/bin/sh ENOENT: Bash tool silently breaks mid-session

Bug Description

The Bash tool silently stops working mid-session with exit code 1 and no output. The error is ENOENT: no such file or directory, posix_spawn '/bin/sh'. All other tools (Read, Write, Edit, Glob, Grep) continue to work normally.

Reproduction

• Platform: macOS 15.3 (Darwin 25.3.0), Apple Silicon (MacBook Pro)
• Shell: zsh
• Observed: 2+ times (Feb 2026)

Steps

1. Start a Claude Code session
2. Perform a burst of file operations (mv, rm -rf, directory restructuring)
3. At some point, the Bash tool starts failing — one command works, the very next returns exit 1 with empty output
4. File tools (Read, Write, Edit) continue working fine
5. Stop hooks also fail with the same ENOENT error

Key observations

• It's not gradual — one Bash call succeeds, the next is dead
• Happens after heavy file operations (moving directories, deleting large trees)
• /bin/sh definitely exists on the filesystem — this appears to be an internal process spawning issue
• Only fix is restarting Claude Code

Expected Behavior

Bash tool should continue working throughout the session regardless of file operations performed.

Actual Behavior

posix_spawn '/bin/sh' fails with ENOENT. All subsequent Bash calls fail silently (exit 1, no output). Stop hooks also fail with the same error.

Error from stop hook

Stop hook error: Failed with non-blocking status code: Error occurred while executing hook command: ENOENT: no such file or directory, posix_spawn '/bin/sh'