Gnt

Run the setup below once and every agent your team runs has a git-native rulebook it has to check over MCP before it acts, approved the same way your code already is: a merged pull request.

• Rules live in your repo as files and ship through normal PRs, not a dashboard click.
• Agents call check_action over MCP before anything risky (a refund, a delete, a message to a customer) and get back an allow/block/escalate verdict.
• Every rule traces back to the git file and the PR that approved it, so "why did the agent do that" always has a paper trail.

Prefer not to run any of this yourself? The hosted version at gntai.dev does the same thing without you standing up a Postgres instance.

Get started (30 seconds)

npm install -g @gnt-ai/cli
gnt login
gnt connect github
gnt prebrain
# merge the opened PR on GitHub. that merge is the approval

Try it with Docker first

To see a real check_action response before installing Node or npm, clone the repository and run the Docker-only demo:

./demo.sh

It builds the full local stack in an isolated gnt-demo Compose project, seeds an approved refund rule, calls check_action, and prints a curl command you can run again. Without an Anthropic key the real fail-closed path returns needs_human; pass GNT_DEMO_ANTHROPIC_API_KEY=sk-ant-... ./demo.sh to opt in to the model's grounded policy verdict. The demo uses deterministic local embeddings and throwaway localhost-only secrets, so it does not need a ZeroEntropy key.

Nothing for gnt prebrain to scan yet? Run gnt init first — it scaffolds rules/ locally with a couple of example rule files so there's something real to look at and edit, and points you at gnt prebrain --starter-packs for a curated pack to start from instead.

That merge lands a rule file in your connected repo, shaped like this:

your-repo/
└── rules/
    ├── refund-approval-threshold.md
    └── contract-legal-cc.md

Each file is plain markdown with YAML frontmatter:

---
title: Never refund over $500 without a manager
status: approved
confidence: 0.91
owner_id: finance-team
source_citations: [...]
source: slack
tags: [refunds, finance]
last_validated_at: 2026-07-20
version: 1
superseded_by: null
approved_by: jane@company.com
approved_at: 2026-07-21T14:03:00Z
created_at: 2026-07-18T09:12:00Z
pr_number: 142
pr_url: https://github.com/your-org/your-repo/pull/142
---

Refunds over $500 need manager sign-off before they go out...

See it in action

There's no captured transcript to show yet (see the gap noted at the bottom of this README). Here's the actual response shape a check_action call returns, straight from the tool's contract:

{
  "verdict": "blocked",
  "reason": "Refund exceeds the $500 threshold without manager sign-off (rules/refund-approval-threshold.md)",
  "cited_rules": [
    { "id": "refund-approval-threshold", "title": "Never refund over $500 without a manager" }
  ],
  "rules_retrieved": 3
}

verdict is one of allowed, blocked, or needs_human. needs_human is the fail-closed default: no approved rule covers the action, retrieval failed, or the check couldn't complete. It never guesses.

What it does

One MCP endpoint, five tools:

Prerequisites

Install

gnt needs Node >=22.13. If the CLI fails to start with a version error, update Node first and confirm with node --version.

Common commands

gnt login                # sign in, store an API key locally
gnt init                 # scaffold a local rules/ dir with example rule files
gnt connect github       # connect the repo your rules PRs open against
gnt prebrain             # scan sources, extract candidate rules, open PRs
gnt review               # review rules awaiting approval
gnt status               # show brain status
gnt pull                 # download the latest skill pack
gnt gaps                 # list uncovered queries with no approved rule

Config

Privacy

• No analytics or telemetry dependency in the CLI or the web app.
• gnt prebrain's default extraction mode is cloud, not on-device: your source text goes straight to Anthropic's API (or Vercel AI Gateway with zero-data-retention, if you configure it), never to gnt's own servers. Fully on-device extraction needs --mode local against a local Ollama daemon.
• The extracted rule candidates still get sent to gnt's API to open the PR. Raw source text stays off gnt's servers in cloud mode; the resulting rule text doesn't.
• Rules live in your connected GitHub repo and in gnt's own database. The MCP tools read from gnt's store, not by cloning your repo on every call.
• Self-hosting: apps/api only sends error data to Sentry if you set SENTRY_DSN yourself. Leave it unset and nothing goes out.

Team setup

• Who writes rules: anyone with access to your connected repo, either through gnt prebrain (batch-extracted from real sources) or gnt review (hand-proposed).
• How approval works: merging the PR is the approval. There's no separate publish step.
• What gets committed: rules/<rule-id>.md files with the frontmatter shown above and a plain markdown body.
• Catching a malformed rule before it's reviewed: gnt rules lint checks a rule file's frontmatter locally, and gnt-ai/gnt/.github/actions/lint-rules runs the same check as a CI step on your rules repo's own PRs, so a bad frontmatter fails the PR instead of the review.

Troubleshooting

Self-hosting: gnt login's browser step has nowhere to land. gnt login opens a browser to a /cli-login page and polls the API for the resulting key — that page is served by the hosted product's web app, which isn't part of this repo. There's no CLI-only login flow (device code or otherwise) today, and no gnt command to set a key manually. Self-hosting this stack currently means building your own thin frontend for that one route (it just needs to complete the sign-in flow and hand the CLI a key). This is a real, open gap in the self-host path, not a config issue — closing it properly means adding a CLI-only login flow.

ValueError: refusing to start: these settings still have their .env.example placeholder value... A change-me-... string is still sitting in apps/api/.env. The error names every offending field; generate a real value for each and retry.

store fails to start with GNT_STORE_INTERNAL_API_SECRET is not set. apps/store/.env wasn't filled in, or wasn't picked up. Confirm the file exists at that exact path, not still named .env.example.

Every store-to-api call gets rejected with 401 or 403, even though both services are up. STORE_INTERNAL_API_SECRET / APPROVAL_SIGNING_SECRET in apps/api/.env don't byte-for-byte match GNT_STORE_INTERNAL_API_SECRET / GNT_APPROVAL_SIGNING_SECRET in apps/store/.env. This fails closed by design. Regenerate both pairs so the two files agree.

A rule fails to save with an embedding or rerank error. apps/store/.env is missing ZEROENTROPY_API_KEY, or it's still empty. Get a real one from zeroentropy.dev.

Full command reference