Guardrails & Security

codex-securityGuardrails

`npx @openai/codex-security scan .` walks a checkout and leaves JSON results on stdout, while `--mode deep` spreads discovery across workers and subagents until it stops turning up anything new. Across runs, `scans compare BEFORE_SCAN_ID AFTER_SCAN_ID` matches findings by root cause and labels them new, persisting, reopened, resolved or unknown, so a second scan reports movement instead of restating the whole report. It is a poor fit as a pre-commit gate: deep discovery runs until `--max-time-hours`, which defaults to 96. Access is also gated — the CLI needs access to Codex Security, and some cybersecurity requests and protected findings require Trusted Access for Cyber approval, so cloning the repo on its own scans nothing.

cloudflare-osSandboxes

Cloudflare OS pairs an agent chat with "Gadgets" — small apps the built-in coding agent writes for you, each running as a Dynamic Worker with its internet access disabled, its client confined to a sandboxed iframe that reaches the server only over Cap'n Web via `postMessage()`. External services are reached through Gatekeepers, per-service Workers that wrap an API in Cap'n Web, log every call, and simulate side-effecting actions so the agent keeps queueing work while approvals wait for you to review them in bulk. The commitment to Workers runs deep: every workspace is a Durable Object, every Gadget a Dynamic Worker Facet, and Facets and Dynamic Workers were added to the runtime specifically for this project — so hosting means a Cloudflare account, and the deploy-to-your-own-servers-on-`workerd` path is still marked COMING SOON in the README. The maintainers call the August 2026 v2 rewrite an early access release with many rough edges, and many Gatekeepers need configuration of their own — including OAuth client credentials per service — before GitHub or Google will connect.

agentgatewayGuardrails

A Rust data plane that sits between agents and everything they call — model providers, MCP servers, other agents — so authentication, RBAC, rate limits and OpenTelemetry export are configured once instead of reimplemented in every agent. Solo.io donated it to the Linux Foundation in August 2025 and it moved under the Agentic AI Foundation in June 2026, alongside MCP and goose. It is young for something that sits in the request path: per-user identity onto downstream MCP servers is still an open issue, so confirm the authentication model you need before putting it in front of production traffic.

numbatGuardrails

numbat is a single binary that watches supported desktop, CLI, IDE and gateway agents through hooks, plugins and OTLP/HTTP log exporters, normalizes their activity into one event model, and evaluates it with a local CEL rule engine that writes versioned NDJSON events, findings and enforcement decisions. It also reconstructs past sessions from on-disk artifacts via `numbat scan`, so you can investigate an agent that was never instrumented. Blocking is deliberately conservative: enforce mode is off by default and every shipped rule is monitor-only, so denying an action means copying the rule YAML into your own `--rules-dir`, keeping its id, adding `enforce: true` and bumping the version. It is a poor fit if you expect coverage of arbitrary agents or a definitive account of what ran — the coverage matrix decides what is observable per host and surface, at-rest reconstruction cannot recover activity an agent never persisted, and findings are rule matches rather than proof that an action completed.