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OpenShell — Nvidia's agent sandbox, where an SMT solver checks every new network rule the agent asks for
OpenShell (Apache-2.0, Rust, 9,923 stars, 978 of them on GitHub trending today, 1,558 commits, 99 contributors, created February 24, v0.1.0 on Friday and v0.1.2 on Monday) runs each agent in its own sandbox and enforces a declared policy at the kernel: which files it can touch, which system calls it can make, and which hosts every outbound connection may reach. Agents never hold real credentials; the gateway adds them only to requests bound for approved endpoints. curl -LsSf .../install.sh | sh installs the CLI and a local gateway on Linux, Apple-silicon macOS or WSL 2 (experimental), and openshell sandbox create gives you a minimal Ubuntu image with no agent in it. The first-agent tutorial runs OpenCode against a free OpenRouter model.
The proof part is the policy prover. When a request is blocked, the optional policy advisor lets the agent propose a narrow network rule (host, port, binary and, for HTTP, method and path). Before the proposal reaches you, the prover compares what the sandbox could reach with and without the rule and flags added risk, such as cloud metadata addresses or a new destination for a credential. A separate boundary check, openshell-prover, verifies that a policy grants nothing beyond a maximum policy you write, so a parent agent can check the policy it hands a subagent. The docs are careful about the limits. The guarantees cover only the policy features the prover models. The two checks answer different questions, so passing one does not imply passing the other. And proposals can only add network rules, not change filesystem or process settings.
Reach for it if your agents need real credentials and real network access and you currently grant both by editing an allowlist when something breaks; it replaces that loop with proposals you approve and a solver's read on each. Delete the --dangerously-skip-permissions alias. Tradeoffs: v0.1 is a week old and the project ships stable releases weekly, with Experimental interfaces free to change in a patch; anonymous telemetry is on by default (OPENSHELL_TELEMETRY_ENABLED=false turns it off); the quick install is curl | sh; and Sentry, the hardware half of Nvidia's announcement, runs on BlueField-4 DPUs, so outside Nvidia's own racks you get the software half.