fix(frank-tts): answer a voice-less request with the declared default

The omp speech device forwards a voice only when the call passes voice_id - there is no setting that feeds one (speech.voice is the TUI speak-aloud Kokoro enum, tts.localVoice belongs to the local backend) - so every harness voiceover arrives with no voice key and the shim answered 400 "unknown voice None". Measured on the deployed endpoint 2026-10-18, from a restarted session with the speech role pointed here.

DEFAULT_VOICE makes the absent case a spoken operator choice instead of a code surprise: the pack named there answers a voice-less request and the journal line is marked (default), so an unrequested voice never reads later like a requested one. An UNKNOWN name still 400s with the list that exists - the no-silent-fallback law that this endpoint was built on is untouched, and the strict shape stays the code default (empty DEFAULT_VOICE), which the second new seam test pins. Ships narrator1 in scripts/frank-tts.env.

dankclaw/voiceservice/app.py

@@ -7,7 +7,10 @@ Consumers (the omp harness, OpenWebUI, open-notebook) speak the OpenAI
 directory under ``$VOICES_DIR`` and ``reference.wav`` inside it is what makes
 the name real. A name that has no reference is not a voice — the shim answers
 400 with the list that is, instead of silently narrating in a fallback voice
-(silent fallback is how a wrong-voice endpoint stays wrong for weeks).
+(silent fallback is how a wrong-voice endpoint stays wrong for weeks). A request
+that names NO voice at all takes ``$DEFAULT_VOICE``: that is a spoken choice in
+the env file rather than a surprise in the code, and the journal marks it
+``(default)`` so a name nobody asked for is never mistaken for one that was.
 
 Two backends sit behind the one surface, chosen by ``TTS_BACKEND``:
 
@@ -70,7 +73,7 @@ class Config:
 
     def __init__(self, voices_dir, backend, upstream, upstream_model, llama_bin,
                  llama_model, llama_mmproj, llama_lang, llama_threads, port,
-                 max_chars, timeout):
+                 max_chars, timeout, default_voice=""):
         self.voices_dir = Path(voices_dir)
         self.backend = backend
         self.upstream = upstream
@@ -83,6 +86,7 @@ class Config:
         self.port = port
         self.max_chars = max_chars
         self.timeout = timeout
+        self.default_voice = default_voice
 
     @classmethod
     def from_env(cls, environ=None):
@@ -100,6 +104,7 @@ class Config:
             port=_int(env, "SHIM_PORT", 7772),
             max_chars=_int(env, "SHIM_MAX_CHARS", 15000),
             timeout=float(_int(env, "SHIM_TIMEOUT", 600)),
+            default_voice=(env.get("DEFAULT_VOICE") or "").strip(),
         )
 
 
@@ -271,8 +276,13 @@ class SpeechHandler(BaseHTTPRequestHandler):
                                    "endpoint serves wav and mp3" % fmt))
             return
 
-        # `voice_id` is the alias the omp harness forwards for `voice`.
-        voice = body.get("voice") or body.get("voice_id")
+        # `voice_id` is the alias the omp harness forwards for `voice`. A request
+        # that names nothing takes the declared default — the harness has no
+        # setting that feeds a voice, so voice-less calls are the normal shape
+        # there, not a client bug.
+        requested = body.get("voice") or body.get("voice_id")
+        defaulted = not requested and bool(cfg.default_voice)
+        voice = requested or cfg.default_voice
         reference = resolve_voice(cfg.voices_dir, voice)
         if reference is None:
             available = list_voices(cfg.voices_dir)
@@ -297,8 +307,9 @@ class SpeechHandler(BaseHTTPRequestHandler):
 
         content_type = MP3_CONTENT_TYPE if fmt == "mp3" else WAV_CONTENT_TYPE
         self._bytes(200, audio, content_type)
-        self.log_message("speech voice=%s format=%s chars=%d -> %d bytes %s",
-                         voice, fmt, len(text), len(audio), content_type)
+        self.log_message("speech voice=%s%s format=%s chars=%d -> %d bytes %s",
+                         voice, " (default)" if defaulted else "", fmt,
+                         len(text), len(audio), content_type)
 
     # -- backends ----------------------------------------------------------
     def _speech_http(self, cfg, model, text, voice, reference):