Select and time signals

Result	Operator
First causally related input to emit or fail	`race`
Resume one occurrence after a duration	`delay`
Fail one signal at a durable deadline	`timeout`

automations/choose-first-timer.automation.ts

import {
  automation,
  delay,
  onHttpRequest,
  race,
  respondToHttpRequest,
  withPrerequisites,
} from "automate.ax"

export default automation("Choose first timer", () => {
  const request = onHttpRequest()
  const winner = withPrerequisites(request, () =>
    race([
      delay("2s").transform(() => "slow"),
      delay("1s").transform(() => "fast"),
    ]),
  )

  respondToHttpRequest({ body: winner, requestId: request.requestId })
})

Use race when completion order matters within one causal occurrence: emission or failure wins, and closed inputs leave the race. Its inputs must share an activation boundary. Use merge when independent trigger streams should start the same flow. Literal delays declare hidden delivery triggers. Scope them to the initiating signal with withPrerequisites. Value-carrying delays and timeouts use their source as the anchor. Use Control event bursts when timing repeated occurrences instead of one causal occurrence.

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Select and time signals