caveman

why many token when few do trick

Caveman make your AI agent say less and read less. Code stay exact. Brain still big.

Cited by Adobe Research · A/B tested by JetBrains · Remade for Elasticsearch on Elasticsearch Labs #1 on Hacker News · #1 on GitHub Trending · "No way this actually works." ThePrimeagen

Install · Six rocks · Proof · Say less · Read less · Auto · Blocks · Commands · Caveman Cloud

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The reason your React component is re-rendering is likely because you're creating a new object reference on each render cycle. When you pass an inline object as a prop, React's shallow comparison sees it as a different object every time, which triggers a re-render. I'd recommend using useMemo to memoize the object.

New object ref each render, so React re-renders. Wrap the prop in useMemo.

Same fix. 63 token become 20. Brain still big.

Pick your club:

Skill	Same answer	Tokens
/caveman	New object ref each render, so React re-renders. Wrap the prop in useMemo.	20
/ultracave	Inline object prop, new ref, re-render. useMemo.	14
/megacave	新參照致重繪。useMemo。	13

Token counts: tiktoken o200k.

Install

npx @caveman-ai/cli@latest

One command. Mac, Linux, Windows. Caveman find your agents and your logins, show what it change. Press Enter. Done. Needs Node.js 22.13+.

After that, plain claude stays caveman'd. So do Codex, Gemini CLI, OpenCode, and 30+ more. It runs on your machine, with your keys and your Claude Pro/Max login. One rock. That it.

Had caveman before 4.0? Say @latest, or the old copy on your machine wins. Already set up? caveman setup opens the screen again. Only want shorter answers? Get just the skill.

Six rocks, one install

New in 4.0: caveman is six parts. All on after install. Each has its own switch.

Rock	What it does	Measured
Say less	Agent answers short. Code stays exact	63 → 20 tokens, same fix
Read less	Logs, JSON, CSV, test output shrink before the model reads them	33.2% fewer input tokens per session
Auto · new	Picks the model and the effort for each ask	54% cheaper than Opus at xhigh, same score
Blocks · new	Code mode: agent keeps the scripts it writes and runs them again	397 → 76 tokens for one test run
Waste fixes	Finds where your tokens go and fixes it. New: keeps the prompt cache warm while you pause	Not measured yet
Browse	Web pages come back compressed	129.8× smaller page

caveman status shows what is on. caveman off browse turns one off. Only Auto needs an account, and it is free. 4.0.0 release notes

Proof

Outside labs first. Ours come with each rock below. Nothing rounded up. Red rows stay red.

Who	Setup	Result
Adobe Research, CAVEWOMAN paper (cites this repo)	Caveman-style output, eight models, five datasets	Cost cut 1.4 to 2.4× per model, up to 3×
Elastic, Elasticsearch Labs	Caveman mode remade for Elasticsearch, eight live MCP scenarios	63.6% fewer response tokens. "Zero information loss."
JetBrains	86 real coding tasks, paired A/B	No measurable quality loss (p = 0.82). 8.5% fewer output tokens

Two findings shaped caveman. Adobe: cavemanning your prompt makes answers worse, so caveman never touches your prompt. JetBrains: agent sessions are mostly code and tool calls, which the voice leaves alone. So caveman grew rocks that shrink what the agent reads and what it runs on.

Say less: the caveman voice

A voice, not broken grammar. Every reply follows the same structure.

Rule	What it means
Answer first	[thing] [action] [reason]. [next step]. No greeting, no "let me", no recap
One idea per sentence	Built on ASD-STE100, the controlled English of aircraft maintenance manuals: 20 words max, active voice, one term per thing
Meaning never dropped	Articles can go. not, never, no, only never go. Numbers and units stay exact
Payload verbatim	Code, commands, paths, and error messages untouched, character for character
No theater	No "me think". No chatter between tool calls. If caveman phrasing isn't shorter, plain wins
Knows when to stop	Security warnings, irreversible actions, and confused users get full sentences. Then grunt resumes
Your prompts stay yours	Never rewritten. Research say that backfire

Ten dev questions on claude-opus-5-5:

Instruction	Output tokens
None	6,983
Answer concisely.	4,334
/caveman	4,119
/ultracave	2,693

"Be concise" is the real baseline; new models already know it. On top of it, /caveman cuts 3% more at the median and /ultracave 35% more. Measured on the 3.1.0 rules, not yet re-run. The rules cost about 1,160 tokens of input, and if you pay per request (GitHub Copilot), shorter answers save nothing. Harness · Every case where caveman loses

Only want this rock? The skill alone, no proxy:

npx skills add JuliusBrussee/caveman -g

Type /caveman ($caveman in Codex) if it doesn't start on its own. Say stop caveman to go back.

Other ways in: Claude app and phone, Claude Code plugin, Gemini, every agent at once, Windows, uninstall

Claude on the web, the phone app, or Cowork? No terminal. Add caveman to your Claude account once, in Customize > Plugins: steps. Not tested end to end yet.

# Claude Code plugin, auto-starts every interactive session, subagents too
claude plugin marketplace add JuliusBrussee/caveman && claude plugin install caveman@caveman

# Gemini CLI
gemini extensions install https://github.com/JuliusBrussee/caveman

# Every agent on your machine at once, plus the Claude Code statusline badge (Node.js 22.13+)
curl -fsSL https://raw.githubusercontent.com/JuliusBrussee/caveman/v4.1.0/install.sh | bash

Already inside Claude Code? Same rock, slash form. Type these where you talk to Claude:

/plugin marketplace add JuliusBrussee/caveman
/plugin install caveman@caveman

Windows, PowerShell 5.1+:

irm https://raw.githubusercontent.com/JuliusBrussee/caveman/v4.1.0/install.ps1 | iex

On npm 12 or newer, new npm block git install. One-liners above handle it themselves from v3.2.0 on. Old one-liner pinned to v3.1.0 or older still fail there: use one above, or this: npx --allow-git=root -y github:JuliusBrussee/caveman#v4.1.0

Changed your mind: npx -y github:JuliusBrussee/caveman -- --uninstall (on npm 12+, add --allow-git=root too)

Only grabbed the skill? npx skills remove JuliusBrussee/caveman -g take it back out.

Install broke? Open your agent in this repo and say "Read CLAUDE.md and INSTALL.md, install caveman for me." Agent fix own brain.

Read less: 33.2% fewer input tokens

The voice shrinks what the agent says. This shrinks what it reads. Same answers: 18 of 18 right.

File type	The file, through caveman	File saved	Whole Claude Code session, 3 runs	Session saved
CSV	28,041 → 314	98.9%	165,823 → 74,484	55.1%
Logs	22,810 → 348	98.5%	148,807 → 74,068	50.2%
YAML	20,447 → 178	99.1%	132,124 → 71,027	46.2%
Test output	18,806 → 203	98.9%	150,377 → 108,514	27.8%
JSON	18,837 → 281	98.5%	147,975 → 108,939	26.4%
HTML	21,670 → 21,670	none yet	140,687 → 154,641	9.9% worse
All six	130,611 → 22,994	82.4%	885,793 → 591,673	33.2%

The file is each test file through today's compressor alone. The session is the whole agent run, which also carries the system prompt and tools, so it moves less. Honest part: the session run is from August 2026 on an older engine, HTML has no compressor yet so it lost, and each test file hides one record in 61 to 72 KB of noise. Yours will vary. Headroom on the same suite: 15 of 18 right, 6.7% fewer tokens. Method

Every original stays on your disk. The agent can pull it back any time.

Auto: 54% cheaper, same score

New model in your agent's picker. Pick Auto and caveman chooses the model and the effort for each ask. Hard ask, big brain. Easy ask, save rocks.

Setup	Tasks solved	Cost per try	Median time
Opus 5.5, xhigh effort, every ask	44.3%	$7.83	35.2 min
Auto, Claude models only	43.7%	$3.59	15.9 min
Auto, plus OpenAI and open models	42.9%	$3.47	16.7 min