Caveman mode and session handoff are not part of Claude Code's default install. They're community-built skills you drop into ~/.claude/skills/ manually. The whole process takes under two minutes per skill.
How Claude Code Skills Work
Claude Code supports a local skills directory at ~/.claude/skills/. Any subdirectory you create there with a SKILL.md file becomes a skill Claude can invoke. No marketplace, no plugin command needed. You create the folder, drop in the file, and the skill is available in every future session.
The structure is always the same:
~/.claude/skills/
├── caveman/
│ └── SKILL.md
└── session-handoff/
└── SKILL.md
That's all there is to it. Claude reads the SKILL.md at session start and knows how to respond to the trigger phrase.
Install Caveman Mode
Caveman is an open-source skill by Julius Brussee with a dedicated installer that auto-detects Claude Code on your machine. Requires Node 18 or higher.
Mac / Linux / WSL / Git Bash:
curl -fsSL https://raw.githubusercontent.com/JuliusBrussee/caveman/main/install.sh | bash
Windows (PowerShell 5.1+):
irm https://raw.githubusercontent.com/JuliusBrussee/caveman/main/install.ps1 | iex
Both installers auto-detect Claude Code, wire the plugin, add hooks, and set up the statusline badge. Takes about 30 seconds. Safe to re-run.
Verify it worked: open any Claude Code session and type /caveman. Claude's next response should be noticeably shorter and more direct. Type stop caveman to return to normal.
If /caveman does nothing, restart Claude Code. Skills load at session start, so a session already open when you ran the installer won't have it yet.
Install Session Handoff
Session handoff is maintained by Leonardo Couy as part of the agent-toolkit collection.
Mac / Linux / WSL / Git Bash:
mkdir -p ~/.claude/skills/session-handoff && \ curl -sL https://raw.githubusercontent.com/softaworks/agent-toolkit/main/skills/session-handoff/SKILL.md \ -o ~/.claude/skills/session-handoff/SKILL.md
Windows (PowerShell 5.1+):
New-Item -ItemType Directory -Force -Path "$HOME\.claude\skills\session-handoff" Invoke-WebRequest -Uri "https://raw.githubusercontent.com/softaworks/agent-toolkit/main/skills/session-handoff/SKILL.md" -OutFile "$HOME\.claude\skills\session-handoff\SKILL.md"
Or install via Claude Code plugin marketplace (any platform):
/plugin marketplace add softaworks/agent-toolkit /plugin install session-handoff@agent-toolkit
Once installed, /session-handoff in any Claude Code session will trigger the skill. It generates a structured handoff document you load at the start of your next session.
The repo also includes optional Python scripts (create_handoff.py, check_staleness.py, validate_handoff.py) that auto-fill git metadata and run quality checks. The SKILL.md alone is all you need to get started — the scripts are an optional enhancement.
What You Now Have
Once both are installed, your session workflow becomes:
- Open Claude Code
- Type
/caveman— compresses all responses for the session (~75% fewer output tokens) - Load a handoff document if continuing from a previous session
- Work
- Type
/session-handoffbefore closing — generates context for your next session
The two skills cover both sides of the cost equation: caveman cuts output tokens within a session, session handoff cuts accumulated input context between sessions. Full breakdown of how to use them together.
Both skills are part of the broader Claude Code toolkit covered in 11 Claude AI Things I Wish I Knew Earlier.
Frequently Asked Questions
Do these work on Windows?
Yes. For caveman, use the PowerShell one-liner: irm https://raw.githubusercontent.com/JuliusBrussee/caveman/main/install.ps1 | iex. For session handoff, use the PowerShell commands in the install section above — they write to $HOME\.claude\skills\session-handoff\, which is where Claude Code looks on Windows.
Do the skills apply to all projects or just one?
User-level. Skills in ~/.claude/skills/ are available in every Claude Code session across all projects. You choose when to activate each one by typing the trigger command.
Can I have both caveman and compress installed?
Yes. caveman:compress is a companion skill (also from JuliusBrussee) that compresses .md files like your CLAUDE.md into caveman-speak to reduce input tokens. Install it the same way from the same GitHub repository.
Will caveman change Claude's behavior automatically?
No. Caveman activates only when you type /caveman. Nothing changes until you invoke it. Session handoff is also fully manual — it only runs when you ask for it.