Modal launches Sidecars, a low-latency trust boundary for Sandboxes

Modal introduced Sidecars in Beta, isolated containers that run alongside a Sandbox on the same host to separate trusted code such as credentials, proxies and harness logic from untrusted agent-generated code. Modal says communication between a Sandbox and its Sidecars is at least 3x faster than between separate Sandboxes in the same region, with p50 travel per call of 0.58ms versus 2.6ms. Each Sidecar has its own outbound network policy, a single Sandbox can run up to 250 Sidecars, and Ramp already uses the feature to run a custom egress proxy next to its Inspect coding agent.