Run events

import type { NikaRunEvent } from '@supernovae-st/nika'

type ViewState = { active: Set<string> }

function reduce(state: ViewState, event: NikaRunEvent) {
  switch (event.kind) {
    case 'task.started':
      if (event.task) state.active.add(event.task)
      break
    case 'task.completed':
    case 'task.failed':
      if (event.task) state.active.delete(event.task)
      break
    default:
      // engine.event and future kinds stay visible to diagnostics
      telemetry.debug('unrendered event', event.kind, event.raw)
  }
}

const run = await nika.run('workflow.nika')
for await (const event of run.events()) reduce(view, event)
const result = await run.result()