Function collectCandidatesByMessage

src/utils/toolResultStorage.ts:600–639

* Extract candidate tool_result blocks grouped by API-level user message. * * normalizeMessagesForAPI merges consecutive user messages into one * (Bedrock compat; 1P does the same server-side), so parallel tool * results that arrive as N separate user messages in our state become * ONE user mes

(
  messages: Message[],
)

 * Only groups with at least one eligible candidate are returned.
 */
function collectCandidatesByMessage(
  messages: Message[],
): ToolResultCandidate[][] {
  const groups: ToolResultCandidate[][] = []
  let current: ToolResultCandidate[] = []

  const flush = () => {
    if (current.length > 0) groups.push(current)
    current = []
  }

  // Track all assistant message.ids seen so far — same-ID fragments are
  // merged by normalizeMessagesForAPI (messages.ts ~2126 walks back PAST
  // different-ID assistants via `continue`), so any re-appearance of a
  // previously-seen ID must NOT create a group boundary. Two scenarios:
  //   • Consecutive: streamingToolExecution yields one AssistantMessage per
  //     content_block_stop (same id); a fast tool drains between blocks;
  //     abort/hook-stop leaves [asst(X), user(trA), asst(X), user(trB)].
  //   • Interleaved: coordinator/teammate streams mix different responses
  //     so [asst(X), user(trA), asst(Y), user(trB), asst(X), user(trC)].
  // In both, normalizeMessagesForAPI merges the X fragments into one wire
  // assistant, and their following tool_results merge into one wire user
  // message — so the budget must see them as one group too.
  const seenAsstIds = new Set<string>()
  for (const message of messages) {
    if (message.type === 'user') {
      current.push(...collectCandidatesFromMessage(message))
    } else if (message.type === 'assistant') {
      if (!seenAsstIds.has(message.message.id)) {
        flush()
        seenAsstIds.add(message.message.id)
      }
    }
    // progress / attachment / system are filtered or merged by
    // normalizeMessagesForAPI — they don't create wire boundaries.
  }
  flush()

  return groups
}

/**
 * Partition candidates by their prior decision state: