[BUG] Cowork desktop sandbox — bash mount serves stale/truncated host-edited files.

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Cowork desktop Linux sandbox — host-side writes are not coherent in the bash mount. Files written to the mounted Windows project folder via the Cowork file tools (host side) are read back through the sandbox bash (cat/grep/wc/tail/md5sum/ls) as stale and/or truncated — a cached prefix (≈ pre-edit length, content past ~14–16 KB dropped) with stale ls size/mtime and intermittent dentry flicker (ENOENT + valid stat in one call). Files written from inside the sandbox are coherent; only externally-applied (host) writes are missed — the signature of a guest FS cache with no external-write invalidation. Host ground truth verified independently (Windows NTFS via Git Bash and PowerShell agree: 35,565 B / 208 lines), and the Cowork Read tool matches — so the data and Write path are correct; the defect is purely the sandbox read/mount layer. Suspected: gVisor gofer in --file-access=exclusive (or a 9p/virtiofs loose-cache config). Asks: (1) confirm the mount type/cache mode; (2) switch to a coherent mode (--file-access=shared / cache=none + adequate msize / virtiofs invalidations); (3) confirm whether the ~14–16 KB cutoff is a separate read-chunk cap (repro: Cowork-Write a brand-new 25 KB file, wc -c in-sandbox). Repro and per-fstype steps available.

What Should Happen?

As per above, shouldn't have incoherency against the bash mount.

Error Messages/Logs

N/A

Steps to Reproduce

See above

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Cowork2.1.161 (Claude Code) — and it's installed right here in the workspace sandbox at /usr/local/bin/claude.

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_