Faster repair of broken conversation histories, and compaction keeps later messages

Claude Code saves each conversation as a transcript, a file where every message points back to the one before it. When those links are broken, Claude Code falls back to ordering messages by their timestamps. That fallback used to scan the whole transcript every time. It now uses a sorted index, which is much quicker on long transcripts.

Compaction is the step that shrinks a long conversation by replacing older messages with a summary. It now records the time at which it drew that line. In some cases it then keeps any messages dated after that time instead of pruning them.