Branch Session

Overview

Create a "branch" of the current conversation by spawning a new tmux session with a forked session. Uses platform-specific fork commands to create a true fork with a new session ID while preserving conversation state. The original session remains untouched.

Platform Detection

This skill automatically detects your environment:

• •Claude Code: Uses ~/.claude/projects/ session files
• •Codex: Uses ~/.codex/sessions/ and the codex fork command

Workflow

Step 1: Get Current Session ID

Claude Code:

1. •Get current working directory
2. •Convert to Claude project path format:
   bash

   # /home/user/projects/myapp -> -home-user-projects-myapp
   PROJECT_PATH=$(echo "$PWD" | sed 's|/|-|g' | sed 's|^-||')
   

3. •Find most recently modified session file:
   bash

   SESSION_FILE=$(ls -t ~/.claude/projects/$PROJECT_PATH/*.jsonl 2>/dev/null | head -1)
   SESSION_ID=$(basename "$SESSION_FILE" .jsonl)
   

Codex:

1. •Find session IDs from the sessions folder:
   bash

   ls -t ~/.codex/sessions/*.jsonl | head -5
   

2. •Or use codex fork --last to fork the most recent session directly

Step 2: Generate Branch Name

Create a unique session name:

SHORT_ID=$(echo "$SESSION_ID" | cut -c1-5)
TIMESTAMP=$(date +%H%M)
BRANCH_NAME="branch-${SHORT_ID}-${TIMESTAMP}"

Step 3: Execute Branch

Claude Code:

~/.claude/skills/branch-session/scripts/branch_session.sh "$PWD" "$SESSION_ID" "$BRANCH_NAME"

Codex:

# Fork most recent session (simplest)
codex fork --last

# Or fork a specific session
codex fork <SESSION_ID>

Step 4: Confirm

Report to user:

Branched session: branch-a1b2c-1508
Directory: /home/user/projects/myapp
Resuming: a1b2c3d4-da03-4ece-8625-582be89f6dff

To attach: tmux attach -t branch-a1b2c-1508

Quick Reference

Invocation: /branch

Session naming: branch-<first-5-chars-of-id>-<HHMM>

Use cases:

• •Explore alternative implementation approaches
• •Test something risky without losing progress
• •Split work into parallel tracks

Setup

Make the scripts executable (one-time):

chmod +x ~/.claude/skills/branch-session/scripts/*.sh

Requirements

• •tmux installed and running
• •Claude Code: claude CLI available
• •Codex: codex CLI available
• •Active session to branch from

Resources

scripts/

• •branch_session.sh - Creates tmux session and resumes Claude Code