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+FROM python:3.11-slim
+
+# Non-root user (required by Hugging Face Spaces, good practice elsewhere).
+RUN useradd -m -u 1000 user
+USER user
+ENV HOME=/home/user PATH=/home/user/.local/bin:$PATH
+WORKDIR /home/user/app
+
+COPY --chown=user requirements.txt .
+RUN pip install --no-cache-dir --user -r requirements.txt
+
+# Pre-download the ONNX embedding model so first query isn't slow.
+RUN python -c "from chromadb.utils.embedding_functions import ONNXMiniLM_L6_V2; ONNXMiniLM_L6_V2()(['warm up'])"
+
+COPY --chown=user app/ app/
+# The prebuilt Chroma index must exist (run scripts/build_index.py first).
+COPY --chown=user data/chroma/ data/chroma/
+
+# Hugging Face Spaces uses port 7860; Render/Railway inject $PORT.
+ENV PORT=7860
+EXPOSE 7860
+
+CMD uvicorn app.main:app --host 0.0.0.0 --port ${PORT}