Modal launches Sidecar containers to isolate agent trusted code on the same host
Same-host isolated containers remove the latency tax on agent trust boundaries; the 3x speedup is a vendor benchmark worth watching in real use.
Cloud platform Modal introduced Sidecars on October 1: isolated containers that run on the same host as the main Sandbox, built to hold trusted code such as credentials, proxies and tool logic.
Splitting an agent's "brain" from its "hands" previously meant every tool call crossed a network round trip, trading latency for security. Sidecars connect over an internal bridge network so the two talk locally; Modal says communication across the trust boundary is 3x faster than using separate Sandboxes, a figure from its own internal benchmarking.
Isolation matches separate Sandboxes, using gVisor or VMs depending on the runtime. The feature is exposed through an experimental API, and real-world gains remain to be seen.
Sources:https://modal.com/blog/introducing-sandbox-sidecars-trust-boundary