From d194d2a226a56933485dd207cb94f3f1d7b4f423 Mon Sep 17 00:00:00 2001
From: lambda <lambda@bjornmossa.net>
Date: Mon, 26 Oct 2026 18:30:47 +0300
Subject: [PATCH] fix: per-cycle control slot to close reconnect race,
 idempotent battery icon

---
 src-tauri/src/ble/source.rs | 20 +++++++++++++-------
 src/main.js                 |  5 ++++-
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/src-tauri/src/ble/source.rs b/src-tauri/src/ble/source.rs
index 09a36fd..a86b613 100644
--- a/src-tauri/src/ble/source.rs
+++ b/src-tauri/src/ble/source.rs
@@ -46,15 +46,17 @@ const CONTROL_POLL_INTERVAL: Duration = Duration::from_millis(50);
 /// Реальный источник данных через btleplug.
 pub(crate) struct BleSource {
     adapter: Adapter,
-    /// Last control result (set by the notification router, awaited by `request_control`).
-    control: Arc<Mutex<Option<ControlResult>>>,
+    /// Current cycle's control-result slot. Each `stream()` swaps in a fresh slot so a
+    /// still-winding-down router from the previous cycle writes to a discarded slot,
+    /// never the one the new cycle's `request_control` polls.
+    control: Mutex<Arc<Mutex<Option<ControlResult>>>>,
 }
 
 impl BleSource {
     pub(crate) fn new(adapter: Adapter) -> Self {
         Self {
             adapter,
-            control: Arc::new(Mutex::new(None)),
+            control: Mutex::new(Arc::new(Mutex::new(None))),
         }
     }
 
@@ -130,7 +132,10 @@ impl SensorSource for BleSource {
         // This keeps the control-result flow concurrent with the telemetry consumer so that
         // `request_control` can await confirmation while telemetry is still being consumed.
         let (tx, rx) = tokio::sync::mpsc::unbounded_channel::<Telemetry>();
-        let control = self.control.clone();
+        // Swap in a fresh control slot for this cycle; the previous cycle's router holds
+        // the old slot and can only write there, so it cannot race this cycle's poll.
+        let control = Arc::new(Mutex::new(None));
+        *self.control.lock().unwrap() = control.clone();
         let (cancel_tx, cancel_rx) = oneshot::channel::<()>();
 
         tokio::spawn(async move {
@@ -191,7 +196,8 @@ impl SensorSource for BleSource {
             .ok_or_else(|| BleError::DeviceNotFound(cp_uuid.to_string()))?;
 
         // Reset and send Request Control (opcode 0x00).
-        *self.control.lock().unwrap() = None;
+        let slot = self.control.lock().unwrap().clone();
+        *slot.lock().unwrap() = None;
         let (_, payload) = encode_command(Command::FtmsRequestControl);
         peripheral
             .write(&ch, &payload, WriteType::WithoutResponse)
@@ -199,9 +205,9 @@ impl SensorSource for BleSource {
             .map_err(BleError::WriteFailed)?;
 
         // Wait for the Control Point Response (routed by the stream's notification task).
-        let result = tokio::time::timeout(CONTROL_CONFIRM_TIMEOUT, async {
+        let result = tokio::time::timeout(CONTROL_CONFIRM_TIMEOUT, async move {
             loop {
-                let current = *self.control.lock().unwrap();
+                let current = *slot.lock().unwrap();
                 if let Some(r) = current {
                     return r;
                 }
diff --git a/src/main.js b/src/main.js
index fa15a92..7eb5121 100644
--- a/src/main.js
+++ b/src/main.js
@@ -142,7 +142,10 @@ once("devices-loaded", (event) => {
 listen("battery", (event) => {
   const { device_id, percent } = event.payload;
   const card = deviceCards.get(device_id);
-  if (card) card.querySelector(".device__head").append(batteryIcon(percent));
+  if (!card) return;
+  const head = card.querySelector(".device__head");
+  head.querySelector(".battery")?.remove();
+  head.append(batteryIcon(percent));
 });
 
 listen("telemetry", (event) => {