diff --git a/Cargo.lock b/Cargo.lock
index ea49221..2a7d1ed 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1642,7 +1642,7 @@ checksum = "09edd9e8b54e49e587e4f6295a7d29c3ea94d469cb40ab8ca70b288248a81db2"
 
 [[package]]
 name = "lesavka_client"
-version = "0.13.7"
+version = "0.13.8"
 dependencies = [
  "anyhow",
  "async-stream",
@@ -1676,7 +1676,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_common"
-version = "0.13.7"
+version = "0.13.8"
 dependencies = [
  "anyhow",
  "base64",
@@ -1688,7 +1688,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_server"
-version = "0.13.7"
+version = "0.13.8"
 dependencies = [
  "anyhow",
  "base64",
diff --git a/client/Cargo.toml b/client/Cargo.toml
index 6d8b315..8882e15 100644
--- a/client/Cargo.toml
+++ b/client/Cargo.toml
@@ -4,7 +4,7 @@ path                    = "src/main.rs"
 
 [package]
 name                    = "lesavka_client"
-version                 = "0.13.7"
+version                 = "0.13.8"
 edition                 = "2024"
 
 [dependencies]
diff --git a/common/Cargo.toml b/common/Cargo.toml
index a901e20..1f74b42 100644
--- a/common/Cargo.toml
+++ b/common/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name                    = "lesavka_common"
-version                 = "0.13.7"
+version                 = "0.13.8"
 edition                 = "2024"
 build                   = "build.rs"
 
diff --git a/scripts/install/server.sh b/scripts/install/server.sh
index 5618ab0..6203022 100755
--- a/scripts/install/server.sh
+++ b/scripts/install/server.sh
@@ -408,6 +408,7 @@ sudo install -Dm755 "$SRC_DIR/target/release/lesavka-server" /usr/local/bin/lesa
 sudo install -Dm755 "$SRC_DIR/target/release/lesavka-uvc"    /usr/local/bin/lesavka-uvc
 sudo install -Dm755 "$SRC_DIR/scripts/daemon/lesavka-core.sh"       /usr/local/bin/lesavka-core.sh
 sudo install -Dm755 "$SRC_DIR/scripts/daemon/lesavka-uvc.sh"        /usr/local/bin/lesavka-uvc.sh
+sudo install -Dm755 "$SRC_DIR/scripts/manual/run_uac_output_sanity.sh" /usr/local/bin/lesavka-uac-sanity
 
 echo "==> 5b. Runtime environment defaults"
 sudo install -d -m 0755 /etc/lesavka
diff --git a/scripts/manual/run_uac_output_sanity.sh b/scripts/manual/run_uac_output_sanity.sh
new file mode 100644
index 0000000..4f4d356
--- /dev/null
+++ b/scripts/manual/run_uac_output_sanity.sh
@@ -0,0 +1,139 @@
+#!/usr/bin/env bash
+# scripts/manual/run_uac_output_sanity.sh - play a short tone into the Theia UAC sink
+set -euo pipefail
+
+if [[ ${EUID:-$(id -u)} -ne 0 ]]; then
+  echo "❌ run this as root so it uses the same UAC leg as lesavka-server." >&2
+  exit 1
+fi
+
+SERVER_ENV=${LESAVKA_SERVER_ENV:-/etc/lesavka/server.env}
+if [[ -r $SERVER_ENV ]]; then
+  set -a
+  # shellcheck disable=SC1090
+  source "$SERVER_ENV"
+  set +a
+fi
+
+DURATION_SECONDS=${LESAVKA_UAC_SANITY_SECONDS:-4}
+TONE_FREQ=${LESAVKA_UAC_SANITY_FREQ:-880}
+TONE_VOLUME=${LESAVKA_UAC_SANITY_VOLUME:-0.45}
+BUFFER_TIME_US=${LESAVKA_UAC_BUFFER_TIME_US:-20000}
+LATENCY_TIME_US=${LESAVKA_UAC_LATENCY_TIME_US:-5000}
+REQUESTED_DEV=${LESAVKA_UAC_SANITY_DEV:-${LESAVKA_UAC_DEV:-hw:UAC2Gadget,0}}
+
+declare -A SEEN_CANDIDATES=()
+CANDIDATES=()
+
+append_candidate() {
+  local candidate="${1:-}"
+  candidate=${candidate//[$'\r\n']/}
+  candidate=${candidate#"${candidate%%[![:space:]]*}"}
+  candidate=${candidate%"${candidate##*[![:space:]]}"}
+  [[ -n $candidate ]] || return 0
+  if [[ -z ${SEEN_CANDIDATES[$candidate]+x} ]]; then
+    CANDIDATES+=("$candidate")
+    SEEN_CANDIDATES["$candidate"]=1
+  fi
+}
+
+append_candidate_family() {
+  local candidate="${1:-}"
+  [[ -n ${candidate//[[:space:]]/} ]] || return 0
+  append_candidate "$candidate"
+  if [[ $candidate == hw:* ]]; then
+    append_candidate "plughw:${candidate#hw:}"
+  elif [[ $candidate == plughw:* ]]; then
+    append_candidate "hw:${candidate#plughw:}"
+  fi
+}
+
+discover_uac_numeric_candidates() {
+  python3 - <<'PY'
+import re
+import subprocess
+
+try:
+    output = subprocess.check_output(["aplay", "-l"], text=True, stderr=subprocess.DEVNULL)
+except Exception:
+    raise SystemExit(0)
+
+seen = set()
+for line in output.splitlines():
+    match = re.search(r"^card\s+(\d+):.*device\s+(\d+):", line)
+    if not match:
+        continue
+    lowered = line.lower()
+    if not any(token in lowered for token in ("uac", "lesavka", "composite", "usb audio")):
+        continue
+    candidate = f"hw:{match.group(1)},{match.group(2)}"
+    if candidate not in seen:
+        print(candidate)
+        seen.add(candidate)
+PY
+}
+
+build_candidates() {
+  while IFS= read -r candidate; do
+    append_candidate_family "$candidate"
+  done < <(discover_uac_numeric_candidates)
+
+  append_candidate_family "$REQUESTED_DEV"
+
+  for alias in \
+    "hw:UAC2Gadget,0" \
+    "hw:UAC2_Gadget,0" \
+    "hw:Composite,0" \
+    "hw:Lesavka,0"
+  do
+    append_candidate_family "$alias"
+  done
+}
+
+run_tone() {
+  local candidate="$1"
+  echo "🎧 trying UAC playback device: $candidate" >&2
+  set +e
+  timeout --signal=INT "${DURATION_SECONDS}s" \
+    gst-launch-1.0 -q \
+      audiotestsrc wave=sine freq="$TONE_FREQ" volume="$TONE_VOLUME" is-live=true \
+      ! audio/x-raw,format=S16LE,channels=2,rate=48000 \
+      ! audioconvert \
+      ! audioresample \
+      ! alsasink \
+          device="$candidate" \
+          sync=false \
+          async=false \
+          provide-clock=false \
+          enable-last-sample=false \
+          buffer-time="$BUFFER_TIME_US" \
+          latency-time="$LATENCY_TIME_US"
+  local rc=$?
+  set -e
+  if [[ $rc -eq 0 || $rc -eq 124 ]]; then
+    echo "✅ UAC tone completed on $candidate" >&2
+    return 0
+  fi
+  echo "⚠️  tone failed on $candidate (rc=$rc)" >&2
+  return "$rc"
+}
+
+build_candidates
+if [[ ${#CANDIDATES[@]} -eq 0 ]]; then
+  echo "❌ no UAC playback candidates found. Check 'aplay -l' and /etc/lesavka/server.env." >&2
+  exit 1
+fi
+
+echo "🎵 running Theia UAC sanity tone for ${DURATION_SECONDS}s at ${TONE_FREQ} Hz" >&2
+printf '   candidates: %s\n' "${CANDIDATES[*]}" >&2
+for candidate in "${CANDIDATES[@]}"; do
+  if run_tone "$candidate"; then
+    exit 0
+  fi
+done
+
+echo "❌ none of the UAC playback candidates accepted the sanity tone." >&2
+echo "   requested device: $REQUESTED_DEV" >&2
+echo "   current aplay -l:" >&2
+aplay -l >&2 || true
+exit 1
diff --git a/server/Cargo.toml b/server/Cargo.toml
index 2f4b86f..99edbf2 100644
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -10,7 +10,7 @@ bench                   = false
 
 [package]
 name                    = "lesavka_server"
-version                 = "0.13.7"
+version                 = "0.13.8"
 edition                 = "2024"
 autobins                = false
 
diff --git a/testing/tests/server_install_script_contract.rs b/testing/tests/server_install_script_contract.rs
index 6c19772..b114a29 100644
--- a/testing/tests/server_install_script_contract.rs
+++ b/testing/tests/server_install_script_contract.rs
@@ -31,3 +31,15 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
     assert!(SERVER_INSTALL.contains("${LESAVKA_HDMI_HEIGHT:-1080}"));
     assert!(SERVER_INSTALL.contains("${LESAVKA_HDMI_SINK:-fbdevsink}"));
 }
+
+#[test]
+fn server_install_keeps_uac_sanity_helper_available() {
+    assert!(
+        SERVER_INSTALL.contains("run_uac_output_sanity.sh"),
+        "install script should ship the root UAC sanity helper"
+    );
+    assert!(
+        SERVER_INSTALL.contains("/usr/local/bin/lesavka-uac-sanity"),
+        "install script should install the UAC sanity helper to a stable path"
+    );
+}