Map

Map derives a list with over, runs each once per item concurrently, and returns the outputs in the original item order. An empty list returns [].

import { Chain, Map } from "@nylorun/agents/define";

export const digest = Chain({
  id: "digest",
  steps: [
    planner,
    Map({
      id: "write",
      over: (plan) => plan.sections,
      each: sectionWriter,
    }),
    {
      run: merge,
      input: ({ value }) => ({ parts: value }),
    },
  ],
});

over is durable workflow logic. Keep it deterministic and return a JSON-safe array. each can be an agent, tool, nested workflow, or slot. A slot can use index while shaping each item's input:

Map({
  id: "write",
  over: (plan) => plan.sections,
  each: {
    run: sectionWriter,
    input: ({ value, index }) => ({ title: value, position: index }),
  },
})

Use Map for data-driven fan-out. Use Parallel when branches have different names or behavior known at definition time.

See the shipped map example, then use Loop for repeat-until-accepted work.