Function extractSelectionReason

cli/src/utils/implementor-helpers.ts:711–729

* Extract the selection reason from multi-prompt agent's set_output block. * set_output wraps data in a 'data' property, so we need to access input.data.reason

(
  blocks: ContentBlock[] | undefined,
)

 * set_output wraps data in a 'data' property, so we need to access input.data.reason
 */
function extractSelectionReason(
  blocks: ContentBlock[] | undefined,
): string | null {
  if (!blocks || blocks.length === 0) return null

  const setOutputBlock = blocks.find(
    (block): block is ToolContentBlock =>
      block.type === 'tool' &&
      block.toolName === 'set_output' &&
      hasSetOutputData(block.input) &&
      typeof block.input.data?.reason === 'string',
  )

  if (!setOutputBlock || !hasSetOutputData(setOutputBlock.input)) {
    return null
  }

  return setOutputBlock.input.data?.reason ?? null
}

/**
 * Generate a progress-focused preview string for multi-prompt editor.