fix docker issue

Dockerfile

@@ -1,27 +1,33 @@
-# Use official slim base
+# → Use official slim Python base
 FROM python:3.12-slim
 
 # Install uv package manager
 COPY --from=ghcr.io/astral-sh/uv:latest /uv /uvx /bin/
 
+# Ensure clean python environment and no stray bytecode
 ENV PYTHONUNBUFFERED=1 \
-    PYTHONDONTWRITEBYTECODE=1 \
-    UV_CACHE_DIR=/app/.uv_cache
+    PYTHONDONTWRITEBYTECODE=1
 
-# Set working directory
+# Set working directory inside container
 WORKDIR /app
 
-# Create writable cache directory
-RUN mkdir -p /app/.uv_cache
-
-# Copy pyproject files
+# Copy lock and project config first for layer caching
 COPY pyproject.toml uv.lock ./.python-version /app/
 
-# Install dependencies
-RUN uv sync --frozen --no-install-project
+# Install dependencies only (not installing the app code yet)
+RUN --mount=type=cache,target=/root/.cache/uv \
+    uv sync --frozen --no-install-project
 
-# Copy app source
+# Copy the full app source code
 COPY . /app
 
+# Install app code on top of deps (no dev dependencies)
+RUN --mount=type=cache,target=/root/.cache/uv \
+    uv sync --frozen --no-dev
+
+# Expose port
+ENV PORT=8000
+EXPOSE $PORT
+
 # Start FastAPI with uvicorn via uv-managed venv
 CMD ["uv", "run", "uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]