Function readStructuredOutputCompleteValue

packages/ai/src/activities/chat/index.ts:2937–2952

* Parse the `value` payload of a `structured-output.complete` CUSTOM event * into a typed shape, returning `null` if the runtime payload doesn't match. * * Uses an `unknown`-input runtime check rather than `as` casts so the engine * stays cast-free in its hot path.

(
  value: unknown,
)

 * stays cast-free in its hot path.
 */
function readStructuredOutputCompleteValue(
  value: unknown,
): { object: unknown; raw: string; reasoning?: string } | null {
  if (typeof value !== 'object' || value === null) return null
  if (!('object' in value) || !('raw' in value)) return null
  const raw = (value as { raw: unknown }).raw
  if (typeof raw !== 'string') return null
  const reasoningField = (value as { reasoning?: unknown }).reasoning
  const reasoning =
    typeof reasoningField === 'string' ? reasoningField : undefined
  return {
    object: (value as { object: unknown }).object,
    raw,
    ...(reasoning !== undefined ? { reasoning } : {}),
  }
}

/**
 * Synthesize a streaming structured-output stream by wrapping a non-streaming