diff --git a/Cargo.lock b/Cargo.lock
index e8cb121..ae22958 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1642,7 +1642,7 @@ checksum = "09edd9e8b54e49e587e4f6295a7d29c3ea94d469cb40ab8ca70b288248a81db2"
 
 [[package]]
 name = "lesavka_client"
-version = "0.14.41"
+version = "0.14.42"
 dependencies = [
  "anyhow",
  "async-stream",
@@ -1676,7 +1676,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_common"
-version = "0.14.41"
+version = "0.14.42"
 dependencies = [
  "anyhow",
  "base64",
@@ -1688,7 +1688,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_server"
-version = "0.14.41"
+version = "0.14.42"
 dependencies = [
  "anyhow",
  "base64",
diff --git a/client/Cargo.toml b/client/Cargo.toml
index 8101de5..27cb5b0 100644
--- a/client/Cargo.toml
+++ b/client/Cargo.toml
@@ -4,7 +4,7 @@ path                    = "src/main.rs"
 
 [package]
 name                    = "lesavka_client"
-version                 = "0.14.41"
+version                 = "0.14.42"
 edition                 = "2024"
 
 [dependencies]
diff --git a/common/Cargo.toml b/common/Cargo.toml
index bc820e4..dfc00a8 100644
--- a/common/Cargo.toml
+++ b/common/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name                    = "lesavka_common"
-version                 = "0.14.41"
+version                 = "0.14.42"
 edition                 = "2024"
 build                   = "build.rs"
 
diff --git a/scripts/daemon/lesavka-core.sh b/scripts/daemon/lesavka-core.sh
index b736d11..aeb12a6 100755
--- a/scripts/daemon/lesavka-core.sh
+++ b/scripts/daemon/lesavka-core.sh
@@ -9,10 +9,22 @@ log() { printf '[lesavka-core] %s\n' "$*"; }
 
 G=/sys/kernel/config/usb_gadget/lesavka
 
-if [[ -r /etc/lesavka/uvc.env ]]; then
-    # shellcheck disable=SC1091
-    source /etc/lesavka/uvc.env
-fi
+load_uvc_env_defaults() {
+    local env_file=/etc/lesavka/uvc.env
+    [[ -r $env_file ]] || return 0
+    local line key value
+    while IFS= read -r line || [[ -n $line ]]; do
+        [[ $line =~ ^[[:space:]]*# || -z $line ]] && continue
+        [[ $line == *=* ]] || continue
+        key=${line%%=*}
+        value=${line#*=}
+        [[ $key =~ ^[A-Za-z_][A-Za-z0-9_]*$ ]] || continue
+        [[ -z ${!key+x} ]] || continue
+        export "$key=$value"
+    done <"$env_file"
+}
+
+load_uvc_env_defaults
 
 find_udc() {
     ls /sys/class/udc 2>/dev/null | head -n1 || true
@@ -505,19 +517,7 @@ EOF
   fi
   popd >/dev/null
 
-  streaming_class_speeds=(fs)
-  control_class_speeds=(fs)
-  case "$MAX_SPEED" in
-    super-speed|super-speed-plus)
-      streaming_class_speeds+=(hs ss)
-      control_class_speeds+=(ss)
-      ;;
-    high-speed)
-      streaming_class_speeds+=(hs)
-      ;;
-  esac
-
-  for s in "${streaming_class_speeds[@]}"; do
+  for s in fs hs ss; do
       mkdir -p "$F/streaming/class/$s"
       pushd "$F/streaming/class/$s" >/dev/null
       ln -s ../../header/h h
@@ -526,12 +526,11 @@ EOF
 
 # ── 4.  Video‑Control interface ─────────────────────────────────────
   mkdir -p "$F/control/header/h"
-  # The kernel UVC gadget docs make the control-speed links optional; only
-  # advertise the descriptor sets that match the configured gadget speed.
+  # The kernel UVC gadget docs require direct symlinks at control/class/fs and
+  # control/class/ss. High-speed control descriptors are not exposed here.
   pushd "$F/control" >/dev/null
-  for s in "${control_class_speeds[@]}"; do
-    ln -s header/h "class/$s" 2>/dev/null || true
-  done
+  ln -s header/h class/fs 2>/dev/null || true
+  ln -s header/h class/ss 2>/dev/null || true
   popd >/dev/null
 
   if [[ -n $UVC_DISABLE_IRQ ]]; then
diff --git a/scripts/daemon/lesavka-uvc.sh b/scripts/daemon/lesavka-uvc.sh
index 4363b6d..20cabcd 100755
--- a/scripts/daemon/lesavka-uvc.sh
+++ b/scripts/daemon/lesavka-uvc.sh
@@ -2,11 +2,24 @@
 # scripts/daemon/lesavka-uvc.sh - launch UVC control helper as a standalone service
 set -euo pipefail
 
-# Optional env file for runtime overrides (debug, width/fps, etc.)
-if [[ -r /etc/lesavka/uvc.env ]]; then
-    # shellcheck disable=SC1091
-    source /etc/lesavka/uvc.env
-fi
+# Optional env file for runtime defaults (debug, width/fps, etc.). Explicit
+# environment from a recovery shell wins so bench overrides are not masked.
+load_uvc_env_defaults() {
+    local env_file=/etc/lesavka/uvc.env
+    [[ -r $env_file ]] || return 0
+    local line key value
+    while IFS= read -r line || [[ -n $line ]]; do
+        [[ $line =~ ^[[:space:]]*# || -z $line ]] && continue
+        [[ $line == *=* ]] || continue
+        key=${line%%=*}
+        value=${line#*=}
+        [[ $key =~ ^[A-Za-z_][A-Za-z0-9_]*$ ]] || continue
+        [[ -z ${!key+x} ]] || continue
+        export "$key=$value"
+    done <"$env_file"
+}
+
+load_uvc_env_defaults
 
 resolve_default_uvc_dev() {
     local ctrl=""
diff --git a/scripts/install/server.sh b/scripts/install/server.sh
index 9f816cf..6d17b84 100755
--- a/scripts/install/server.sh
+++ b/scripts/install/server.sh
@@ -829,7 +829,8 @@ echo "==> 6b. Systemd units - lesavka-server"
 cat <<'UNIT' | sudo tee /etc/systemd/system/lesavka-server.service >/dev/null
 [Unit]
 Description=lesavka gRPC relay
-After=network.target lesavka-core.service
+After=network.target lesavka-core.service lesavka-uvc.service
+Wants=lesavka-uvc.service
 StartLimitIntervalSec=30
 StartLimitBurst=10
 
@@ -850,11 +851,12 @@ Environment=LESAVKA_EYE_FPS=20
 Environment=LESAVKA_MIC_INIT_ATTEMPTS=5
 Environment=LESAVKA_MIC_INIT_DELAY_MS=250
 Environment=LESAVKA_ALLOW_GADGET_CYCLE=1
+Environment=LESAVKA_SERVER_LOG_PATH=/var/log/lesavka/server.log
 EnvironmentFile=-/etc/lesavka/uvc.env
 EnvironmentFile=-/etc/lesavka/server.env
 Restart=always
 RestartSec=5
-StandardError=append:/tmp/lesavka-server.stderr
+StandardError=append:/var/log/lesavka/server.stderr
 User=root
 
 [Install]
@@ -862,7 +864,9 @@ WantedBy=multi-user.target
 UNIT
 
 echo "==> 6c. Systemd units - initialization"
-sudo truncate -s 0 /tmp/lesavka-server.log
+sudo install -d -m 0755 /var/log/lesavka
+sudo rm -f /tmp/lesavka-server.log
+sudo truncate -s 0 /var/log/lesavka/server.log
 sudo systemctl daemon-reload
 sudo systemctl enable lesavka-core lesavka-server
 
@@ -878,6 +882,8 @@ if [[ "$UVC_ENV_CHANGED" == "1" ]] && is_attached_state "$UDC_STATE"; then
 fi
 if [[ -n ${LESAVKA_ALLOW_GADGET_RESET:-} ]] || [[ "$FORCE_GADGET_REBUILD" == "1" ]] || ! is_attached_state "$UDC_STATE"; then
   echo "⚠️  UDC state is '$UDC_STATE' - forcing a Lesavka gadget rebuild before server start."
+  sudo systemctl stop lesavka-uvc >/dev/null 2>&1 || true
+  sudo systemctl reset-failed lesavka-uvc >/dev/null 2>&1 || true
   sudo env \
     LESAVKA_ALLOW_GADGET_RESET=1 \
     LESAVKA_ATTACH_WRITE_UDC=1 \
@@ -906,7 +912,7 @@ RestartSec=2
 KillSignal=SIGTERM
 KillMode=control-group
 TimeoutStopSec=10
-StandardError=append:/tmp/lesavka-uvc.stderr
+StandardError=append:/var/log/lesavka/uvc.stderr
 User=root
 EnvironmentFile=-/etc/lesavka/uvc.env
 
@@ -934,12 +940,14 @@ if [[ "$UVC_ENV_CHANGED" == "1" ]] && systemctl is-active --quiet lesavka-uvc; t
 elif systemctl is-active --quiet lesavka-uvc; then
   echo "✅  lesavka-uvc already active; runtime settings unchanged."
 else
-  echo "⚠️  lesavka-uvc is not active; start via lesavka-core dependency path."
+  sudo truncate -s 0 /var/log/lesavka/uvc.stderr
+  sudo systemctl start lesavka-uvc
+  echo "✅  lesavka-uvc started to attach the UVC gadget to the host."
 fi
 
 validate_uvc_gadget_ready
 
-sudo truncate -s 0 /tmp/lesavka-server.stderr
+sudo truncate -s 0 /var/log/lesavka/server.stderr
 sudo systemctl stop lesavka-server >/dev/null 2>&1 || true
 clear_stale_server_listener
 sudo systemctl reset-failed lesavka-server >/dev/null 2>&1 || true
diff --git a/scripts/manual/run_upstream_av_sync.sh b/scripts/manual/run_upstream_av_sync.sh
index 8055b79..f90bbf9 100755
--- a/scripts/manual/run_upstream_av_sync.sh
+++ b/scripts/manual/run_upstream_av_sync.sh
@@ -15,7 +15,10 @@ LESAVKA_SERVER_CONNECT_HOST=${LESAVKA_SERVER_CONNECT_HOST:-38.28.125.112}
 LESAVKA_SERVER_ADDR=${LESAVKA_SERVER_ADDR:-auto}
 PROBE_DURATION_SECONDS=${PROBE_DURATION_SECONDS:-10}
 PROBE_WARMUP_SECONDS=${PROBE_WARMUP_SECONDS:-4}
-LEAD_IN_SECONDS=${LEAD_IN_SECONDS:-8}
+# Do not open the UVC host capture far ahead of the probe. The gadget side only
+# has frames once the sync probe is feeding the server, and some hosts time out
+# VIDIOC_STREAMON if the camera is starved during pre-roll.
+LEAD_IN_SECONDS=${LEAD_IN_SECONDS:-0}
 TAIL_SECONDS=${TAIL_SECONDS:-2}
 CAPTURE_SECONDS=${CAPTURE_SECONDS:-$((PROBE_DURATION_SECONDS + PROBE_WARMUP_SECONDS + LEAD_IN_SECONDS + TAIL_SECONDS))}
 REMOTE_CAPTURE=${REMOTE_CAPTURE:-/tmp/lesavka-upstream-av-sync.mkv}
@@ -773,6 +776,11 @@ if [[ -f "${LOCAL_CAPTURE_LOG}" ]] \
   && grep -q 'VIDIOC_QBUF): Bad file descriptor' "${LOCAL_CAPTURE_LOG}"; then
   capture_v4l2_fault=1
 fi
+capture_streamon_timeout=0
+if [[ -f "${LOCAL_CAPTURE_LOG}" ]] \
+  && grep -q 'VIDIOC_STREAMON.*Connection timed out' "${LOCAL_CAPTURE_LOG}"; then
+  capture_streamon_timeout=1
+fi
 
 if ssh ${SSH_OPTS} "${TETHYS_HOST}" "test -f '${REMOTE_CAPTURE}'"; then
   remote_fetch_capture="${REMOTE_CAPTURE}"
@@ -826,6 +834,10 @@ if [[ "${probe_status}" -ne 0 ]]; then
   exit "${probe_status}"
 fi
 if [[ "${capture_status}" -ne 0 ]]; then
+  if [[ "${capture_streamon_timeout}" -eq 1 ]]; then
+    echo "Tethys capture timed out during VIDIOC_STREAMON; the UVC host opened before MJPEG frames reached the gadget." >&2
+    echo "Keep LEAD_IN_SECONDS=0 and restart lesavka-uvc/lesavka-server before retrying if the gadget is wedged from an earlier failed run." >&2
+  fi
   if [[ "${capture_status}" -eq 141 && ( -f "${LOCAL_CAPTURE}" || -f "${LOCAL_ANALYSIS_JSON}" ) ]]; then
     echo "Tethys capture ended with PipeWire SIGPIPE after ffmpeg closed; accepting preserved analysis artifacts" >&2
   elif [[ "${capture_status}" -eq 124 && ( -f "${LOCAL_CAPTURE}" || -f "${LOCAL_ANALYSIS_JSON}" ) ]]; then
diff --git a/server/Cargo.toml b/server/Cargo.toml
index c40975d..382e392 100644
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -10,7 +10,7 @@ bench                   = false
 
 [package]
 name                    = "lesavka_server"
-version                 = "0.14.41"
+version                 = "0.14.42"
 edition                 = "2024"
 autobins                = false
 
diff --git a/server/src/runtime_support/hid_recovery.rs b/server/src/runtime_support/hid_recovery.rs
index 9909283..04183d4 100644
--- a/server/src/runtime_support/hid_recovery.rs
+++ b/server/src/runtime_support/hid_recovery.rs
@@ -29,32 +29,66 @@ pub fn init_tracing() -> anyhow::Result<WorkerGuard> {
 
 #[cfg(not(coverage))]
 pub fn init_tracing() -> anyhow::Result<WorkerGuard> {
-    let file = std::fs::OpenOptions::new()
-        .create(true)
-        .truncate(true)
-        .write(true)
-        .open("/tmp/lesavka-server.log")?;
-    let (file_writer, guard) = tracing_appender::non_blocking(file);
-
     let env_filter = EnvFilter::try_from_default_env()
         .unwrap_or_else(|_| EnvFilter::new("lesavka_server=info,lesavka_server::video=warn"));
     let filter_str = env_filter.to_string();
+    let file = open_server_log_file();
+    let log_open_error = file.as_ref().err().map(ToString::to_string);
+    let (file_writer, guard) = match file {
+        Ok(file) => {
+            let (writer, guard) = tracing_appender::non_blocking(file);
+            (Some(writer), guard)
+        }
+        Err(_) => {
+            let (_writer, guard) = tracing_appender::non_blocking(std::io::sink());
+            (None, guard)
+        }
+    };
 
-    tracing_subscriber::registry()
+    let registry = tracing_subscriber::registry()
         .with(env_filter)
-        .with(fmt::layer().with_target(true).with_thread_ids(true))
-        .with(
-            fmt::layer()
-                .with_writer(file_writer)
-                .with_ansi(false)
-                .with_target(true)
-                .with_level(true),
-        )
-        .init();
+        .with(fmt::layer().with_target(true).with_thread_ids(true));
+    if let Some(file_writer) = file_writer {
+        registry
+            .with(
+                fmt::layer()
+                    .with_writer(file_writer)
+                    .with_ansi(false)
+                    .with_target(true)
+                    .with_level(true),
+            )
+            .init();
+    } else {
+        registry.init();
+    }
     tracing::info!("📜 effective RUST_LOG = \"{}\"", filter_str);
+    if let Some(error) = log_open_error {
+        tracing::warn!("file logging disabled: {error}");
+    }
     Ok(guard)
 }
 
+#[cfg(not(coverage))]
+fn open_server_log_file() -> std::io::Result<std::fs::File> {
+    let preferred = std::env::var("LESAVKA_SERVER_LOG_PATH")
+        .unwrap_or_else(|_| "/var/log/lesavka/server.log".to_string());
+    for path in [preferred.as_str(), "/tmp/lesavka-server.log"] {
+        match std::fs::OpenOptions::new()
+            .create(true)
+            .truncate(true)
+            .write(true)
+            .open(path)
+        {
+            Ok(file) => return Ok(file),
+            Err(error) if path != "/tmp/lesavka-server.log" => {
+                eprintln!("lesavka-server: failed to open {path}: {error}; trying /tmp fallback");
+            }
+            Err(error) => return Err(error),
+        }
+    }
+    unreachable!("static log path list is non-empty")
+}
+
 /// Open a HID gadget endpoint with bounded retry logic.
 ///
 /// Inputs: the path of the gadget device node to open.
diff --git a/testing/tests/client_manual_sync_script_contract.rs b/testing/tests/client_manual_sync_script_contract.rs
index f5dc56f..c83b833 100644
--- a/testing/tests/client_manual_sync_script_contract.rs
+++ b/testing/tests/client_manual_sync_script_contract.rs
@@ -19,6 +19,9 @@ fn upstream_sync_script_tunnels_auto_server_addr_through_ssh() {
         "RESOLVED_LESAVKA_SERVER_ADDR=\"http://127.0.0.1:${SERVER_TUNNEL_LOCAL_PORT}\"",
         "tunneled to ${LESAVKA_SERVER_HOST}:127.0.0.1:${SERVER_TUNNEL_REMOTE_PORT}",
         "CAPTURE_READY_MARKER=\"__LESAVKA_CAPTURE_READY__\"",
+        "LEAD_IN_SECONDS=${LEAD_IN_SECONDS:-0}",
+        "VIDIOC_STREAMON.*Connection timed out",
+        "the UVC host opened before MJPEG frames reached the gadget",
         "Tethys capture failed before the sync probe could start",
         "wait_for_capture_ready",
         "Timed out waiting for Tethys capture to become ready",
@@ -34,7 +37,9 @@ fn upstream_sync_script_tunnels_auto_server_addr_through_ssh() {
         );
     }
     assert!(
-        !SYNC_SCRIPT.contains("RESOLVED_LESAVKA_SERVER_ADDR=\"http://${LESAVKA_SERVER_CONNECT_HOST}:${port}\""),
+        !SYNC_SCRIPT.contains(
+            "RESOLVED_LESAVKA_SERVER_ADDR=\"http://${LESAVKA_SERVER_CONNECT_HOST}:${port}\""
+        ),
         "auto server resolution should not guess a public gRPC host when SSH is already required"
     );
 }
diff --git a/testing/tests/server_core_script_contract.rs b/testing/tests/server_core_script_contract.rs
index edf130f..6edbed6 100644
--- a/testing/tests/server_core_script_contract.rs
+++ b/testing/tests/server_core_script_contract.rs
@@ -43,9 +43,8 @@ fn core_script_skips_soft_connect_for_dwc2() {
 fn core_script_uses_kernel_doc_control_header_links() {
     for expected in [
         "pushd \"$F/control\" >/dev/null",
-        "ln -s header/h \"class/$s\"",
-        "control_class_speeds=(fs)",
-        "for s in \"${control_class_speeds[@]}\"; do",
+        "ln -s header/h class/fs",
+        "ln -s header/h class/ss",
     ] {
         assert!(
             CORE_SCRIPT.contains(expected),
@@ -59,21 +58,31 @@ fn core_script_uses_kernel_doc_control_header_links() {
 }
 
 #[test]
-fn core_script_matches_uvc_descriptor_speeds_to_max_speed() {
-    for expected in [
-        "streaming_class_speeds=(fs)",
-        "control_class_speeds=(fs)",
-        "case \"$MAX_SPEED\" in",
-        "super-speed|super-speed-plus)",
-        "streaming_class_speeds+=(hs ss)",
-        "control_class_speeds+=(ss)",
-        "high-speed)",
-        "streaming_class_speeds+=(hs)",
-        "for s in \"${streaming_class_speeds[@]}\"; do",
-    ] {
+fn core_script_keeps_known_good_uvc_descriptor_links() {
+    for expected in ["for s in fs hs ss; do", "ln -s ../../header/h h"] {
         assert!(
             CORE_SCRIPT.contains(expected),
-            "lesavka-core speed guard missing: {expected}"
+            "lesavka-core descriptor guard missing: {expected}"
+        );
+    }
+    for unexpected in ["streaming_class_speeds", "control_class_speeds"] {
+        assert!(
+            !CORE_SCRIPT.contains(unexpected),
+            "lesavka-core should not trim UVC descriptor links by gadget speed: {unexpected}"
+        );
+    }
+}
+
+#[test]
+fn core_script_treats_uvc_env_as_defaults_not_overrides() {
+    for expected in [
+        "load_uvc_env_defaults()",
+        "[[ -z ${!key+x} ]] || continue",
+        "export \"$key=$value\"",
+    ] {
+        assert!(
+            CORE_SCRIPT.contains(expected),
+            "lesavka-core env-default guard missing: {expected}"
         );
     }
 }
diff --git a/testing/tests/server_install_script_contract.rs b/testing/tests/server_install_script_contract.rs
index 20bb978..e793c5e 100644
--- a/testing/tests/server_install_script_contract.rs
+++ b/testing/tests/server_install_script_contract.rs
@@ -57,7 +57,8 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
         "install script should not let ambient LESAVKA_UVC_CODEC leak into persisted defaults"
     );
     assert!(
-        !SERVER_INSTALL.contains("LESAVKA_SERVER_BIND_ADDR=${LESAVKA_SERVER_BIND_ADDR:-0.0.0.0:50051}"),
+        !SERVER_INSTALL
+            .contains("LESAVKA_SERVER_BIND_ADDR=${LESAVKA_SERVER_BIND_ADDR:-0.0.0.0:50051}"),
         "install script should not let ambient LESAVKA_SERVER_BIND_ADDR leak into persisted defaults"
     );
     assert!(
@@ -81,13 +82,19 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
         "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."),
+        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("lesavka-core gadget rebuilt directly."),
         "install script should trust the direct forced rebuild instead of immediately rerunning the oneshot core unit"
     );
+    assert!(
+        SERVER_INSTALL.contains("sudo systemctl stop lesavka-uvc"),
+        "install script should stop the UVC helper before directly rebuilding the gadget underneath it"
+    );
     assert!(
         !SERVER_INSTALL.contains("sudo systemctl restart lesavka-core"),
         "install script should not immediately rerun lesavka-core after a successful direct forced rebuild"
@@ -112,6 +119,26 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
         SERVER_INSTALL.contains("lesavka-uvc already active; runtime settings unchanged."),
         "install script should avoid unnecessary UVC restarts when nothing changed"
     );
+    assert!(
+        SERVER_INSTALL.contains("sudo systemctl start lesavka-uvc"),
+        "install script should start the UVC helper so the host enumerates the UVC function"
+    );
+    assert!(
+        SERVER_INSTALL.contains("lesavka-uvc started to attach the UVC gadget to the host."),
+        "install script should report when it starts the UVC helper for enumeration"
+    );
+    assert!(
+        SERVER_INSTALL.contains("Wants=lesavka-uvc.service"),
+        "server unit should pull in the external UVC helper on UVC installs"
+    );
+    assert!(
+        SERVER_INSTALL.contains("/var/log/lesavka/server.log"),
+        "install script should keep server logs out of sticky /tmp"
+    );
+    assert!(
+        SERVER_INSTALL.contains("LESAVKA_SERVER_LOG_PATH=/var/log/lesavka/server.log"),
+        "server unit should point tracing at the non-sticky log path"
+    );
     assert!(
         SERVER_INSTALL.contains("clear_stale_server_listener"),
         "install script should clear stale server listeners before restart"