Harden production workflows and agent admission

server/Dockerfile

@@ -20,8 +20,17 @@ RUN --mount=type=cache,target=/root/.cache/uv uv sync --frozen --no-dev
 FROM python:3.14-slim
 ENV PATH="/app/.venv/bin:$PATH" \
     PYTHONUNBUFFERED=1
+
+# PH-015: non-root runtime user. UID/GID are stable so bind-mounts can be
+# pre-chowned by operators if they need writable host paths.
+RUN groupadd --system --gid 1000 monlet \
+    && useradd --system --uid 1000 --gid monlet --home-dir /app --shell /usr/sbin/nologin monlet
+
 WORKDIR /app
 COPY --from=builder /app /app
+RUN chown -R monlet:monlet /app
 
+USER monlet:monlet
 EXPOSE 8000
+STOPSIGNAL SIGTERM
 CMD ["uvicorn", "monlet_server.main:app", "--host", "0.0.0.0", "--port", "8000"]