[BUG] `claude --print` produces no output when `CLAUDECODE` env var is unset inside a session

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?

Running claude --print hello from within a Claude Code session (e.g., via Bash tool) is blocked by the nested session check. When bypassing the check by unsetting CLAUDECODE, the command exits 0 but produces no output at all.

What Should Happen?

claude --print is a non-interactive subcommand. It should either work inside a Claude Code session without triggering the nested session guard, or produce correct output when the guard is bypassed.

Error Messages/Logs

⏺ Bash(claude --print hello)
  ⎿  Error: Exit code 1
     Error: Claude Code cannot be launched inside another Claude Code session.
     Nested sessions share runtime resources and will crash all active sessions.
     To bypass this check, unset the CLAUDECODE environment variable.

     Error: Claude Code cannot be launched inside another Claude Code session.
     Nested sessions share runtime resources and will crash all active sessions.
     To bypass this check, unset the CLAUDECODE environment variable.

⏺ Claude Code can't be launched inside another Claude Code session — it detects the nested session and blocks it.
  You'd need to run claude --print hello from a separate terminal outside of this Claude Code session, or unset the
  CLAUDECODE environment variable first:

⏺ Bash(unset CLAUDECODE && claude --print hello)
  ⎿  (No output)

Steps to Reproduce

1. Start a Claude Code session
2. Ask Claude to run claude --print hello via the Bash tool
3. Observe the nested session error
4. Run CLAUDECODE= claude --print "hello" 2>&1
5. Command exits 0 but produces no output

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.63

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_