fix(sync): rebuild incomplete uvc gadgets

Cargo.lock

@@ -1642,7 +1642,7 @@ checksum = "09edd9e8b54e49e587e4f6295a7d29c3ea94d469cb40ab8ca70b288248a81db2"
 
 [[package]]
 name = "lesavka_client"
-version = "0.14.29"
+version = "0.14.30"
 dependencies = [
  "anyhow",
  "async-stream",
@@ -1676,7 +1676,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_common"
-version = "0.14.29"
+version = "0.14.30"
 dependencies = [
  "anyhow",
  "base64",
@@ -1688,7 +1688,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_server"
-version = "0.14.29"
+version = "0.14.30"
 dependencies = [
  "anyhow",
  "base64",

client/Cargo.toml

@@ -4,7 +4,7 @@ path                    = "src/main.rs"
 
 [package]
 name                    = "lesavka_client"
-version                 = "0.14.29"
+version                 = "0.14.30"
 edition                 = "2024"
 
 [dependencies]

client/src/sync_probe/capture/tests.rs

@@ -472,3 +472,52 @@ async fn runtime_probe_video_packets_change_across_a_pulse_boundary() {
         "expected decoded pulse frame to be much brighter than decoded dark frame, got dark={dark_mean} pulse={pulse_mean}"
     );
 }
+
+#[cfg(not(coverage))]
+#[tokio::test]
+async fn runtime_probe_dark_video_packets_do_not_alternate_frame_to_frame() {
+    let capture = SyncProbeCapture::new(
+        CameraConfig {
+            codec: CameraCodec::Mjpeg,
+            width: 640,
+            height: 480,
+            fps: 20,
+        },
+        PulseSchedule::new(
+            Duration::from_secs(4),
+            Duration::from_secs(1),
+            Duration::from_millis(120),
+            5,
+        ),
+        Duration::from_secs(3),
+    )
+    .expect("runtime capture");
+
+    let video_queue = capture.video_queue();
+    let mut dark_means = Vec::new();
+
+    loop {
+        let next = video_queue.pop_fresh().await;
+        let Some(packet) = next.packet else {
+            break;
+        };
+        if packet.pts >= 1_000_000 {
+            break;
+        }
+        dark_means.push(decode_mjpeg_packet_mean_luma(&packet));
+        if dark_means.len() >= 8 {
+            break;
+        }
+    }
+
+    assert!(
+        dark_means.len() >= 4,
+        "expected several dark packets before the first pulse, got {dark_means:?}"
+    );
+    let min = *dark_means.iter().min().expect("dark min");
+    let max = *dark_means.iter().max().expect("dark max");
+    assert!(
+        max.saturating_sub(min) <= 2,
+        "expected consecutive dark MJPEG packets to stay visually stable, got {dark_means:?}"
+    );
+}

common/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name                    = "lesavka_common"
-version                 = "0.14.29"
+version                 = "0.14.30"
 edition                 = "2024"
 build                   = "build.rs"
 

scripts/daemon/lesavka-core.sh

@@ -81,6 +81,18 @@ attach_gadget() {
     return 0
 }
 
+gadget_has_expected_functions() {
+    [[ -d $G/functions/hid.usb0 ]] || return 1
+    [[ -d $G/functions/hid.usb1 ]] || return 1
+    if [[ -z ${DISABLE_UAC:-} ]]; then
+        [[ -d $G/functions/uac2.usb0 ]] || return 1
+    fi
+    if [[ -z ${DISABLE_UVC:-} ]]; then
+        [[ -d $G/functions/uvc.usb0 ]] || return 1
+    fi
+    return 0
+}
+
 case "${1:-}" in
     --detach)
         detach_gadget
@@ -314,10 +326,13 @@ log "✅ UDC detected: $UDC"
 # If a gadget is already configured, avoid tearing it down unless forced.
 if [[ -d $G && -z $ALLOW_RESET ]]; then
     if [[ -s $G/UDC || -d $G/configs/c.1 ]]; then
-        log "🔒 gadget already configured; skipping reset."
+        if gadget_has_expected_functions; then
-        log "    Set LESAVKA_ALLOW_GADGET_RESET=1 to force rebuild."
+            log "🔒 gadget already configured; skipping reset."
-        attach_gadget || true
+            log "    Set LESAVKA_ALLOW_GADGET_RESET=1 to force rebuild."
-        exit 0
+            attach_gadget || true
+            exit 0
+        fi
+        log "⚠️  gadget is configured but missing expected functions; continuing toward rebuild."
     fi
 fi
 

scripts/install/server.sh

@@ -90,6 +90,10 @@ validate_uvc_gadget_ready() {
   echo "✅  UVC gadget output ready at ${node}"
 }
 
+uvc_gadget_present() {
+  [[ -d /sys/kernel/config/usb_gadget/lesavka/functions/uvc.usb0 ]]
+}
+
 udc_state() {
   local udc=""
   udc=$(ls /sys/class/udc 2>/dev/null | head -n1 || true)
@@ -644,6 +648,10 @@ sudo systemctl enable lesavka-core lesavka-server
 
 UDC_STATE=$(udc_state)
 FORCE_GADGET_REBUILD=0
+if [[ -z ${LESAVKA_DISABLE_UVC:-} ]] && ! uvc_gadget_present; then
+  FORCE_GADGET_REBUILD=1
+  echo "⚠️  UVC function is missing from the live gadget; forcing a rebuild before server start."
+fi
 if [[ "$UVC_ENV_CHANGED" == "1" ]] && is_attached_state "$UDC_STATE"; then
   FORCE_GADGET_REBUILD=1
   echo "⚠️  UVC runtime settings changed while the host is attached; forcing a gadget rebuild so the new descriptors take effect."
@@ -676,7 +684,7 @@ ExecStart=/usr/local/bin/lesavka-uvc.sh
 Restart=always
 RestartSec=2
 KillSignal=SIGTERM
-KillMode=process
+KillMode=control-group
 TimeoutStopSec=10
 StandardError=append:/tmp/lesavka-uvc.stderr
 User=root

server/Cargo.toml

@@ -10,7 +10,7 @@ bench                   = false
 
 [package]
 name                    = "lesavka_server"
-version                 = "0.14.29"
+version                 = "0.14.30"
 edition                 = "2024"
 autobins                = false
 

testing/tests/server_install_script_contract.rs

@@ -70,6 +70,14 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
         SERVER_INSTALL.contains("validate_uvc_gadget_ready"),
         "install script should verify that the UVC gadget comes back before declaring success"
     );
+    assert!(
+        SERVER_INSTALL.contains("uvc_gadget_present"),
+        "install script should detect when the live gadget is missing the expected UVC function"
+    );
+    assert!(
+        SERVER_INSTALL.contains("UVC function is missing from the live gadget; forcing a rebuild before server start."),
+        "install script should force a rebuild when the live gadget is attached but missing UVC"
+    );
     assert!(
         SERVER_INSTALL.contains("video-output node did not appear after rebuild"),
         "install script should explain why it refuses a half-applied UVC install"
@@ -78,6 +86,10 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
         !SERVER_INSTALL.contains("RefuseManualStop=yes"),
         "install script should not generate a UVC unit that blocks legitimate refreshes"
     );
+    assert!(
+        SERVER_INSTALL.contains("KillMode=control-group"),
+        "install script should stop the whole UVC helper cgroup instead of leaving child processes behind"
+    );
     assert!(
         SERVER_INSTALL.contains("lesavka-uvc already active; runtime settings unchanged."),
         "install script should avoid unnecessary UVC restarts when nothing changed"