fix: switch to Docker SDK so Python + launch are fully under our control

Gradio 4.44.1 + HF default Python 3.13 hit ModuleNotFoundError(pyaudioop)
because pyaudioop was removed from stdlib in 3.13 — and pydub (gradio's
audio dep) hardcodes that import. Pinning python_version to 3.10/3.11
exposed a separate gradio runtime issue ('localhost not accessible').

Switching to Docker SDK (python:3.11-slim) gives us:
- working pydub / gradio audio
- mediapipe wheel installs cleanly (no 3.13 wheel exists yet)
- explicit GRADIO_SERVER_NAME=0.0.0.0 and port 7860
- predictable layered build (cached pip install of requirements.txt)

app.py keeps its env-driven server_name/port for parity with the
Dockerfile defaults.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,33 @@
+# HF Space Docker SDK runtime — pin python 3.11 (mediapipe + gradio happy)
+FROM python:3.11-slim
+
+# System deps for OpenCV / gradio video / pillow
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    git \
+    libgl1 \
+    libglib2.0-0 \
+    libsm6 \
+    libxext6 \
+    libxrender1 \
+    ffmpeg \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+# HF Spaces Docker SDK convention: app expects user "user" with UID 1000
+RUN useradd -m -u 1000 user
+USER user
+ENV HOME=/home/user PATH=/home/user/.local/bin:$PATH HF_HOME=/home/user/.cache/huggingface
+
+COPY --chown=user requirements.txt /app/requirements.txt
+RUN pip install --no-cache-dir --user -r /app/requirements.txt
+
+COPY --chown=user . /app
+
+# HF Spaces Docker convention: app must listen on 0.0.0.0:7860
+ENV GRADIO_SERVER_NAME=0.0.0.0 \
+    GRADIO_SERVER_PORT=7860 \
+    GRADIO_ANALYTICS_ENABLED=False
+EXPOSE 7860
+
+CMD ["python", "app.py"]

README.md

@@ -3,9 +3,8 @@ title: SignBridge
 emoji: 🤟
 colorFrom: indigo
 colorTo: pink
-sdk: gradio
-sdk_version: 4.44.1
-app_file: app.py
+sdk: docker
+app_port: 7860
 pinned: false
 thumbnail: assets/cover.png
 license: mit

app.py

@@ -17,11 +17,13 @@ from signbridge.space import build_demo
 def main() -> None:
     load_dotenv()
     demo = build_demo()
-    # On HF Spaces the gradio runtime sets GRADIO_SERVER_NAME / SERVER_PORT
-    # in env and auto-launches; passing custom server_name/port can collide
-    # with the pre-startup localhost check. Calling .launch() with no args
-    # is the documented "just works" pattern for HF Spaces.
-    demo.queue().launch()
+    # Docker-SDK Space: we own the runtime, bind explicitly. Env vars from
+    # the Dockerfile set GRADIO_SERVER_NAME=0.0.0.0 / PORT=7860 already; the
+    # explicit args here are belt-and-suspenders.
+    demo.queue().launch(
+        server_name=os.getenv("GRADIO_SERVER_NAME", "0.0.0.0"),
+        server_port=int(os.getenv("GRADIO_SERVER_PORT", "7860")),
+    )
 
 
 if __name__ == "__main__":