Improved handling of the cache diagnosis beta feature. If the server rejects the beta header, it's now detected and dropped gracefully: "[cache-diagnosis] server rejected beta — dropping header latch". A retry mechanism ("retry:cache-diagnosis-beta") handles transient failures.
Evidence
Cache diagnosis handling (search for "cache-diagnosis" and "retry:cache-diagnosis-beta").
Strings lifted out of the shipped bundle, so the claim above can be checked against them.