A non-UTF-8 argv byte aborts the process: std::env::args() unwraps instead of args_os() #9401

claude -p $'\xff\xfe\x80abc\xc3\x28'
  node : rc=1   "Not logged in · Please run /login"
  perry: rc=134 (SIGABRT)
         thread '<unnamed>' panicked at library/std/src/env.rs:878:51:
         called `Result::unwrap()` on an `Err` value: "\xFF\xFE\x80abc\xC3("

std::env::args() panics on any argument that is not valid UTF-8. Non-UTF-8 filenames are ordinary on Linux, so this is reachable by a user simply passing a path, and the panic text leaks Rust internals into the program's stderr.

Fix: use std::env::args_os() and convert lossily (or preserve the bytes) at the boundary, matching node, which accepts the argument and proceeds.

A grep for env::args() elsewhere in the runtime is worthwhile — the same unwrap pattern may appear on other paths.

Found by a differential stress-test of cc 2.1.112 under perry 757beace0.