DSTS is a minimal, AI SDK–aligned prompt optimizer for TypeScript. It optimizes prompts for both generateObject (with Zod schemas) and generateText with the latest GEPA optimizer (soft G like “giraffe”). GEPA evolves a prompt along a Pareto frontier across multiple objectives that matter in practice: task performance, latency, and cost.

• AI Gateway–aligned: pass model ids as strings; generateObject with a Zod schema for a structured object or generateText with a string.
• Minimal abstractions: one default adapter to call generateObject/generateText and one optimizer.
• Multi‑objective first: correctness + latency (and cost) tracked per iteration; Pareto front and hyper‑volume (2D) reported.
• Persistence & budgets: checkpoint/resume, per‑call cost estimation (via tokenlens) and budget caps, seeded minibatching.

npm i @currentai/dsts zod

import { z } from "zod";
import { optimize, DefaultAdapterTask } from "@currentai/dsts";

// Define schema (generateObject)
const Item = z.object({ title: z.string(), url: z.string().url() });

// Training data: use schema ⇒ generateObject; provide expectedOutput and/or a scorer
const trainset: DefaultAdapterTask<z.infer<typeof Item>>[] = [
  {
    input: "link to TS docs",
    expectedOutput: {
      title: "TypeScript",
      url: "https://www.typescriptlang.org",
    },
    schema: Item,
  },
];

const result = await optimize({
  seedCandidate: { system: "Extract a title and a valid URL from the text." },
  trainset,
  // Optional valset (defaults to trainset)
  taskLM: {
    model: "openai/gpt-5-nano",
    // Any extra fields are passed through to AI SDK calls
    temperature: 0.2,
    providerOptions: { openai: { service_tier: "default" } },
  },
  reflectionLM: "openai/o3",
  // Simple way to steer reflection without templates
  reflectionHint: "Prioritize exact field correctness; avoid hallucinating properties.",
  maxIterations: 5,
  maxMetricCalls: 200,
  maxBudgetUSD: 50,
  reflectionMinibatchSize: 3,
  candidateSelectionStrategy: "pareto",
  componentSelector: "round_robin",
  logger: {
    log: (lvl, msg, data) => {
      if (lvl === "info") console.log(`[${lvl}] ${msg}`, data || "");
    },
  },
  persistence: {
    dir: "runs/quickstart",
    checkpointEveryIterations: 1,
    resume: true,
  },
});

console.log("Best system prompt:", result.bestCandidate.system);

• Email extraction to a rich object schema: examples/email-extraction.ts
• Message spam classification: examples/message-spam.ts

Each example:

• Loads .env locally (AI Gateway by default),
• Prints total iterations, metric calls, cost (USD), and duration (ms),
• Enables persistence to runs/....

Run:

npm run example              # email extraction
npm run example:message-spam # spam classification

• Default adapter decides generateObject vs generateText based on schema presence in each task; collects per‑instance scores, latency_ms, and cost_usd (via tokenlens when usage is available).
• GEPA optimizer maintains a candidate archive, runs minibatch reflection, and accepts improving children. It computes per‑candidate metrics:
  • correctness = average(score[])
  • latency = −avg(latency_ms) (stored negative so higher is better)
  • cost is tracked cumulatively and enforced via maxBudgetUSD.
• Pareto front and 2D hyper‑volume (when exactly two objectives) are logged per iteration and at the end.

Pass the object variant for taskLM to forward extra options directly into AI SDK calls (both generateObject and generateText). All unknown fields are spread through to the adapter and then to the SDK:

optimize({
  // ...
  taskLM: {
    model: "openai/gpt-5-nano",
    temperature: 0.2,
    providerOptions: { openai: { service_tier: "default" } },
    // tools, stopWhen, toolChoice, maxToolRoundtrips, experimentalTelemetry, etc. are also supported
  },
})

Use reflectionHint to insert a short guidance string at the top of the reflection prompt. Keep it concise:

optimize({
  // ...
  reflectionHint: "Prioritize exact field correctness; avoid hallucinating properties.",
})

Key files:

• Optimizer: src/gepa.ts
• Adapter: src/adapters/default-adapter.ts (default maxConcurrency = 10)
• Pareto utilities: src/pareto-utils.ts
• Types: src/types.ts
• Persistence: src/persistence.ts

• No custom LLM classes: pass model ids as strings (Gateway format, e.g., openai/gpt-5-nano). The adapter uses AI SDK directly.
• Minimal knobs: set budgets (maxMetricCalls, maxBudgetUSD), minibatch size, and selectors. Concurrency defaults to 10.
• Multi‑objective by default: we optimise for correctness and latency together; add cost as an explicit objective later if desired.

• AI Gateway by default. Set AI_GATEWAY_API_KEY in .env or export it in your shell.
• If you prefer provider‑direct, swap to @ai-sdk/openai models and pass model objects; the adapter will forward them.

• Centralized eval helper for exact metric‑call counting and pre‑call budget gates.
• Parent minibatch result reuse to avoid duplicate evaluations.
• Extend hyper‑volume and objectives (e.g., cost as a third dimension) with explicit reference points.
• Reflection concurrency (optional) and parent/child evaluation parallelism.