You'll notice
Session-message cache priming now merges into an already-in-progress cache load instead of dropping the new data
What
When Claude Code primes its cache of session message UUIDs and a cache entry for that session is already being built, it used to simply skip the new priming request and do nothing further. Now it waits for the in-flight cache load to finish and merges the newly supplied UUIDs into the resulting set.
Why
This prevents UUIDs from being silently lost when two priming calls for the same session overlap, ensuring the cache ends up complete rather than missing entries that arrived while a load was already underway.