[BUG] `--fork-session` flag ignored when using `--resume` with TUI session picker

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?

When using claude --resume --fork-session without specifying a session ID, the interactive TUI picker opens as expected. However, after selecting a session from the picker, the session is resumed directly instead of being forked. The --fork-session flag is silently ignored.

What Should Happen?

When --fork-session is passed alongside --resume, selecting a session from the TUI picker should create a fork of that session (new session ID, preserving conversation history) rather than resuming the original session directly.

Error Messages/Logs

No error messages - the flag is silently ignored. The session resumes with the original session ID instead of creating a new forked session.

Steps to Reproduce

1. Have at least one existing session (run claude and have a conversation, then exit)
2. Run claude --resume --fork-session
3. TUI picker appears - select a session
4. Check /status - the session ID is the same as the original session, not a new forked session

Expected: New session ID (fork created)
Actual: Same session ID (resumed directly, fork flag ignored)

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.76

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

Workaround: Specify the session ID explicitly:
claude --resume <session-id> --fork-session

This works correctly and creates a fork. The bug only occurs when the TUI picker is used (no session ID specified).