Remote file reads can resolve paths against an anchor

What

A remote client, such as the sidebar file viewer in a remote session, can ask Claude Code to read a file. Before, it had to give an absolute path, the full path from the top of the disk.

• anchor: a new internal option on read_file (handled by readFileForRemote). It names a starting folder: workspace_root (the folder list_directory lists from), diff_root, or a repo given by owner and name. The path is resolved against that folder before reading.
• Permission checks run on the resolved path.
• The response includes an optional anchor field saying which kind of root was used.

Why

Remote viewers can open repository files by a path relative to the workspace or repo, and can tell which root a path was resolved against, while the usual permission checks still apply to the real file.