fix: Docker container Python symlink broken at runtime (#510)

Signed-off-by: Drew Cain <groksrc@gmail.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Dockerfile

@@ -8,8 +8,13 @@ ARG GID=1000
 COPY --from=ghcr.io/astral-sh/uv:latest /uv /uvx /bin/
 
 # Set environment variables
+# UV_PYTHON_INSTALL_DIR ensures Python is installed to a persistent location
+# that survives in the final image (not in /root/.local which gets lost)
+# UV_PYTHON_PREFERENCE=only-managed tells uv to use its managed Python version
 ENV PYTHONUNBUFFERED=1 \
-    PYTHONDONTWRITEBYTECODE=1
+    PYTHONDONTWRITEBYTECODE=1 \
+    UV_PYTHON_INSTALL_DIR=/python \
+    UV_PYTHON_PREFERENCE=only-managed
 
 # Create a group and user with the provided UID/GID
 # Check if the GID already exists, if not create appgroup
@@ -19,9 +24,10 @@ RUN (getent group ${GID} || groupadd --gid ${GID} appgroup) && \
 # Copy the project into the image
 ADD . /app
 
-# Sync the project into a new environment, asserting the lockfile is up to date
+# Install Python 3.13 explicitly and sync the project
 WORKDIR /app
-RUN uv sync --locked
+RUN uv python install 3.13
+RUN uv sync --locked --python 3.13
 
 # Create necessary directories and set ownership
 RUN mkdir -p /app/data/basic-memory /app/.basic-memory && \
@@ -43,4 +49,4 @@ HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
     CMD basic-memory --version || exit 1
 
 # Use the basic-memory entrypoint to run the MCP server with default SSE transport
-CMD ["basic-memory", "mcp", "--transport", "sse", "--host", "0.0.0.0", "--port", "8000"]
+CMD ["basic-memory", "mcp", "--transport", "sse", "--host", "0.0.0.0", "--port", "8000"]