Function buildFileHistorySnapshotChain

src/utils/sessionStorage.ts:2249–2273

* Builds a filie history snapshot chain from the conversation

(
  fileHistorySnapshots: Map<UUID, FileHistorySnapshotMessage>,
  conversation: TranscriptMessage[],
)

 * Builds a filie history snapshot chain from the conversation
 */
function buildFileHistorySnapshotChain(
  fileHistorySnapshots: Map<UUID, FileHistorySnapshotMessage>,
  conversation: TranscriptMessage[],
): FileHistorySnapshot[] {
  const snapshots: FileHistorySnapshot[] = []
  // messageId → last index in snapshots[] for O(1) update lookup
  const indexByMessageId = new Map<string, number>()
  for (const message of conversation) {
    const snapshotMessage = fileHistorySnapshots.get(message.uuid)
    if (!snapshotMessage) {
      continue
    }
    const { snapshot, isSnapshotUpdate } = snapshotMessage
    const existingIndex = isSnapshotUpdate
      ? indexByMessageId.get(snapshot.messageId)
      : undefined
    if (existingIndex === undefined) {
      indexByMessageId.set(snapshot.messageId, snapshots.length)
      snapshots.push(snapshot)
    } else {
      snapshots[existingIndex] = snapshot
    }
  }
  return snapshots
}

/**
 * Builds an attribution snapshot chain from the conversation.