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Agent Security & Sandboxing

Numbat

Numbat is an open-source Go tool for endpoint visibility into AI-agent activity. It collects supported live activity through hooks, plugins, and OTLP/HTTP logs, and can scan supported session artifacts stored on disk. A shared event model feeds a local CEL rule engine for detection, with records available as NDJSON through stdout, local files, or optional HTTP delivery.

Independent OpenViST project profile, based on linked sources.

Numbat — OpenViST project profile in Agent Security & Sandboxing.
OpenViST project illustration. See the linked sources for product details.
Understand the project

Practical overview

When it fits

Use Numbat when endpoint-local monitoring, read-only artifact review, or structured investigation of supported AI-agent activity is needed. Start with inventory and scans for retrospective review; configure hooks for live capture, and consider enforcement only after checking coverage and policy requirements.

Who it is for

  • Developers and security teams who need local visibility into supported AI agents on endpoints.
  • Operators who want to inspect stored agent sessions or investigate activity through timelines and case bundles.

Documented uses

  • Discover agents and scan supported stored session artifacts.
  • Collect live agent activity and evaluate it against built-in, sequence, or custom YAML rules.
  • Export structured events and findings for local review or optional HTTP delivery.
  • Reconstruct activity from supported on-disk artifacts without prior Numbat instrumentation.
  • Optionally block selected actions through supported pre-action hooks and explicitly enforced rules.
Before you choose

Requirements & limits

Numbat is open source under the Apache-2.0 license. Its repository documents single-binary releases for macOS, Linux, and Windows on amd64 and arm64, and installation with Go 1.26.6 or newer.

  • Coverage is specific to each agent, host, and surface; the project's coverage matrix is the reference for support.
  • All shipped rules are monitor-only, and enforcement requires an operator policy marked enforce: true plus a supported synchronous pre-action hook.
  • Hook configuration status does not confirm that events execute or reach their destination.
  • Normal record output does not contain a complete raw transcript; adding raw evidence files to case bundles is opt-in.
  • The tool supports output to stdout or local files and optional HTTP delivery.

Check current requirements in the official documentation. Source-based guidance does not mean OpenViST has run or independently tested this project.

Source-based practical guide

Inventory agents and scan supported session artifacts

Use Numbat's read-only discovery and scanning commands to inspect available parser-backed agents and their supported artifacts.

Before you start

  • Install Numbat for macOS, Linux, or Windows, or install it with Go 1.26.6 or newer.

Steps

  1. Run numbat agents to discover agents.

  2. Run numbat scan to scan all discovered parser-backed agents.

  3. To limit automatic discovery to Codex, run numbat scan --agent codex.

Expected outcome

Numbat performs read-only discovery and scans supported on-disk session artifacts without installing hooks or changing agent configuration.

Guide limitations

  • Scanning applies to discovered parser-backed agents and supported artifacts; consult the agent coverage matrix for host and surface coverage.
Source-based practical guide

Install Codex live monitoring in monitor-only mode

Configure a Codex user hook to emit Numbat monitoring records.

Before you start

  • Install Numbat.
  • Use an agent and surface with live-capture support.
  • Review and trust the current Codex user hook definition in the CLI hooks directory or the app's Settings > Hooks.

Steps

  1. Run numbat hook install --agent codex --emit all.

  2. Run numbat hook status --agent codex to check the hook configuration.

Expected outcome

The hook is installed in monitor-only mode and is configured to write events, findings, indicators, and applicable enforcement decisions to `~/.numbat/records.ndjson`.

Guide limitations

  • Hook status verifies configuration, not execution or delivery.
  • Coverage varies by agent and surface; blocking is off by default and limited to supported synchronous pre-action hooks.
Evidence and transparency

Sources & review

Source record details
Source availability
Active
Sources checked
12 October 2026
Original website title
perplexityai/numbat · Official homepage title · retained in its source language