Use krino

Configuration

Every createKrino option and its default, the three decision modes, the risk gate policy, decision providers, traces, and prices.

createKrino(config) checks the config and throws KrinoConfigurationError on a bad value. Every default lives in the exported KRINO_CONFIG_DEFAULTS.

Options

Field	Default	What it does
`projectName`	required	Names the trace folder and the project in reports.
`decisionModes`	every decision `shadow`	The mode for `toolSelection` and `riskGate`.
`minimumConfidence`	`0.8`	Tool selection only: below this probability, send all tools.
`decisionTimeoutInMilliseconds`	`800`	How long enforce mode waits for an answer.
`explorationRate`	`0.05`	Enforce only: the share of runs that skip enforcement to keep comparison data.
`riskGatePolicy`	none	Block list, allow list, and per-tool thresholds (below).
`decisionProvider`	the fake provider, with a warning	Who answers the questions.
`traceSink`	the file sink	Where traces go.
`redactContent`	`true`	Keeps raw task text and messages out of traces.
`priceOverrides`	none	Your own `ModelPrice` rows. They replace table rows for the same model.

Decision modes

Set a mode per decision in decisionModes.

Mode	What krino does
`off`	Does not ask.
`shadow`	Asks in the background and records the answer. Your agent waits for nothing.
`enforce`	Waits for the answer, up to `decisionTimeoutInMilliseconds`, and applies it.

In v0.1, the risk gate runs in shadow mode only.

Risk gate policy

TypeScript

import { createKrino, type RiskGatePolicy, thresholdFromCosts } from "@krinolabs/krino";
 
const riskGatePolicy: RiskGatePolicy = {
  blockedToolNames: ["dropDatabase"],
  alwaysAllowedToolNames: ["searchLogs"],
  // Example costs: asking a person costs $0.50, a bad call costs $50.
  allowThresholdByToolName: {
    restartService: thresholdFromCosts({ costOfAskingInUsd: 0.5, costOfBadCallInUsd: 50 }),
  },
};
 
const krino = createKrino({
  projectName: "my-agent",
  decisionModes: { riskGate: "shadow" },
  riskGatePolicy,
});

A blocked tool is always block. An always-allowed tool is always allow. Your lists win over the model.
For any other tool, krino asks whether the call is safe and suggests allow only when the probability reaches that tool's threshold. Otherwise it suggests askHuman.
A tool with no threshold gets askHuman, with status skippedUnsupported.
thresholdFromCosts returns 1 - costOfAsking / costOfBadCall, clamped to 0 to 1. With the example costs above, that is 0.99.

Decision providers

Jev (createJevAiGatewayProvider() from @krinolabs/krino/providers/jev) asks Jev through Vercel AI Gateway. It reads AI_GATEWAY_API_KEY from the environment, sends all questions for a step in one request, and cancels it on timeout.
Fake (createFakeDecisionProvider() from the root entry) answers offline, from a script. Use it in tests. It is the default when you pass no provider, and krino prints a warning.

Traces

The default file sink writes one JSON object per line to traces-YYYY-MM-DD.jsonl (UTC day) and starts a new file at 50 MB. A write failure is logged once to stderr; it never throws into your agent. The trace folder is, in order:

$KRINO_TRACE_DIRECTORY
$XDG_STATE_HOME/krino/traces/<project>, when XDG_STATE_HOME is an absolute path
~/.krino/traces/<project>

To pick your own folder, pass a file sink:

TypeScript

import { createFileTraceSink, createKrino } from "@krinolabs/krino";
 
const krino = createKrino({
  projectName: "my-agent",
  decisionModes: { toolSelection: "shadow" },
  traceSink: createFileTraceSink({ projectName: "my-agent", traceDirectory: "/var/log/krino" }),
});

Shadow decisions finish in the background. In a short process, call await krino.flushAll(DEFAULT_FLUSH_TIMEOUT_IN_MILLISECONDS) before you exit. It waits up to 2 s. Decisions still open are written with status cutOff.

Prices

costFromUsage(tokenUsage, modelPrice) prices a step and always counts cache read and cache write tokens. DEFAULT_MODEL_PRICES holds dated prices for Claude Opus 5.5, Sonnet 5.5, Haiku 4.5, and Jev. Every row has a verifiedOn date, and reports show it. Prices change: use priceOverrides for your own rates.