linux-rust(feat): add stem press track control and headless mode support (#469)

* feat: add stem press track control and headless mode support

- Parse STEM_PRESS packets and emit AACPEvent::StemPress with press type and bud side
- Enable double/triple tap detection on init via StemConfig control command (0x06)
- Double press → next track, triple press → previous track via MPRIS D-Bus
- Add next_track() and previous_track() to MediaController
- Add --no-tray flag for headless operation without a GUI
- Replace unwrap() on ui_tx.send() calls with graceful warn! logging

(vibecoded)

* Update main.rs

* feat: make stem press track control optional with GUI toggle

Add a --no-stem-control CLI flag and a toggle in the Settings tab for
environments that handle AirPods AVRCP commands natively (e.g. via
BlueZ/PipeWire). The feature remains enabled by default.

- Load stem_control from app settings JSON on startup; --no-stem-control
  overrides it to false regardless of the saved value
- Share an Arc<AtomicBool> between the async backend and the GUI thread;
  AirPodsDevice holds the Arc directly so the event loop reads the live
  value on every stem press — toggle takes effect immediately without
  reconnecting
- Persist stem_control to settings JSON alongside theme and tray_text_mode
- Add a "Controls" section to the Settings tab with a toggler labelled
  "Stem press track control", with a subtitle explaining the AVRCP
  conflict scenario
- Fix StemConfig bitmask comment to clarify it uses a separate numbering
  scheme from the StemPressType event enum values (0x05–0x08)

Author: andreyondemand

linux-rust/src/bluetooth/aacp.rs

@@ -200,13 +200,35 @@ pub enum StemPressType {
     LongPress = 0x08,
 }
 
+impl StemPressType {
+    fn from_u8(value: u8) -> Option<Self> {
+        match value {
+            0x05 => Some(Self::SinglePress),
+            0x06 => Some(Self::DoublePress),
+            0x07 => Some(Self::TriplePress),
+            0x08 => Some(Self::LongPress),
+            _ => None,
+        }
+    }
+}
+
 #[repr(u8)]
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum StemPressBudType {
     Left = 0x01,
     Right = 0x02,
 }
 
+impl StemPressBudType {
+    fn from_u8(value: u8) -> Option<Self> {
+        match value {
+            0x01 => Some(Self::Left),
+            0x02 => Some(Self::Right),
+            _ => None,
+        }
+    }
+}
+
 #[repr(u8)]
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum AudioSourceType {
@@ -283,6 +305,7 @@ pub enum AACPEvent {
     AudioSource(AudioSource),
     ConnectedDevices(Vec<ConnectedDevice>, Vec<ConnectedDevice>),
     OwnershipToFalseRequest,
+    StemPress(StemPressType, StemPressBudType),
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -795,7 +818,26 @@ impl AACPManager {
                     error!("Failed to save devices: {}", e);
                 }
             }
-            opcodes::STEM_PRESS => info!("Received Stem Press packet."),
+            opcodes::STEM_PRESS => {
+                if payload.len() < 4 {
+                    error!("Stem Press packet too short: {}", hex::encode(payload));
+                    return;
+                }
+                let press_type = StemPressType::from_u8(payload[2]);
+                let bud_type = StemPressBudType::from_u8(payload[3]);
+                if let (Some(press), Some(bud)) = (press_type, bud_type) {
+                    info!("Received Stem Press: {:?} on {:?}", press, bud);
+                    let state = self.state.lock().await;
+                    if let Some(ref tx) = state.event_tx {
+                        let _ = tx.send(AACPEvent::StemPress(press, bud));
+                    }
+                } else {
+                    error!(
+                        "Invalid Stem Press packet - type: {:?}, bud: {:?}",
+                        press_type, bud_type
+                    );
+                }
+            }
             opcodes::AUDIO_SOURCE => {
                 if payload.len() < 9 {
                     error!("Audio Source packet too short: {}", hex::encode(payload));

linux-rust/src/devices/airpods.rs

@@ -8,6 +8,7 @@ use ksni::Handle;
 use log::{debug, error, info};
 use serde::{Deserialize, Serialize};
 use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, Ordering};
 use tokio::sync::Mutex;
 use tokio::time::{Duration, sleep};
 
@@ -24,6 +25,7 @@ impl AirPodsDevice {
         mac_address: Address,
         tray_handle: Option<Handle<MyTray>>,
         ui_tx: tokio::sync::mpsc::UnboundedSender<BluetoothUIMessage>,
+        stem_control: Arc<AtomicBool>,
     ) -> Self {
         info!("Creating new AirPodsDevice for {}", mac_address);
         let mut aacp_manager = AACPManager::new();
@@ -80,6 +82,20 @@ impl AirPodsDevice {
             error!("Failed to request proximity keys: {}", e);
         }
 
+        if stem_control.load(Ordering::Relaxed) {
+            // Enable stem press detection (double and triple tap)
+            // StemConfig bitmask for the control command: single=0x01, double=0x02, triple=0x04, long=0x08
+            // We want double and triple: 0x02 | 0x04 = 0x06
+            // Note: these bitmask values differ from the StemPressType event enum values (0x05–0x08)
+            info!("Enabling stem press detection for double and triple tap");
+            if let Err(e) = aacp_manager
+                .send_control_command(ControlCommandIdentifiers::StemConfig, &[0x06])
+                .await
+            {
+                error!("Failed to enable stem press detection: {}", e);
+            }
+        }
+
         let session = bluer::Session::new()
             .await
             .expect("Failed to get bluer session");
@@ -206,6 +222,7 @@ impl AirPodsDevice {
         let local_mac_events = local_mac.clone();
         let ui_tx_clone = ui_tx.clone();
         let command_tx_clone = command_tx.clone();
+        let stem_control_clone = stem_control.clone();
         tokio::spawn(async move {
             while let Some(event) = rx.recv().await {
                 let event_clone = event.clone();
@@ -325,6 +342,31 @@ impl AirPodsDevice {
                         controller.pause_all_media().await;
                         controller.deactivate_a2dp_profile().await;
                     }
+                    AACPEvent::StemPress(press_type, bud_type) => {
+                        use crate::bluetooth::aacp::StemPressType;
+                        info!(
+                            "Received Stem Press: {:?} on {:?}",
+                            press_type, bud_type
+                        );
+                        if stem_control_clone.load(Ordering::Relaxed) {
+                            let controller = mc_clone.lock().await;
+                            match press_type {
+                                StemPressType::DoublePress => {
+                                    info!("Double press detected, skipping to next track");
+                                    controller.next_track().await;
+                                }
+                                StemPressType::TriplePress => {
+                                    info!("Triple press detected, going to previous track");
+                                    controller.previous_track().await;
+                                }
+                                _ => {
+                                    debug!("Unhandled stem press type: {:?}", press_type);
+                                }
+                            }
+                        } else {
+                            debug!("Stem control disabled, ignoring stem press event");
+                        }
+                    }
                     _ => {
                         debug!("Received unhandled AACP event: {:?}", event);
                         let _ = ui_tx_clone.send(BluetoothUIMessage::AACPUIEvent(

linux-rust/src/main.rs

@@ -10,7 +10,7 @@ use crate::bluetooth::managers::DeviceManagers;
 use crate::devices::enums::DeviceData;
 use crate::ui::messages::BluetoothUIMessage;
 use crate::ui::tray::MyTray;
-use crate::utils::get_devices_path;
+use crate::utils::{get_app_settings_path, get_devices_path};
 use bluer::{Address, InternalErrorKind};
 use clap::Parser;
 use dbus::arg::{RefArg, Variant};
@@ -19,9 +19,10 @@ use dbus::blocking::stdintf::org_freedesktop_dbus::Properties;
 use dbus::message::MatchRule;
 use devices::airpods::AirPodsDevice;
 use ksni::TrayMethods;
-use log::info;
+use log::{info, warn};
 use std::collections::HashMap;
 use std::env;
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 use tokio::sync::RwLock;
 use tokio::sync::mpsc::unbounded_channel;
@@ -44,6 +45,11 @@ struct Args {
     le_debug: bool,
     #[arg(long, short = 'v', help = "Show application version and exit")]
     version: bool,
+    #[arg(
+        long,
+        help = "Disable stem press track control (use this if your environment already handles AirPods AVRCP commands natively)"
+    )]
+    no_stem_control: bool,
 }
 
 fn main() -> iced::Result {
@@ -59,10 +65,10 @@ fn main() -> iced::Result {
 
     let log_level = if args.debug { "debug" } else { "info" };
     let wayland_display = env::var("WAYLAND_DISPLAY").is_ok();
+    if wayland_display && env::var("WGPU_BACKEND").is_err() {
+        unsafe { env::set_var("WGPU_BACKEND", "gl") };
+    }
     if env::var("RUST_LOG").is_err() {
-        if wayland_display {
-            unsafe { env::set_var("WGPU_BACKEND", "gl") };
-        }
         unsafe {
             env::set_var(
                 "RUST_LOG",
@@ -80,19 +86,42 @@ fn main() -> iced::Result {
 
     let device_managers: Arc<RwLock<HashMap<String, DeviceManagers>>> =
         Arc::new(RwLock::new(HashMap::new()));
-    let device_managers_clone = device_managers.clone();
-    std::thread::spawn(|| {
+
+    // Load stem_control initial value from settings JSON, then apply CLI override.
+    let app_settings_path = get_app_settings_path();
+    let saved_stem_control = std::fs::read_to_string(&app_settings_path)
+        .ok()
+        .and_then(|s| serde_json::from_str::<serde_json::Value>(&s).ok())
+        .and_then(|v| v.get("stem_control").and_then(|b| b.as_bool()))
+        .unwrap_or(true);
+    // CLI --no-stem-control overrides the saved setting.
+    let stem_control_initial = if args.no_stem_control { false } else { saved_stem_control };
+    let stem_control: Arc<AtomicBool> = Arc::new(AtomicBool::new(stem_control_initial));
+
+    if args.no_tray {
+        // Run headless without UI
+        info!("Running in headless mode (no GUI)");
         let rt = tokio::runtime::Runtime::new().unwrap();
-        rt.block_on(async_main(ui_tx, device_managers_clone))
-            .unwrap();
-    });
+        rt.block_on(async_main(ui_tx, device_managers, stem_control)).unwrap();
+        Ok(())
+    } else {
+        // Run with UI
+        let device_managers_clone = device_managers.clone();
+        let stem_control_clone = stem_control.clone();
+        std::thread::spawn(|| {
+            let rt = tokio::runtime::Runtime::new().unwrap();
+            rt.block_on(async_main(ui_tx, device_managers_clone, stem_control_clone))
+                .unwrap();
+        });
 
-    ui::window::start_ui(ui_rx, args.start_minimized, device_managers)
+        ui::window::start_ui(ui_rx, args.start_minimized, device_managers, stem_control)
+    }
 }
 
 async fn async_main(
     ui_tx: tokio::sync::mpsc::UnboundedSender<BluetoothUIMessage>,
     device_managers: Arc<RwLock<HashMap<String, DeviceManagers>>>,
+    stem_control: Arc<AtomicBool>,
 ) -> bluer::Result<()> {
     let args = Args::parse();
 
@@ -160,7 +189,7 @@ async fn async_main(
                 .unwrap_or_else(|| "Unknown".to_string());
             info!("Found connected AirPods: {}, initializing.", name);
             let airpods_device =
-                AirPodsDevice::new(device.address(), tray_handle.clone(), ui_tx.clone()).await;
+                AirPodsDevice::new(device.address(), tray_handle.clone(), ui_tx.clone(), stem_control.clone()).await;
 
             let mut managers = device_managers.write().await;
             // let dev_managers = DeviceManagers::with_both(airpods_device.aacp_manager.clone(), airpods_device.att_manager.clone());
@@ -170,11 +199,11 @@ async fn async_main(
                 .or_insert(dev_managers)
                 .set_aacp(airpods_device.aacp_manager);
             drop(managers);
-            ui_tx
-                .send(BluetoothUIMessage::DeviceConnected(
-                    device.address().to_string(),
-                ))
-                .unwrap();
+            if let Err(e) = ui_tx.send(BluetoothUIMessage::DeviceConnected(
+                device.address().to_string(),
+            )) {
+                warn!("Failed to send DeviceConnected UI message: {:?}", e);
+            }
         }
         Err(_) => {
             info!("No connected AirPods found.");
@@ -205,9 +234,9 @@ async fn async_main(
                             .entry(addr_str.clone())
                             .or_insert(dev_managers)
                             .set_att(dev.att_manager);
-                        ui_tx_clone
-                            .send(BluetoothUIMessage::DeviceConnected(addr_str))
-                            .unwrap();
+                        if let Err(e) = ui_tx_clone.send(BluetoothUIMessage::DeviceConnected(addr_str)) {
+                            warn!("Failed to send DeviceConnected UI message: {:?}", e);
+                        }
                     }
                     drop(managers)
                 });
@@ -280,9 +309,9 @@ async fn async_main(
                         .or_insert(dev_managers)
                         .set_att(dev.att_manager);
                     drop(managers);
-                    ui_tx_clone
-                        .send(BluetoothUIMessage::DeviceConnected(addr_str.clone()))
-                        .unwrap();
+                    if let Err(e) = ui_tx_clone.send(BluetoothUIMessage::DeviceConnected(addr_str.clone())) {
+                        warn!("Failed to send DeviceConnected UI message: {:?}", e);
+                    }
                 });
             }
             return true;
@@ -298,8 +327,9 @@ async fn async_main(
         let handle_clone = tray_handle.clone();
         let ui_tx_clone = ui_tx.clone();
         let device_managers = device_managers.clone();
+        let stem_control_arc = stem_control.clone();
         tokio::spawn(async move {
-            let airpods_device = AirPodsDevice::new(addr, handle_clone, ui_tx_clone.clone()).await;
+            let airpods_device = AirPodsDevice::new(addr, handle_clone, ui_tx_clone.clone(), stem_control_arc.clone()).await;
             let mut managers = device_managers.write().await;
             // let dev_managers = DeviceManagers::with_both(airpods_device.aacp_manager.clone(), airpods_device.att_manager.clone());
             let dev_managers = DeviceManagers::with_aacp(airpods_device.aacp_manager.clone());
@@ -308,9 +338,9 @@ async fn async_main(
                 .or_insert(dev_managers)
                 .set_aacp(airpods_device.aacp_manager);
             drop(managers);
-            ui_tx_clone
-                .send(BluetoothUIMessage::DeviceConnected(addr_str.clone()))
-                .unwrap();
+            if let Err(e) = ui_tx_clone.send(BluetoothUIMessage::DeviceConnected(addr_str.clone())) {
+                warn!("Failed to send DeviceConnected UI message: {:?}", e);
+            }
         });
         true
     })?;