feat(hermes-voice): route Whisper language to multilingual Piper

Port the original #27 detected-language pipeline onto the verified PR #39 prerequisite while preserving the current-main conversation instrument and host continuity changes. Keep voice selection server-side with no user selector or client voice field. Reuse 207c16ab only for its stricter exact-code trust boundary, omitting malformed or absent language so Piper defaults to Amy.
feat(hermes-tts): prepare fixed multilingual voice policy
2026-08-21 11:52:49 +00:00 · 2026-08-21 11:26:54 +00:00
22 changed files with 2186 additions and 41 deletions
--- a/dockerfiles/Dockerfile.hermes-jetson-tts
+++ b/dockerfiles/Dockerfile.hermes-jetson-tts
@ -24,18 +24,41 @@ ADD --checksum=sha256:f7d01dde371555732c4c314111ac79672b1a5ce2fc19266ab42178fd8d
 ADD --checksum=sha256:45754dfdebb3b8661c3fc564713772deec6e064feeb5b4e9594857dc7305193a --chmod=0444 \
    https://huggingface.co/rhasspy/piper-voices/resolve/ea046e8458f6acd997706d6e6066a022b42f6fb1/en/en_US/lessac/low/en_US-lessac-low.onnx.json?download=true \
    /opt/models/piper/en_US-lessac-low.onnx.json
+
+# Multilingual chat voice policy: English -> amy, Russian -> irina, Spanish ->
+# claude (Mexican Spanish, the only "claude" voice rhasspy/piper-voices
+# publishes; there is no es_ES-claude).
+ADD --checksum=sha256:b3a6e47b57b8c7fbe6a0ce2518161a50f59a9cdd8a50835c02cb02bdd6206c18 --chmod=0444 \
+    https://huggingface.co/rhasspy/piper-voices/resolve/ea046e8458f6acd997706d6e6066a022b42f6fb1/en/en_US/amy/medium/en_US-amy-medium.onnx?download=true \
+    /opt/models/piper/en_US-amy-medium.onnx
+ADD --checksum=sha256:95a23eb4d42909d38df73bb9ac7f45f597dbfcde2d1bf9526fdeaf5466977d77 --chmod=0444 \
+    https://huggingface.co/rhasspy/piper-voices/resolve/ea046e8458f6acd997706d6e6066a022b42f6fb1/en/en_US/amy/medium/en_US-amy-medium.onnx.json?download=true \
+    /opt/models/piper/en_US-amy-medium.onnx.json
+ADD --checksum=sha256:8ff38212d23da300bbe3705c645e6e5b9475f0bfde01558eb17813e22acaaaaa --chmod=0444 \
+    https://huggingface.co/rhasspy/piper-voices/resolve/ea046e8458f6acd997706d6e6066a022b42f6fb1/ru/ru_RU/irina/medium/ru_RU-irina-medium.onnx?download=true \
+    /opt/models/piper/ru_RU-irina-medium.onnx
+ADD --checksum=sha256:c2ec28bb38e2b59e93b959b3e40348c1afebbd272f30fed5d41205d08e98a9d7 --chmod=0444 \
+    https://huggingface.co/rhasspy/piper-voices/resolve/ea046e8458f6acd997706d6e6066a022b42f6fb1/ru/ru_RU/irina/medium/ru_RU-irina-medium.onnx.json?download=true \
+    /opt/models/piper/ru_RU-irina-medium.onnx.json
+ADD --checksum=sha256:3ef40a71ea63852cd8ab7e6fa7d2ecdcfa67a0b47c9c48e3f10e02ee02083ea0 --chmod=0444 \
+    https://huggingface.co/rhasspy/piper-voices/resolve/ea046e8458f6acd997706d6e6066a022b42f6fb1/es/es_MX/claude/high/es_MX-claude-high.onnx?download=true \
+    /opt/models/piper/es_MX-claude-high.onnx
+ADD --checksum=sha256:1afc81f703c0e4cb3b4d7c0dca096b8b54a98806807f0170cf5eb5557723c12d --chmod=0444 \
+    https://huggingface.co/rhasspy/piper-voices/resolve/ea046e8458f6acd997706d6e6066a022b42f6fb1/es/es_MX/claude/high/es_MX-claude-high.onnx.json?download=true \
+    /opt/models/piper/es_MX-claude-high.onnx.json
 RUN chmod 0555 /opt/models /opt/models/piper

 COPY dockerfiles/hermes-jetson-tts-server.py /opt/atlas/hermes-jetson-tts-server.py
 RUN chmod 0555 /opt/atlas/hermes-jetson-tts-server.py

-# Load the actual pinned voice during the ARM64 build. This catches package or
-# model-format drift before the image can reach Flux.
-RUN python -c "import stat; from pathlib import Path; from piper import PiperVoice; p=Path('/opt/models/piper'); models=[p/'en_US-lessac-high.onnx',p/'en_US-lessac-medium.onnx',p/'en_US-lessac-low.onnx']; assert stat.S_IMODE(p.stat().st_mode)==0o555; assert all(stat.S_IMODE(model.stat().st_mode)==0o444 for model in models); voices=[PiperVoice.load(model,Path(str(model)+'.json'),use_cuda=False,download_dir=p) for model in models]; assert all(voice.config.sample_rate>0 for voice in voices)"
+# Load every pinned voice during the ARM64 build, including the three baked
+# for the multilingual chat policy. This catches package or model-format
+# drift before the image can reach Flux.
+RUN python -c "import stat; from pathlib import Path; from piper import PiperVoice; p=Path('/opt/models/piper'); models=[p/'en_US-lessac-high.onnx',p/'en_US-lessac-medium.onnx',p/'en_US-lessac-low.onnx',p/'en_US-amy-medium.onnx',p/'ru_RU-irina-medium.onnx',p/'es_MX-claude-high.onnx']; assert stat.S_IMODE(p.stat().st_mode)==0o555; assert all(stat.S_IMODE(model.stat().st_mode)==0o444 for model in models); voices=[PiperVoice.load(model,Path(str(model)+'.json'),use_cuda=False,download_dir=p) for model in models]; assert all(voice.config.sample_rate>0 for voice in voices)"

 ENV HERMES_TTS_HOST=0.0.0.0 \
    HERMES_TTS_PORT=9001 \
-    HERMES_TTS_VOICE=en_US-lessac-medium \
+    HERMES_TTS_VOICE=en_US-amy-medium \
    HERMES_TTS_CACHE=/opt/models/piper \
    OMP_NUM_THREADS=2 \
    PYTHONDONTWRITEBYTECODE=1 \
--- a/dockerfiles/Dockerfile.hermes-webui
+++ b/dockerfiles/Dockerfile.hermes-webui
@ -116,9 +116,16 @@ RUN /opt/hermes/.venv/bin/python -c 'import cryptography, yaml' \
    && grep -Fq 'routing_priority:priority' /opt/hermes-webui/static/atlas-router.js \
    && grep -Fq "'atlas/auto/fast':'Automatic · Fast'" /opt/hermes-webui/static/atlas-router.js \
    && grep -Fq 'explicit_reasoning_effort' /opt/hermes-webui/api/gateway_chat.py \
+    && grep -Fq '"language": detected_language' /opt/hermes/tools/transcription_tools.py \
+    && grep -Fq "'language': detected" /opt/hermes-webui/api/upload.py \
+    && grep -Fq 'def _atlas_tts_language(body):' /opt/hermes-webui/api/routes.py \
+    && grep -Fq 'request_payload["language"] = _atlas_language' /opt/hermes-webui/api/routes.py \
+    && grep -Fq 'takeSttLanguage(token)' /opt/hermes-webui/static/atlas-voice.js \
    && /opt/hermes/.venv/bin/python -m py_compile \
        /opt/hermes-webui/api/routes.py \
-        /opt/hermes-webui/api/gateway_chat.py
+        /opt/hermes-webui/api/upload.py \
+        /opt/hermes-webui/api/gateway_chat.py \
+        /opt/hermes/tools/transcription_tools.py

 # Exercise the real server process in the target architecture before publish.
 RUN set -eu; \
--- a/dockerfiles/hermes-jetson-stt-server.py
+++ b/dockerfiles/hermes-jetson-stt-server.py
@ -62,6 +62,34 @@ def _clean_transcript(result: dict) -> str:
    return " ".join(kept).strip()


+def _detected_language(result: object) -> str:
+    """Return the bare ISO-639 code Whisper decoded with, or nothing at all.
+
+    ``whisper.transcribe`` reports the language it auto-detected (or the one it
+    was told to use) as a plain lowercase token such as ``en``/``ru``/``yue``.
+    Anything that is not that exact shape is dropped rather than guessed at, so
+    a surprising model result can never become a downstream voice selector.
+    """
+    if not isinstance(result, dict):
+        return ""
+    value = result.get("language")
+    if not isinstance(value, str):
+        return ""
+    code = value.strip().lower()
+    if not 2 <= len(code) <= 3 or not code.isascii() or not code.isalpha():
+        return ""
+    return code
+
+
+def _transcription_payload(result: dict) -> dict:
+    """Build the transcription contract: text plus the model's own language."""
+    return {
+        "text": _clean_transcript(result),
+        "model": MODEL_NAME,
+        "language": _detected_language(result),
+    }
+
+
 def _json(handler: BaseHTTPRequestHandler, status: int, payload: dict) -> None:
    body = json.dumps(payload).encode("utf-8")
    handler.send_response(status)
@ -148,8 +176,7 @@ class SpeechHandler(BaseHTTPRequestHandler):
                    no_speech_threshold=0.5,
                    verbose=False,
                )
-            transcript = _clean_transcript(result)
-            _json(self, 200, {"text": transcript, "model": MODEL_NAME})
+            _json(self, 200, _transcription_payload(result))
        except Exception as exc:
            print(f"[stt] transcription failed: {exc}", flush=True)
            _json(self, 500, {"error": "transcription failed"})
--- a/dockerfiles/hermes-jetson-tts-server.py
+++ b/dockerfiles/hermes-jetson-tts-server.py
@ -17,12 +17,50 @@ from piper import PiperConfig, PiperVoice, SynthesisConfig

 HOST = os.getenv("HERMES_TTS_HOST", "0.0.0.0")
 PORT = int(os.getenv("HERMES_TTS_PORT", "9001"))
-VOICE_NAME = os.getenv("HERMES_TTS_VOICE", "en_US-lessac-high")
 CACHE_DIR = Path(os.getenv("HERMES_TTS_CACHE", "/cache/piper"))
 MAX_TEXT_CHARS = 5000
 ONNX_THREADS = max(1, int(os.getenv("HERMES_TTS_ONNX_THREADS", "4")))
 VOICE_LOCK = threading.Lock()

+# Fixed, allow-listed language -> baked voice mapping. This is the ONLY path
+# from a client-supplied string to a model name: client input is looked up
+# here and never used to build a filesystem path directly. Both "-" and "_"
+# separators and any case are accepted; anything not present here falls back
+# to DEFAULT_VOICE_NAME (safe English default), never an error and never an
+# unbaked model.
+LANGUAGE_VOICE_MAP = {
+    "en": "en_US-amy-medium",
+    "en-us": "en_US-amy-medium",
+    "ru": "ru_RU-irina-medium",
+    "ru-ru": "ru_RU-irina-medium",
+    "es": "es_MX-claude-high",
+    "es-mx": "es_MX-claude-high",
+    "es-es": "es_MX-claude-high",
+}
+BAKED_VOICE_NAMES = frozenset(LANGUAGE_VOICE_MAP.values())
+DEFAULT_VOICE_NAME = os.getenv("HERMES_TTS_VOICE", "en_US-amy-medium")
+
+
+def normalize_language(value: object) -> str | None:
+    """Lowercase and fold "_"/"-" separators; reject non-string/blank input."""
+    if not isinstance(value, str):
+        return None
+    normalized = value.strip().lower().replace("_", "-")
+    return normalized or None
+
+
+def resolve_voice_name(language: object) -> str:
+    """Map a client-supplied language to one of the baked policy voices.
+
+    Unknown, missing, or malformed language always resolves to the safe
+    default rather than raising, and the result is always a member of
+    BAKED_VOICE_NAMES.
+    """
+    normalized = normalize_language(language)
+    if normalized is None:
+        return DEFAULT_VOICE_NAME
+    return LANGUAGE_VOICE_MAP.get(normalized, DEFAULT_VOICE_NAME)
+

 def _json(handler: BaseHTTPRequestHandler, status: int, payload: dict) -> None:
    body = json.dumps(payload).encode("utf-8")
@ -46,7 +84,16 @@ class SpeechHandler(BaseHTTPRequestHandler):
        if self.path != "/health":
            _json(self, 404, {"error": "not found"})
            return
-        _json(self, 200, {"ok": True, "voice": VOICE_NAME, "device": "cpu"})
+        _json(
+            self,
+            200,
+            {
+                "ok": True,
+                "voices": sorted(self.server.voices),  # type: ignore[attr-defined]
+                "default_voice": self.server.default_voice_name,  # type: ignore[attr-defined]
+                "device": "cpu",
+            },
+        )

    def do_POST(self) -> None:
        if self.path != "/v1/audio/speech":
@ -71,10 +118,16 @@ class SpeechHandler(BaseHTTPRequestHandler):
            return
        speed = min(2.0, max(0.5, speed))

+        # Policy is driven ONLY by "language". A client-supplied "voice"
+        # field is deliberately never read here; it cannot override the
+        # allow-listed mapping.
+        voice_name = resolve_voice_name(payload.get("language"))
+        voice = self.server.voices[voice_name]  # type: ignore[attr-defined]
+
        output = io.BytesIO()
        try:
            with VOICE_LOCK, wave.open(output, "wb") as wav_file:
-                self.server.voice.synthesize_wav(  # type: ignore[attr-defined]
+                voice.synthesize_wav(
                    text,
                    wav_file,
                    SynthesisConfig(length_scale=1.0 / speed),
@ -84,6 +137,7 @@ class SpeechHandler(BaseHTTPRequestHandler):
            self.send_header("Content-Type", "audio/wav")
            self.send_header("Content-Length", str(len(audio)))
            self.send_header("Cache-Control", "no-store")
+            self.send_header("X-TTS-Voice", voice_name)
            self.end_headers()
            self.wfile.write(audio)
        except Exception as exc:
@ -91,30 +145,54 @@ class SpeechHandler(BaseHTTPRequestHandler):
            _json(self, 500, {"error": "speech synthesis failed"})


-def main() -> None:
-    """Load the checksum-pinned voice from the image and serve it on CPU."""
-    CACHE_DIR.mkdir(parents=True, exist_ok=True)
-    model_path = CACHE_DIR / f"{VOICE_NAME}.onnx"
-    config_path = CACHE_DIR / f"{VOICE_NAME}.onnx.json"
+def _load_voice(cache_dir: Path, voice_name: str, threads: int) -> PiperVoice:
+    model_path = cache_dir / f"{voice_name}.onnx"
+    config_path = cache_dir / f"{voice_name}.onnx.json"
    if not model_path.exists() or not config_path.exists():
-        raise RuntimeError(f"baked Piper voice is missing: {VOICE_NAME}")
+        raise RuntimeError(f"baked Piper voice is missing: {voice_name}")
    with config_path.open("r", encoding="utf-8") as config_file:
        config = PiperConfig.from_dict(json.load(config_file))
    session_options = onnxruntime.SessionOptions()
-    session_options.intra_op_num_threads = ONNX_THREADS
+    session_options.intra_op_num_threads = threads
    session_options.inter_op_num_threads = 1
    session = onnxruntime.InferenceSession(
        str(model_path),
        sess_options=session_options,
        providers=["CPUExecutionProvider"],
    )
-    voice = PiperVoice(session=session, config=config, download_dir=CACHE_DIR)
+    return PiperVoice(session=session, config=config, download_dir=cache_dir)
+
+
+def load_voices(cache_dir: Path, threads: int) -> dict[str, PiperVoice]:
+    """Eagerly load all three policy voices.
+
+    Preload (not lazy-load-on-first-use) was chosen deliberately: measured
+    RSS on this model set is ~88MB for one voice and ~243MB for all three
+    (~+155MB versus the previous single-voice baseline), which comfortably
+    fits the pod's memory budget on the CPU-only voice node. Preloading
+    avoids a slow, request-serializing first synthesis per language and
+    keeps the fail-closed missing-model check (below) at process start
+    rather than deferring a possible crash to a live user request.
+    """
+    return {name: _load_voice(cache_dir, name, threads) for name in sorted(BAKED_VOICE_NAMES)}
+
+
+def main() -> None:
+    """Load the checksum-pinned policy voices from the image and serve them on CPU."""
+    CACHE_DIR.mkdir(parents=True, exist_ok=True)
+    if DEFAULT_VOICE_NAME not in BAKED_VOICE_NAMES:
+        raise RuntimeError(
+            f"HERMES_TTS_VOICE must name one of the baked policy voices: {sorted(BAKED_VOICE_NAMES)}"
+        )
+    voices = load_voices(CACHE_DIR, ONNX_THREADS)
    print(
-        f"[tts] loaded Piper voice {VOICE_NAME} on CPU with {ONNX_THREADS} ONNX threads",
+        f"[tts] loaded {len(voices)} Piper voices on CPU with {ONNX_THREADS} ONNX threads each: "
+        + ", ".join(sorted(voices)),
        flush=True,
    )
    server = ThreadingHTTPServer((HOST, PORT), SpeechHandler)
-    server.voice = voice  # type: ignore[attr-defined]
+    server.voices = voices  # type: ignore[attr-defined]
+    server.default_voice_name = DEFAULT_VOICE_NAME  # type: ignore[attr-defined]
    print(f"[tts] ready on {HOST}:{PORT}", flush=True)
    server.serve_forever(poll_interval=0.25)

--- a/dockerfiles/hermes-webui-atlas-patch.py
+++ b/dockerfiles/hermes-webui-atlas-patch.py
@ -6,6 +6,9 @@ from pathlib import Path


 ROOT = Path(os.environ.get("HERMES_WEBUI_PATCH_ROOT", "/opt/hermes-webui"))
+# The WebUI imports the pinned agent's STT tooling from the same image, so the
+# local-command transcription envelope is patched alongside the WebUI itself.
+AGENT_ROOT = Path(os.environ.get("HERMES_AGENT_PATCH_ROOT", "/opt/hermes"))


 def replace_exact(path: Path, before: str, after: str, count: int = 1) -> None:
@ -16,6 +19,43 @@ def replace_exact(path: Path, before: str, after: str, count: int = 1) -> None:
    path.write_text(source.replace(before, after, count), encoding="utf-8")


+def replace_between_exact(
+    path: Path, start: str, end: str, after: str = "", count: int = 1
+) -> None:
+    """Replace one exact, bounded upstream region and fail when the pin drifts."""
+    source = path.read_text(encoding="utf-8")
+    if source.count(start) != count or source.count(end) != count:
+        raise SystemExit(
+            f"Atlas voice patch context changed in {path}: {start[:80]!r}"
+        )
+    start_index = source.index(start)
+    end_index = source.index(end, start_index) + len(end)
+    path.write_text(
+        source[:start_index] + after + source[end_index:], encoding="utf-8"
+    )
+
+
+def assert_absent(path: Path, *needles: str) -> None:
+    """Fail the image build if a removed voice-choice surface remains."""
+    source = path.read_text(encoding="utf-8")
+    remaining = [needle for needle in needles if needle in source]
+    if remaining:
+        raise SystemExit(f"Atlas voice choice remains in {path}: {remaining!r}")
+
+
+def remove_lines_containing(path: Path, *needles: str) -> None:
+    """Remove all pinned translation entries for a retired settings control."""
+    source = path.read_text(encoding="utf-8")
+    for needle in needles:
+        if needle not in source:
+            raise SystemExit(f"Atlas voice patch context changed in {path}: {needle!r}")
+    lines = source.splitlines(keepends=True)
+    path.write_text(
+        "".join(line for line in lines if not any(n in line for n in needles)),
+        encoding="utf-8",
+    )
+
+
 index = ROOT / "static/index.html"
 replace_exact(
    index,
@ -29,6 +69,16 @@ replace_exact(
    '<option value="browser">Browser speech synthesis</option><option value="edge">Edge TTS (server)</option>',
    '<option value="atlas">Atlas Jetson (private)</option><option value="browser">Browser speech synthesis</option><option value="edge">Edge TTS (server)</option>',
 )
+replace_exact(
+    index,
+    '''<div class="settings-field"><label for="settingsTtsVoice" data-i18n="settings_label_tts_voice">Voice</label>
+              <select id="settingsTtsVoice" style="width:100%;padding:8px;background:var(--code-bg);color:var(--text);border:1px solid var(--border2);border-radius:6px">
+                <option value="">Default system voice</option>
+              </select>
+              <div style="font-size:11px;color:var(--muted);margin-top:4px" data-i18n="settings_desc_tts_voice">Preferred voice. Populated from your browser's available voices.</div>
+            </div>''',
+    "",
+)
 replace_exact(
    index,
    '<script src="static/boot.js?v=__WEBUI_VERSION__" defer></script>',
@ -62,11 +112,33 @@ replace_exact(
 )

 ui = ROOT / "static/ui.js"
+replace_exact(
+    ui,
+    '''  const savedVoice=localStorage.getItem('hermes-tts-voice');
+  const voices=speechSynthesis.getVoices();
+  if(savedVoice&&voices.length){
+    const match=voices.find(v=>v.name===savedVoice);
+    if(match) utter.voice=match;
+  }
+''',
+    "",
+)
 replace_exact(ui, "function _playEdgeTtsChunked(text, btn){", "function _playEdgeTtsChunked(text, btn, engineOverride){")
+replace_exact(
+    ui,
+    "    const voice=localStorage.getItem('hermes-tts-voice')||'zh-CN-XiaoxiaoNeural';\n",
+    "",
+)
 replace_exact(
    ui,
    "body:JSON.stringify({text:chunk, voice:voice, rate:rate, pitch:pitch})",
-    "body:JSON.stringify({text:chunk, voice:voice, rate:rate, pitch:pitch, engine:engineOverride||'edge'})",
+    "body:JSON.stringify({text:chunk, rate:rate, pitch:pitch, engine:engineOverride||'edge'})",
+)
+replace_exact(
+    ui,
+    "      voice: localStorage.getItem('hermes-tts-voice')||'',\n",
+    "",
+    count=2,
 )
 replace_exact(
    ui,
@ -79,7 +151,177 @@ replace_exact(
    "if(engine==='edge'||engine==='atlas'){\n    _playEdgeTtsChunked(clean, null, engine);",
 )

+panels = ROOT / "static/panels.js"
+replace_exact(panels, "  tts_voice:'hermes-tts-voice',\n", "")
+replace_exact(
+    panels,
+    '''  const ttsVoiceSel=$('settingsTtsVoice');
+  if(ttsVoiceSel) _setOwnedSpeechPayload(payload,'tts_voice',ttsVoiceSel.value||'');
+''',
+    "",
+)
+replace_exact(
+    panels,
+    '''        localStorage.setItem('hermes-tts-engine',this.value);
+        window._populateTtsVoices();
+        _schedulePreferencesAutosave();''',
+    '''        localStorage.setItem('hermes-tts-engine',this.value);
+        _schedulePreferencesAutosave();''',
+)
+replace_between_exact(
+    panels,
+    "    // Populate voice selector based on engine\n",
+    "    // TTS rate/pitch sliders\n",
+    "    // TTS speaker selection is intentionally server policy only.\n",
+)
+replace_exact(
+    panels,
+    "let _settingsSpeechChangedKeys=new Set();\n",
+    "let _settingsSpeechChangedKeys=new Set();\n"
+    "try{localStorage.removeItem('hermes-tts-voice');}catch(_){}\n",
+)
+
+boot = ROOT / "static/boot.js"
+replace_exact(
+    boot,
+    '''        voice: localStorage.getItem("hermes-tts-voice")||'',
+''',
+    "",
+)
+replace_exact(
+    boot,
+    '''      const voice=localStorage.getItem("hermes-tts-voice")||"zh-CN-XiaoxiaoNeural";
+''',
+    "",
+)
+replace_exact(
+    boot,
+    "        body: JSON.stringify({text: clean, voice, rate, pitch})",
+    "        body: JSON.stringify({text: clean, rate, pitch})",
+)
+replace_exact(
+    boot,
+    '''    const savedVoice=localStorage.getItem('hermes-tts-voice');
+    const voices=speechSynthesis.getVoices();
+    if(savedVoice&&voices.length){
+      const match=voices.find(v=>v.name===savedVoice);
+      if(match) utter.voice=match;
+    }
+''',
+    "",
+)
+replace_exact(boot, "    tts_voice:'',\n", "")
+replace_exact(boot, "    ['tts_voice','hermes-tts-voice'],\n", "")
+
+config = ROOT / "api/config.py"
+replace_exact(config, '    "tts_voice": "",\n', "")
+replace_exact(config, '    "tts_voice",\n', "")
+replace_exact(
+    config,
+    '''            if k == "tts_voice":
+                if not isinstance(v, str) or len(v) > 200 or "\\x00" in v:
+                    continue
+''',
+    "",
+)
+
+assert_absent(index, "settingsTtsVoice", "settings_label_tts_voice")
+assert_absent(ui, "hermes-tts-voice", "voice:voice")
+assert_absent(panels, "settingsTtsVoice", "tts_voice")
+assert_absent(boot, "hermes-tts-voice", "tts_voice", "text: clean, voice")
+assert_absent(config, '"tts_voice"')
+
+i18n = ROOT / "static/i18n.js"
+remove_lines_containing(
+    i18n,
+    "settings_label_tts_voice:",
+    "settings_desc_tts_voice:",
+)
+assert_absent(i18n, "settings_label_tts_voice", "settings_desc_tts_voice")
+
+# The private Whisper service reports the language it decoded with. Carry that
+# through the agent's local-command STT envelope so the WebUI can hand a voice
+# hint to Piper instead of guessing the reply's language from its text.
+transcription = AGENT_ROOT / "tools/transcription_tools.py"
+replace_exact(
+    transcription,
+    '''            transcript_text = txt_files[0].read_text(encoding="utf-8").strip()
+            logger.info(
+                "Transcribed %s via local STT command (%s, %d chars)",
+                Path(file_path).name,
+                normalized_model,
+                len(transcript_text),
+            )
+            return {"success": True, "transcript": transcript_text, "provider": "local_command"}
+''',
+    '''            transcript_text = txt_files[0].read_text(encoding="utf-8").strip()
+            logger.info(
+                "Transcribed %s via local STT command (%s, %d chars)",
+                Path(file_path).name,
+                normalized_model,
+                len(transcript_text),
+            )
+            detected_language = ""
+            language_files = sorted(Path(output_dir).glob("*.language"))
+            if language_files:
+                try:
+                    candidate = language_files[0].read_text(encoding="utf-8").strip().lower()
+                except (OSError, ValueError):
+                    candidate = ""
+                if 2 <= len(candidate) <= 3 and candidate.isascii() and candidate.isalpha():
+                    detected_language = candidate
+            return {
+                "success": True,
+                "transcript": transcript_text,
+                "provider": "local_command",
+                "language": detected_language,
+            }
+''',
+)
+
+upload = ROOT / "api/upload.py"
+replace_exact(
+    upload,
+    """        transcript = str(result.get('transcript') or '').strip()
+        return j(handler, {'ok': True, 'transcript': transcript})
+""",
+    """        transcript = str(result.get('transcript') or '').strip()
+        detected = str(result.get('language') or '').strip().lower()
+        if not (2 <= len(detected) <= 3 and detected.isascii() and detected.isalpha()):
+            detected = ''
+        return j(handler, {'ok': True, 'transcript': transcript, 'language': detected})
+""",
+)
+
 routes = ROOT / "api/routes.py"
+replace_exact(
+    routes,
+    "def _tts_open(req, *, timeout=30, opener_factory=None):",
+    '''ATLAS_TTS_LANGUAGES = ("en", "ru", "es")
+
+
+def _atlas_tts_language(body):
+    """Return a plain, allow-listed en/ru/es code, or "" to send no language.
+
+    This is a trust boundary, not a parser. Only the exact normalized codes the
+    private Piper deployment bakes a voice for are forwarded; a missing field,
+    a wrong type, a region tag, padding, control characters, a traversal or
+    injection string, an oversized value, an object, an array, a number or a
+    client-supplied "voice" all resolve to "" and the language field is then
+    omitted entirely, so the Jetson service applies its own English default.
+    Coercing a malformed value into a supported code would let a browser
+    describe hostile input as a language we support; omission cannot.
+    """
+    if not isinstance(body, dict):
+        return ""
+    value = body.get("language")
+    if not isinstance(value, str):
+        return ""
+    return value if value in ATLAS_TTS_LANGUAGES else ""
+
+
+def _tts_open(req, *, timeout=30, opener_factory=None):''',
+)
 marker = "    # ── ElevenLabs TTS ──────────────────────────────────────────────────\n"
 atlas = '''    # ── Atlas private Jetson TTS ─────────────────────────────────────────
    if engine == "atlas":
@ -94,12 +336,19 @@ atlas = '''    # ── Atlas private Jetson TTS ──────────
                speed = max(0.5, min(2.0, 1.0 + (float(rate_str.rstrip("%")) / 100.0)))
            except ValueError:
                speed = 1.0
-        request_body = json.dumps({
+        request_payload = {
            "model": "piper",
            "input": text,
-            "voice": "en_US-lessac-high",
            "speed": speed,
-        }).encode("utf-8")
+        }
+        # Attach a language ONLY when the browser sent a plain allow-listed
+        # code. Omitting it is the fail-safe: the Jetson service then speaks
+        # its own English default, which is also what every partially rolled
+        # out combination of these components degrades to.
+        _atlas_language = _atlas_tts_language(data)
+        if _atlas_language:
+            request_payload["language"] = _atlas_language
+        request_body = json.dumps(request_payload).encode("utf-8")
        request = Request(atlas_url, data=request_body, headers={
            "Content-Type": "application/json",
            "Accept": "audio/wav",
--- a/dockerfiles/hermes-webui-atlas-voice.js
+++ b/dockerfiles/hermes-webui-atlas-voice.js
@ -31,9 +31,37 @@
    error:'Voice unavailable',
    idle:'',
  };
+  // The only language signal this file trusts is the one the private Whisper
+  // service returned for the audio of the turn currently being answered. It is
+  // bound to that turn's generation token and consumed exactly once.
+  let sttLanguage='';
+  let sttLanguageToken=-1;
+  const TTS_LANGUAGES=['en','ru','es'];
  const originalAutoRead=window.autoReadLastAssistant;
  const originalApplyPreference=window._applyVoiceModePref;

+  function normalizeSttLanguage(value){
+    if(typeof value!=='string') return '';
+    const code=value.trim().toLowerCase();
+    return TTS_LANGUAGES.indexOf(code)>=0?code:'';
+  }
+
+  function clearSttLanguage(){
+    sttLanguage='';
+    sttLanguageToken=-1;
+  }
+
+  function rememberSttLanguage(language, token){
+    sttLanguage=language||'';
+    sttLanguageToken=sttLanguage?token:-1;
+  }
+
+  function takeSttLanguage(token){
+    const language=sttLanguageToken===token?sttLanguage:'';
+    clearSttLanguage();
+    return language;
+  }
+
  function toast(message){
    if(typeof window.showToast==='function') window.showToast(message,3000);
  }
@ -107,6 +135,7 @@
    active=false;
    thinkingSession=null;
    clearErrorTimer();
+    clearSttLanguage();
    stopCapture();
    stopPlayback();
    modeBtn.classList.remove('active');
@ -120,13 +149,14 @@
    },delay||500);
  }

-  function sendTranscript(transcript, token){
+  function sendTranscript(transcript, token, language){
    if(!active||token!==generation) return;
    const text=String(transcript||'').trim();
-    if(!text){restartSoon(token,350);return;}
+    if(!text){clearSttLanguage();restartSoon(token,350);return;}
    composer.value=text;
    if(typeof window.autoResize==='function') window.autoResize();
    thinkingSession=(typeof S!=='undefined'&&S.session)?S.session.session_id:null;
+    rememberSttLanguage(language,token);
    setState('thinking');
    if(typeof window.send==='function') window.send();
  }
@ -141,7 +171,7 @@
      const response=await fetch('/api/transcribe',{method:'POST',body:form});
      const payload=await response.json().catch(function(){return {};});
      if(!response.ok) throw new Error(payload.error||('Whisper request failed: '+response.status));
-      sendTranscript(payload.transcript,token);
+      sendTranscript(payload.transcript,token,normalizeSttLanguage(payload.language));
    }catch(error){
      if(!active||token!==generation) return;
      const message=errorMessage(error,'Private Whisper is unavailable');
@ -159,6 +189,7 @@
  async function startListening(token){
    if(!active||token!==generation) return;
    stopCapture();
+    clearSttLanguage();
    setState('listening');
    try{
      const capture=await navigator.mediaDevices.getUserMedia({
@ -273,11 +304,15 @@
    });
  }

-  async function fetchSpeech(chunk){
+  async function fetchSpeech(chunk, language){
+    // `language` is only ever the private STT result for this turn. When it is
+    // absent the field is omitted entirely and the server picks English.
+    const request={text:chunk,engine:'atlas'};
+    if(language) request.language=language;
    const response=await fetch('/api/tts',{
      method:'POST',
      headers:{'Content-Type':'application/json'},
-      body:JSON.stringify({text:chunk,engine:'atlas'}),
+      body:JSON.stringify(request),
    });
    if(!response.ok){
      const payload=await response.json().catch(function(){return {};});
@ -291,10 +326,12 @@
    const currentSession=(typeof S!=='undefined'&&S.session)?S.session.session_id:null;
    if(thinkingSession&&currentSession&&thinkingSession!==currentSession){
      thinkingSession=null;
+      clearSttLanguage();
      restartSoon(token,250);
      return;
    }
    thinkingSession=null;
+    const language=takeSttLanguage(token);
    const rows=document.querySelectorAll('.msg-row[data-role="assistant"], .assistant-segment[data-raw-text]');
    if(!rows.length){restartSoon(token,250);return;}
    const text=cleanForSpeech(rows[rows.length-1].dataset.rawText||'');
@ -302,11 +339,11 @@
    setState('speaking');
    const chunks=typeof window._splitForTTS==='function'?window._splitForTTS(text,280):[text];
    try{
-      let pending=fetchSpeech(chunks[0]);
+      let pending=fetchSpeech(chunks[0],language);
      for(let index=0;index<chunks.length;index+=1){
        if(!active||token!==generation) return;
        const blob=await pending;
-        if(index+1<chunks.length) pending=fetchSpeech(chunks[index+1]);
+        if(index+1<chunks.length) pending=fetchSpeech(chunks[index+1],language);
        await playBlob(blob,token);
      }
    }catch(error){
@ -324,6 +361,7 @@
    const token=generation;
    active=true;
    clearErrorTimer();
+    clearSttLanguage();
    modeBtn.classList.add('active');
    toast('Hands-free private voice mode on');
    if(typeof window.stopTTS==='function') window.stopTTS();
--- a/services/hermes/NOTES.md
+++ b/services/hermes/NOTES.md
@ -40,6 +40,40 @@ or the WebUI. Browser chat remains available when `bot_token` is empty.
 The bot token and relay key must never be added to Git or a Kubernetes Secret.
 The router does not log prompt bodies, raw Telegram IDs, link codes, or tokens.

+## Private Jetson voice: multilingual TTS policy
+
+`hermes-tts` on `titan-21` bakes three checksum-pinned Piper voices and
+selects one per request from a fixed, allow-listed `language` field: `en`/
+`en-US` → `en_US-amy-medium`, `ru`/`ru-RU` → `ru_RU-irina-medium`, `es`/
+`es-MX`/`es-ES` → `es_MX-claude-high` (Piper's `claude` voice is Mexican
+Spanish; there is no Castilian `es_ES-claude`). Matching is case-insensitive
+and accepts both `_` and `-` separators. Any language that is missing,
+unrecognized, or malformed falls back to English amy rather than erroring.
+The mapping is a fixed dict from `language` to one of the three baked model
+names only — a client-supplied `voice` field is never read, so no client
+input can select or construct a model path. All three voices are preloaded
+at process start (see `dockerfiles/hermes-jetson-tts-server.py`).
+
+Hermes Chat deliberately exposes no TTS speaker/model choice. The deterministic
+WebUI image patch removes the pinned upstream voice selector, its label and
+translations, its browser/server preference persistence, and every outbound
+client `voice` field while preserving the TTS engine, speech rate/pitch,
+dictation, hands-free Voice Mode, and the conversation instrument. Legacy
+`hermes-tts-voice` browser state is deleted. Voice choice is therefore policy,
+not a client preference: validated English maps to amy, Russian to irina,
+Spanish to claude, and every unsupported or absent language falls back to amy.
+
+The private WebUI voice bridge (`dockerfiles/hermes-webui-atlas-voice.js`,
+patched into `api/routes.py` by `hermes-webui-atlas-patch.py`) has no signal
+for the language of the assistant reply it is about to speak — it sends only
+`text` and `engine`. Until the WebUI or gateway attaches an explicit
+`language` field to that request, every reply speaks in the safe English
+default regardless of its actual language. Closing that gap needs a language
+signal upstream of the TTS call (e.g. tagging the assistant turn with a
+detected/declared reply language and threading it through
+`hermes-webui-atlas-voice.js` → `api/routes.py` → the `language` field), not
+client- or server-side guessing bolted onto the TTS service itself.
+
 ## The one-sentence explanation

 Hermes is the persistent agent runtime and control surface; Codex or the local
@ -347,6 +381,40 @@ Use this short explanation:
 - `Use $tune-atlas-alerts. Trace one currently firing alert to its generated source and raw PromQL, but do not edit it.`
 - `Use $master-hermes-on-atlas. Assess me on the request path and permission boundary. One question at a time.`

+## Private voice: choosing the Piper voice from the STT-detected language
+
+Hands-free voice mode in `chat.hermes.bstein.dev` selects the private Piper
+voice from the language the private Jetson Whisper service reports for the
+user's own speech. The signal travels one way only, and every hop narrows it:
+
+1. `hermes-stt` returns `{text, model, language}`. `language` is whatever
+   Whisper decoded with, accepted only as a bare ISO-639 token (`en`, `ru`,
+   `es`, `yue`, …); anything else is reported as empty.
+2. `hermes_stt_client.py` writes the usual `<stem>.txt` transcript plus a
+   `<stem>.language` sidecar. The transcript stays the only `.txt` in the
+   output directory, so the stock Hermes local-command contract is unchanged.
+3. The patched local-command STT envelope reads that sidecar and adds
+   `language` to its result; `/api/transcribe` re-validates it and returns it
+   next to `transcript`.
+4. `atlas-voice.js` keeps that value only for the turn it belongs to. It is
+   bound to the voice-mode generation token and the chat session id, consumed
+   exactly once by the reply that turn produced, and cleared on cancellation,
+   restart, session change, an empty transcript, or a transcription error.
+5. `/api/tts` accepts `language` only from the fixed allow-list and otherwise
+   sends English. The Jetson TTS service applies the same allow-list again as
+   the final authority.
+
+**What this does not claim.** The language is the language the *user spoke*,
+not the language of the reply. A model asked a Russian question may answer in
+English and will then be read aloud by the Russian voice, and vice versa; this
+is a deliberate policy choice for hands-free mode, not a detection failure.
+Nothing here detects the language of assistant text.
+
+**Everything else stays English.** Typed messages, the manual read-aloud
+button, and any assistant reply that was not produced by a hands-free spoken
+turn carry no trusted STT signal, so they synthesize with `en_US-amy-medium`.
+A `voice` field from a browser is never honoured at any hop.
+
 ## Honest limits

 - Hermes does not currently apply production or cluster changes autonomously.
--- a/services/hermes/scripts/hermes_stt_client.py
+++ b/services/hermes/scripts/hermes_stt_client.py
@ -12,6 +12,34 @@ from pathlib import Path
 from urllib.request import Request, urlopen


+LANGUAGE_SUFFIX = ".language"
+
+
+def _normalize_language(value: object) -> str:
+    """Accept only a bare ISO-639 code from the private Whisper response."""
+    if not isinstance(value, str):
+        return ""
+    code = value.strip().lower()
+    if not 2 <= len(code) <= 3 or not code.isascii() or not code.isalpha():
+        return ""
+    return code
+
+
+def _write_result(output_dir: Path, stem: str, transcript: str, language: str) -> Path:
+    """Write the .txt Hermes reads, plus the language sidecar when we have one.
+
+    Hermes' local-command contract is "leave a .txt in --output-dir"; it globs
+    ``*.txt`` and reads the first match. The sidecar deliberately uses another
+    suffix so the transcript stays the only ``.txt`` in the directory.
+    """
+    output_dir.mkdir(parents=True, exist_ok=True)
+    transcript_path = output_dir / f"{stem}.txt"
+    transcript_path.write_text(transcript, encoding="utf-8")
+    if language:
+        (output_dir / f"{stem}{LANGUAGE_SUFFIX}").write_text(language, encoding="utf-8")
+    return transcript_path
+
+
 def _multipart(audio: Path, language: str, model: str) -> tuple[bytes, str]:
    boundary = f"atlas-hermes-{secrets.token_hex(12)}"
    mime = mimetypes.guess_type(audio.name)[0] or "application/octet-stream"
@ -67,9 +95,12 @@ def main() -> None:
    with urlopen(request, timeout=120) as response:
        result = json.loads(response.read().decode("utf-8"))
    transcript = str(result.get("text") or "").strip()
-    args.output_dir.mkdir(parents=True, exist_ok=True)
-    output = args.output_dir / f"{args.input_path.stem}.txt"
-    output.write_text(transcript, encoding="utf-8")
+    _write_result(
+        args.output_dir,
+        args.input_path.stem,
+        transcript,
+        _normalize_language(result.get("language")),
+    )


 if __name__ == "__main__":
--- a/testing/fixtures/hermes-agent/tools/transcription_tools.py
+++ b/testing/fixtures/hermes-agent/tools/transcription_tools.py
@ -0,0 +1,28 @@
+"""Pinned local-command STT envelope anchor used by image-patch tests."""
+
+import contextlib
+from pathlib import Path
+
+
+class _Logger:
+    def info(self, *args):
+        return None
+
+
+logger = _Logger()
+
+
+def _transcribe_local_command(file_path, normalized_model, output_dir):
+    try:
+        with contextlib.nullcontext(output_dir):
+            txt_files = sorted(Path(output_dir).glob("*.txt"))
+            transcript_text = txt_files[0].read_text(encoding="utf-8").strip()
+            logger.info(
+                "Transcribed %s via local STT command (%s, %d chars)",
+                Path(file_path).name,
+                normalized_model,
+                len(transcript_text),
+            )
+            return {"success": True, "transcript": transcript_text, "provider": "local_command"}
+    except OSError as error:
+        return {"success": False, "transcript": "", "error": str(error)}
--- a/testing/fixtures/hermes-webui-0.52.181/api/config.py
+++ b/testing/fixtures/hermes-webui-0.52.181/api/config.py
@ -0,0 +1,10 @@
+_SETTINGS_DEFAULTS = {
+    "tts_voice": "",
+}
+_SETTINGS_SPEECH_KEYS = {
+    "tts_voice",
+}
+UPSTREAM_VALIDATION_FRAGMENT = '''            if k == "tts_voice":
+                if not isinstance(v, str) or len(v) > 200 or "\x00" in v:
+                    continue
+'''
--- a/testing/fixtures/hermes-webui-0.52.181/api/routes.py
+++ b/testing/fixtures/hermes-webui-0.52.181/api/routes.py
@ -1,3 +1,41 @@
-def tts(handler, engine):
+"""Pinned Atlas TTS route anchors used by image-patch tests."""
+
+import json
+import os
+from urllib.request import ProxyHandler, Request, build_opener
+
+
+class _NoRedirectTtsHandler:
+    """Placeholder for the upstream no-redirect opener handler."""
+
+
+class _Logger:
+    def exception(self, message):
+        return None
+
+
+logger = _Logger()
+
+
+class _Upstream:
+    def read(self):
+        return b"RIFFsynthetic"
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc_info):
+        return False
+
+
+def _buffer_tts_audio_response(response):
+    return response.read()
+
+
+def _tts_open(req, *, timeout=30, opener_factory=None):
+    return _Upstream()
+
+
+def _handle_tts(handler, data, text, rate_str, engine):
    # ── ElevenLabs TTS ──────────────────────────────────────────────────
-    return False
+    return None
--- a/testing/fixtures/hermes-webui-0.52.181/api/upload.py
+++ b/testing/fixtures/hermes-webui-0.52.181/api/upload.py
@ -0,0 +1,13 @@
+"""Pinned upstream /api/transcribe response anchor used by image-patch tests."""
+
+
+def j(handler, payload, status=200):
+    return {"status": status, "payload": payload}
+
+
+def handle_transcribe(handler, result):
+    try:
+        transcript = str(result.get('transcript') or '').strip()
+        return j(handler, {'ok': True, 'transcript': transcript})
+    except ValueError as error:
+        return j(handler, {'error': str(error)}, status=400)
--- a/testing/fixtures/hermes-webui-0.52.181/static/boot.js
+++ b/testing/fixtures/hermes-webui-0.52.181/static/boot.js
@ -0,0 +1,34 @@
+function speakWithRegisteredEngine(){
+      const _opts={
+        voice: localStorage.getItem("hermes-tts-voice")||'',
+        rate: parseFloat(localStorage.getItem("hermes-tts-rate")),
+      };
+      return _opts;
+}
+function speakWithEdge(clean){
+      const voice=localStorage.getItem("hermes-tts-voice")||"zh-CN-XiaoxiaoNeural";
+      const rate='';
+      const pitch='';
+      return fetch('/api/tts', {
+        body: JSON.stringify({text: clean, voice, rate, pitch})
+      });
+}
+function speakWithBrowser(clean){
+    const utter=new SpeechSynthesisUtterance(clean);
+    const savedVoice=localStorage.getItem('hermes-tts-voice');
+    const voices=speechSynthesis.getVoices();
+    if(savedVoice&&voices.length){
+      const match=voices.find(v=>v.name===savedVoice);
+      if(match) utter.voice=match;
+    }
+    return utter;
+}
+function _mirrorSpeechSettingsFromServer(s){
+  const defaults={
+    tts_voice:'',
+  };
+  [
+    ['tts_voice','hermes-tts-voice'],
+  ].forEach(([settingKey,storageKey])=>localStorage.setItem(storageKey,s[settingKey]));
+  return defaults;
+}
--- a/testing/fixtures/hermes-webui-0.52.181/static/i18n.js
+++ b/testing/fixtures/hermes-webui-0.52.181/static/i18n.js
@ -0,0 +1,4 @@
+const EN = {
+    settings_label_tts_voice: 'Voice',
+    settings_desc_tts_voice: "Preferred voice. Populated from your browser's available voices.",
+};
--- a/testing/fixtures/hermes-webui-0.52.181/static/index.html
+++ b/testing/fixtures/hermes-webui-0.52.181/static/index.html
@ -5,6 +5,12 @@
 </head>
 <body>
 <select id="settingsTtsEngine"><option value="browser">Browser speech synthesis</option><option value="edge">Edge TTS (server)</option></select>
+<div class="settings-field"><label for="settingsTtsVoice" data-i18n="settings_label_tts_voice">Voice</label>
+              <select id="settingsTtsVoice" style="width:100%;padding:8px;background:var(--code-bg);color:var(--text);border:1px solid var(--border2);border-radius:6px">
+                <option value="">Default system voice</option>
+              </select>
+              <div style="font-size:11px;color:var(--muted);margin-top:4px" data-i18n="settings_desc_tts_voice">Preferred voice. Populated from your browser's available voices.</div>
+            </div>
      <div class="composer-box" id="composerBox">
        <div class="voice-mode-bar" id="voiceModeBar" style="display:none">
          <span class="voice-mode-indicator" id="voiceModeIndicator"></span>
--- a/testing/fixtures/hermes-webui-0.52.181/static/panels.js
+++ b/testing/fixtures/hermes-webui-0.52.181/static/panels.js
@ -0,0 +1,44 @@
+const _SETTINGS_SPEECH_STORAGE_KEYS={
+  tts_engine:'hermes-tts-engine',
+  tts_voice:'hermes-tts-voice',
+  tts_rate:'hermes-tts-rate',
+};
+let _settingsSpeechChangedKeys=new Set();
+
+function _speechPreferencesPayloadFromUi(){
+  const payload={};
+  const ttsVoiceSel=$('settingsTtsVoice');
+  if(ttsVoiceSel) _setOwnedSpeechPayload(payload,'tts_voice',ttsVoiceSel.value||'');
+  return payload;
+}
+
+function loadSettingsPanel(){
+  const ttsEngineSel=$('settingsTtsEngine');
+  if(ttsEngineSel){
+    ttsEngineSel.onchange=function(){
+        localStorage.setItem('hermes-tts-engine',this.value);
+        window._populateTtsVoices();
+        _schedulePreferencesAutosave();
+    };
+  }
+    // Populate voice selector based on engine
+    const ttsVoiceSel=$('settingsTtsVoice');
+    window._populateTtsVoices=function(){
+      if(!ttsVoiceSel) return;
+      const engine=localStorage.getItem('hermes-tts-engine')||'browser';
+      const current=String(_speechSetting('tts_voice','hermes-tts-voice','')||'');
+      _syncSpeechPreferenceCache('tts_voice',current);
+      if(engine==='edge'){
+        const edgeVoices=[
+          {value:'en-US-AriaNeural',label:'Aria (English, Female)'},
+        ];
+        ttsVoiceSel.innerHTML='<option value="">Default (Xiaoxiao)</option>';
+        edgeVoices.forEach(v=>ttsVoiceSel.appendChild(v));
+      }
+    };
+    if(ttsVoiceSel&&'speechSynthesis' in window){
+      window._populateTtsVoices();
+      ttsVoiceSel.onchange=function(){_markSpeechPreferenceChanged('tts_voice');localStorage.setItem('hermes-tts-voice',this.value);_schedulePreferencesAutosave();};
+    }
+    // TTS rate/pitch sliders
+}
--- a/testing/fixtures/hermes-webui-0.52.181/static/ui.js
+++ b/testing/fixtures/hermes-webui-0.52.181/static/ui.js
@ -1,4 +1,15 @@
+function _buildBrowserUtterance(text, btn){
+  const utter=new SpeechSynthesisUtterance(text);
+  const savedVoice=localStorage.getItem('hermes-tts-voice');
+  const voices=speechSynthesis.getVoices();
+  if(savedVoice&&voices.length){
+    const match=voices.find(v=>v.name===savedVoice);
+    if(match) utter.voice=match;
+  }
+  return utter;
+}
 function _playEdgeTtsChunked(text, btn){
+    const voice=localStorage.getItem('hermes-tts-voice')||'zh-CN-XiaoxiaoNeural';
  return fetch('/api/tts',{body:JSON.stringify({text:chunk, voice:voice, rate:rate, pitch:pitch})});
 }
 function speakSelected(clean, btn, engine){
@ -11,3 +22,14 @@ function speakAutomatically(clean, engine){
    _playEdgeTtsChunked(clean, null);
  }
 }
+function registeredTts(engine, clean){
+  const _opts={
+      voice: localStorage.getItem('hermes-tts-voice')||'',
+      rate: parseFloat(localStorage.getItem('hermes-tts-rate')),
+  };
+  const autoOpts={
+      voice: localStorage.getItem('hermes-tts-voice')||'',
+      pitch: parseFloat(localStorage.getItem('hermes-tts-pitch')),
+  };
+  return [engine, clean, _opts, autoOpts];
+}
--- a/testing/tests/data/atlas_voice_language_probe.js
+++ b/testing/tests/data/atlas_voice_language_probe.js
@ -0,0 +1,463 @@
+// Deterministic browser stub that drives dockerfiles/hermes-webui-atlas-voice.js
+// through complete hands-free turns with no microphone, audio device or GPU.
+//
+// The script under test is an IIFE with no exported seams, so the only honest
+// way to assert what reaches POST /api/tts is to run it against a fake DOM and
+// fake clock and record the requests it actually makes. Usage:
+//
+//     node atlas_voice_language_probe.js <path-to-atlas-voice.js>
+//
+// It prints one JSON object describing every scenario to stdout.
+'use strict';
+
+const fs = require('fs');
+const vm = require('vm');
+
+const SCRIPT_PATH = process.argv[2];
+if (!SCRIPT_PATH) {
+  throw new Error('usage: atlas_voice_language_probe.js <atlas-voice.js>');
+}
+const SOURCE = fs.readFileSync(SCRIPT_PATH, 'utf8');
+
+function flush() {
+  // Four macrotask hops drain the promise chains the script builds around
+  // fetch()/json()/blob()/play() without ever waiting on wall-clock time.
+  return new Promise((resolve) => {
+    let hops = 0;
+    (function hop() {
+      hops += 1;
+      if (hops > 12) {
+        resolve();
+        return;
+      }
+      setImmediate(hop);
+    })();
+  });
+}
+
+function makeElement(id) {
+  return {
+    id,
+    style: {
+      values: new Map(),
+      setProperty(name, value) { this.values.set(name, String(value)); },
+      removeProperty(name) { this.values.delete(name); },
+      getPropertyValue(name) { return this.values.get(name) || ''; },
+    },
+    dataset: {},
+    attributes: {},
+    value: '',
+    textContent: '',
+    className: '',
+    classList: {
+      entries: new Set(),
+      add(name) { this.entries.add(name); },
+      remove(name) { this.entries.delete(name); },
+      contains(name) { return this.entries.has(name); },
+    },
+    listeners: [],
+    setAttribute(name, value) { this.attributes[name] = String(value); },
+    getAttribute(name) {
+      return Object.prototype.hasOwnProperty.call(this.attributes, name)
+        ? this.attributes[name] : null;
+    },
+    addEventListener(type, handler) { this.listeners.push({ type, handler }); },
+    removeEventListener(type, handler) {
+      this.listeners = this.listeners.filter((entry) => entry.handler !== handler);
+    },
+    click() {
+      const event = { preventDefault() {}, stopImmediatePropagation() {} };
+      this.listeners
+        .filter((entry) => entry.type === 'click')
+        .forEach((entry) => entry.handler(event));
+    },
+    querySelector() { return null; },
+    insertBefore() {},
+    appendChild() {},
+  };
+}
+
+function makeHarness() {
+  const clock = { now: 1000000 };
+  const timeouts = [];
+  const intervals = new Map();
+  let timerId = 1;
+
+  const ttsRequests = [];
+  const transcribeCalls = [];
+  const toasts = [];
+  const sends = [];
+
+  let capability = { ok: true, available: true, provider: 'local_command' };
+  let transcribeResponse = { ok: true, transcript: 'hello', language: 'en' };
+  let transcribeStatus = 200;
+  let assistantRows = [];
+  let loud = false;
+  let recorder = null;
+
+  const storage = new Map();
+  const elements = {};
+  ['btnVoiceMode', 'voiceModeBar', 'voiceModeIndicator', 'voiceModeLabel', 'msg']
+    .forEach((id) => { elements[id] = makeElement(id); });
+
+  function MediaRecorder() {
+    this.state = 'recording';
+    this.ondataavailable = null;
+    this.onstop = null;
+    recorder = this;
+  }
+  MediaRecorder.prototype.start = function start() { this.state = 'recording'; };
+  MediaRecorder.prototype.stop = function stop() {
+    if (this.state === 'inactive') return;
+    this.state = 'inactive';
+    if (this.onstop) this.onstop();
+  };
+  MediaRecorder.isTypeSupported = function isTypeSupported() { return true; };
+
+  function AudioContext() {
+    this.createAnalyser = () => ({
+      fftSize: 2048,
+      getByteTimeDomainData(samples) {
+        for (let i = 0; i < samples.length; i += 1) {
+          samples[i] = loud ? (i % 2 ? 200 : 56) : 128;
+        }
+      },
+    });
+    this.createBiquadFilter = () => ({
+      type: '', frequency: { value: 0 }, Q: { value: 0 }, connect() {},
+    });
+    this.createMediaStreamSource = () => ({ connect() {} });
+    this.close = () => {};
+  }
+
+  function AudioElement() {
+    this.currentTime = 0;
+    this.onended = null;
+    this.onerror = null;
+    this.pause = () => {};
+    this.play = () => {
+      setImmediate(() => { if (this.onended) this.onended(); });
+      return Promise.resolve();
+    };
+  }
+
+  async function fetchStub(url, init) {
+    if (url === '/api/transcribe/capability') {
+      return { ok: true, status: 200, json: async () => capability };
+    }
+    if (url === '/api/transcribe') {
+      transcribeCalls.push({ body: init && init.body });
+      return {
+        ok: transcribeStatus < 400,
+        status: transcribeStatus,
+        json: async () => transcribeResponse,
+      };
+    }
+    if (url === '/api/tts') {
+      ttsRequests.push(JSON.parse(init.body));
+      return {
+        ok: true,
+        status: 200,
+        blob: async () => ({ synthetic: true }),
+        json: async () => ({}),
+      };
+    }
+    throw new Error(`unexpected fetch: ${url}`);
+  }
+
+  const context = {
+    console,
+    Uint8Array,
+    Promise,
+    Math,
+    JSON,
+    String,
+    Number,
+    Error,
+    parseInt,
+    isNaN,
+    Set,
+    Map,
+    Array,
+    Object,
+    Date: { now: () => clock.now },
+    Blob: function Blob(parts, options) { this.parts = parts; this.type = (options || {}).type || ''; },
+    File: function File(parts, name, options) {
+      this.parts = parts; this.name = name; this.type = (options || {}).type || '';
+    },
+    FormData: function FormData() { this.entries = []; this.append = (k, v) => this.entries.push([k, v]); },
+    URL: { createObjectURL: () => 'blob:atlas-test', revokeObjectURL() {} },
+    Audio: AudioElement,
+    MediaRecorder,
+    AudioContext,
+    fetch: fetchStub,
+    localStorage: {
+      getItem: (key) => (storage.has(key) ? storage.get(key) : null),
+      setItem: (key, value) => { storage.set(key, String(value)); },
+      removeItem: (key) => { storage.delete(key); },
+    },
+    navigator: {
+      mediaDevices: {
+        getUserMedia: async () => ({ getTracks: () => [{ stop() {} }] }),
+        getSupportedConstraints: () => ({}),
+      },
+    },
+    document: {
+      getElementById: (id) => elements[id] || null,
+      querySelectorAll: () => assistantRows,
+      createElement: () => ({ value: '', textContent: '' }),
+    },
+    S: { session: { session_id: 'session-1' }, busy: false },
+    setTimeout: (fn, delay) => {
+      const id = timerId; timerId += 1;
+      timeouts.push({ id, fn, at: clock.now + (delay || 0) });
+      return id;
+    },
+    clearTimeout: (id) => {
+      const index = timeouts.findIndex((entry) => entry.id === id);
+      if (index >= 0) timeouts.splice(index, 1);
+    },
+    setInterval: (fn, delay) => {
+      const id = timerId; timerId += 1;
+      intervals.set(id, { fn, delay: delay || 0 });
+      return id;
+    },
+    clearInterval: (id) => { intervals.delete(id); },
+  };
+  context.window = context;
+  context.showToast = (message) => { toasts.push(message); };
+  context.send = () => { sends.push(elements.msg.value); };
+  context.autoResize = () => {};
+
+  vm.createContext(context);
+  vm.runInContext(SOURCE, context, { filename: 'atlas-voice.js' });
+
+  function runDueTimeouts() {
+    const due = timeouts.filter((entry) => entry.at <= clock.now);
+    due.forEach((entry) => {
+      const index = timeouts.indexOf(entry);
+      if (index >= 0) timeouts.splice(index, 1);
+      entry.fn();
+    });
+  }
+
+  function tick(ms) {
+    clock.now += ms;
+    Array.from(intervals.values()).forEach((entry) => entry.fn());
+    runDueTimeouts();
+  }
+
+  return {
+    context,
+    elements,
+    ttsRequests,
+    transcribeCalls,
+    toasts,
+    sends,
+    clock,
+    recorder: () => recorder,
+    setLoud: (value) => { loud = value; },
+    setCapability: (value) => { capability = value; },
+    setTranscribeResponse: (value, status) => {
+      transcribeResponse = value;
+      transcribeStatus = status === undefined ? 200 : status;
+    },
+    setAssistantReply: (text) => { assistantRows = [{ dataset: { rawText: text } }]; },
+    setSession: (id) => { context.S.session = { session_id: id }; },
+    advance: (ms) => { clock.now += ms; },
+    tick,
+    runDueTimeouts,
+    flush,
+  };
+}
+
+// Walk one capture window: pre-roll audio, three loud frames so the VAD latches
+// speech, then silence past the hangover so MediaRecorder.stop() fires.
+async function captureSpeech(harness) {
+  const active = harness.recorder();
+  if (!active) throw new Error('voice mode never created a recorder');
+  active.ondataavailable({ data: { size: 512 } });
+  harness.setLoud(true);
+  for (let i = 0; i < 4; i += 1) harness.tick(100);
+  active.ondataavailable({ data: { size: 512 } });
+  harness.setLoud(false);
+  harness.advance(2500);
+  harness.tick(100);
+  await harness.flush();
+}
+
+async function startVoiceMode(harness) {
+  await harness.flush();
+  harness.elements.btnVoiceMode.click();
+  await harness.flush();
+}
+
+// One complete turn: speak, transcribe, let the app "answer", read it back.
+async function runTurn(harness, { transcript, language, reply }) {
+  const payload = { ok: true, transcript };
+  if (language !== undefined) payload.language = language;
+  harness.setTranscribeResponse(payload);
+  await captureSpeech(harness);
+  harness.setAssistantReply(reply || 'An answer.');
+  harness.context.autoReadLastAssistant();
+  await harness.flush();
+}
+
+async function restartListening(harness) {
+  harness.advance(1000);
+  harness.runDueTimeouts();
+  await harness.flush();
+}
+
+const scenarios = {};
+
+scenarios.english_turn_speaks_english = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  await runTurn(harness, { transcript: 'What is the weather?', language: 'en' });
+  return { tts: harness.ttsRequests };
+};
+
+scenarios.russian_turn_speaks_russian = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  await runTurn(harness, { transcript: 'Как дела?', language: 'ru', reply: 'Всё хорошо.' });
+  return { tts: harness.ttsRequests };
+};
+
+scenarios.spanish_turn_speaks_spanish = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  await runTurn(harness, { transcript: '¿Qué tal?', language: 'es', reply: 'Muy bien.' });
+  return { tts: harness.ttsRequests };
+};
+
+scenarios.missing_language_falls_back = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  await runTurn(harness, { transcript: 'Hello there.' });
+  return { tts: harness.ttsRequests };
+};
+
+scenarios.unsupported_language_falls_back = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  await runTurn(harness, { transcript: 'Bonjour tout le monde.', language: 'fr' });
+  return { tts: harness.ttsRequests };
+};
+
+scenarios.hostile_language_values_are_dropped = async () => {
+  const results = [];
+  const hostile = [
+    'ru; rm -rf /',
+    '../../ru_RU-irina-medium',
+    'ru',
+    'RUSSIAN',
+    { language: 'ru' },
+    ['ru'],
+    42,
+    null,
+    'r',
+    'ru ru',
+    'x'.repeat(4096),
+  ];
+  for (const language of hostile) {
+    const harness = makeHarness();
+    // eslint-disable-next-line no-await-in-loop
+    await startVoiceMode(harness);
+    // eslint-disable-next-line no-await-in-loop
+    await runTurn(harness, { transcript: 'Say something.', language });
+    results.push({ sent: String(language), tts: harness.ttsRequests });
+  }
+  return { results };
+};
+
+scenarios.voice_field_is_never_sent = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  await runTurn(harness, { transcript: 'Как дела?', language: 'ru' });
+  return { tts: harness.ttsRequests };
+};
+
+scenarios.language_does_not_leak_into_later_turn = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  await runTurn(harness, { transcript: 'Как дела?', language: 'ru', reply: 'Всё хорошо.' });
+  await restartListening(harness);
+  await runTurn(harness, { transcript: 'And in English?', language: undefined });
+  await restartListening(harness);
+  await runTurn(harness, { transcript: '¿Y ahora?', language: 'es' });
+  return { tts: harness.ttsRequests };
+};
+
+scenarios.empty_transcript_does_not_arm_a_language = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  harness.setTranscribeResponse({ ok: true, transcript: '   ', language: 'ru' });
+  await captureSpeech(harness);
+  const sendsAfterBlank = harness.sends.slice();
+  // A reply landing while the blank turn winds down must not inherit a
+  // language that transcript never earned.
+  harness.setAssistantReply('A stray answer.');
+  harness.context.autoReadLastAssistant();
+  await harness.flush();
+  await restartListening(harness);
+  await runTurn(harness, { transcript: 'Hello.', language: undefined });
+  return { sendsAfterBlank, tts: harness.ttsRequests, sends: harness.sends };
+};
+
+scenarios.session_change_discards_language = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  harness.setTranscribeResponse({ ok: true, transcript: 'Как дела?', language: 'ru' });
+  await captureSpeech(harness);
+  harness.setSession('session-2');
+  harness.setAssistantReply('Reply that belongs to another chat.');
+  harness.context.autoReadLastAssistant();
+  await harness.flush();
+  const afterSwitch = harness.ttsRequests.slice();
+  await restartListening(harness);
+  await runTurn(harness, { transcript: 'Hello again.', language: undefined });
+  return { afterSwitch, tts: harness.ttsRequests };
+};
+
+scenarios.deactivation_discards_language = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  harness.setTranscribeResponse({ ok: true, transcript: 'Как дела?', language: 'ru' });
+  await captureSpeech(harness);
+  harness.elements.btnVoiceMode.click();
+  await harness.flush();
+  harness.setAssistantReply('Late reply after the user left voice mode.');
+  harness.context.autoReadLastAssistant();
+  await harness.flush();
+  const afterDeactivate = harness.ttsRequests.slice();
+  harness.elements.btnVoiceMode.click();
+  await harness.flush();
+  await runTurn(harness, { transcript: 'Fresh start.', language: undefined });
+  return { afterDeactivate, tts: harness.ttsRequests };
+};
+
+scenarios.transcribe_error_speaks_nothing = async () => {
+  const harness = makeHarness();
+  await startVoiceMode(harness);
+  harness.setTranscribeResponse({ error: 'Whisper is down' }, 503);
+  await captureSpeech(harness);
+  harness.setAssistantReply('Some earlier answer.');
+  harness.context.autoReadLastAssistant();
+  await harness.flush();
+  return { tts: harness.ttsRequests, toasts: harness.toasts };
+};
+
+(async () => {
+  const output = {};
+  const names = Object.keys(scenarios);
+  for (const name of names) {
+    // eslint-disable-next-line no-await-in-loop
+    output[name] = await scenarios[name]();
+  }
+  process.stdout.write(JSON.stringify(output, null, 1));
+})().catch((error) => {
+  process.stderr.write(String((error && error.stack) || error));
+  process.exit(1);
+});
--- a/testing/tests/test_hermes_chat_quality.py
+++ b/testing/tests/test_hermes_chat_quality.py
@ -343,7 +343,7 @@ def test_chat_voice_uses_private_jetson_services_and_shared_auto_route():
    assert "/api/tts" in voice_script
    assert "speakResponse(generation)" in voice_script
    assert "window._splitForTTS(text,280)" in voice_script
-    assert "pending=fetchSpeech(chunks[index+1])" in voice_script
+    assert "pending=fetchSpeech(chunks[index+1],language)" in voice_script
    assert "restartSoon(token,450)" in voice_script
    assert "constraints.voiceIsolation=true" in voice_script
    assert "highpass.frequency.value=140" in voice_script
@ -398,13 +398,27 @@ def test_voice_models_are_baked_and_runtime_has_no_public_egress():
    assert "HERMES_STT_CACHE=/opt/models/whisper" in stt_dockerfile
    assert "ADD --checksum=sha256:4cabf7c3" in tts_dockerfile
    assert "ADD --checksum=sha256:db42b97d" in tts_dockerfile
-    assert tts_dockerfile.count("--chmod=0444") == 6
+    assert "ADD --checksum=sha256:b3a6e47b57b8c7fbe6a0ce2518161a50f59a9cdd8a50835c02cb02bdd6206c18" in tts_dockerfile
+    assert "ADD --checksum=sha256:95a23eb4d42909d38df73bb9ac7f45f597dbfcde2d1bf9526fdeaf5466977d77" in tts_dockerfile
+    assert "ADD --checksum=sha256:8ff38212d23da300bbe3705c645e6e5b9475f0bfde01558eb17813e22acaaaaa" in tts_dockerfile
+    assert "ADD --checksum=sha256:c2ec28bb38e2b59e93b959b3e40348c1afebbd272f30fed5d41205d08e98a9d7" in tts_dockerfile
+    assert "ADD --checksum=sha256:3ef40a71ea63852cd8ab7e6fa7d2ecdcfa67a0b47c9c48e3f10e02ee02083ea0" in tts_dockerfile
+    assert "ADD --checksum=sha256:1afc81f703c0e4cb3b4d7c0dca096b8b54a98806807f0170cf5eb5557723c12d" in tts_dockerfile
+    assert tts_dockerfile.count("--chmod=0444") == 12
+    assert "/opt/models/piper/en_US-amy-medium.onnx" in tts_dockerfile
+    assert "/opt/models/piper/ru_RU-irina-medium.onnx" in tts_dockerfile
+    assert "/opt/models/piper/es_MX-claude-high.onnx" in tts_dockerfile
    assert "chmod 0555 /opt/models /opt/models/piper" in tts_dockerfile
    assert "HERMES_TTS_CACHE=/opt/models/piper" in tts_dockerfile
+    assert "HERMES_TTS_VOICE=en_US-amy-medium" in tts_dockerfile
    tts_server = (ROOT / "dockerfiles" / "hermes-jetson-tts-server.py").read_text()
    assert "download_voice" not in tts_server
    assert "baked Piper voice is missing" in tts_server
-    assert "session_options.intra_op_num_threads = ONNX_THREADS" in tts_server
+    assert "session_options.intra_op_num_threads = threads" in tts_server
+    assert 'LANGUAGE_VOICE_MAP = {' in tts_server
+    assert '"en": "en_US-amy-medium"' in tts_server
+    assert '"ru": "ru_RU-irina-medium"' in tts_server
+    assert '"es": "es_MX-claude-high"' in tts_server

    policies = _documents(HERMES / "networkpolicy.yaml")
    voice_policy = next(
--- a/testing/tests/test_hermes_tts_language_routing.py
+++ b/testing/tests/test_hermes_tts_language_routing.py
@ -0,0 +1,220 @@
+"""Language allow-list contracts for the private Hermes chat TTS voice policy."""
+
+from __future__ import annotations
+
+import importlib.util
+import io
+import json
+import sys
+from types import SimpleNamespace
+
+import pytest
+
+from testing.tests.test_hermes_chat_support import ROOT
+
+AMY = "en_US-amy-medium"
+IRINA = "ru_RU-irina-medium"
+CLAUDE = "es_MX-claude-high"
+
+
+def _load_tts_server(monkeypatch):
+    server_path = ROOT / "dockerfiles" / "hermes-jetson-tts-server.py"
+    spec = importlib.util.spec_from_file_location("hermes_jetson_tts_server", server_path)
+    assert spec and spec.loader
+    module = importlib.util.module_from_spec(spec)
+
+    class _FakeSessionOptions:
+        def __init__(self) -> None:
+            self.intra_op_num_threads = None
+            self.inter_op_num_threads = None
+
+    fake_onnxruntime = SimpleNamespace(
+        SessionOptions=_FakeSessionOptions,
+        InferenceSession=lambda *a, **k: SimpleNamespace(),
+    )
+    fake_piper = SimpleNamespace(
+        PiperConfig=SimpleNamespace(from_dict=lambda d: d),
+        PiperVoice=lambda **kwargs: SimpleNamespace(**kwargs),
+        SynthesisConfig=lambda **kwargs: SimpleNamespace(**kwargs),
+    )
+    monkeypatch.setitem(sys.modules, "onnxruntime", fake_onnxruntime)
+    monkeypatch.setitem(sys.modules, "piper", fake_piper)
+    spec.loader.exec_module(module)
+    return module
+
+
+@pytest.fixture
+def tts(monkeypatch):
+    return _load_tts_server(monkeypatch)
+
+
+@pytest.mark.parametrize(
+    "language,expected",
+    [
+        ("en", AMY),
+        ("en-US", AMY),
+        ("en_US", AMY),
+        ("EN", AMY),
+        ("En-Us", AMY),
+        ("ru", IRINA),
+        ("ru-RU", IRINA),
+        ("ru_RU", IRINA),
+        ("RU", IRINA),
+        ("es", CLAUDE),
+        ("es-MX", CLAUDE),
+        ("es_MX", CLAUDE),
+        ("es-ES", CLAUDE),
+        ("es_ES", CLAUDE),
+        ("ES", CLAUDE),
+    ],
+)
+def test_allow_listed_languages_resolve_to_the_approved_voice(tts, language, expected):
+    assert tts.resolve_voice_name(language) == expected
+
+
+@pytest.mark.parametrize(
+    "language",
+    [
+        None,
+        "",
+        "  ",
+        "fr",
+        "fr-FR",
+        "de-DE",
+        "xx",
+        "en-GB",
+        "es-AR",
+        "english",
+        123,
+        1.5,
+        True,
+        [],
+        {},
+        {"lang": "ru"},
+        "../../etc/passwd",
+        "en_US-amy-medium/../../ru_RU-irina-medium",
+        "\x00ru",
+        "ru\x00",
+    ],
+)
+def test_unknown_missing_or_malformed_language_falls_back_to_amy(tts, language):
+    assert tts.resolve_voice_name(language) == AMY
+
+
+def test_default_voice_name_matches_the_dockerfile_env_default(tts):
+    assert tts.DEFAULT_VOICE_NAME == AMY
+
+
+def test_resolved_voice_is_always_one_of_the_three_baked_names(tts):
+    assert frozenset({AMY, IRINA, CLAUDE}) == tts.BAKED_VOICE_NAMES
+    fuzz_inputs = [
+        "en", "ru", "es", "unknown", "", None, 42, "../../../etc/shadow",
+        "en_US-amy-medium\x00; rm -rf /", "RU-ru", "Es-Es", "en-us-extra",
+    ]
+    for value in fuzz_inputs:
+        assert tts.resolve_voice_name(value) in tts.BAKED_VOICE_NAMES
+
+
+def test_client_voice_field_cannot_override_the_language_policy(tts):
+    """The POST handler must select the voice from "language" only.
+
+    A malicious or stale "voice" field in a hostile/legacy request must never
+    change which baked model answers the request.
+    """
+    calls: list[str] = []
+
+    class _RecordingVoice:
+        def __init__(self, name: str) -> None:
+            self.name = name
+
+        def synthesize_wav(self, text, wav_file, syn_config) -> None:
+            calls.append(self.name)
+            wav_file.setnchannels(1)
+            wav_file.setsampwidth(2)
+            wav_file.setframerate(16_000)
+            wav_file.writeframes(b"\x00\x00")
+
+    class _RecordingHandler(tts.SpeechHandler):
+        def __init__(self, payload):
+            request = json.dumps(payload).encode("utf-8")
+            self.path = "/v1/audio/speech"
+            self.headers = {"Content-Length": str(len(request))}
+            self.rfile = io.BytesIO(request)
+            self.wfile = io.BytesIO()
+            self.status = None
+            self.response_headers = {}
+            self.server = SimpleNamespace(
+                voices={
+                    AMY: _RecordingVoice(AMY),
+                    IRINA: _RecordingVoice(IRINA),
+                    CLAUDE: _RecordingVoice(CLAUDE),
+                },
+                default_voice_name=AMY,
+            )
+
+        def send_response(self, status, message=None):
+            self.status = status
+
+        def send_header(self, name, value):
+            self.response_headers[name] = value
+
+        def end_headers(self):
+            return None
+
+    # A payload that supplies an attacker/legacy "voice" value but no
+    # language must resolve to the safe default, never the "voice" value.
+    handler = _RecordingHandler({"input": "hi", "voice": IRINA})
+    handler.do_POST()
+    assert handler.status == 200
+    assert handler.response_headers["X-TTS-Voice"] == AMY
+
+    # A payload supplying both must still be governed by "language" alone.
+    handler = _RecordingHandler({"input": "hi", "voice": CLAUDE, "language": "ru"})
+    handler.do_POST()
+    assert handler.status == 200
+    assert handler.response_headers["X-TTS-Voice"] == IRINA
+
+    assert calls == [AMY, IRINA]
+
+
+def test_no_client_string_reaches_a_filesystem_path(tts):
+    """resolve_voice_name must only ever return a fixed, baked literal.
+
+    This is the property that keeps a client from ever causing the server to
+    build a Path out of attacker-controlled text: the return value is always
+    a member of the fixed allow-list, regardless of input shape.
+    """
+    hostile_inputs = [
+        "../../../../etc/passwd",
+        "/etc/passwd",
+        "en_US-amy-medium/../../../etc/passwd",
+        "ru_RU-irina-medium\x00.onnx",
+        "es_MX-claude-high; cat /etc/shadow",
+        "\n\ren",
+        "en" + "/" * 200,
+        " ",
+    ]
+    for value in hostile_inputs:
+        result = tts.resolve_voice_name(value)
+        assert result in tts.BAKED_VOICE_NAMES
+        assert "/" not in result
+        assert ".." not in result
+        assert "\x00" not in result
+
+
+def test_normalize_language_rejects_non_string_input(tts):
+    assert tts.normalize_language(None) is None
+    assert tts.normalize_language(123) is None
+    assert tts.normalize_language([]) is None
+    assert tts.normalize_language("") is None
+    assert tts.normalize_language("   ") is None
+    assert tts.normalize_language("En_US") == "en-us"
+
+
+def test_default_voice_name_is_one_of_the_baked_voices(tts):
+    assert tts.DEFAULT_VOICE_NAME in tts.BAKED_VOICE_NAMES
+
+
+def test_load_voices_fails_closed_when_a_baked_model_is_missing(tts, tmp_path):
+    with pytest.raises(RuntimeError, match="baked Piper voice is missing"):
+        tts.load_voices(tmp_path, threads=1)
--- a/testing/tests/test_hermes_voice_instrument.py
+++ b/testing/tests/test_hermes_voice_instrument.py
@ -12,6 +12,7 @@ import sys

 ROOT = Path(__file__).resolve().parents[2]
 FIXTURE = ROOT / "testing/fixtures/hermes-webui-0.52.181"
+AGENT_FIXTURE = ROOT / "testing/fixtures/hermes-agent"
 PATCHER = ROOT / "dockerfiles/hermes-webui-atlas-patch.py"
 VOICE_JS = ROOT / "dockerfiles/hermes-webui-atlas-voice.js"
 VOICE_CSS = ROOT / "dockerfiles/hermes-webui-atlas-voice.css"
@ -20,9 +21,12 @@ DOM_PROBE = ROOT / "testing/probes/hermes_voice_instrument_probe.js"

 def _patched_fixture(tmp_path: Path) -> Path:
    target = tmp_path / "hermes-webui"
+    agent_target = tmp_path / "hermes-agent"
    shutil.copytree(FIXTURE, target)
+    shutil.copytree(AGENT_FIXTURE, agent_target)
    env = os.environ.copy()
    env["HERMES_WEBUI_PATCH_ROOT"] = str(target)
+    env["HERMES_AGENT_PATCH_ROOT"] = str(agent_target)
    subprocess.run(
        [sys.executable, str(PATCHER)],
        cwd=ROOT,
@ -57,6 +61,52 @@ def test_real_upstream_fixture_receives_visual_instrument_contract(tmp_path: Pat
    assert '<button' not in index[index.index('id="voiceModeBar"') : index.index('<textarea')]


+def test_patched_webui_has_no_user_voice_choice_or_client_voice_field(
+    tmp_path: Path,
+):
+    """The pinned settings DOM and every TTS path leave speakers to policy."""
+    target = _patched_fixture(tmp_path)
+    index = (target / "static/index.html").read_text(encoding="utf-8")
+    ui = (target / "static/ui.js").read_text(encoding="utf-8")
+    panels = (target / "static/panels.js").read_text(encoding="utf-8")
+    boot = (target / "static/boot.js").read_text(encoding="utf-8")
+    i18n = (target / "static/i18n.js").read_text(encoding="utf-8")
+    config = (target / "api/config.py").read_text(encoding="utf-8")
+    routes = (target / "api/routes.py").read_text(encoding="utf-8")
+
+    assert "settingsTtsVoice" not in index
+    assert "settings_label_tts_voice" not in index
+    assert "settings_desc_tts_voice" not in index
+    assert "Default system voice" not in index
+    assert 'id="settingsTtsEngine"' in index
+    assert 'id="btnVoiceMode"' in index
+    assert 'id="voiceModeBar"' in index
+
+    assert "hermes-tts-voice" not in ui
+    assert "voice:voice" not in ui
+    assert (
+        "body:JSON.stringify({text:chunk, rate:rate, pitch:pitch, "
+        "engine:engineOverride||'edge'})"
+    ) in ui
+    assert "settingsTtsVoice" not in panels
+    assert "tts_voice" not in panels
+    assert "localStorage.removeItem('hermes-tts-voice')" in panels
+    assert panels.count("hermes-tts-voice") == 1
+    assert "hermes-tts-voice" not in boot
+    assert "tts_voice" not in boot
+    assert "text: clean, voice" not in boot
+    assert '"tts_voice"' not in config
+    assert "settings_label_tts_voice" not in i18n
+    assert "settings_desc_tts_voice" not in i18n
+
+    atlas_route = routes.split('if engine == "atlas":', 1)[1].split(
+        "# ── ElevenLabs TTS", 1
+    )[0]
+    assert '"input": text' in atlas_route
+    assert '"voice"' not in atlas_route
+    assert 'request_payload["language"] = _atlas_language' in atlas_route
+
+
 def test_visual_states_have_distinct_layers_finite_error_and_reduced_motion():
    css = VOICE_CSS.read_text(encoding="utf-8")

@ -101,8 +151,9 @@ def test_visual_slice_preserves_private_voice_request_and_capture_contract():
    assert script.count("navigator.mediaDevices.getUserMedia(") == 1
    assert "form.append('file',new File([blob],'voice-input.'+ext" in script
    assert "fetch('/api/transcribe',{method:'POST',body:form})" in script
-    assert "body:JSON.stringify({text:chunk,engine:'atlas'})" in script
+    assert "const request={text:chunk,engine:'atlas'}" in script
+    assert "if(language) request.language=language" in script
    assert "speakResponse(generation)" in script
    assert "window._voiceModeImmediateSend" in script
    assert "mute" not in script.lower()
-    assert "language" not in script.lower()
+    assert "const TTS_LANGUAGES=['en','ru','es']" in script
--- a/testing/tests/test_hermes_voice_language_routing.py
+++ b/testing/tests/test_hermes_voice_language_routing.py
@ -0,0 +1,677 @@
+"""Voice-mode language routing: private Whisper STT decides the Piper voice.
+
+Every assertion here runs without a GPU, a microphone or a cluster. The browser
+contract is exercised by driving the real ``atlas-voice.js`` inside a stub DOM
+(``testing/tests/data/atlas_voice_language_probe.js``), and the two server-side
+trust boundaries are exercised by applying the real image patch to fixtures that
+carry the exact upstream anchors and then importing the patched result.
+"""
+
+from __future__ import annotations
+
+import importlib.util
+import json
+import os
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+from types import SimpleNamespace
+
+import pytest
+
+from testing.tests.test_hermes_chat_support import HERMES, ROOT
+
+DOCKERFILES = ROOT / "dockerfiles"
+ATLAS_PATCH = DOCKERFILES / "hermes-webui-atlas-patch.py"
+VOICE_SCRIPT = DOCKERFILES / "hermes-webui-atlas-voice.js"
+VOICE_PROBE = ROOT / "testing" / "tests" / "data" / "atlas_voice_language_probe.js"
+WEBUI_FIXTURE = ROOT / "testing" / "fixtures" / "hermes-webui-0.52.181"
+ATLAS_TTS_URL = "http://hermes-tts.hermes.svc.cluster.local:9001/v1/audio/speech"
+
+# Voices baked by the multilingual Piper work (PR #26): en=amy, ru=irina,
+# es=claude. Anything outside this set must resolve to English.
+SUPPORTED = ("en", "ru", "es")
+
+
+# ---------------------------------------------------------------------------
+# Module loaders
+# ---------------------------------------------------------------------------
+
+
+def _load_stt_server(monkeypatch):
+    """Import the Jetson Whisper service without CUDA, torch or whisper."""
+    path = DOCKERFILES / "hermes-jetson-stt-server.py"
+    spec = importlib.util.spec_from_file_location("hermes_jetson_stt_server", path)
+    assert spec and spec.loader
+    module = importlib.util.module_from_spec(spec)
+    monkeypatch.setitem(sys.modules, "cgi", SimpleNamespace())
+    monkeypatch.setitem(
+        sys.modules,
+        "torch",
+        SimpleNamespace(cuda=SimpleNamespace(is_available=lambda: False)),
+    )
+    monkeypatch.setitem(sys.modules, "whisper", SimpleNamespace())
+    spec.loader.exec_module(module)
+    return module
+
+
+def _load_stt_client():
+    """Import the local-command STT client that Hermes shells out to."""
+    path = HERMES / "scripts" / "hermes_stt_client.py"
+    spec = importlib.util.spec_from_file_location("hermes_stt_client", path)
+    assert spec and spec.loader
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+# ---------------------------------------------------------------------------
+# Patch fixtures — each file carries the exact upstream fragment the image
+# patch pins, so importing the patched result exercises the inserted code.
+# ---------------------------------------------------------------------------
+
+
+INDEX_FIXTURE = (
+    '<select id="settingsTtsEngine">'
+    '<option value="browser">Browser speech synthesis</option>'
+    '<option value="edge">Edge TTS (server)</option></select>\n'
+    '<script src="static/boot.js?v=__WEBUI_VERSION__" defer></script>\n'
+)
+
+UI_FIXTURE = """function _playEdgeTtsChunked(text, btn){
+  fetch('/api/tts',{method:'POST',body:JSON.stringify({text:chunk, voice:voice, rate:rate, pitch:pitch})});
+}
+function readAloud(clean, btn, engine){
+  if(engine==='edge'){
+    _playEdgeTtsChunked(clean, btn);
+  }
+}
+function autoRead(clean, engine){
+  if(engine==='edge'){
+    _playEdgeTtsChunked(clean, null);
+  }
+}
+"""
+
+HELPERS_FIXTURE = '''"""Stand-in for the WebUI helper module the patched code imports."""
+
+
+def bad(handler, message, status=400):
+    return {"status": status, "error": message}
+'''
+
+ROUTES_FIXTURE = '''"""Stand-in carrying the exact upstream anchors the Atlas TTS patch pins."""
+
+import json
+import os
+from urllib.request import ProxyHandler, Request, build_opener
+
+
+class _NoRedirectTtsHandler:
+    """Placeholder for the upstream no-redirect opener handler."""
+
+
+class _Logger:
+    def __init__(self):
+        self.failures = []
+
+    def exception(self, message):
+        self.failures.append(message)
+
+
+logger = _Logger()
+UPSTREAM_REQUESTS = []
+
+
+class _Upstream:
+    def __init__(self, payload):
+        self._payload = payload
+
+    def read(self):
+        return self._payload
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc_info):
+        return False
+
+
+def _buffer_tts_audio_response(response):
+    return response.read()
+
+
+def _tts_open(req, *, timeout=30, opener_factory=None):
+    """Thin network seam for the TTS upstream fetch so tests can intercept it."""
+    UPSTREAM_REQUESTS.append(json.loads(req.data.decode("utf-8")))
+    return _Upstream(b"RIFFsynthetic")
+
+
+def _handle_tts(handler, data, text, rate_str, engine):
+    # ── ElevenLabs TTS ──────────────────────────────────────────────────
+    return None
+'''
+
+UPLOAD_FIXTURE = '''"""Stand-in carrying the exact upstream /api/transcribe response anchor."""
+
+
+def j(handler, payload, status=200):
+    return {"status": status, "payload": payload}
+
+
+def handle_transcribe(handler, result):
+    try:
+        transcript = str(result.get('transcript') or '').strip()
+        return j(handler, {'ok': True, 'transcript': transcript})
+    except ValueError as error:
+        return j(handler, {'error': str(error)}, status=400)
+'''
+
+TRANSCRIPTION_FIXTURE = '''"""Stand-in carrying the exact upstream local-command STT envelope anchor."""
+
+import contextlib
+from pathlib import Path
+
+
+class _Logger:
+    def info(self, *args):
+        return None
+
+
+logger = _Logger()
+
+
+def _transcribe_local_command(file_path, normalized_model, output_dir):
+    try:
+        with contextlib.nullcontext(output_dir):
+            txt_files = sorted(Path(output_dir).glob("*.txt"))
+            transcript_text = txt_files[0].read_text(encoding="utf-8").strip()
+            logger.info(
+                "Transcribed %s via local STT command (%s, %d chars)",
+                Path(file_path).name,
+                normalized_model,
+                len(transcript_text),
+            )
+            return {"success": True, "transcript": transcript_text, "provider": "local_command"}
+    except OSError as error:
+        return {"success": False, "transcript": "", "error": str(error)}
+'''
+
+
+def _write(path: Path, text: str) -> None:
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_text(text, encoding="utf-8")
+
+
+@pytest.fixture
+def patched_webui(tmp_path, monkeypatch):
+    """Apply the real Atlas image patch to fixture trees and import the result."""
+    webui = tmp_path / "hermes-webui"
+    agent = tmp_path / "hermes"
+    # Start with the pinned full-surface fixture introduced by PR #39 so this
+    # test proves the language pipeline composes with its voice-selector removal
+    # and conversation instrument, not merely with the older #27 anchors.
+    shutil.copytree(WEBUI_FIXTURE, webui)
+    _write(webui / "api" / "__init__.py", "")
+    _write(webui / "api" / "helpers.py", HELPERS_FIXTURE)
+    _write(webui / "api" / "routes.py", ROUTES_FIXTURE)
+    _write(webui / "api" / "upload.py", UPLOAD_FIXTURE)
+    _write(agent / "tools" / "__init__.py", "")
+    _write(agent / "tools" / "transcription_tools.py", TRANSCRIPTION_FIXTURE)
+
+    environment = dict(os.environ)
+    environment["HERMES_WEBUI_PATCH_ROOT"] = str(webui)
+    environment["HERMES_AGENT_PATCH_ROOT"] = str(agent)
+    completed = subprocess.run(
+        [sys.executable, str(ATLAS_PATCH)],
+        env=environment,
+        capture_output=True,
+        text=True,
+    )
+    assert completed.returncode == 0, completed.stderr or completed.stdout
+
+    for name in ("api", "api.helpers", "api.routes", "api.upload", "tools",
+                 "tools.transcription_tools"):
+        sys.modules.pop(name, None)
+    monkeypatch.syspath_prepend(str(agent))
+    monkeypatch.syspath_prepend(str(webui))
+    import api.routes as routes  # noqa: PLC0415
+    import api.upload as upload  # noqa: PLC0415
+    import tools.transcription_tools as transcription  # noqa: PLC0415
+
+    yield SimpleNamespace(
+        webui=webui,
+        agent=agent,
+        routes=routes,
+        upload=upload,
+        transcription=transcription,
+    )
+
+    for name in ("api", "api.helpers", "api.routes", "api.upload", "tools",
+                 "tools.transcription_tools"):
+        sys.modules.pop(name, None)
+
+
+class _Handler:
+    """Just enough BaseHTTPRequestHandler surface for the Atlas TTS branch."""
+
+    def __init__(self):
+        self.status = None
+        self.headers_sent = {}
+        self.wfile = SimpleNamespace(write=self._write)
+        self.body = b""
+
+    def send_response(self, status):
+        self.status = status
+
+    def send_header(self, name, value):
+        self.headers_sent[name] = value
+
+    def end_headers(self):
+        return None
+
+    def _write(self, payload):
+        self.body += payload
+
+
+def _atlas_tts(patched, monkeypatch, data):
+    """Run the patched Atlas branch and return the JSON it sent to hermes-tts."""
+    monkeypatch.setenv("HERMES_WEBUI_ATLAS_TTS_URL", ATLAS_TTS_URL)
+    patched.routes.UPSTREAM_REQUESTS.clear()
+    handler = _Handler()
+    result = patched.routes._handle_tts(handler, data, "Some reply.", "", "atlas")
+    assert result is True, "the Atlas branch must own the response"
+    assert handler.status == 200
+    assert len(patched.routes.UPSTREAM_REQUESTS) == 1
+    return patched.routes.UPSTREAM_REQUESTS[0]
+
+
+# ---------------------------------------------------------------------------
+# 1. Whisper service reports the language it actually decoded with
+# ---------------------------------------------------------------------------
+
+
+def test_stt_response_carries_whisper_detected_language(monkeypatch):
+    module = _load_stt_server(monkeypatch)
+    payload = module._transcription_payload(
+        {
+            "language": "ru",
+            "segments": [
+                {"text": " Как дела?", "no_speech_prob": 0.1, "avg_logprob": -0.2}
+            ],
+        }
+    )
+    assert payload["text"] == "Как дела?"
+    assert payload["language"] == "ru"
+    assert payload["model"] == module.MODEL_NAME
+
+
+@pytest.mark.parametrize(
+    ("raw", "expected"),
+    [
+        ("en", "en"),
+        ("RU", "ru"),
+        ("  es  ", "es"),
+        ("yue", "yue"),
+        ("fr", "fr"),
+        ("en-US", ""),
+        ("en_US", ""),
+        ("e", ""),
+        ("english", ""),
+        ("", ""),
+        ("../en", ""),
+        ("en\x00", ""),
+        ("ru; rm -rf /", ""),
+        ("рус", ""),
+        (None, ""),
+        (7, ""),
+        (["ru"], ""),
+        ({"language": "ru"}, ""),
+    ],
+)
+def test_stt_language_field_is_shape_validated(monkeypatch, raw, expected):
+    module = _load_stt_server(monkeypatch)
+    assert module._detected_language({"language": raw}) == expected
+
+
+def test_stt_language_absent_when_whisper_omits_it(monkeypatch):
+    module = _load_stt_server(monkeypatch)
+    assert module._detected_language({}) == ""
+    assert module._detected_language("not a result") == ""
+    assert module._transcription_payload({"text": "hi"})["language"] == ""
+
+
+# ---------------------------------------------------------------------------
+# 2. The local-command client carries the language without breaking the
+#    .txt contract Hermes reads the transcript from
+# ---------------------------------------------------------------------------
+
+
+def test_stt_client_writes_language_sidecar_beside_the_txt_contract(tmp_path):
+    module = _load_stt_client()
+    module._write_result(tmp_path, "voice-input", "Как дела?", "ru")
+    assert (tmp_path / "voice-input.txt").read_text(encoding="utf-8") == "Как дела?"
+    assert (tmp_path / "voice-input.language").read_text(encoding="utf-8") == "ru"
+    # Hermes globs *.txt and reads the first match: the sidecar must not join it.
+    assert sorted(p.name for p in tmp_path.glob("*.txt")) == ["voice-input.txt"]
+
+
+def test_stt_client_omits_the_sidecar_when_no_language_was_detected(tmp_path):
+    module = _load_stt_client()
+    module._write_result(tmp_path, "voice-input", "Hello.", "")
+    assert (tmp_path / "voice-input.txt").exists()
+    assert not (tmp_path / "voice-input.language").exists()
+
+
+@pytest.mark.parametrize(
+    ("raw", "expected"),
+    [
+        ("en", "en"),
+        ("ES", "es"),
+        (" ru ", "ru"),
+        ("en-US", ""),
+        ("", ""),
+        ("../../etc/passwd", ""),
+        ("en\n", "en"),
+        ("e", ""),
+        (None, ""),
+        (12, ""),
+        (["en"], ""),
+    ],
+)
+def test_stt_client_normalises_the_service_language_field(raw, expected):
+    module = _load_stt_client()
+    assert module._normalize_language(raw) == expected
+
+
+# ---------------------------------------------------------------------------
+# 3. The patched agent envelope and /api/transcribe response carry it through
+# ---------------------------------------------------------------------------
+
+
+def test_patched_local_command_envelope_carries_the_sidecar_language(patched_webui, tmp_path):
+    output = tmp_path / "stt-out"
+    output.mkdir()
+    (output / "voice-input.txt").write_text("Как дела?", encoding="utf-8")
+    (output / "voice-input.language").write_text("ru\n", encoding="utf-8")
+    result = patched_webui.transcription._transcribe_local_command(
+        "/tmp/voice-input.wav", "small", output
+    )
+    assert result == {
+        "success": True,
+        "transcript": "Как дела?",
+        "provider": "local_command",
+        "language": "ru",
+    }
+
+
+def test_patched_local_command_envelope_defaults_to_no_language(patched_webui, tmp_path):
+    output = tmp_path / "stt-out"
+    output.mkdir()
+    (output / "voice-input.txt").write_text("Hello.", encoding="utf-8")
+    result = patched_webui.transcription._transcribe_local_command(
+        "/tmp/voice-input.wav", "small", output
+    )
+    assert result["transcript"] == "Hello."
+    assert result["language"] == ""
+
+
+@pytest.mark.parametrize(
+    "hostile",
+    ["en-US", "../../en", "en; rm -rf /", "e", "english", "", "\x00en", "e n"],
+)
+def test_patched_local_command_envelope_rejects_malformed_sidecars(
+    patched_webui, tmp_path, hostile
+):
+    output = tmp_path / "stt-out"
+    output.mkdir()
+    (output / "voice-input.txt").write_text("Hello.", encoding="utf-8")
+    (output / "voice-input.language").write_text(hostile, encoding="utf-8")
+    result = patched_webui.transcription._transcribe_local_command(
+        "/tmp/voice-input.wav", "small", output
+    )
+    assert result["language"] == ""
+
+
+def test_patched_local_command_envelope_survives_an_undecodable_sidecar(
+    patched_webui, tmp_path
+):
+    """A corrupt sidecar must cost the language, never the transcript."""
+    output = tmp_path / "stt-out"
+    output.mkdir()
+    (output / "voice-input.txt").write_text("Hello.", encoding="utf-8")
+    (output / "voice-input.language").write_bytes(b"\xff\xfe\x00ru")
+    result = patched_webui.transcription._transcribe_local_command(
+        "/tmp/voice-input.wav", "small", output
+    )
+    assert result["success"] is True
+    assert result["transcript"] == "Hello."
+    assert result["language"] == ""
+
+
+def test_patched_transcribe_response_reports_the_language(patched_webui):
+    response = patched_webui.upload.handle_transcribe(
+        None, {"success": True, "transcript": " Как дела? ", "language": "ru"}
+    )
+    assert response["payload"] == {"ok": True, "transcript": "Как дела?", "language": "ru"}
+
+
+@pytest.mark.parametrize(
+    "hostile",
+    ["", None, "en-US", "englishhh", "../en", 5, ["ru"], {"a": "b"}, "e"],
+)
+def test_patched_transcribe_response_blanks_untrusted_languages(patched_webui, hostile):
+    response = patched_webui.upload.handle_transcribe(
+        None, {"success": True, "transcript": "Hello.", "language": hostile}
+    )
+    assert response["payload"]["language"] == ""
+    assert response["payload"]["transcript"] == "Hello."
+
+
+# ---------------------------------------------------------------------------
+# 4. The /api/tts trust boundary: allow-list only, and never `voice`
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.parametrize("language", SUPPORTED)
+def test_atlas_tts_forwards_allow_listed_languages(patched_webui, monkeypatch, language):
+    body = _atlas_tts(patched_webui, monkeypatch, {"engine": "atlas", "language": language})
+    assert body["language"] == language
+    assert body["model"] == "piper"
+
+
+@pytest.mark.parametrize(
+    "hostile",
+    [
+        "fr",
+        "de",
+        "",
+        None,
+        "EN-GB",
+        " RU ",
+        "ru-RU",
+        "es_MX",
+        "../../ru_RU-irina-medium",
+        "ru; rm -rf /",
+        "ru\x00",
+        "ру",
+        5,
+        ["ru"],
+        {"language": "ru"},
+        True,
+        "x" * 8192,
+    ],
+)
+def test_atlas_tts_omits_untrusted_languages(
+    patched_webui, monkeypatch, hostile
+):
+    body = _atlas_tts(patched_webui, monkeypatch, {"engine": "atlas", "language": hostile})
+    assert "language" not in body
+
+
+def test_atlas_tts_language_is_absent_when_the_client_sends_none(patched_webui, monkeypatch):
+    body = _atlas_tts(patched_webui, monkeypatch, {"engine": "atlas"})
+    assert "language" not in body
+
+
+def test_atlas_tts_voice_field_cannot_steer_synthesis(patched_webui, monkeypatch):
+    body = _atlas_tts(
+        patched_webui,
+        monkeypatch,
+        {"engine": "atlas", "voice": "ru_RU-irina-medium", "language": "en"},
+    )
+    assert body["language"] == "en"
+    body = _atlas_tts(
+        patched_webui,
+        monkeypatch,
+        {"engine": "atlas", "voice": "es_MX-claude-high"},
+    )
+    assert "language" not in body
+
+
+def test_atlas_tts_language_helper_only_ever_returns_a_baked_voice_language(patched_webui):
+    resolve = patched_webui.routes._atlas_tts_language
+    hostile = [
+        None, 0, 1, -1, True, False, [], {}, set(), object(), b"ru",
+        "", " ", "\t\n", "en", "EN", "en-US", "en_us", "ru-RU", "es-MX",
+        "e", "eng", "english", "ru ru", "ru;es", "../ru", "ru\x00", "ру",
+        "x" * 65536, "en" * 4096,
+    ]
+    for value in hostile:
+        expected = value if value in SUPPORTED else ""
+        assert resolve({"language": value}) == expected
+    for value in hostile:
+        assert resolve(value) == ""
+    assert resolve({"voice": "ru_RU-irina-medium"}) == ""
+
+
+def test_manual_tts_button_body_still_carries_no_language(patched_webui):
+    """The read-aloud button has no trusted STT signal, so it must stay Amy."""
+    ui = (patched_webui.webui / "static" / "ui.js").read_text(encoding="utf-8")
+    assert "engine:engineOverride||'edge'" in ui
+    assert "language" not in ui
+
+
+# ---------------------------------------------------------------------------
+# 5. Browser contract, driven through the real atlas-voice.js
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture(scope="module")
+def voice_probe():
+    node = shutil.which("node")
+    if not node:
+        pytest.skip("node is required to drive the browser voice-mode contract")
+    completed = subprocess.run(
+        [node, str(VOICE_PROBE), str(VOICE_SCRIPT)],
+        capture_output=True,
+        text=True,
+        timeout=180,
+    )
+    assert completed.returncode == 0, completed.stderr
+    return json.loads(completed.stdout)
+
+
+@pytest.mark.parametrize(
+    ("scenario", "expected"),
+    [
+        ("english_turn_speaks_english", "en"),
+        ("russian_turn_speaks_russian", "ru"),
+        ("spanish_turn_speaks_spanish", "es"),
+    ],
+)
+def test_voice_mode_speaks_the_language_whisper_detected(voice_probe, scenario, expected):
+    requests = voice_probe[scenario]["tts"]
+    assert requests, "voice mode never reached /api/tts"
+    for request in requests:
+        assert request["engine"] == "atlas"
+        assert request["language"] == expected
+
+
+@pytest.mark.parametrize(
+    "scenario", ["missing_language_falls_back", "unsupported_language_falls_back"]
+)
+def test_voice_mode_omits_language_without_a_trusted_signal(voice_probe, scenario):
+    requests = voice_probe[scenario]["tts"]
+    assert requests, "voice mode never reached /api/tts"
+    for request in requests:
+        assert "language" not in request
+
+
+def test_voice_mode_drops_hostile_language_values(voice_probe):
+    for case in voice_probe["hostile_language_values_are_dropped"]["results"]:
+        for request in case["tts"]:
+            assert "language" not in request, case["sent"]
+
+
+def test_voice_mode_never_sends_a_voice_field(voice_probe):
+    for request in voice_probe["voice_field_is_never_sent"]["tts"]:
+        assert set(request) <= {"text", "engine", "language"}
+        assert "voice" not in request
+
+
+def test_voice_mode_does_not_reuse_a_previous_turn_language(voice_probe):
+    requests = voice_probe["language_does_not_leak_into_later_turn"]["tts"]
+    assert len(requests) == 3
+    assert requests[0]["language"] == "ru"
+    assert "language" not in requests[1]
+    assert requests[2]["language"] == "es"
+
+
+def test_voice_mode_ignores_language_from_an_empty_transcript(voice_probe):
+    result = voice_probe["empty_transcript_does_not_arm_a_language"]
+    assert result["sendsAfterBlank"] == []
+    assert result["sends"] == ["Hello."]
+    assert result["tts"], "the follow-up turn should still be spoken"
+    for request in result["tts"]:
+        assert "language" not in request
+
+
+def test_voice_mode_discards_language_when_the_session_changes(voice_probe):
+    result = voice_probe["session_change_discards_language"]
+    assert result["afterSwitch"] == []
+    for request in result["tts"]:
+        assert "language" not in request
+
+
+def test_voice_mode_discards_language_when_voice_mode_is_turned_off(voice_probe):
+    result = voice_probe["deactivation_discards_language"]
+    assert result["afterDeactivate"] == []
+    for request in result["tts"]:
+        assert "language" not in request
+
+
+def test_voice_mode_speaks_nothing_when_transcription_fails(voice_probe):
+    result = voice_probe["transcribe_error_speaks_nothing"]
+    assert result["tts"] == []
+    assert any("Whisper is down" in toast for toast in result["toasts"])
+
+
+# ---------------------------------------------------------------------------
+# 6. Build-time enforcement and documented semantics
+# ---------------------------------------------------------------------------
+
+
+def test_image_build_verifies_every_language_routing_patch():
+    dockerfile = (DOCKERFILES / "Dockerfile.hermes-webui").read_text(encoding="utf-8")
+    assert "'language': detected" in dockerfile
+    assert "def _atlas_tts_language(body):" in dockerfile
+    assert 'request_payload["language"] = _atlas_language' in dockerfile
+    assert '"language": detected_language' in dockerfile
+    assert "takeSttLanguage(token)" in dockerfile
+    assert "/opt/hermes-webui/api/upload.py" in dockerfile
+    assert "/opt/hermes/tools/transcription_tools.py" in dockerfile
+
+
+def test_atlas_patch_roots_are_overridable_for_offline_verification():
+    patch = ATLAS_PATCH.read_text(encoding="utf-8")
+    assert 'os.environ.get("HERMES_WEBUI_PATCH_ROOT", "/opt/hermes-webui")' in patch
+    assert 'os.environ.get("HERMES_AGENT_PATCH_ROOT", "/opt/hermes")' in patch
+
+
+def test_notes_document_the_stt_driven_voice_selection_and_its_limits():
+    notes = (HERMES / "NOTES.md").read_text(encoding="utf-8")
+    assert "STT-detected language" in notes
+    for marker in ("hands-free", "Typed messages", "en_US-amy-medium"):
+        assert marker in notes