trying to fix, not success yet

flake.nix

@@ -25,6 +25,7 @@
         cargo-espflash
         espup
 	mosquitto
+	mermaid-cli
       ];
 
 shellHook = ''

mqtt_display/docs/critical_data_flow_points.mermaid

@@ -0,0 +1,37 @@
+graph TD
+    START[MPU reads @50ms = 20 Hz] --> A{IMU_CHANNEL<br/>try_send}
+    
+    A -->|Full| DROP1[❌ DROP: Channel full<br/>16 slots @ 50ms = 800ms buffer]
+    A -->|OK| B[Main Loop receive]
+    
+    B --> C[Drain loop:<br/>Get freshest reading]
+    C --> D{Time check:<br/>≥3s since last?}
+    
+    D -->|No| E[Skip MQTT]
+    D -->|Yes| F{mqtt_set_imu<br/>try_lock IMU_LATEST}
+    
+    F -->|Locked| DROP2[❌ SKIP: Mutex busy]
+    F -->|OK| G[Store payload]
+    
+    E --> H[show_imu]
+    G --> H
+    
+    H --> I{DISPLAY_CHANNEL<br/>try_send}
+    I -->|Full| DROP3[❌ DROP: Display slow<br/>8 slots @ 100ms = 800ms buffer]
+    I -->|OK| J[Display renders]
+    
+    G --> K[MQTT Task loop]
+    K --> L{IMU_LATEST<br/>try_lock}
+    
+    L -->|Empty/Locked| M[Skip this iteration]
+    L -->|Has data| N[Send to broker<br/>QoS0 no retain]
+    
+    N --> O{TCP send result}
+    O -->|Fail| RECONNECT[❌ Session dies<br/>Reconnect in 5s]
+    O -->|OK| P[✅ Data sent]
+    
+    style DROP1 fill:#ffcccc
+    style DROP2 fill:#ffcccc
+    style DROP3 fill:#ffcccc
+    style RECONNECT fill:#ffcccc
+    style P fill:#ccffcc

mqtt_display/docs/mpu_data_flow.mermaid

@@ -0,0 +1,54 @@
+sequenceDiagram
+    participant HW as MPU6050 Hardware
+    participant MPU as MPU Task<br/>(Core 0)
+    participant CH as IMU_CHANNEL<br/>[16 slots]
+    participant MAIN as Main Loop<br/>(Core 0)
+    participant LATEST as IMU_LATEST<br/>(Mutex)
+    participant MQTT as MQTT Task<br/>(Core 1)
+    participant DISP as Display API
+    
+    Note over MPU: Every 50ms
+    MPU->>HW: Read sensor (I2C)
+    HW-->>MPU: Raw data
+    MPU->>MPU: Convert to ImuReading
+    MPU->>CH: try_send(reading)
+    
+    alt Channel full
+        CH--xMPU: Drop (log warning)
+    else Channel has space
+        CH-->>MPU: OK
+    end
+    
+    Note over MAIN: Continuous loop
+    MAIN->>CH: receive() [blocking]
+    CH-->>MAIN: reading
+    
+    Note over MAIN: Drain queue
+    loop While available
+        MAIN->>CH: try_receive()
+        CH-->>MAIN: newer reading
+    end
+    
+    MAIN->>DISP: show_imu(reading)<br/>[try_send]
+    
+    Note over MAIN: Every 3 seconds
+    alt Time >= 3s since last
+        MAIN->>MAIN: Format JSON payload
+        MAIN->>LATEST: mqtt_set_imu()<br/>[try_lock]
+        
+        alt Mutex available
+            LATEST-->>MAIN: Stored
+        else Mutex locked
+            LATEST--xMAIN: Skip
+        end
+    end
+    
+    Note over MQTT: Continuous loop
+    MQTT->>LATEST: try_lock()
+    
+    alt Data available
+        LATEST-->>MQTT: payload
+        MQTT->>MQTT: send_message("esp32/imu")
+    else No data
+        LATEST--xMQTT: None
+    end

mqtt_display/docs/overall_system_architecture.mermaid

@@ -0,0 +1,42 @@
+graph TB
+    subgraph "Core 0 - Application"
+        MPU[MPU Task<br/>50ms sampling]
+        DISPLAY[Display Task<br/>100ms refresh]
+        MAIN[Main Loop]
+        BUTTONS[Button Task]
+    end
+    
+    subgraph "Core 1 - Network"
+        WIFI[WiFi Connection Task]
+        NETWORK[Network Stack Runner]
+        MQTT[MQTT Task]
+    end
+    
+    subgraph "Shared Channels"
+        IMU_CH[(IMU_CHANNEL<br/>size: 16)]
+        DISP_CH[(DISPLAY_CHANNEL<br/>size: 8)]
+        CMD_CH[(CMD_CHAN<br/>size: 8)]
+        EVT_CH[(EVT_CHAN<br/>size: 8)]
+        IMU_LATEST[(IMU_LATEST<br/>Mutex)]
+    end
+    
+    subgraph "Hardware"
+        MPU_HW[MPU6050<br/>I2C 0x68]
+        OLED[SSD1306<br/>I2C]
+        BROKER[MQTT Broker]
+    end
+    
+    MPU_HW -->|I2C Read| MPU
+    MPU -->|send| IMU_CH
+    IMU_CH -->|receive| MAIN
+    MAIN -->|try_send| DISP_CH
+    MAIN -->|mqtt_set_imu| IMU_LATEST
+    DISP_CH -->|receive| DISPLAY
+    DISPLAY -->|I2C Write| OLED
+    IMU_LATEST -->|try_lock| MQTT
+    MQTT <-->|TCP/IP| BROKER
+    BUTTONS -->|push_key| DISP_CH
+    
+    style IMU_CH fill:#ff9999
+    style DISP_CH fill:#99ccff
+    style IMU_LATEST fill:#ffcc99

mqtt_display/src/bin/main.rs

@@ -15,7 +15,7 @@ use embassy_sync::signal::Signal;
 use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
 use embassy_time::{Duration, Timer, Instant};
 use projekt_final::bus::I2cInner;
-use projekt_final::mqtt::client::mqtt_set_imu;
+use projekt_final::mqtt::client;
 
 use esp_alloc as _;
 use esp_backtrace as _;
@@ -39,6 +39,8 @@ use log::info;
 use rust_mqtt::packet::v5::publish_packet::QualityOfService;
 use static_cell::StaticCell;
 use core::cell::RefCell;
+use heapless::String;
+use core::fmt::Write;
 
 use projekt_final::{
     bus,
@@ -106,7 +108,7 @@ async fn main(spawner: Spawner) -> ! {
 
     let wifi_interface = interfaces.sta;
     let timg1 = TimerGroup::new(peripherals.TIMG1);
-    esp_hal_embassy::init(timg1.timer0);
+    esp_hal_embassy::init([timg1.timer0, timg1.timer1]);
 
     let seed = (rng.random() as u64) << 32 | rng.random() as u64;
 
@@ -174,15 +176,9 @@ async fn main(spawner: Spawner) -> ! {
 
                 // 3. Nahraďte pôvodnú podmienku týmto časovým zámkom
                 if last_mqtt_publish.elapsed() >= mqtt_publish_interval {
-                    let payload = format!(
-                        "{{\"ax\":{:.2},\"ay\":{:.2},\"az\":{:.2},\"t\":{:.1}}}",
-                        reading.accel_g[0], reading.accel_g[1], reading.accel_g[2], reading.temp_c
-                    );
-                    mqtt_set_imu(payload.as_bytes());
-                    
-                    // Aktualizujeme čas posledného odoslania
+                    let payload = client::encode_imu_json(&reading);
+                    client::mqtt_set_imu_payload(payload);
                     last_mqtt_publish = Instant::now();
-                    log::info!("MQTT IMU payload buffered (freshest data)");
                 }
             }
             Either3::Third(_) => {

mqtt_display/src/bus/mod.rs

@@ -1,17 +1,19 @@
 // src/bus/mod.rs
+//! Shared access to the hardware I2C peripheral on a
+//! single core.
 
 use core::cell::RefCell;
 use embedded_hal_bus::i2c::RefCellDevice;
 use esp_hal::i2c::master::I2c;
 use esp_hal::Async;
 
-/// The underlying I2C peripheral type
+/// I2C peripheral type
 pub type I2cInner = I2c<'static, Async>;
 
 /// RefCell to share the bus on a single core.
 pub type SharedI2c = RefCell<I2cInner>;
 
-/// A handle to a shared I2C device.
+/// Shared I2C device.
 pub type I2cDevice = RefCellDevice<'static, I2cInner>;
 
 /// New I2C device handle from the shared bus.

mqtt_display/src/contracts.rs

@@ -1,10 +1,9 @@
 // src/contracts.rs
 //! Cross-feature message contracts.
 //! 
-//! This is the ONLY coupling point between features.
 //! Features depend on these types, not on each other.
 
-use heapless::String as HString;
+use heapless::String;
 use pages_tui::input::Key;
 
 /// IMU sensor reading from MPU6050
@@ -20,17 +19,13 @@ pub struct ImuReading {
 /// Commands that can be sent to the display actor
 #[derive(Clone, Debug)]
 pub enum DisplayCommand {
-    /// Show IMU sensor data
     SetImu(ImuReading),
-    /// Show a status line (max 32 chars)
-    SetStatus(HString<32>),
-    /// Show an error message (max 64 chars)
-    ShowError(HString<64>),
-    /// Show MQTT connection status
+    SetStatus(String<32>),
+    ShowError(String<64>),
     SetMqttStatus { connected: bool, msg_count: u32 },
     /// Clear the display to default state
     Clear,
 
     PushKey(Key),
-    AddChatMessage(HString<24>),
+    AddChatMessage(String<24>),
 }

mqtt_display/src/display/api.rs

@@ -1,5 +1,5 @@
 // src/display/api.rs
-//! Public API for the display feature.
+//! display API
 
 use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
 use embassy_sync::channel::{Channel, Receiver, TrySendError};
@@ -29,7 +29,7 @@ pub(crate) fn receiver() -> Receiver<'static, CriticalSectionRawMutex, DisplayCo
 
 /// Show IMU data - NON-BLOCKING to prevent backpressure deadlock
 pub fn show_imu(reading: ImuReading) {
-    // CRITICAL FIX: Use try_send instead of send().await
+    // try_send instead of send().await
     // If display is slow, we drop the reading rather than blocking the main loop
     let _ = try_send(DisplayCommand::SetImu(reading));
 }

mqtt_display/src/display/task.rs

@@ -9,7 +9,7 @@ use ssd1306::{mode::BufferedGraphicsMode, prelude::*, I2CDisplayInterface, Ssd13
 
 use crate::bus::I2cDevice;
 use crate::display::api::receiver;
-use crate::display::tui::{render_frame, next_page_id, prev_page_id, DisplayState, Screen, ScreenEvent};
+use crate::display::tui::{render_frame, DisplayState, Screen, ScreenEvent};
 use crate::contracts::DisplayCommand;
 use pages_tui::prelude::*;
 
@@ -43,14 +43,15 @@ pub async fn display_task(i2c: I2cDevice) {
     let rx = receiver();
 
     // Register pages
-    orchestrator.register_page("menu".into(), Screen::Menu);
-    orchestrator.register_page("imu".into(), Screen::Imu);
-    orchestrator.register_page("chat".into(), Screen::Chat);
+    // Enum-based registration
+    orchestrator.register(Screen::Menu);
+    orchestrator.register(Screen::Imu);
+    orchestrator.register(Screen::Chat);
 
     orchestrator.bind(Key::tab(), ComponentAction::Next);
     orchestrator.bind(Key::enter(), ComponentAction::Select);
 
-    let _ = orchestrator.navigate_to("menu".into());
+    let _ = orchestrator.navigate_to(Screen::Menu);
 
     info!("Display ready");
 
@@ -59,27 +60,27 @@ pub async fn display_task(i2c: I2cDevice) {
             match cmd {
                 DisplayCommand::PushKey(key) => {
                     if key == Key::tab() {
-                        orchestrator.focus_manager_mut().wrap_next();
+                        orchestrator.focus_manager_mut().next();
                     } else if key == Key::enter() {
                         if let Ok(events) = orchestrator.process_frame(key) {
                             for event in events {
                                 match event {
                                     ScreenEvent::GoToImu => {
-                                        let _ = orchestrator.navigate_to("imu".into());
+                                        let _ = orchestrator.navigate_to(Screen::Imu);
                                     }
                                     ScreenEvent::GoToChat => {
-                                        let _ = orchestrator.navigate_to("chat".into());
+                                        let _ = orchestrator.navigate_to(Screen::Chat);
                                     }
                                     ScreenEvent::NavigatePrev => {
-                                        if let Some(cur) = orchestrator.current_id() {
-                                            let prev = prev_page_id(cur.as_str());
-                                            let _ = orchestrator.navigate_to(prev.into());
+                                        if let Some(cur) = orchestrator.current() {
+                                            let prev = cur.prev();
+                                            let _ = orchestrator.navigate_to(prev);
                                         }
                                     }
                                     ScreenEvent::NavigateNext => {
-                                        if let Some(cur) = orchestrator.current_id() {
-                                            let next = next_page_id(cur.as_str());
-                                            let _ = orchestrator.navigate_to(next.into());
+                                        if let Some(cur) = orchestrator.current() {
+                                            let next = cur.next();
+                                            let _ = orchestrator.navigate_to(next);
                                         }
                                     }
                                 }

mqtt_display/src/display/tui.rs

@@ -1,7 +1,7 @@
 // src/display/tui.rs
 use crate::contracts::{DisplayCommand, ImuReading};
 use alloc::format;
-use heapless::String as HString;
+use heapless::String;
 use pages_tui::prelude::*;
 use ratatui::{
     layout::Rect,
@@ -27,25 +27,25 @@ const NAV_TARGETS: &[PageFocus] = &[PageFocus::NavPrev, PageFocus::NavNext];
 
 /// Display state
 pub struct DisplayState {
-    pub(crate) status: HString<32>,
+    pub(crate) status: String<32>,
     pub(crate) last_imu: Option<ImuReading>,
-    pub(crate) last_error: Option<HString<64>>,
+    pub(crate) last_error: Option<String<64>>,
     pub(crate) mqtt_connected: bool,
     pub(crate) mqtt_msg_count: u32,
-    pub(crate) chat_msg1: HString<24>,
-    pub(crate) chat_msg2: HString<24>,
+    pub(crate) chat_msg1: String<24>,
+    pub(crate) chat_msg2: String<24>,
 }
 
 impl Default for DisplayState {
     fn default() -> Self {
         Self {
-            status: HString::new(),
+            status: String::new(),
             last_imu: None,
             last_error: None,
             mqtt_connected: false,
             mqtt_msg_count: 0,
-            chat_msg1: HString::new(),
-            chat_msg2: HString::new(),
+            chat_msg1: String::new(),
+            chat_msg2: String::new(),
         }
     }
 }
@@ -66,7 +66,7 @@ impl DisplayState {
             DisplayCommand::Clear => {
                 self.last_imu = None;
                 self.last_error = None;
-                self.status = HString::new();
+                self.status = String::new();
             }
             DisplayCommand::PushKey(_) => {}
             DisplayCommand::AddChatMessage(msg) => {
@@ -137,16 +137,30 @@ impl Component for Screen {
 }
 
 // PAGE ORDER
-const PAGE_ORDER: &[&str] = &["menu", "imu", "chat"];
+const PAGE_ORDER: &[Screen] = &[Screen::Menu, Screen::Imu, Screen::Chat];
 
-pub fn next_page_id(current: &str) -> &'static str {
-    let idx = PAGE_ORDER.iter().position(|&p| p == current).unwrap_or(0);
-    PAGE_ORDER[(idx + 1) % PAGE_ORDER.len()]
+impl Screen {
+    pub fn next(&self) -> Screen {
+        let idx = PAGE_ORDER.iter().position(|p| p == self).unwrap_or(0);
+        PAGE_ORDER[(idx + 1) % PAGE_ORDER.len()].clone()
     }
 
-pub fn prev_page_id(current: &str) -> &'static str {
-    let idx = PAGE_ORDER.iter().position(|&p| p == current).unwrap_or(0);
-    if idx == 0 { PAGE_ORDER[PAGE_ORDER.len() - 1] } else { PAGE_ORDER[idx - 1] }
+    pub fn prev(&self) -> Screen {
+        let idx = PAGE_ORDER.iter().position(|p| p == self).unwrap_or(0);
+        if idx == 0 {
+            PAGE_ORDER[PAGE_ORDER.len() - 1].clone()
+        } else {
+            PAGE_ORDER[idx - 1].clone()
+        }
+    }
+
+    pub fn to_str(&self) -> &'static str {
+        match self {
+            Screen::Menu => "menu",
+            Screen::Imu => "imu",
+            Screen::Chat => "chat",
+        }
+    }
 }
 
 // RENDERING

mqtt_display/src/i2c/com.rs

@@ -5,73 +5,8 @@ use esp_hal::{
     i2c::master::{Config, I2c},
     peripherals::Peripherals,
 };
-use ssd1306::mode::BufferedGraphicsMode;
 use log::info;
 
-#[embassy_executor::task]
-pub async fn display_task() {
-    use mousefood::{EmbeddedBackend, EmbeddedBackendConfig};
-    use ratatui::{
-        layout::{Constraint, Direction, Layout},
-        widgets::{Block, Borders, Paragraph},
-        Terminal,
-    };
-    use ssd1306::{prelude::*, I2CDisplayInterface, Ssd1306};
-
-    let peripherals = unsafe { Peripherals::steal() };
-
-    let i2c = I2c::new(peripherals.I2C0, Config::default())
-        .expect("Failed to initialize I2C")
-        .with_sda(peripherals.GPIO21)
-        .with_scl(peripherals.GPIO22);
-
-    let interface = I2CDisplayInterface::new(i2c);
-    let mut display = Ssd1306::new(interface, DisplaySize128x64, DisplayRotation::Rotate0)
-        .into_buffered_graphics_mode();
-
-    display.init().unwrap();
-
-    let config = EmbeddedBackendConfig {
-        flush_callback: alloc::boxed::Box::new(|display| {
-            let d: &mut Ssd1306<_, _, BufferedGraphicsMode<DisplaySize128x64>> = display;
-            d.flush().unwrap();
-        }),
-        ..Default::default()
-    };
-
-    let backend = EmbeddedBackend::new(&mut display, config);
-    let mut terminal = Terminal::new(backend).unwrap();
-
-    let mut counter = 0;
-
-    loop {
-        terminal
-            .draw(|f| {
-                let chunks = Layout::default()
-                    .direction(Direction::Vertical)
-                    .constraints([Constraint::Length(3), Constraint::Min(0)])
-                    .split(f.area());
-
-                f.render_widget(
-                    Block::default().title(" ESP32 Status ").borders(Borders::ALL),
-                    chunks[0],
-                );
-
-                let content = alloc::format!("MQTT Active\nCounter: {}", counter);
-                f.render_widget(
-                    Paragraph::new(content).block(
-                        Block::default().borders(Borders::LEFT | Borders::RIGHT | Borders::BOTTOM),
-                    ),
-                    chunks[1],
-                );
-            })
-            .unwrap();
-
-        counter += 1;
-        Timer::after(Duration::from_millis(1000)).await;
-    }
-}
-
 #[embassy_executor::task]
 pub async fn i2c_check() {
     let peripherals = unsafe { Peripherals::steal() };

mqtt_display/src/mqtt/client.rs

@@ -1,8 +1,8 @@
 // src/mqtt/client.rs
 
-use embassy_futures::select::{select, Either};
 use embassy_net::{tcp::TcpSocket, Stack};
-use embassy_time::{Duration, Timer, with_timeout, Instant};
+use embassy_time::{Duration, Timer, Instant};
+use embassy_futures::select::{select, Either};
 use rust_mqtt::client::client::MqttClient;
 use rust_mqtt::client::client_config::{ClientConfig, MqttVersion};
 use rust_mqtt::packet::v5::publish_packet::QualityOfService;
@@ -12,16 +12,24 @@ use rust_mqtt::utils::rng_generator::CountingRng;
 use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
 use embassy_sync::mutex::Mutex;
 use embassy_sync::channel::{Channel, Receiver};
+use embassy_sync::signal::Signal;
 use heapless::{String, Vec};
 use static_cell::ConstStaticCell;
+use core::fmt::Write;
 use log::{info, warn};
 
 use crate::mqtt::config::mqtt_broker_endpoint;
+use crate::contracts::ImuReading;
 
 const RECONNECT_DELAY_SECS: u64 = 5;
 const KEEPALIVE_SECS: u64 = 60;
 const PING_PERIOD: Duration = Duration::from_secs(KEEPALIVE_SECS / 2);
-const PING_TIMEOUT: Duration = Duration::from_secs(2);
+const SOCKET_POLL_TIMEOUT: Duration = Duration::from_secs(1);
+const PING_TIMEOUT: Duration = Duration::from_secs(5);
+// Must be > PING_PERIOD, ideally > KEEPALIVE
+const NO_SUCCESS_TIMEOUT: Duration = Duration::from_secs(120);
+const NO_IMU_SIG_WARN: Duration = Duration::from_secs(10);
+const SUBS_MAX: usize = 8;
 
 // Limits for static buffers
 pub const TOPIC_MAX: usize = 128;
@@ -64,13 +72,14 @@ enum Command {
 static CMD_CHAN: Channel<CriticalSectionRawMutex, Command, COMMAND_QUEUE> = Channel::new();
 static EVT_CHAN: Channel<CriticalSectionRawMutex, IncomingMsg, EVENT_QUEUE> = Channel::new();
 
-/// Shared latest IMU payload (non-blocking, latest-value semantics)
-static IMU_LATEST: Mutex<CriticalSectionRawMutex, Option<Vec<u8, PAYLOAD_MAX>>> =
-    Mutex::new(None);
+/// Latest-value + wake-up semantics for IMU publish payload (single consumer: MQTT task)
+static IMU_SIG: Signal<CriticalSectionRawMutex, Vec<u8, PAYLOAD_MAX>> = Signal::new();
+
+static SUBS: Mutex<CriticalSectionRawMutex, Vec<String<TOPIC_MAX>, SUBS_MAX>> =
+    Mutex::new(Vec::new());
 
 /// Public API
 
-/// Blocking publish for command/response messages.
 pub async fn mqtt_publish(topic: &str, payload: &[u8], qos: QualityOfService, retain: bool) {
     CMD_CHAN
         .send(Command::Publish(PublishMsg {
@@ -82,7 +91,6 @@ pub async fn mqtt_publish(topic: &str, payload: &[u8], qos: QualityOfService, re
         .await;
 }
 
-/// Non-blocking publish for other traffic (fire-and-forget)
 pub fn mqtt_try_publish(topic: &str, payload: &[u8], qos: QualityOfService, retain: bool) -> bool {
     CMD_CHAN
         .try_send(Command::Publish(PublishMsg {
@@ -94,19 +102,41 @@ pub fn mqtt_try_publish(topic: &str, payload: &[u8], qos: QualityOfService, reta
         .is_ok()
 }
 
-/// Set latest IMU telemetry payload (non-blocking, overwrites previous)
-pub fn mqtt_set_imu(payload: &[u8]) {
-    if let Ok(mut guard) = IMU_LATEST.try_lock() {
-        let mut buf: Vec<u8, PAYLOAD_MAX> = Vec::new();
-        let _ = buf.extend_from_slice(&payload[..payload.len().min(PAYLOAD_MAX)]);
-        *guard = Some(buf);
+pub fn mqtt_set_imu(reading: ImuReading) {
+    // Encode JSON into a bounded buffer (no alloc::format!)
+    let payload = encode_imu_json(&reading);
+    IMU_SIG.signal(payload);
 }
+
+pub fn mqtt_set_imu_payload(payload: Vec<u8, PAYLOAD_MAX>) {
+    IMU_SIG.signal(payload);
+}
+
+pub fn encode_imu_json(reading: &ImuReading) -> Vec<u8, PAYLOAD_MAX> {
+    let mut s: String<256> = String::new();
+    let _ = write!(
+        &mut s,
+        "{{\"ax\":{:.2},\"ay\":{:.2},\"az\":{:.2},\"gx\":{:.1},\"gy\":{:.1},\"gz\":{:.1},\"t\":{:.1},\"ts\":{}}}",
+        reading.accel_g[0], reading.accel_g[1], reading.accel_g[2],
+        reading.gyro_dps[0], reading.gyro_dps[1], reading.gyro_dps[2],
+        reading.temp_c,
+        reading.timestamp_ms
+    );
+    let mut v: Vec<u8, PAYLOAD_MAX> = Vec::new();
+    let _ = v.extend_from_slice(s.as_bytes());
+    v
 }
 
 pub async fn mqtt_subscribe(topic: &str) {
-    CMD_CHAN
-        .send(Command::Subscribe(truncate_str::<TOPIC_MAX>(topic)))
-        .await;
+    let t = truncate_str::<TOPIC_MAX>(topic);
+    {
+        let mut subs = SUBS.lock().await;
+        let exists = subs.iter().any(|s| s.as_str() == t.as_str());
+        if !exists {
+            let _ = subs.push(t.clone());
+        }
+    }
+    CMD_CHAN.send(Command::Subscribe(t)).await;
 }
 
 pub fn mqtt_events(
@@ -126,7 +156,6 @@ fn truncate_str<const N: usize>(s: &str) -> String<N> {
         return h;
     }
 
-    // Cut on a UTF-8 char boundary to avoid panics.
     let mut cut = N;
     while cut > 0 && !s.is_char_boundary(cut) {
         cut -= 1;
@@ -144,36 +173,16 @@ fn truncate_payload(data: &[u8]) -> Vec<u8, PAYLOAD_MAX> {
 async fn handle_command(client: &mut Client<'_, '_>, cmd: Command) -> Result<(), ReasonCode> {
     match cmd {
         Command::Publish(msg) => {
-            match with_timeout(
-                Duration::from_secs(5),
-                client.send_message(msg.topic.as_str(), &msg.payload, msg.qos, msg.retain),
-            )
+            client
+                .send_message(msg.topic.as_str(), &msg.payload, msg.qos, msg.retain)
                 .await
-            {
-                Ok(result) => result,
-                Err(_) => {
-                    warn!("MQTT send timed out, forcing reconnect");
-                    Err(ReasonCode::UnspecifiedError)
-                }
-            }
         }
         Command::Subscribe(topic) => {
-            match with_timeout(
-                Duration::from_secs(5),
-                client.subscribe_to_topic(topic.as_str()),
-            )
-            .await
-            {
-                Ok(result) => {
-                    result?;
+            let res = client.subscribe_to_topic(topic.as_str()).await;
+            if res.is_ok() {
                 info!("Subscribed to '{}'", topic);
-                    Ok(())
-                }
-                Err(_) => {
-                    warn!("MQTT subscribe timed out");
-                    Err(ReasonCode::UnspecifiedError)
-                }
             }
+            res
         }
     }
 }
@@ -198,7 +207,7 @@ async fn run_one_session(
     mqtt_rx: &mut [u8],
 ) -> Result<(), ()> {
     let mut socket = TcpSocket::new(stack, tcp_rx, tcp_tx);
-    socket.set_timeout(Some(Duration::from_secs(20)));
+    socket.set_timeout(Some(SOCKET_POLL_TIMEOUT * 10));
     match socket.connect(mqtt_broker_endpoint()).await {
         Ok(_) => info!("Connected TCP to MQTT broker"),
         Err(e) => {
@@ -207,7 +216,6 @@ async fn run_one_session(
         }
     }
 
-    // MQTT configuration and client setup
     let mut cfg: ClientConfig<8, CountingRng> =
         ClientConfig::new(MqttVersion::MQTTv5, CountingRng(0));
     cfg.keep_alive = KEEPALIVE_SECS as u16;
@@ -224,79 +232,188 @@ async fn run_one_session(
         }
     }
 
+    // Re-subscribe after every (re)connect
+    let mut subs_snapshot: Vec<String<TOPIC_MAX>, SUBS_MAX> = Vec::new();
+    {
+        let subs = SUBS.lock().await;
+        for t in subs.iter() {
+            let _ = subs_snapshot.push(t.clone());
+        }
+    }
+    for t in subs_snapshot.iter() {
+        match client.subscribe_to_topic(t.as_str()).await {
+            Ok(_) => info!("Subscribed to '{}'", t),
+            Err(e) => {
+                warn!("MQTT resubscribe failed: {:?}", e);
+                return Err(());
+            }
+        }
+    }
+
     let mut next_ping_at = Instant::now() + PING_PERIOD;
+    let cmd_rx = CMD_CHAN.receiver();
+
+    // Only restart the session after N consecutive IMU publish failures
+    let mut imu_tx_fail_streak: u8 = 0;
+    let mut hb_at = Instant::now() + Duration::from_secs(10);
+    let mut tx_ok: u32 = 0;
+    let mut tx_err: u32 = 0;
+    let mut rx_ok: u32 = 0;
+    let mut ping_ok: u32 = 0;
+    let mut last_ok = Instant::now();        // last successful MQTT I/O (tx/rx/ping)
+    let mut last_imu_sig = Instant::now();   // last time we received IMU_SIG in MQTT task
 
     loop {
-        // Send latest IMU payload if available
-        if let Ok(mut guard) = IMU_LATEST.try_lock() {
-            if let Some(payload) = guard.take() {
-                drop(guard);
+        let now = Instant::now();
 
-                log::info!("MQTT IMU TX start ({} bytes)", payload.len());
+        if now - last_ok > NO_SUCCESS_TIMEOUT {
+            warn!(
+                "MQTT no successful I/O for {:?} -> restart session",
+                now - last_ok
+            );
+            return Err(());
+        }
 
-                // Limit send to max 2 seconds to catch network stalls
-                let send_res = with_timeout(
-                    Duration::from_secs(2),
-                    client.send_message("esp32/imu", &payload, QualityOfService::QoS0, false),
+        if now - last_imu_sig > NO_IMU_SIG_WARN {
+            // This is diagnostic: if core0 claims it's sending, but this prints, you have cross-core signaling loss.
+            warn!(
+                "MQTT hasn't received IMU_SIG for {:?} (core0->core1 sync likely broken)",
+                now - last_imu_sig
+            );
+            // Rate-limit the warning
+            last_imu_sig = now;
+        }
+
+        let ping_in = if next_ping_at > now { next_ping_at - now } else { Duration::from_secs(0) };
+
+        // Timebox receive_message() even if lower layers misbehave.
+        let recv_fut = async {
+            match select(client.receive_message(), Timer::after(SOCKET_POLL_TIMEOUT)).await {
+                Either::First(res) => Some(res),
+                Either::Second(_) => None,
+            }
+        };
+
+        // 4-way select using nested selects to avoid relying on select4()
+        match select(
+            select(cmd_rx.receive(), IMU_SIG.wait()),
+            select(recv_fut, Timer::after(ping_in)),
         )
-                    .await;
-
-                match send_res {
-                    Ok(Ok(_)) => {
-                        log::info!("MQTT IMU TX ok");
-                        next_ping_at = Instant::now() + PING_PERIOD;
-                    }
-                    Ok(Err(e)) => {
-                        log::warn!("MQTT IMU TX failed: {:?}", e);
-                        return Err(());
-                    }
-                    Err(_) => {
-                        log::warn!("MQTT IMU TX timed out, restarting session");
-                        return Err(());
-                    }
-                }
-            }
-        }
-
-        // Process any queued control commands
-        while let Ok(cmd) = CMD_CHAN.try_receive() {
+        .await
+        {
+            // Command received
+            Either::First(Either::First(cmd)) => {
                 handle_command(&mut client, cmd).await.map_err(|_| ())?;
                 next_ping_at = Instant::now() + PING_PERIOD;
+                last_ok = Instant::now();
+
+                // Drain any additional queued commands quickly
+                while let Ok(cmd) = CMD_CHAN.try_receive() {
+                    handle_command(&mut client, cmd).await.map_err(|_| ())?;
+                    last_ok = Instant::now();
+                    next_ping_at = Instant::now() + PING_PERIOD;
+                }
             }
 
-        // Check for incoming messages with timeout
-        match with_timeout(Duration::from_millis(100), client.receive_message()).await {
-            Ok(Ok((topic, payload))) => {
-                // Handle incoming message
+            // IMU update signaled (latest value semantics)
+            Either::First(Either::Second(payload)) => {
+                last_imu_sig = Instant::now();
+                // Enable temporarily for diagnostics:
+                // info!("IMU_SIG received in MQTT task (len={})", payload.len());
+
+                // Timebox the publish so we don't hang forever inside send_message().await
+                let send_res = match select(
+                    client.send_message("esp32/imu", &payload, QualityOfService::QoS0, false),
+                    Timer::after(Duration::from_secs(5)),
+                )
+                    .await
+                    {
+                        Either::First(res) => res,
+                        Either::Second(_) => Err(ReasonCode::NetworkError),
+                    };
+
+                match send_res {
+                    Ok(_) => {
+                        next_ping_at = Instant::now() + PING_PERIOD;
+                        imu_tx_fail_streak = 0;
+                        last_ok = Instant::now();
+
+                        tx_ok = tx_ok.wrapping_add(1);
+                        if (tx_ok % 10) == 0 {
+                            info!(
+                                "MQTT alive: tx_ok={} tx_err={} rx_ok={} streak={}",
+                                tx_ok, tx_err, rx_ok, imu_tx_fail_streak
+                            );
+                        }
+                    }
+                    Err(e) => {
+                        tx_err = tx_err.wrapping_add(1);
+                        imu_tx_fail_streak = imu_tx_fail_streak.saturating_add(1);
+                        warn!("MQTT IMU TX fail {}/5: {:?}", imu_tx_fail_streak, e);
+
+                        if imu_tx_fail_streak >= 5 {
+                            warn!("MQTT IMU TX fail 5x -> restart session");
+                            return Err(());
+                        }
+                    }
+                }
+            }
+
+            // Incoming message (or None on timeout)
+            Either::Second(Either::First(opt)) => {
+                if let Some(res) = opt {
+                    match res {
+                        Ok((topic, payload)) => {
+                            rx_ok = rx_ok.wrapping_add(1);
                             let _ = handle_incoming(Ok((topic, payload))).await;
+
+                            last_ok = Instant::now();
+                            imu_tx_fail_streak = 0;
                             next_ping_at = Instant::now() + PING_PERIOD;
                         }
-            Ok(Err(e)) => {
-                log::warn!("MQTT receive error: {:?}", e);
+                        Err(ReasonCode::NetworkError) => {
+                            // idle tick
+                        }
+                        Err(e) => {
+                            warn!("MQTT receive error (fatal): {:?}", e);
                             return Err(());
                         }
-            Err(_) => {
                     }
                 }
-        if Instant::now() >= next_ping_at {
-            match with_timeout(PING_TIMEOUT, client.send_ping()).await {
-                Ok(Ok(_)) => {
+            }
+
+            // Ping timer fired
+            Either::Second(Either::Second(_)) => {
+                if Instant::now() >= hb_at {
+                    info!(
+                        "MQTT hb tx_ok={} tx_err={} rx_ok={} ping_ok={} streak={}",
+                        tx_ok, tx_err, rx_ok, ping_ok, imu_tx_fail_streak
+                    );
+                    hb_at = Instant::now() + Duration::from_secs(10);
+                }
+
+                let ping_res = match select(client.send_ping(), Timer::after(PING_TIMEOUT)).await {
+                    Either::First(res) => res,
+                    Either::Second(_) => Err(ReasonCode::NetworkError),
+                };
+
+                match ping_res {
+                    Ok(_) => {
+                        ping_ok = ping_ok.wrapping_add(1);
+                        imu_tx_fail_streak = 0;
+                        last_ok = Instant::now();
                         next_ping_at = Instant::now() + PING_PERIOD;
                     }
-                Ok(Err(e)) => {
-                    warn!("MQTT ping failed: {:?}", e);
+                    Err(e) => {
+                        warn!("MQTT ping failed/timeout: {:?}", e);
                         return Err(());
                     }
-                Err(_) => {
-                    warn!("MQTT ping timed out, restarting session");
-                    return Err(());
                 }
             }
         }
     }
 }
 
-/// Main MQTT embassy task
 #[embassy_executor::task]
 pub async fn mqtt_task(stack: Stack<'static>) {
     info!("MQTT task starting...");