Function smooshIntoToolResult

src/utils/messages.ts:2534–2598

* Fold content blocks into a tool_result's content. Returns the updated * tool_result, or `null` if smoosh is impossible (tool_reference constraint). * * Valid block types inside tool_result.content per SDK: text, image, * search_result, document. All of these smoosh. tool_reference (beta) canno

(
  tr: ToolResultBlockParam,
  blocks: ContentBlockParam[],
)

 * - otherwise → array, with adjacent text merged (notebook.ts idiom)
 */
function smooshIntoToolResult(
  tr: ToolResultBlockParam,
  blocks: ContentBlockParam[],
): ToolResultBlockParam | null {
  if (blocks.length === 0) return tr

  const existing = tr.content
  if (Array.isArray(existing) && existing.some(isToolReferenceBlock)) {
    return null
  }

  // API constraint: is_error tool_results must contain only text blocks.
  // Queued-command siblings can carry images (pasted screenshot) — smooshing
  // those into an error result produces a transcript that 400s on every
  // subsequent call and can't be recovered by /fork. The image isn't lost:
  // it arrives as a proper user turn anyway.
  if (tr.is_error) {
    blocks = blocks.filter(b => b.type === 'text')
    if (blocks.length === 0) return tr
  }

  const allText = blocks.every(b => b.type === 'text')

  // Preserve string shape when existing was string/undefined and all incoming
  // blocks are text — this is the common case (hook reminders into Bash/Read
  // results) and matches the legacy smoosh output shape.
  if (allText && (existing === undefined || typeof existing === 'string')) {
    const joined = [
      (existing ?? '').trim(),
      ...blocks.map(b => (b as TextBlockParam).text.trim()),
    ]
      .filter(Boolean)
      .join('\n\n')
    return { ...tr, content: joined }
  }

  // General case: normalize to array, concat, merge adjacent text
  const base: ToolResultContentItem[] =
    existing === undefined
      ? []
      : typeof existing === 'string'
        ? existing.trim()
          ? [{ type: 'text', text: existing.trim() }]
          : []
        : [...existing]

  const merged: ToolResultContentItem[] = []
  for (const b of [...base, ...blocks]) {
    if (b.type === 'text') {
      const t = b.text.trim()
      if (!t) continue
      const prev = merged.at(-1)
      if (prev?.type === 'text') {
        merged[merged.length - 1] = { ...prev, text: `${prev.text}\n\n${t}` } // lvalue
      } else {
        merged.push({ type: 'text', text: t })
      }
    } else {