static L<GazelleTree> dm_gazelle_revisitChatLine(long msgID, O... _) {
  O line = dm_call(dm_gazelle_linesCRUD(), 'lineForID, msgID);
  if (line == null) null;
  long channelID = toLong(call(line, 'channelID));
  L lines = cast dm_call(dm_gazelle_linesCRUD(), 'linesInChannel, channelID);
  int i = indexOf(lines, line);
  if (i < 0) ret null with print("Line not found in channel " + channelID);
  LS preContext = collect text(takeLast(10, takeFirst(i, lines)));
  print("preContext (last first): " + sfu(reversed(preContext)));
  ret gazelle_reason_repeat(
    getString text(line),
    paramsPlus(_, 
      userName := call(line, 'userName),
      +preContext));
}