Under the hood
Claude Code adds its own pure-JavaScript zip file reader for extracting entries like MCPB packages
What
A new, self-contained zip-file parser was added, handling local file headers, the central directory, the end-of-central-directory record, Zip64 (for large archives), and both stored and deflate-compressed entries. It exposes a function that reads a zip file's contents into a map of entry names to their raw bytes, and is used for extracting entries such as those from MCPB packages.
Why
This gives Claude Code its own zip-reading code for unpacking archives like MCPB packages, rather than relying on some other mechanism for that job.