Function computeDiffStatsBetweenMessages

src/components/MessageSelector.tsx:723–767

* Computes the diff stats for all the file edits in-between two messages.

(messages: Message[], fromMessageId: UUID, toMessageId: UUID | undefined)

 * Computes the diff stats for all the file edits in-between two messages.
 */
function computeDiffStatsBetweenMessages(messages: Message[], fromMessageId: UUID, toMessageId: UUID | undefined): DiffStats | undefined {
  const startIndex = messages.findIndex(msg => msg.uuid === fromMessageId);
  if (startIndex === -1) {
    return undefined;
  }
  let endIndex = toMessageId ? messages.findIndex(msg => msg.uuid === toMessageId) : messages.length;
  if (endIndex === -1) {
    endIndex = messages.length;
  }
  const filesChanged: string[] = [];
  let insertions = 0;
  let deletions = 0;
  for (let i = startIndex + 1; i < endIndex; i++) {
    const msg = messages[i];
    if (!msg || !isToolUseResultMessage(msg)) {
      continue;
    }
    const result = msg.toolUseResult as FileEditOutput | FileWriteToolOutput;
    if (!result || !result.filePath || !result.structuredPatch) {
      continue;
    }
    if (!filesChanged.includes(result.filePath)) {
      filesChanged.push(result.filePath);
    }
    try {
      if ('type' in result && result.type === 'create') {
        insertions += result.content.split(/\r?\n/).length;
      } else {
        for (const hunk of result.structuredPatch) {
          const additions = count(hunk.lines, line => line.startsWith('+'));
          const removals = count(hunk.lines, line => line.startsWith('-'));
          insertions += additions;
          deletions += removals;
        }
      }
    } catch {
      continue;
    }
  }
  return {
    filesChanged,
    insertions,
    deletions
  };
}
export function selectableUserMessagesFilter(message: Message): message is UserMessage {
  if (message.type !== 'user') {
    return false;