The Memory Sidecar v3.5.1 prioritizes operational maturity over new features for production deployments. It introduces tighter resource governance through systemd drop-in units and cgroup v2 integration, preventing sidecars from exhausting host resources. Process-level isolation is achieved by running each sidecar within its own MemoryZone, ensuring independence and preventing interference. Resilient I/O paths are implemented with an internal write-ahead log (WAL) to protect against transient storage outages. Observability is enhanced with structured JSON logging and optional OpenTelemetry trace propagation. Metrics are now exported to a dedicated endpoint for Prometheus scraping. The hermes-memory-installer facilitates deployment, configuration of resource limits, and automatic setup of observability. This release addresses key failure modes like uncontrolled resource consumption, cross-instance contamination, and data loss. Upgrading from earlier versions is handled in-place by the installer without manual data migration. v3.5.1 hardens the Memory Sidecar for stable, predictable operation in production environments. The focus is on enabling teams to build memory-aware agents with confidence.