Function recordTranscript

src/utils/sessionStorage.ts:1526–1607

(
  messages: Message[],
  teamInfo?: TeamInfo,
  startingParentUuidHint?: UUID,
  allMessages?: readonly Message[],
)

}

export async function recordTranscript(
  messages: Message[],
  teamInfo?: TeamInfo,
  startingParentUuidHint?: UUID,
  allMessages?: readonly Message[],
): Promise<UUID | null> {
  const sessionId = getSessionId() as UUID
  const messageSet = await getSessionMessages(sessionId)

  // Fast path: new messages are almost always appended at the end.
  // Scan backward to find the first new message from the end.
  let firstNewIdx = messages.length
  while (firstNewIdx > 0 && messageSet.has(messages[firstNewIdx - 1]!.uuid as UUID)) {
    firstNewIdx--
  }

  // All messages already recorded (loop decremented all the way to 0)
  if (firstNewIdx === 0) {
    const lastRecorded = messages.findLast(
      m => isChainParticipant(m) && messageSet.has(m.uuid as UUID),
    )
    return (lastRecorded?.uuid as UUID | undefined) ?? startingParentUuidHint ?? null
  }

  // Verify the prefix before firstNewIdx looks like a normal contiguous
  // recorded prefix (not a compaction mix where new messages are interleaved).
  // Spot-check up to SPOT_CHECK_DEPTH messages before the boundary.
  const SPOT_CHECK_DEPTH = 10
  const boundaryIdx = firstNewIdx - 1
  const beforeNew = boundaryIdx >= 0 ? messages[boundaryIdx] : undefined
  let canFastPath =
    beforeNew !== undefined &&
    messageSet.has(beforeNew.uuid as UUID) &&
    isChainParticipant(beforeNew)

  if (canFastPath) {
    for (let i = boundaryIdx - 1; i >= boundaryIdx - SPOT_CHECK_DEPTH && i >= 0; i--) {
      if (!messageSet.has(messages[i]!.uuid as UUID)) {
        canFastPath = false
        break
      }
    }
  }

  if (!canFastPath) {
    return recordTranscriptFull(
      messages,
      teamInfo,
      startingParentUuidHint,
      allMessages,
    )
  }

  // Fast path confirmed: only clean the new suffix
  const startingParentUuid = beforeNew.uuid as UUID
  const suffix = messages.slice(firstNewIdx)
  const cleanedMessages = cleanMessagesForLogging(suffix, allMessages)
  const newMessages: typeof cleanedMessages = []