Initial voice-assistant-stack: open-webui + spotify-voice-assistant submodules, asr/tts sidecars

- open-webui: submodule, LAN OIDC/Authentik-fronted, GPU-passthrough ollama,
  ollama-auth proxy, asr/tts wired via docker-compose.audio.yaml
- spotify-voice-assistant: submodule, Home Assistant custom integration
- tts-server / asr-server: plain directories, built as sidecars by
  open-webui/docker-stack.sh (no separate git history)

asr-server/Dockerfile

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+FROM python:3.11-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libsndfile1 ffmpeg \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+# The Titan Xp (Pascal, sm_61) needs a torch build old enough to still ship
+# Pascal kernels; recent default PyPI wheels dropped sm_60/sm_61 entirely.
+ENV PIP_EXTRA_INDEX_URL=https://download.pytorch.org/whl/cu124
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY app.py .
+
+EXPOSE 8020
+CMD ["uvicorn", "app:app", "--host", "0.0.0.0", "--port", "8020"]

asr-server/app.py

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+import hmac
+import logging
+import os
+import tempfile
+
+import torch
+from fastapi import Depends, FastAPI, File, Form, HTTPException, UploadFile
+from fastapi.responses import JSONResponse, PlainTextResponse
+from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
+from transformers import AutoModelForRNNT, AutoProcessor
+from transformers.audio_utils import load_audio
+
+logging.basicConfig(level=logging.INFO)
+log = logging.getLogger("asr-server")
+
+AUTH_TOKEN = os.environ["ASR_AUTH_TOKEN"]
+bearer_scheme = HTTPBearer()
+
+
+def require_auth(creds: HTTPAuthorizationCredentials = Depends(bearer_scheme)) -> None:
+    if not hmac.compare_digest(creds.credentials, AUTH_TOKEN):
+        raise HTTPException(status_code=401, detail="invalid token")
+
+
+MODEL_ID = os.environ.get("ASR_MODEL_ID", "nvidia/nemotron-3.5-asr-streaming-0.6b")
+DEVICE = "cuda" if torch.cuda.is_available() else "cpu"
+DTYPE = torch.float16 if DEVICE == "cuda" else torch.float32
+
+# The RNN-T decoder's LSTM layers hit cuDNN's fused RNN kernel on `.to(device)`,
+# which requires SM >= 7.5 in recent cuDNN builds. This GPU (Pascal, SM 6.1) is
+# below that floor, so disable cuDNN and fall back to PyTorch's generic CUDA
+# RNN kernels instead.
+torch.backends.cudnn.enabled = False
+
+app = FastAPI()
+
+log.info("Loading %s on %s (%s)", MODEL_ID, DEVICE, DTYPE)
+processor = AutoProcessor.from_pretrained(MODEL_ID)
+model = AutoModelForRNNT.from_pretrained(MODEL_ID, dtype=DTYPE).to(DEVICE).eval()
+SAMPLING_RATE = processor.feature_extractor.sampling_rate
+log.info("Model ready (sampling_rate=%s)", SAMPLING_RATE)
+
+
+@app.get("/health")
+def health():
+    return {"status": "ok", "device": DEVICE}
+
+
+@app.post("/v1/audio/transcriptions", dependencies=[Depends(require_auth)])
+async def transcribe(
+    file: UploadFile = File(...),
+    model_name: str = Form("nemotron-3.5-asr-streaming-0.6b", alias="model"),
+    language: str | None = Form(None),
+    response_format: str = Form("json"),
+):
+    suffix = os.path.splitext(file.filename or "")[1] or ".wav"
+    data = await file.read()
+
+    with tempfile.NamedTemporaryFile(suffix=suffix) as tmp:
+        tmp.write(data)
+        tmp.flush()
+        try:
+            audio = load_audio(tmp.name, sampling_rate=SAMPLING_RATE)
+        except Exception as exc:
+            raise HTTPException(status_code=400, detail=f"could not decode audio: {exc}") from exc
+
+    lang = language or "auto"
+    inputs = processor(audio, sampling_rate=SAMPLING_RATE, language=lang)
+    inputs = inputs.to(DEVICE, dtype=DTYPE)
+
+    with torch.inference_mode():
+        output = model.generate(**inputs, return_dict_in_generate=True)
+
+    text = processor.decode(output.sequences, skip_special_tokens=True)
+    if isinstance(text, list):
+        text = text[0] if text else ""
+
+    if response_format == "text":
+        return PlainTextResponse(text)
+    return JSONResponse({"text": text})

asr-server/requirements.txt

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+fastapi==0.115.*
+uvicorn[standard]==0.32.*
+python-multipart==0.0.*
+torch==2.6.0
+transformers>=5.13.0
+soundfile
+librosa
+accelerate