[Bug] /rewind creates in-file branches not visible in resume picker, contrary to documentation

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?

The documentation states that "Forked sessions (created with /rewind or --fork-session) are grouped together under their root session" with →/← keys to expand/collapse. However, /rewind creates in-file branches (via parentUuid relationships within a single session file), NOT separate session files. These in-file branches are not visible in the resume picker, and the documented expand/collapse functionality does not work.

From Common Workflows documentation:

"Forked sessions (created with /rewind or --fork-session) are grouped together under their root session" "Use arrow keys (→/←) to expand or collapse grouped sessions"

Actual behavior:

• /rewind creates in-file branches via parentUuid tree within a SINGLE session file
• No separate session files are created for branches
• Resume picker shows flat list - no grouping, no expand/collapse
• Arrow keys (→/←) have no effect
• 483 branch points in my session file are completely invisible in UI

What Should Happen?

Based on documentation:

• /rewind should create forked sessions visible in the resume picker
• Forked sessions should be grouped under their root session
• Arrow keys (→/←) should expand/collapse to show branches
• Users should be able to navigate and resume from different branch points

Error Messages/Logs

No error messages - the feature silently doesn't work. The data exists but isn't surfaced:


# Analyzing session file d6ea9071-7c07-4cc9-9938-0b406b452f45.jsonl
file_size = 57.5 MB
total_entries = 29,344
branch_points = 483 (entries with multiple children via parentUuid)
unique_conversation_endpoints = 330 (leafUuid in summaries)
separate_fork_session_files_created = 0

# sessions-index.json for this session
{
  "sessionId": "d6ea9071-...",
  "isSidechain": false,
  "messageCount": 9733
  // MISSING: parentSessionId, rootSessionId, forkedFrom, forkDepth
}

Steps to Reproduce

1. Start a new Claude Code session
2. Have a conversation with multiple exchanges
3. Use /rewind or Esc+Esc to go back to an earlier point
4. Continue the conversation (this should create a branch)
5. Repeat steps 3-4 multiple times to create multiple branches
6. Run claude --resume to open the session picker
7. Observe: Flat list with no grouped/hierarchical view of branches
8. Press → or ←: No expand/collapse behavior occurs

My test case:

• Session spanning Dec 8, 2025 - Jan 19, 2026 (42 days)
• 483 branch points created via interruptions/rewind
• 330 unique conversation endpoints (via leafUuid)
• All branches stored in-file via parentUuid, none as separate session files

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.4

Claude Code Version

2.1.12

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_