build: allow VERSION and VERSION_DEV to be overridden via environment

Changed from immediate assignment (:=) to conditional assignment (?=)
to allow developers to override version numbers when building.

This enables building with custom versions for testing:
  VERSION=0.4.9 ./dev_deploy.sh -r <ip> --install

Useful for testing version-gated features without bumping the
default production version.

Makefile

@@ -2,8 +2,8 @@ BRANCH    := $(shell git rev-parse --abbrev-ref HEAD)
 BUILDDATE := $(shell date -u +%FT%T%z)
 BUILDTS   := $(shell date -u +%s)
 REVISION  := $(shell git rev-parse HEAD)
-VERSION_DEV := 0.4.9-dev$(shell date +%Y%m%d%H%M)
+VERSION_DEV ?= 0.4.9-dev$(shell date +%Y%m%d%H%M)
-VERSION := 0.4.8
+VERSION ?= 0.4.8
 
 PROMETHEUS_TAG := github.com/prometheus/common/version
 KVM_PKG_NAME := github.com/jetkvm/kvm

config.go

@@ -117,6 +117,7 @@ type Config struct {
 	DefaultLogLevel      string               `json:"default_log_level"`
 	SessionSettings      *SessionSettings     `json:"session_settings"`
 	VideoSleepAfterSec   int                  `json:"video_sleep_after_sec"`
+	VideoQualityFactor   float64              `json:"video_quality_factor"`
 }
 
 func (c *Config) GetDisplayRotation() uint16 {

display.go

@@ -70,7 +70,7 @@ func updateDisplay() {
 		nativeInstance.UpdateLabelIfChanged("hdmi_status_label", "Disconnected")
 		_, _ = nativeInstance.UIObjClearState("hdmi_status_label", "LV_STATE_CHECKED")
 	}
-	nativeInstance.UpdateLabelIfChanged("cloud_status_label", fmt.Sprintf("%d active", actionSessions))
+	nativeInstance.UpdateLabelIfChanged("cloud_status_label", fmt.Sprintf("%d active", getActiveSessions()))
 
 	if networkManager != nil && networkManager.IsUp() {
 		nativeInstance.UISetVar("main_screen", "home_screen")

internal/native/cgo/ctrl.c

@@ -405,8 +405,8 @@ char *jetkvm_video_log_status() {
     return (char *)videoc_log_status();
 }
 
-int jetkvm_video_init() {
+int jetkvm_video_init(float factor) {
-    return video_init();
+    return video_init(factor);
 }
 
 void jetkvm_video_shutdown() {

internal/native/cgo/ctrl.h

@@ -52,7 +52,7 @@ const char *jetkvm_ui_get_lvgl_version();
 
 const char *jetkvm_ui_event_code_to_name(int code);
 
-int jetkvm_video_init();
+int jetkvm_video_init(float quality_factor);
 void jetkvm_video_shutdown();
 void jetkvm_video_start();
 void jetkvm_video_stop();

internal/native/cgo/video.c

@@ -29,6 +29,7 @@
 
 #define VIDEO_DEV "/dev/video0"
 #define SUB_DEV "/dev/v4l-subdev2"
+#define SLEEP_MODE_FILE "/sys/devices/platform/ff470000.i2c/i2c-4/4-000f/sleep_mode"
 
 #define RK_ALIGN(x, a) (((x) + (a)-1) & ~((a)-1))
 #define RK_ALIGN_2(x) RK_ALIGN(x, 2)
@@ -39,6 +40,7 @@ int sub_dev_fd = -1;
 #define VENC_CHANNEL 0
 MB_POOL memPool = MB_INVALID_POOLID;
 
+bool sleep_mode_available = false;
 bool should_exit = false;
 float quality_factor = 1.0f;
 
@@ -51,6 +53,45 @@ RK_U64 get_us()
     return (RK_U64)time.tv_sec * 1000000 + (RK_U64)time.tv_nsec / 1000; /* microseconds */
 }
 
+static void ensure_sleep_mode_disabled()
+{
+    if (!sleep_mode_available)
+    {
+        return;
+    }
+
+    int fd = open(SLEEP_MODE_FILE, O_RDWR);
+    if (fd < 0)
+    {
+        log_error("Failed to open sleep mode file: %s", strerror(errno));
+        return;
+    }
+    lseek(fd, 0, SEEK_SET);
+    char buffer[1];
+    read(fd, buffer, 1);
+    if (buffer[0] == '0') {
+        close(fd);
+        return;
+    }
+    log_warn("HDMI sleep mode is not disabled, disabling it");
+    lseek(fd, 0, SEEK_SET);
+    write(fd, "0", 1);
+    close(fd);
+
+    usleep(1000); // give some time to the system to disable the sleep mode
+    return;
+}
+
+static void detect_sleep_mode()
+{
+    if (access(SLEEP_MODE_FILE, F_OK) != 0) {
+        sleep_mode_available = false;
+        return;
+    }
+    sleep_mode_available = true;
+    ensure_sleep_mode_disabled();
+}
+
 double calculate_bitrate(float bitrate_factor, int width, int height)
 {
     const int32_t base_bitrate_high = 2000;
@@ -190,8 +231,15 @@ static int32_t buf_init()
 
 pthread_t *format_thread = NULL;
 
-int video_init()
+int video_init(float factor)
 {
+    detect_sleep_mode();
+
+    if (factor < 0 || factor > 1) {
+        factor = 1.0f;
+    }
+    quality_factor = factor;
+
     if (RK_MPI_SYS_Init() != RK_SUCCESS)
     {
         log_error("RK_MPI_SYS_Init failed");
@@ -301,11 +349,29 @@ static void *venc_read_stream(void *arg)
 }
 
 uint32_t detected_width, detected_height;
-bool detected_signal = false, streaming_flag = false;
+bool detected_signal = false, streaming_flag = false, streaming_stopped = true;
 
 pthread_t *streaming_thread = NULL;
 pthread_mutex_t streaming_mutex = PTHREAD_MUTEX_INITIALIZER;
 
+bool get_streaming_flag()
+{
+    log_info("getting streaming flag");
+    pthread_mutex_lock(&streaming_mutex);
+    bool flag = streaming_flag;
+    pthread_mutex_unlock(&streaming_mutex);
+    return flag;
+}
+
+void set_streaming_flag(bool flag)
+{
+    log_info("setting streaming flag to %d", flag);
+
+    pthread_mutex_lock(&streaming_mutex);
+    streaming_flag = flag;
+    pthread_mutex_unlock(&streaming_mutex);
+}
+
 void write_buffer_to_file(const uint8_t *buffer, size_t length, const char *filename)
 {
     FILE *file = fopen(filename, "wb");
@@ -319,6 +385,8 @@ void *run_video_stream(void *arg)
 
     log_info("running video stream");
 
+    streaming_stopped = false;
+
     while (streaming_flag)
     {
         if (detected_signal == false)
@@ -401,7 +469,7 @@ void *run_video_stream(void *arg)
             {
                 log_error("get mb blk failed!");
                 close(video_dev_fd);
-                return ;
+                return (void *)errno;
             }
             log_info("Got memory block for buffer %d", i);
 
@@ -538,6 +606,18 @@ void *run_video_stream(void *arg)
             log_error("VIDIOC_STREAMOFF failed: %s", strerror(errno));
         }
 
+        // Explicitly free V4L2 buffer queue
+        struct v4l2_requestbuffers req_free;
+        memset(&req_free, 0, sizeof(req_free));
+        req_free.count = 0;
+        req_free.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+        req_free.memory = V4L2_MEMORY_DMABUF;
+
+        if (ioctl(video_dev_fd, VIDIOC_REQBUFS, &req_free) < 0)
+        {
+            log_error("Failed to free V4L2 buffers: %s", strerror(errno));
+        }
+
         venc_stop();
 
         for (int i = 0; i < input_buffer_count; i++)
@@ -553,6 +633,9 @@ void *run_video_stream(void *arg)
     }
 
     log_info("video stream thread exiting");
+
+    streaming_stopped = true;
+
     return NULL;
 }
 
@@ -577,61 +660,80 @@ void video_shutdown()
         RK_MPI_MB_DestroyPool(memPool);
     }
     log_info("Destroyed memory pool");
-    
+
     pthread_mutex_destroy(&streaming_mutex);
     log_info("Destroyed streaming mutex");
 }
 
-
 void video_start_streaming()
 {
-    pthread_mutex_lock(&streaming_mutex);
+    log_info("starting video streaming");
     if (streaming_thread != NULL)
     {
+        if (streaming_stopped == true) {
+            log_error("video streaming already stopped but streaming_thread is not NULL");
+            assert(streaming_stopped == true);
+        }
         log_warn("video streaming already started");
-        goto cleanup;
+        return;
     }
-    
+
     pthread_t *new_thread = malloc(sizeof(pthread_t));
     if (new_thread == NULL)
     {
         log_error("Failed to allocate memory for streaming thread");
-        goto cleanup;
+        return;
     }
-    
+
-    streaming_flag = true;
+    set_streaming_flag(true);
     int result = pthread_create(new_thread, NULL, run_video_stream, NULL);
     if (result != 0)
     {
         log_error("Failed to create streaming thread: %s", strerror(result));
-        streaming_flag = false;
+        set_streaming_flag(false);
         free(new_thread);
-        goto cleanup;
+        return;
     }
-    
+
-    // Only set streaming_thread after successful creation, and before unlocking the mutex
+    // Only set streaming_thread after successful creation
     streaming_thread = new_thread;
-cleanup:
-    pthread_mutex_unlock(&streaming_mutex);
-    return;
 }
 
 void video_stop_streaming()
 {
-    pthread_mutex_lock(&streaming_mutex);
+    if (streaming_thread == NULL) {
-    if (streaming_thread != NULL)
+        log_info("video streaming already stopped");
-    {
+        return;
-        streaming_flag = false;
-        log_info("stopping video streaming");
-        // wait 100ms for the thread to exit
-        usleep(1000000);
-        log_info("waiting for video streaming thread to exit");
-        pthread_join(*streaming_thread, NULL);
-        free(streaming_thread);
-        streaming_thread = NULL;
-        log_info("video streaming stopped");
     }
-    pthread_mutex_unlock(&streaming_mutex);
+
+    log_info("stopping video streaming");
+    set_streaming_flag(false);
+
+    log_info("waiting for video streaming thread to exit");
+    int attempts = 0;
+    while (!streaming_stopped && attempts < 30) {
+        usleep(100000); // 100ms
+        attempts++;
+    }
+    if (!streaming_stopped) {
+        log_error("video streaming thread did not exit after 30s");
+    }
+
+    pthread_join(*streaming_thread, NULL);
+    free(streaming_thread);
+    streaming_thread = NULL;
+
+    log_info("video streaming stopped");
+}
+
+void video_restart_streaming()
+{
+    if (get_streaming_flag() == true)
+    {
+        log_info("restarting video streaming");
+        video_stop_streaming();
+    }
+    video_start_streaming();
 }
 
 void *run_detect_format(void *arg)
@@ -650,6 +752,8 @@ void *run_detect_format(void *arg)
 
     while (!should_exit)
     {
+        ensure_sleep_mode_disabled();
+
         memset(&dv_timings, 0, sizeof(dv_timings));
         if (ioctl(sub_dev_fd, VIDIOC_QUERY_DV_TIMINGS, &dv_timings) != 0)
         {
@@ -689,21 +793,17 @@ void *run_detect_format(void *arg)
                                         (dv_timings.bt.width + dv_timings.bt.hfrontporch + dv_timings.bt.hsync +
                                          dv_timings.bt.hbackporch));
             log_info("Frames per second: %.2f fps", frames_per_second);
+
+            bool should_restart = dv_timings.bt.width != detected_width || dv_timings.bt.height != detected_height || !detected_signal;
+
             detected_width = dv_timings.bt.width;
             detected_height = dv_timings.bt.height;
             detected_signal = true;
             video_report_format(true, NULL, detected_width, detected_height, frames_per_second);
-            pthread_mutex_lock(&streaming_mutex);
+
-            if (streaming_flag == true)
+            if (should_restart) {
-            {
+                log_info("restarting video streaming due to format change");
-                pthread_mutex_unlock(&streaming_mutex);
+                video_restart_streaming();
-                log_info("restarting on going video streaming");
-                video_stop_streaming();
-                video_start_streaming();
-            }
-            else
-            {
-                pthread_mutex_unlock(&streaming_mutex);
             }
         }
 
@@ -731,21 +831,9 @@ void video_set_quality_factor(float factor)
     quality_factor = factor;
 
     // TODO: update venc bitrate without stopping streaming
-
+    video_restart_streaming();
-    pthread_mutex_lock(&streaming_mutex);
-    if (streaming_flag == true)
-    {
-        pthread_mutex_unlock(&streaming_mutex);
-        log_info("restarting on going video streaming due to quality factor change");
-        video_stop_streaming();
-        video_start_streaming();
-    }
-    else
-    {
-        pthread_mutex_unlock(&streaming_mutex);
-    }
 }
 
 float video_get_quality_factor() {
     return quality_factor;
-}
+}

internal/native/cgo/video.h

@@ -6,7 +6,7 @@
  *
  * @return int 0 on success, -1 on failure
  */
-int video_init();
+int video_init(float quality_factor);
 
 /**
  * @brief Shutdown the video subsystem

internal/native/cgo_linux.go

@@ -129,11 +129,13 @@ func uiTick() {
 	C.jetkvm_ui_tick()
 }
 
-func videoInit() error {
+func videoInit(factor float64) error {
 	cgoLock.Lock()
 	defer cgoLock.Unlock()
 
-	ret := C.jetkvm_video_init()
+	factorC := C.float(factor)
+
+	ret := C.jetkvm_video_init(factorC)
 	if ret != 0 {
 		return fmt.Errorf("failed to initialize video: %d", ret)
 	}

internal/native/native.go

@@ -15,6 +15,7 @@ type Native struct {
 	systemVersion        *semver.Version
 	appVersion           *semver.Version
 	displayRotation      uint16
+	defaultQualityFactor float64
 	onVideoStateChange   func(state VideoState)
 	onVideoFrameReceived func(frame []byte, duration time.Duration)
 	onIndevEvent         func(event string)
@@ -22,12 +23,14 @@ type Native struct {
 	sleepModeSupported   bool
 	videoLock            sync.Mutex
 	screenLock           sync.Mutex
+	extraLock            sync.Mutex
 }
 
 type NativeOptions struct {
 	SystemVersion        *semver.Version
 	AppVersion           *semver.Version
 	DisplayRotation      uint16
+	DefaultQualityFactor float64
 	OnVideoStateChange   func(state VideoState)
 	OnVideoFrameReceived func(frame []byte, duration time.Duration)
 	OnIndevEvent         func(event string)
@@ -65,6 +68,11 @@ func NewNative(opts NativeOptions) *Native {
 
 	sleepModeSupported := isSleepModeSupported()
 
+	defaultQualityFactor := opts.DefaultQualityFactor
+	if defaultQualityFactor < 0 || defaultQualityFactor > 1 {
+		defaultQualityFactor = 1.0
+	}
+
 	return &Native{
 		ready:                make(chan struct{}),
 		l:                    nativeLogger,
@@ -72,6 +80,7 @@ func NewNative(opts NativeOptions) *Native {
 		systemVersion:        opts.SystemVersion,
 		appVersion:           opts.AppVersion,
 		displayRotation:      opts.DisplayRotation,
+		defaultQualityFactor: defaultQualityFactor,
 		onVideoStateChange:   onVideoStateChange,
 		onVideoFrameReceived: onVideoFrameReceived,
 		onIndevEvent:         onIndevEvent,
@@ -97,7 +106,7 @@ func (n *Native) Start() {
 	n.initUI()
 	go n.tickUI()
 
-	if err := videoInit(); err != nil {
+	if err := videoInit(n.defaultQualityFactor); err != nil {
 		n.l.Error().Err(err).Msg("failed to initialize video")
 	}
 

internal/native/video.go

@@ -1,11 +1,18 @@
 package native
 
 import (
+	"fmt"
 	"os"
+	"time"
 )
 
 const sleepModeFile = "/sys/devices/platform/ff470000.i2c/i2c-4/4-000f/sleep_mode"
 
+// DefaultEDID is the default EDID for the video stream.
+const DefaultEDID = "00ffffffffffff0052620188008888881c150103800000780a0dc9a05747982712484c00000001010101010101010101010101010101023a801871382d40582c4500c48e2100001e011d007251d01e206e285500c48e2100001e000000fc00543734392d6648443732300a20000000fd00147801ff1d000a202020202020017b"
+
+var extraLockTimeout = 5 * time.Second
+
 // VideoState is the state of the video stream.
 type VideoState struct {
 	Ready          bool    `json:"ready"`
@@ -66,12 +73,32 @@ func (n *Native) VideoSleepModeSupported() bool {
 	return n.sleepModeSupported
 }
 
+// useExtraLock uses the extra lock to execute a function.
+// if the lock is currently held by another goroutine, returns an error.
+//
+// it's used to ensure that only one change is made to the video stream at a time.
+// as the change usually requires to restart video streaming
+// TODO: check video streaming status instead of using a hardcoded timeout
+func (n *Native) useExtraLock(fn func() error) error {
+	if !n.extraLock.TryLock() {
+		return fmt.Errorf("the previous change hasn't been completed yet")
+	}
+	err := fn()
+	if err == nil {
+		time.Sleep(extraLockTimeout)
+	}
+	n.extraLock.Unlock()
+	return err
+}
+
 // VideoSetQualityFactor sets the quality factor for the video stream.
 func (n *Native) VideoSetQualityFactor(factor float64) error {
 	n.videoLock.Lock()
 	defer n.videoLock.Unlock()
 
-	return videoSetStreamQualityFactor(factor)
+	return n.useExtraLock(func() error {
+		return videoSetStreamQualityFactor(factor)
+	})
 }
 
 // VideoGetQualityFactor gets the quality factor for the video stream.
@@ -87,7 +114,13 @@ func (n *Native) VideoSetEDID(edid string) error {
 	n.videoLock.Lock()
 	defer n.videoLock.Unlock()
 
-	return videoSetEDID(edid)
+	if edid == "" {
+		edid = DefaultEDID
+	}
+
+	return n.useExtraLock(func() error {
+		return videoSetEDID(edid)
+	})
 }
 
 // VideoGetEDID gets the EDID for the video stream.

jsonrpc.go

@@ -366,7 +366,6 @@ func rpcGetEDID() (string, error) {
 func rpcSetEDID(edid string) error {
 	if edid == "" {
 		logger.Info().Msg("Restoring EDID to default")
-		edid = "00ffffffffffff0052620188008888881c150103800000780a0dc9a05747982712484c00000001010101010101010101010101010101023a801871382d40582c4500c48e2100001e011d007251d01e206e285500c48e2100001e000000fc00543734392d6648443732300a20000000fd00147801ff1d000a202020202020017b"
 	} else {
 		logger.Info().Str("edid", edid).Msg("Setting EDID")
 	}

native.go

@@ -17,9 +17,10 @@ var (
 
 func initNative(systemVersion *semver.Version, appVersion *semver.Version) {
 	nativeInstance = native.NewNative(native.NativeOptions{
-		SystemVersion:   systemVersion,
+		SystemVersion:        systemVersion,
-		AppVersion:      appVersion,
+		AppVersion:           appVersion,
-		DisplayRotation: config.GetDisplayRotation(),
+		DisplayRotation:      config.GetDisplayRotation(),
+		DefaultQualityFactor: config.VideoQualityFactor,
 		OnVideoStateChange: func(state native.VideoState) {
 			lastVideoState = state
 			triggerVideoStateUpdate()
@@ -70,7 +71,13 @@ func initNative(systemVersion *semver.Version, appVersion *semver.Version) {
 			})
 		},
 	})
+
 	nativeInstance.Start()
+	go func() {
+		if err := nativeInstance.VideoSetEDID(config.EdidString); err != nil {
+			nativeLogger.Warn().Err(err).Msg("error setting EDID")
+		}
+	}()
 
 	if os.Getenv("JETKVM_CRASH_TESTING") == "1" {
 		nativeInstance.DoNotUseThisIsForCrashTestingOnly()

session_cleanup_handlers.go

@@ -25,6 +25,18 @@ func (sm *SessionManager) attemptEmergencyPromotion(ctx emergencyPromotionContex
 	sm.emergencyWindowMutex.Lock()
 	defer sm.emergencyWindowMutex.Unlock()
 
+	// CRITICAL: Bypass all rate limits if no primary exists to prevent deadlock
+	// System availability takes priority over DoS protection
+	noPrimaryExists := (sm.primarySessionID == "")
+	if noPrimaryExists {
+		sm.logger.Info().
+			Str("triggerSessionID", ctx.triggerSessionID).
+			Str("triggerReason", ctx.triggerReason).
+			Msg("Bypassing emergency promotion rate limits - no primary exists")
+		promotedSessionID := sm.findMostTrustedSessionForEmergency()
+		return promotedSessionID, true, false
+	}
+
 	const slidingWindowDuration = 60 * time.Second
 	const maxEmergencyPromotionsPerMinute = 3
 
@@ -187,19 +199,21 @@ func (sm *SessionManager) promoteAfterGraceExpiration(expiredSessionID string, n
 // handlePendingSessionTimeout removes timed-out pending sessions (DoS protection)
 // Returns true if any pending session was removed
 func (sm *SessionManager) handlePendingSessionTimeout(now time.Time) bool {
-	needsCleanup := false
+	toDelete := make([]string, 0)
 	for id, session := range sm.sessions {
 		if session.Mode == SessionModePending &&
 			now.Sub(session.CreatedAt) > defaultPendingSessionTimeout {
-			websocketLogger.Info().
+			websocketLogger.Debug().
 				Str("sessionId", id).
 				Dur("age", now.Sub(session.CreatedAt)).
 				Msg("Removing timed-out pending session")
-			delete(sm.sessions, id)
+			toDelete = append(toDelete, id)
-			needsCleanup = true
 		}
 	}
-	return needsCleanup
+	for _, id := range toDelete {
+		delete(sm.sessions, id)
+	}
+	return len(toDelete) > 0
 }
 
 // handleObserverSessionCleanup removes inactive observer sessions with closed RPC channels
@@ -210,21 +224,23 @@ func (sm *SessionManager) handleObserverSessionCleanup(now time.Time) bool {
 		observerTimeout = time.Duration(currentSessionSettings.ObserverTimeout) * time.Second
 	}
 
-	needsCleanup := false
+	toDelete := make([]string, 0)
 	for id, session := range sm.sessions {
 		if session.Mode == SessionModeObserver {
 			if session.RPCChannel == nil && now.Sub(session.LastActive) > observerTimeout {
-				sm.logger.Info().
+				sm.logger.Debug().
 					Str("sessionId", id).
 					Dur("inactiveFor", now.Sub(session.LastActive)).
 					Dur("observerTimeout", observerTimeout).
 					Msg("Removing inactive observer session with closed RPC channel")
-				delete(sm.sessions, id)
+				toDelete = append(toDelete, id)
-				needsCleanup = true
 			}
 		}
 	}
-	return needsCleanup
+	for _, id := range toDelete {
+		delete(sm.sessions, id)
+	}
+	return len(toDelete) > 0
 }
 
 // handlePrimarySessionTimeout checks and handles primary session timeout

session_manager.go

@@ -250,6 +250,10 @@ func (sm *SessionManager) AddSession(session *Session, clientSettings *SessionSe
 		// Ensure session has auto-generated nickname if needed
 		sm.ensureNickname(session)
 
+		if !nicknameReserved && session.Nickname != "" {
+			sm.nicknameIndex[session.Nickname] = session
+		}
+
 		sm.sessions[session.ID] = session
 
 		// If this was the primary, try to restore primary status
@@ -1200,8 +1204,8 @@ func (sm *SessionManager) transferPrimaryRole(fromSessionID, toSessionID, transf
 	// Promote target session
 	toSession.Mode = SessionModePrimary
 	toSession.hidRPCAvailable = false
-	// Reset LastActive only for emergency promotions to prevent immediate re-timeout
+	// Reset LastActive for all emergency promotions to prevent immediate re-timeout
-	if transferType == "emergency_timeout_promotion" || transferType == "emergency_promotion_deadlock_prevention" {
+	if strings.HasPrefix(transferType, "emergency_") {
 		toSession.LastActive = time.Now()
 	}
 	sm.primarySessionID = toSessionID

ui/src/routes/devices.$id.settings.hardware.tsx

@@ -1,13 +1,15 @@
-import { useEffect } from "react";
+import { useEffect, useState } from "react";
 
 import { SettingsItem } from "@components/SettingsItem";
 import { SettingsPageHeader } from "@components/SettingsPageheader";
+import { SettingsSectionHeader } from "@components/SettingsSectionHeader";
 import { BacklightSettings, useSettingsStore } from "@/hooks/stores";
 import { JsonRpcResponse, useJsonRpc } from "@/hooks/useJsonRpc";
 import { SelectMenuBasic } from "@components/SelectMenuBasic";
 import { UsbDeviceSetting } from "@components/UsbDeviceSetting";
 import { usePermissions } from "@/hooks/usePermissions";
 import { Permission } from "@/types/permissions";
+import { Checkbox } from "@components/Checkbox";
 
 import notifications from "../notifications";
 import { UsbInfoSetting } from "../components/UsbInfoSetting";
@@ -18,6 +20,7 @@ export default function SettingsHardwareRoute() {
   const settings = useSettingsStore();
   const { setDisplayRotation } = useSettingsStore();
   const { hasPermission, isLoading, permissions } = usePermissions();
+  const [powerSavingEnabled, setPowerSavingEnabled] = useState(false);
 
   const handleDisplayRotationChange = (rotation: string) => {
     setDisplayRotation(rotation);
@@ -61,7 +64,21 @@ export default function SettingsHardwareRoute() {
     });
   };
 
-  // Check permissions before fetching settings data
+  const handlePowerSavingChange = (enabled: boolean) => {
+    setPowerSavingEnabled(enabled);
+    const duration = enabled ? 90 : -1;
+    send("setVideoSleepMode", { duration }, (resp: JsonRpcResponse) => {
+      if ("error" in resp) {
+        notifications.error(
+          `Failed to set power saving mode: ${resp.error.data || "Unknown error"}`,
+        );
+        setPowerSavingEnabled(!enabled); // Revert on error
+        return;
+      }
+      notifications.success(`Power saving mode ${enabled ? "enabled" : "disabled"}`);
+    });
+  };
+
   useEffect(() => {
     // Only fetch settings if user has permission
     if (!isLoading && permissions[Permission.SETTINGS_READ] === true) {
@@ -77,6 +94,17 @@ export default function SettingsHardwareRoute() {
     }
   }, [send, setBacklightSettings, isLoading, permissions]);
 
+  useEffect(() => {
+    send("getVideoSleepMode", {}, (resp: JsonRpcResponse) => {
+      if ("error" in resp) {
+        console.error("Failed to get power saving mode:", resp.error);
+        return;
+      }
+      const result = resp.result as { enabled: boolean; duration: number };
+      setPowerSavingEnabled(result.duration >= 0);
+    });
+  }, [send]);
+
   // Return early if permissions are loading
   if (isLoading) {
     return (
@@ -192,6 +220,26 @@ export default function SettingsHardwareRoute() {
         </p>
       </div>
 
+      <FeatureFlag minAppVersion="0.4.9">
+        <div className="space-y-4">
+          <div className="h-px w-full bg-slate-800/10 dark:bg-slate-300/20" />
+          <SettingsSectionHeader
+            title="Power Saving"
+            description="Reduce power consumption when not in use"
+          />
+          <SettingsItem
+            badge="Experimental"
+            title="HDMI Sleep Mode"
+            description="Turn off capture after 90 seconds of inactivity"
+          >
+            <Checkbox
+              checked={powerSavingEnabled}
+              onChange={(e) => handlePowerSavingChange(e.target.checked)}
+            />
+          </SettingsItem>
+        </div>
+      </FeatureFlag>
+
       <FeatureFlag minAppVersion="0.3.8">
         <UsbDeviceSetting />
       </FeatureFlag>

ui/src/routes/devices.$id.tsx

@@ -898,10 +898,11 @@ export default function KvmIdRoute() {
 
   useEffect(() => {
     if (appVersion) return;
+    if (rpcDataChannel?.readyState !== "open") return;
 
     getLocalVersion();
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [appVersion]);
+  }, [appVersion, rpcDataChannel?.readyState]);
 
   const ConnectionStatusElement = useMemo(() => {
     const isOtherSession = location.pathname.includes("other-session");

webrtc.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/coder/websocket"
@@ -66,24 +67,14 @@ type Session struct {
 	keysDownStateQueue chan usbgadget.KeysDownState
 }
 
-var (
+var actionSessions atomic.Int32
-	actionSessions      int = 0
-	activeSessionsMutex     = &sync.Mutex{}
-)
 
-func incrActiveSessions() int {
+func incrActiveSessions() int32 {
-	activeSessionsMutex.Lock()
+	return actionSessions.Add(1)
-	defer activeSessionsMutex.Unlock()
-
-	actionSessions++
-	return actionSessions
 }
 
-func getActiveSessions() int {
+func getActiveSessions() int32 {
-	activeSessionsMutex.Lock()
+	return actionSessions.Load()
-	defer activeSessionsMutex.Unlock()
-
-	return actionSessions
 }
 
 // CheckRPCRateLimit checks if the session has exceeded RPC rate limits (DoS protection)
@@ -494,9 +485,9 @@ func newSession(config SessionConfig) (*Session, error) {
 
 		if isConnected {
 			isConnected = false
-			actionSessions--
+			newCount := actionSessions.Add(-1)
 			onActiveSessionsChanged()
-			if actionSessions == 0 {
+			if newCount == 0 {
 				onLastSessionDisconnected()
 			}
 		}