/branch fails with 'No conversation to branch' in all session types

Bug

/branch command fails with Failed to branch conversation: No conversation to branch in both background job sessions and what appears to be any session context.

Steps to reproduce

1. Start a Claude Code session (background job or interactive)
2. Have a conversation with multiple turns
3. Run /branch
4. Get: Failed to branch conversation: No conversation to branch

Expected behavior

/branch should fork the current conversation into a new session with the existing context preserved.

Actual behavior

Always fails with the error above regardless of session type or conversation length.

Environment

• Claude Code CLI (background job session)
• macOS Darwin 25.4.0
• Model: claude-opus-4-6 (1M context)

Notes

This was encountered during a long multi-hour background session with extensive tool use and conversation history. The conversation clearly exists (hundreds of turns), so the error message is incorrect.