System One

System One makes semantic decisions from application state, a question, and a fixed answer space. It returns the selected answer and its probability without requiring prompt construction or structured-output parsing.

Create a client with the URL the platform assigns to your deployed AI Gateway. Inside a Tailor Function, aigateway.get() returns it as url. Omit token; the platform authenticates the request:

import { createSystemOne } from "@tailor-platform/sdk/ai";
import { aigateway } from "@tailor-platform/sdk/runtime";

const { url } = await aigateway.get("my-aigateway");
const systemOne = createSystemOne({ baseURL: url });

External clients pass the same URL, which tailor show lists, directly with an access token issued by the AI Gateway's auth namespace:

import { createSystemOne } from "@tailor-platform/sdk/ai";

const systemOne = createSystemOne({
  baseURL: "https://my-aigateway-{WORKSPACE_HASH}.ai.erp.dev",
  token: accessToken,
});

Choice decisions

Use choice() to select one value from an answer space. Literal types are inferred without as const:

const result = await systemOne.choice({
  state: { ticket, customer },
  question: "Which department should handle this ticket?",
  choices: ["billing", "sales", "support"],
});

// result.value: "billing" | "sales" | "support"
// result.probabilities: Record<"billing" | "sales" | "support", number>

Boolean decisions

Use boolean() for a binary decision. value is true when the probability of "yes" is at least 0.5, and probability is the probability of the selected answer:

const result = await systemOne.boolean({
  state: invoice,
  question: "Is this invoice a duplicate?",
});

if (result.value && result.probability > 0.95) {
  // Apply the appropriate business rule.
}

Ordered scores

Use score() when the answer space has a meaningful order. Levels are ordered from lowest to highest, and value is the level with the highest probability:

const result = await systemOne.score({
  state: transaction,
  question: "Assess the risk of this transaction.",
  levels: ["low", "medium", "high"],
});

Models

Decisions use jev-1.13.0 unless a call passes model. jev-latest always points to the newest model, so its probabilities can shift when a new model is released. Use it only when your logic does not compare probabilities against fixed thresholds:

const result = await systemOne.boolean({
  state: invoice,
  question: "Is this invoice a duplicate?",
  model: "jev-latest",
});

Errors

Failures throw SystemOneError with a provider-independent code. Applications can handle stable codes such as UNAUTHORIZED, RATE_LIMITED, PROVIDER_TIMEOUT, and PROVIDER_UNAVAILABLE without depending on a model provider.

A decision waits until AI Gateway responds. To fail with PROVIDER_TIMEOUT instead, pass timeoutMs:

const systemOne = createSystemOne({ baseURL: url, timeoutMs: 10_000 });