success: recording the timestamp only
+        // after a successful send meant a missing Waybar bypassed the debounce
+        // entirely, so nothing throttled the work below.
+        if let Some(last) = self.last_signal_sent.get(&signal_num)
+            && last.elapsed() < SIGNAL_DEBOUNCE
+        {
+            return;
+        }
+        self.last_signal_sent.insert(signal_num, Instant::now());
+
+        let Some(pid) = self.resolve_pid() else {
+            return;
+        };
+
+        let sig = libc::SIGRTMIN() + signal_num;
+        if unsafe { libc::kill(pid, sig) } == 0 {
+            debug!("Sent SIGRTMIN+{} to waybar (PID: {})", signal_num, pid);
         } else {
-            debug!("Waybar process not found, skipping signal.");
+            warn!("Failed to send SIGRTMIN+{} to waybar", signal_num);
+            self.cached_pid = None;
         }
     }
 }

src/stream.rs

@@ -0,0 +1,176 @@
+//! Push-based module streaming for bars that are not Waybar.
+//!
+//! Waybar's model is *signal the bar, the bar re-runs a command*, so the
+//! one-shot `fluxo <module>` client is the natural fit there. Every other shell
+//! (Quickshell, ags, eww, …) has to emulate it by polling — spawning a process
+//! per module per interval. At a 2 s interval over five modules that is 2.5
+//! forks a second, each one exec'ing and dynamically linking a 13 MB binary to
+//! read a value the daemon already has in memory, and it still shows values up
+//! to one interval stale.
+//!
+//! This module is the alternative: one long-lived connection, over which the
+//! daemon writes a JSON line whenever a subscribed module's rendered output
+//! actually changes.
+//!
+//!     $ fluxo stream cpu mem net
+//!     {"module":"cpu","text":"7.4|41.0"}
+//!     {"module":"mem","text":"9.41|15.49"}
+//!     {"module":"cpu","text":"6.9|40.5"}
+//!
+//! Each line is one complete JSON object with a `module` key naming the source
+//! and the module's usual fields (`text`, and `tooltip`/`class`/`percentage`
+//! when set) flattened alongside it. Unlike the one-shot client, `text` is *not*
+//! passed through [`crate::output::stabilize_text`]: the figure-space and
+//! zero-width-space padding exists to stop Waybar's proportional font from
+//! reflowing, and it is noise to a consumer that does its own layout.
+
+use crate::config::Config;
+use crate::output::WaybarOutput;
+use crate::state::AppReceivers;
+use serde::Serialize;
+use std::collections::HashMap;
+use std::sync::Arc;
+use tokio::io::AsyncWriteExt;
+use tokio::sync::RwLock;
+use tokio::time::{Duration, sleep};
+use tracing::debug;
+
+/// How often subscribed modules are re-evaluated regardless of channel
+/// activity.
+///
+/// This covers the dispatch-only modules (`power`, `game`, `pool`), which have
+/// no watch channel to wake us, and doubles as a safety net for any state that
+/// changes without its channel firing. Unchanged output is never written, so a
+/// quiet tick costs nothing on the wire.
+const SWEEP_INTERVAL: Duration = Duration::from_secs(5);
+
+/// One line of the stream: the module's own fields plus which module they came
+/// from.
+#[derive(Serialize)]
+struct StreamEvent<'a> {
+    module: &'a str,
+    #[serde(flatten)]
+    output: WaybarOutput,
+}
+
+/// Render `module_name` and return its serialised [`StreamEvent`] line.
+async fn render_line(
+    module_name: &str,
+    state: &AppReceivers,
+    config: &Config,
+) -> Option<String> {
+    let args = crate::registry::signaler_default_args(module_name);
+    let output = crate::registry::dispatch(module_name, config, state, args)
+        .await
+        .ok()?;
+    let mut line = serde_json::to_string(&StreamEvent {
+        module: module_name,
+        output,
+    })
+    .ok()?;
+    line.push('\n');
+    Some(line)
+}
+
+/// Generates [`run_stream`] from the central module registry.
+///
+/// The shape mirrors [`crate::signaler`]: one cfg-gated `changed()` future per
+/// watched module, and one `select!` arm per module that re-renders the module
+/// names that channel feeds.
+macro_rules! gen_stream {
+    ($( { $feature:literal, $field:ident, $state:ty, [$($name:literal),+], [$($sig_name:literal),+], $module:path, $signal:ident, [$($default_arg:literal),*], $config:ident } )*) => {
+        /// Serve one `stream` connection until the client disconnects.
+        ///
+        /// `requested` holds the module names the client subscribed to; any name
+        /// the registry does not know simply never produces output.
+        pub async fn run_stream<W: AsyncWriteExt + Unpin>(
+            mut writer: W,
+            requested: Vec<String>,
+            receivers: AppReceivers,
+            config_lock: Arc<RwLock<Config>>,
+        ) {
+            debug!(modules = ?requested, "Stream client subscribed");
+
+            // Two handles on the same channels: `watchers` is what we await
+            // changes on (needs `&mut`), `evaluator` is what module rendering
+            // reads from (needs `&`). Splitting them keeps the borrow checker
+            // out of the `select!` below; a `watch::Receiver` clone still sees
+            // the latest published value, so reads are unaffected.
+            let mut watchers = receivers.clone();
+            let evaluator = receivers;
+
+            let mut last: HashMap<String, String> = HashMap::new();
+
+            // Re-render every subscribed module and write the ones that moved.
+            // Returns false once the client is gone.
+            macro_rules! flush_modules {
+                ($names:expr) => {{
+                    let mut alive = true;
+                    for name in $names {
+                        if !requested.iter().any(|r| r == name) {
+                            continue;
+                        }
+                        let line = {
+                            let config = config_lock.read().await;
+                            render_line(name, &evaluator, &config).await
+                        };
+                        let Some(line) = line else { continue };
+                        if last.get(name).is_some_and(|prev| prev == &line) {
+                            continue;
+                        }
+                        last.insert(name.to_string(), line.clone());
+                        if writer.write_all(line.as_bytes()).await.is_err()
+                            || writer.flush().await.is_err()
+                        {
+                            alive = false;
+                            break;
+                        }
+                    }
+                    alive
+                }};
+            }
+
+            // Prime the client with a full snapshot so a bar renders correctly
+            // the instant it connects, rather than after the first change.
+            let all: Vec<&str> = requested.iter().map(|s| s.as_str()).collect();
+            if !flush_modules!(all.iter().copied()) {
+                debug!("Stream client disconnected during initial snapshot");
+                return;
+            }
+
+            loop {
+                $(
+                    #[cfg(not(feature = $feature))]
+                    let $field = std::future::pending::<
+                        std::result::Result<(), tokio::sync::watch::error::RecvError>,
+                    >();
+                    #[cfg(feature = $feature)]
+                    let $field = watchers.$field.changed();
+                )*
+
+                let alive = tokio::select! {
+                    $(
+                        res = $field => {
+                            if res.is_ok() {
+                                flush_modules!([$($sig_name),+])
+                            } else {
+                                true
+                            }
+                        }
+                    )*
+                    _ = sleep(SWEEP_INTERVAL) => {
+                        flush_modules!(all.iter().copied())
+                    }
+                };
+
+                if !alive {
+                    break;
+                }
+            }
+
+            debug!("Stream client disconnected");
+        }
+    };
+}
+
+for_each_watched_module!(gen_stream);