Under the hood
Edit, Write, and Read/PDF tools were refactored internally to build themselves from a per-session factory function
What
The internal implementation of tools like Edit, Write, and the reader that handles files and PDFs was restructured. Previously each tool had flat methods for checking permissions, validating input, and running. Now each tool has a create() factory function that builds those methods bound to the specific session and context of the current invocation, giving uniform access to things like permissions, the tool list, remote-call handling, and the active model.
Why
This is an internal code reorganization with no described effect on what these tools do from a user's perspective; it standardizes how the tools are built internally.