diff --git a/Cargo.lock b/Cargo.lock
index 4711c4b..2dac07a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1652,7 +1652,7 @@ checksum = "09edd9e8b54e49e587e4f6295a7d29c3ea94d469cb40ab8ca70b288248a81db2"
 
 [[package]]
 name = "lesavka_client"
-version = "0.22.14"
+version = "0.22.15"
 dependencies = [
  "anyhow",
  "async-stream",
@@ -1686,7 +1686,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_common"
-version = "0.22.14"
+version = "0.22.15"
 dependencies = [
  "anyhow",
  "base64",
@@ -1698,7 +1698,7 @@ dependencies = [
 
 [[package]]
 name = "lesavka_server"
-version = "0.22.14"
+version = "0.22.15"
 dependencies = [
  "anyhow",
  "base64",
diff --git a/Cargo.toml b/Cargo.toml
index d0a4e78..f272243 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -484,6 +484,10 @@ path = "tests/manual/artifacts/probe_artifact_contract.rs"
 name = "hardware_media_smoke_contract"
 path = "tests/manual/hardware_media/hardware_media_smoke_contract.rs"
 
+[[test]]
+name = "tethys_downstream_audio_manual_contract"
+path = "tests/manual/audio/tethys_downstream_audio_manual_contract.rs"
+
 [[test]]
 name = "client_uplink_performance_contract"
 path = "tests/performance/client/uplink/client_uplink_performance_contract.rs"
diff --git a/client/Cargo.toml b/client/Cargo.toml
index 4011f7b..118d54a 100644
--- a/client/Cargo.toml
+++ b/client/Cargo.toml
@@ -4,7 +4,7 @@ path                    = "src/main.rs"
 
 [package]
 name                    = "lesavka_client"
-version                 = "0.22.14"
+version                 = "0.22.15"
 edition                 = "2024"
 
 [dependencies]
diff --git a/common/Cargo.toml b/common/Cargo.toml
index 85711c2..31d88db 100644
--- a/common/Cargo.toml
+++ b/common/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name                    = "lesavka_common"
-version                 = "0.22.14"
+version                 = "0.22.15"
 edition                 = "2024"
 build                   = "build.rs"
 
diff --git a/docs/operational-env.md b/docs/operational-env.md
index 3078975..e7b3734 100644
--- a/docs/operational-env.md
+++ b/docs/operational-env.md
@@ -258,6 +258,7 @@ from `LESAVKA_CLIENT_PKI_SSH_SOURCE` over SSH. Runtime clients require the insta
 | `LESAVKA_UAC_COMPENSATION_US` | server audio sink latency override |
 | `LESAVKA_UAC_DEV` | server hardware/device override |
 | `LESAVKA_UAC_HDMI_COMPENSATION_US` | server HDMI audio sink latency override; defaults to `205000` to hold gadget audio back toward the host-observed HDMI video path |
+| `LESAVKA_UAC_HOST_MIXER_CONTROLS` | server gadget descriptor override; defaults to `0` so host PipeWire/WirePlumber cannot persist broken UAC hardware-volume channel maps |
 | `LESAVKA_UAC_LATENCY_TIME_US` | server audio sink latency override |
 | `LESAVKA_UAC_SESSION_CLOCK_ALIGN` | server audio sink clock-alignment override; defaults to `0` |
 | `LESAVKA_TEST_CAM_U32` | test/build contract variable; not runtime operator config |
diff --git a/scripts/daemon/lesavka-core.sh b/scripts/daemon/lesavka-core.sh
index 11729cf..2e0b327 100755
--- a/scripts/daemon/lesavka-core.sh
+++ b/scripts/daemon/lesavka-core.sh
@@ -470,6 +470,20 @@ if [[ -z $DISABLE_UAC ]]; then
   echo 0x3     >"$U/c_chmask"
   echo 48000   >"$U/c_srate"
   echo 2       >"$U/c_ssize"
+  # Keep host-visible USB mixer controls out of the descriptor by default.
+  # PipeWire/WirePlumber can persist empty channel maps for gadget hardware
+  # volume controls, leaving the Lesavka sink routed but stuck at digital zero.
+  if [[ ${LESAVKA_UAC_HOST_MIXER_CONTROLS:-0} == 1 ]]; then
+    echo 1 >"$U/p_volume_present" 2>/dev/null || true
+    echo 1 >"$U/p_mute_present" 2>/dev/null || true
+    echo 1 >"$U/c_volume_present" 2>/dev/null || true
+    echo 1 >"$U/c_mute_present" 2>/dev/null || true
+  else
+    echo 0 >"$U/p_volume_present" 2>/dev/null || true
+    echo 0 >"$U/p_mute_present" 2>/dev/null || true
+    echo 0 >"$U/c_volume_present" 2>/dev/null || true
+    echo 0 >"$U/c_mute_present" 2>/dev/null || true
+  fi
   # The dwc2-backed gadget path behaves more reliably with adaptive capture
   # than with the default async+feedback mode for the host-facing mic stream.
   echo adaptive >"$U/c_sync"    2>/dev/null || true
diff --git a/scripts/install/server.sh b/scripts/install/server.sh
index c9cabb2..ae333f8 100755
--- a/scripts/install/server.sh
+++ b/scripts/install/server.sh
@@ -1473,6 +1473,7 @@ SERVER_ENV_TMP=$(mktemp)
   printf 'LESAVKA_HDMI_PRESENTATION_DELAY_US=%s\n' "${LESAVKA_HDMI_PRESENTATION_DELAY_US:-180000}"
   printf 'LESAVKA_UAC_DEV=%s\n' "${LESAVKA_UAC_DEV:-hw:UAC2Gadget,0}"
   printf 'LESAVKA_ALSA_DEV=%s\n' "${LESAVKA_ALSA_DEV:-hw:UAC2Gadget,0}"
+  printf 'LESAVKA_UAC_HOST_MIXER_CONTROLS=%s\n' "${LESAVKA_UAC_HOST_MIXER_CONTROLS:-0}"
   printf 'LESAVKA_UAC_HDMI_COMPENSATION_US=%s\n' "${LESAVKA_UAC_HDMI_COMPENSATION_US:-205000}"
   printf 'LESAVKA_UAC_SESSION_CLOCK_ALIGN=%s\n' "${LESAVKA_UAC_SESSION_CLOCK_ALIGN:-0}"
   printf 'LESAVKA_UPSTREAM_PLAYOUT_DELAY_MS=%s\n' "${LESAVKA_UPSTREAM_PLAYOUT_DELAY_MS:-350}"
diff --git a/scripts/manual/run_tethys_downstream_audio_sanity.sh b/scripts/manual/run_tethys_downstream_audio_sanity.sh
new file mode 100755
index 0000000..f41419d
--- /dev/null
+++ b/scripts/manual/run_tethys_downstream_audio_sanity.sh
@@ -0,0 +1,144 @@
+#!/usr/bin/env bash
+# scripts/manual/run_tethys_downstream_audio_sanity.sh - inspect the Tethys Lesavka speaker sink
+# Manual: downstream audio host sanity probe; no sudo or in-cluster changes.
+set -euo pipefail
+
+TETHYS_HOST=${LESAVKA_TETHYS_HOST:-tethys@titan-24}
+REPAIR_WIREPLUMBER=${LESAVKA_TETHYS_AUDIO_REPAIR:-0}
+RESTART_AUDIO=${LESAVKA_TETHYS_AUDIO_RESTART:-0}
+
+ssh "$TETHYS_HOST" \
+  LESAVKA_TETHYS_AUDIO_REPAIR="$REPAIR_WIREPLUMBER" \
+  LESAVKA_TETHYS_AUDIO_RESTART="$RESTART_AUDIO" \
+  'bash -s' <<'REMOTE'
+set -euo pipefail
+
+export XDG_RUNTIME_DIR=${XDG_RUNTIME_DIR:-/run/user/$(id -u)}
+export DBUS_SESSION_BUS_ADDRESS=${DBUS_SESSION_BUS_ADDRESS:-unix:path=$XDG_RUNTIME_DIR/bus}
+PULSE_TIMEOUT=${LESAVKA_TETHYS_AUDIO_TIMEOUT_SECONDS:-5}
+
+failures=0
+warn() { printf '⚠️  %s\n' "$*" >&2; }
+fail() { printf '❌ %s\n' "$*" >&2; failures=$((failures + 1)); }
+pass() { printf '✅ %s\n' "$*" >&2; }
+run_pactl() { timeout "${PULSE_TIMEOUT}s" pactl "$@"; }
+run_wpctl() { timeout "${PULSE_TIMEOUT}s" wpctl "$@"; }
+
+print_rebind_hint() {
+  local card iface driver
+  card=$(aplay -l 2>/dev/null | awk '/Lesavka|Composite|UAC2|USB Audio/ {if (match($0, /card [0-9]+/)) {print substr($0, RSTART + 5, RLENGTH - 5); exit}}' || true)
+  if [[ -n ${card:-} && -e /sys/class/sound/card${card}/device ]]; then
+    iface=$(basename "$(readlink -f "/sys/class/sound/card${card}/device")")
+    driver=$(basename "$(readlink -f "/sys/class/sound/card${card}/device/driver" 2>/dev/null || true)")
+    if [[ -n $iface && -n $driver ]]; then
+      echo "Tethys root-level soft rebind, if the user audio graph is wedged:" >&2
+      echo "  sudo sh -c 'echo -n \"$iface\" > /sys/bus/usb/drivers/$driver/unbind; sleep 2; echo -n \"$iface\" > /sys/bus/usb/drivers/$driver/bind'" >&2
+    fi
+  fi
+}
+
+if ! command -v pactl >/dev/null 2>&1; then
+  fail "pactl is unavailable in the Tethys desktop session"
+  exit 1
+fi
+
+if ! run_pactl info >/dev/null 2>&1; then
+  fail "Pulse/PipeWire is unreachable for $(id -un); XDG_RUNTIME_DIR=$XDG_RUNTIME_DIR"
+  print_rebind_hint
+  exit 1
+fi
+
+sink_line=$(run_pactl list short sinks | awk '/alsa_output\.usb-Lesavka|Lesavka|Composite|UAC2/ {print; exit}')
+if [[ -z ${sink_line:-} ]]; then
+  fail "no Lesavka USB speaker sink is visible to PipeWire/Pulse"
+  run_pactl list short sinks >&2 || true
+  exit 1
+fi
+sink_name=$(awk '{print $2}' <<<"$sink_line")
+pass "found Lesavka sink: $sink_name"
+
+sink_dump=$(mktemp)
+trap 'rm -f "$sink_dump"' EXIT
+run_pactl list sinks >"$sink_dump"
+
+sink_block=$(awk -v sink="$sink_name" '
+  /^Sink #[0-9]+/ {printing=0}
+  $0 ~ "Name: " sink {printing=1}
+  printing {print}
+' "$sink_dump")
+
+if grep -q 'State: RUNNING' <<<"$sink_block"; then
+  pass "Lesavka sink is RUNNING"
+elif grep -q 'State: SUSPENDED' <<<"$sink_block"; then
+  warn "Lesavka sink is SUSPENDED; this is okay only when no stream is actively playing"
+else
+  warn "Lesavka sink state is not RUNNING"
+fi
+
+if grep -Eq 'Volume:.* / 0% /' <<<"$sink_block"; then
+  fail "Lesavka sink volume is persisted at 0%; Tethys can route audio into digital silence"
+else
+  pass "Lesavka sink Pulse volume is not 0%"
+fi
+
+if grep -Eq 'Mute: yes' <<<"$sink_block"; then
+  fail "Lesavka sink is muted in Pulse/PipeWire"
+else
+  pass "Lesavka sink is not muted"
+fi
+
+if command -v wpctl >/dev/null 2>&1; then
+  object_id=$(awk -F' = ' '/object.id =/ {gsub(/"/, "", $2); print $2; exit}' <<<"$sink_block")
+  if [[ -n ${object_id:-} ]]; then
+    wp_dump=$(run_wpctl inspect "$object_id" 2>/dev/null || true)
+    if grep -Eq 'audio\.channels = "?0"?' <<<"$wp_dump"; then
+      fail "WirePlumber reports audio.channels=0 for the Lesavka sink"
+    elif [[ -n $wp_dump ]]; then
+      pass "WirePlumber exposes a non-zero channel count for the Lesavka sink"
+    fi
+  fi
+fi
+
+state_file="$HOME/.local/state/wireplumber/stream-properties"
+if [[ -r $state_file ]] && grep -Eq 'Audio/(Sink|Source):node\.name:.*(usb-Lesavka|Lesavka).*"channelVolumes":\[\]' "$state_file"; then
+  fail "WirePlumber has persisted empty Lesavka channelVolumes/channelMap in $state_file"
+  if [[ ${LESAVKA_TETHYS_AUDIO_REPAIR:-0} == 1 ]]; then
+    backup="$state_file.lesavka-audio.$(date +%Y%m%d%H%M%S).bak"
+    cp "$state_file" "$backup"
+    python3 - "$state_file" <<'PY'
+import sys
+from pathlib import Path
+path = Path(sys.argv[1])
+fixed = []
+for line in path.read_text().splitlines():
+    if line.startswith("Audio/Sink:node.name:") and "Lesavka" in line and '"channelVolumes":[]' in line:
+        key = line.split("=", 1)[0]
+        line = key + '={"mute":false, "volume":1.000000, "channelVolumes":[1.000000, 1.000000], "channelMap":["FL", "FR"]}'
+    elif line.startswith("Audio/Source:node.name:") and "Lesavka" in line and '"channelVolumes":[]' in line:
+        key = line.split("=", 1)[0]
+        line = key + '={"mute":false, "volume":1.000000, "channelVolumes":[1.000000, 1.000000], "channelMap":["FL", "FR"]}'
+    fixed.append(line)
+path.write_text("\n".join(fixed) + "\n")
+PY
+    pass "repaired WirePlumber Lesavka channel state; backup: $backup"
+    if [[ ${LESAVKA_TETHYS_AUDIO_RESTART:-0} == 1 ]]; then
+      systemctl --user restart wireplumber pipewire-pulse pipewire || true
+    else
+      warn "restart Tethys user audio or replug/rebind the Lesavka USB audio interface before retesting"
+    fi
+  fi
+else
+  pass "WirePlumber stream-properties has no empty Lesavka channel map"
+fi
+
+if ps -eo stat,comm,args | awk '$1 ~ /D/ && $2 ~ /wireplumber|pipewire/ {found=1} END {exit !found}'; then
+  fail "Tethys has PipeWire/WirePlumber stuck in uninterruptible I/O sleep"
+fi
+
+print_rebind_hint
+
+if [[ $failures -gt 0 ]]; then
+  exit 1
+fi
+pass "Tethys downstream audio host checks passed"
+REMOTE
diff --git a/server/Cargo.toml b/server/Cargo.toml
index 207f38d..2dd6f4a 100644
--- a/server/Cargo.toml
+++ b/server/Cargo.toml
@@ -10,7 +10,7 @@ bench                   = false
 
 [package]
 name                    = "lesavka_server"
-version                 = "0.22.14"
+version                 = "0.22.15"
 edition                 = "2024"
 autobins                = false
 
diff --git a/tests/contract/scripts/daemon/server_core_script_contract.rs b/tests/contract/scripts/daemon/server_core_script_contract.rs
index 5972a42..461c2bb 100644
--- a/tests/contract/scripts/daemon/server_core_script_contract.rs
+++ b/tests/contract/scripts/daemon/server_core_script_contract.rs
@@ -104,3 +104,22 @@ fn core_script_keeps_uvc_output_on_supported_mjpeg_descriptor() {
         );
     }
 }
+
+#[test]
+fn core_script_hides_uac_hardware_mixer_controls_by_default() {
+    for expected in [
+        "LESAVKA_UAC_HOST_MIXER_CONTROLS:-0",
+        "echo 0 >\"$U/p_volume_present\"",
+        "echo 0 >\"$U/p_mute_present\"",
+        "echo 0 >\"$U/c_volume_present\"",
+        "echo 0 >\"$U/c_mute_present\"",
+        "echo 1 >\"$U/p_volume_present\"",
+        "echo 1 >\"$U/c_volume_present\"",
+        "PipeWire/WirePlumber can persist empty channel maps",
+    ] {
+        assert!(
+            CORE_SCRIPT.contains(expected),
+            "lesavka-core UAC mixer guard missing: {expected}"
+        );
+    }
+}
diff --git a/tests/installer/scripts/install/server_install_script_contract.rs b/tests/installer/scripts/install/server_install_script_contract.rs
index 41e37c1..240ae94 100644
--- a/tests/installer/scripts/install/server_install_script_contract.rs
+++ b/tests/installer/scripts/install/server_install_script_contract.rs
@@ -44,6 +44,7 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
         "LESAVKA_UVC_FRAME_META=%s",
         "LESAVKA_UVC_FRAME_META_LOG_PATH=%s",
         "LESAVKA_UVC_CONTROL_READ_ONLY=",
+        "LESAVKA_UAC_HOST_MIXER_CONTROLS=%s",
         "LESAVKA_REQUIRE_TLS=%s",
         "LESAVKA_TLS_CERT=%s",
         "LESAVKA_TLS_KEY=%s",
@@ -82,6 +83,7 @@ fn server_install_pins_hdmi_camera_and_display_defaults() {
     assert!(SERVER_INSTALL.contains("${LESAVKA_HDMI_WIDTH:-1920}"));
     assert!(SERVER_INSTALL.contains("${LESAVKA_HDMI_HEIGHT:-1080}"));
     assert!(SERVER_INSTALL.contains("${LESAVKA_HDMI_SINK:-fbdevsink}"));
+    assert!(SERVER_INSTALL.contains("${LESAVKA_UAC_HOST_MIXER_CONTROLS:-0}"));
     assert!(SERVER_INSTALL.contains("${LESAVKA_UPSTREAM_PLAYOUT_DELAY_MS:-350}"));
     assert!(SERVER_INSTALL.contains("${LESAVKA_UPSTREAM_MAX_LIVE_LAG_MS:-1000}"));
     assert!(SERVER_INSTALL.contains("${LESAVKA_UPSTREAM_STARTUP_TIMEOUT_MS:-60000}"));
diff --git a/tests/manual/audio/tethys_downstream_audio_manual_contract.rs b/tests/manual/audio/tethys_downstream_audio_manual_contract.rs
new file mode 100644
index 0000000..ddb8f20
--- /dev/null
+++ b/tests/manual/audio/tethys_downstream_audio_manual_contract.rs
@@ -0,0 +1,50 @@
+// Contract tests for the Tethys downstream audio sanity helper.
+//
+// Scope: inspect `scripts/manual/run_tethys_downstream_audio_sanity.sh`.
+// Targets: downstream UAC host regressions where PipeWire routes audio into a
+// broken zero-channel or zero-volume Lesavka sink.
+
+const SCRIPT: &str = include_str!(concat!(
+    env!("CARGO_MANIFEST_DIR"),
+    "/scripts/manual/run_tethys_downstream_audio_sanity.sh"
+));
+
+#[test]
+fn tethys_audio_probe_detects_zero_volume_and_channel_map_regressions() {
+    for expected in [
+        "LESAVKA_TETHYS_HOST",
+        "LESAVKA_TETHYS_AUDIO_REPAIR",
+        "LESAVKA_TETHYS_AUDIO_TIMEOUT_SECONDS",
+        "run_pactl()",
+        "pactl list short sinks",
+        "Volume:.* / 0% /",
+        "audio.channels=0",
+        "channelVolumes",
+        "channelMap",
+        "WirePlumber has persisted empty Lesavka channelVolumes/channelMap",
+    ] {
+        assert!(
+            SCRIPT.contains(expected),
+            "Tethys downstream audio probe missing guard: {expected}"
+        );
+    }
+}
+
+#[test]
+fn tethys_audio_probe_keeps_repair_explicit_and_non_sudo_by_default() {
+    for expected in [
+        "LESAVKA_TETHYS_AUDIO_REPAIR:-0",
+        "LESAVKA_TETHYS_AUDIO_RESTART:-0",
+        "restart Tethys user audio or replug/rebind",
+        "Tethys root-level soft rebind, if the user audio graph is wedged",
+    ] {
+        assert!(
+            SCRIPT.contains(expected),
+            "Tethys downstream audio probe should make recovery explicit: {expected}"
+        );
+    }
+    assert!(
+        !SCRIPT.contains("sudo sh -c") || SCRIPT.contains("echo \"  sudo sh -c"),
+        "the helper may print a sudo recovery command but must not run sudo itself"
+    );
+}