Conversation history is now saved one write at a time

Claude Code saves a running record of each conversation, which is what lets you resume it later. If a new update to that record arrives while an earlier save is still in progress, Claude Code now queues it and writes it once the earlier save finishes. Previously each save started straight away. Updates that end at a compaction point (where older messages were replaced by a summary) are skipped. Claude Code also records usage data on how long saves take, how many updates were overtaken and whether it waited at exit.