What
When Claude Code fetches attachments, it now records more telemetry, which is usage data sent back about how things performed:
slowestTimeToHeadersMsslowestJoinWaitMsreusedFileCountprefetchedFileCountjoinedInFlightCount
Why
These measure how long the slowest attachment took, and how many files were reused, fetched ahead of time, or shared between requests waiting for the same download.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
The finding does not settle whether attachments are actually reused, prefetched or shared in this release, or only counted.