What
The Read tool now blocks attempts to read device files that would block or produce infinite output.
Details
Blocked device files include:
/dev/zero,/dev/random,/dev/urandom,/dev/full/dev/stdin,/dev/tty,/dev/console/dev/stdout,/dev/stderr,/dev/fd/0,/dev/fd/1,/dev/fd/2
Error message: "Cannot read '[path]': this device file would block or produce infinite output."
Evidence
Device file blocklist (search for "device file would block")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agree
Fixed FileReadTool blocking the process on FIFOs, /dev/stdin, and large files