Stored transcripts that cannot be fully read are now kept instead of treated as empty

Claude Code checks whether a stored transcript actually holds a conversation. A transcript is the saved record of a session. Before, it only looked at the records through its usual reader.

In some cases it now reads the stored transcript right to its end. If it still cannot tell, it logs a warning saying it could not read the transcript to its end and is keeping it as if it holds a conversation.

Separately, when an ultraplan or MCP task ends, Claude Code can now be told to keep the controller that stops the task running, rather than always clearing it.