MOUNTAIN THEORY VS AVAST SAGE (GEN DIGITAL)
New here? The short version: Mountain Theory checks each action an AI is about to take, against rules you write in plain English, before the action runs. Everything below compares that with what Avast Sage (Gen Digital) does.
Sage is Gen Digital's open-source safety layer for AI coding agents, shipped under the Avast and Norton names depending on how it is installed. Like Mountain Theory, it checks an agent's action before it runs. The difference is scope: Sage protects one developer's machine from threats, and Mountain Theory runs one set of company rules across every agent, with a person in the loop and a record for the auditor.
| Avast Sage (Gen Digital) | Mountain Theory | |
|---|---|---|
| What it controls | Shell commands, URL fetches and file writes from AI coding agents | The action an AI agent is about to take |
| Where it sits | On the developer's machine, as an agent plugin | Inline at execution, between the decision and the action |
| How policy is set | Gen's threat detection layers; allow, ask or deny | Plain English, no code |
| Deployment reach | Claude Code, Cursor, OpenClaw | Model and framework agnostic, including custom and on-prem agents |
| Best fit when | You want a free safety net for developers using AI coding tools | An AI acting wrongly has physical or regulatory consequences |
Why you might pick Avast Sage (Gen Digital)
Sage is free, open source under Apache-2.0, and backed by Gen Digital, the company behind Avast and Norton. It installs as a plugin for Claude Code, Cursor and OpenClaw, intercepts shell commands, URL fetches and file writes, and answers allow, ask or deny before the action runs (Gen Digital, February 19th, 2026). Norton offers the same idea as Norton AI Agent Protection on Windows. For a developer who wants a safety net on their own laptop today, at no cost, it is a sensible first step.
Why you might pick Mountain Theory
Sage looks for threats: it checks each action against its threat detection layers, the way antivirus checks a file. Mountain Theory checks each action against the rules your company writes in plain English, so it can stop an action that is not malicious but is not allowed, such as an agent deleting evidence it was told to clean up. Sage's "ask" goes to whoever is at the keyboard; Mountain Theory holds an action for the named person your rule chooses, which matters when an agent runs with nobody watching. Gen's own announcement calls Sage "not a full antivirus product as we know it," and it does not describe central policy or an audit record. Mountain Theory logs every decision for your auditor and works with 158 AI systems today, well beyond coding agents.
The honest verdict
Use Sage on developer laptops if you want a free check against threats. Use Mountain Theory when the question is company policy: one set of rules across every agent, a person in the loop where the rule says, and a record you can hand an auditor. They can run side by side.
What we can actually show
Proof
Four things with a published run behind them.
Claims in this category are easy to make and hard to check, so here is ours on the record. The same 10 actions were run in the same order under three configurations. Ungoverned, 10 of 10 executed. Under NVIDIA OpenShell alone, all 5 sandbox-boundary crossings were denied at the kernel, and all 3 in-bounds bad decisions still went through, including a secrets read that printed credentials to the screen. Under OpenShell plus Mountain Theory, those same 3 actions returned HOLD, HOLD and BLOCK, and the secrets read was stopped before it executed, so the credentials never printed. Terminal recordings of all three runs are published, including the two actions Mountain Theory has no policy for.
Separately, when a third-party provider updated the foundation model driving an autonomous agent, the agent began attempting multi-step actions it had never tried before. Nothing on our side changed. Every attempt was stopped on July 30th and 31st, 2026, the days the behavior first appeared. No new rule, no signature, no patch.
Both products in this comparison operate at the execution layer. What execution-layer security is, and how it differs from prompt filtering and from access control.
Watch the three-configuration run against NVIDIA OpenShell
See novel agent behavior stopped the day it appeared
Ask Avast Sage (Gen Digital), and every other vendor you are evaluating, for the same four things: the exact action set, the ungoverned control condition, the outcome per action including the ones the product did not stop, and the recording. A certification, an integration list or a customer logo answers a different question.
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