README.md
August 16, 2026 · View on GitHub
why use many token when few do trick
Original skill made agents say less. Caveman 2 makes them read less too.
33.2% fewer provider-reported input tokens in a pinned Claude Code benchmark. benchmark_counterfactual
Keep your agent. Brain big. Context small.
See it · Install · Learn · Proxy · Pixel · Wrap · Docs · License
See it
| 🗣️ Normal agent — 69 tokens | |
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Same fix, fewer words. That was Caveman 1. Agent mouth got smaller. Appetite did not: tool schemas, files, logs, and history still cross the wire in full, every turn. Caveman 2 shrinks that too.
Install
Two products. Pick one or both.
Save input with Caveman Proxy, the new release. A local proxy that shrinks what your agent reads before every provider call, with byte-exact recovery. BSL-1.1 runtime, MIT CLI.
npm install -g @caveman-ai/cli && caveman setup --install
caveman claude # or codex · gemini · aider · opencode · hermes · openclaw
Save output with the skill, the original. Your agent answers in tight caveman-speak while code, commands, and errors stay byte-for-byte exact. MIT, works in 30+ agents.
npx skills add JuliusBrussee/caveman
Full installer, Windows, one agent only, uninstall
The full installer also wires the Claude Code hooks and statusline, finds every supported agent on your machine, and is safe to rerun (Node.js 18+):
curl -fsSL https://raw.githubusercontent.com/JuliusBrussee/caveman/v2.1.0/install.sh | bash
Windows (PowerShell 5.1+):
irm https://raw.githubusercontent.com/JuliusBrussee/caveman/v2.1.0/install.ps1 | iex
One agent only:
# Claude Code
claude plugin marketplace add JuliusBrussee/caveman && claude plugin install caveman@caveman
# Gemini CLI
gemini extensions install https://github.com/JuliusBrussee/caveman
# Codex, Cursor, Windsurf, Cline, and other skills-compatible agents
npx skills add JuliusBrussee/caveman --skill '*' -a codex --yes # replace codex with your agent profile
Full 30+ agent matrix, dry run, flags, verification, and uninstall: INSTALL.md.
Prefer building the proxy from source instead of signed binaries? scripts/install-local-cli.sh (macOS/Linux) or pwsh -File scripts/install-local-cli.ps1 (Windows); needs Go and pnpm.
Where your tokens go
You have months of agent history on disk. caveman learn reads it and scores your setup. Local, read-only, no account.
caveman learn # scan Claude Code + Codex history, open the report
The report shows your Cave Score, every token sink ranked by flow with a one-line fix behind each row, how deep each session ran into its context window, a replay of what the fixes would have cut from your past sessions, and a list-price illustration of what the ranked sinks cost over 30 days. Sink and cost numbers are inferred; the saved-so-far card is proxy-measured. None of it is a bill.
Every sink wears its class: safe fix (a bloated CLAUDE.md, a skill you never invoke), offload (context you re-paste every session, moved to caveman memory when recall measures cheaper), habit (numbers plus a soft suggestion, never an imperative), load-bearing (config you need, counted in the score and never touched).
caveman learn implement # hand the plan to Claude Code or Codex
The analyzer never edits your files. learn implement opens your own agent with the plan and the caveman-learn skill, which instructs it to propose each fix as a diff, apply only on your yes, re-measure, and revert anything that did not lower tokens per turn. Caveman never makes your agent dumber to make it cheaper.
Caveman Proxy
One command wraps your agent and routes provider traffic through a local proxy powered by Caveman Engine. In a pinned 54-run Claude Code benchmark it used 33.2% fewer provider-reported input tokens than direct Claude Code while passing all 18 exact-answer checks. Method, per-case results, and limits. benchmark_counterfactual
No code change, no Caveman backend: the proxy forwards each request to your chosen provider, and recovery copies stay on your disk. Claude Pro/Max OAuth credentials pass through to Anthropic as-is.
| Mode | What it does | Bytes the model sees |
|---|---|---|
default stack (caveman claude) | Structural compression routed per content type, plus JSON tool results re-encoded as TOON when measured smaller. | Changed, recoverable |
--off | Counts tokens and cost. Changes nothing. | Byte-identical |
--pixel | Dense text slabs rendered to PNG pages for vision models. | Changed, recoverable |
Three rules keep it safe:
- CCR first. Original bytes land in a content-addressed store on your disk before any lossy transform ships. The agent pulls them back with
caveman_retrieve. Parse problem, store failure, or larger result sends original bytes unchanged. - Visible declines. Every transform runs only when it measures smaller, and every decline states its reason.
- Labeled evidence. Local results say
inferred.verifiedrequires real traffic and eval gates; offline caveman never says it.
What the engine does to a payload — per-type compressors and targets
detect() types each payload, then routes it to a compressor that keeps what answers depend on:
| Detected type | Keeps | Target |
|---|---|---|
json | keys, structure, error/message subtrees; collapses repetitive arrays | 70–90% |
log | errors, stack traces, first/last lines; drops INFO and progress noise | 85–95% |
code | imports, signatures, types; elides function bodies, syntax stays valid | 40–70% |
diff | file/hunk headers and changed lines; elides repeated context | 60–80% |
search-result | top/bottom hits plus diagnostic/security hits | 80–95% |
text / HTML | headings, opening/closing context, important sections | 50–80% |
All targets inferred. The code compressor uses tree-sitter (Go, Python, JS/TS) under cgo, with a pure-Go fallback that handles Go only. contextwindow.Pack() additionally fits candidate context into a token budget by BM25 relevance, recency, and error signal, returned in original order so chronology survives.
The same engine powers a set of verbs:
caveman learn # scan your real agent history → score + ranked token sinks
caveman learn implement # fix the findings with your own agent, consent-gated per edit
caveman explore install # read-only FastContext subagent: finds code as path:line
caveman shrink -- pnpm test # compress noisy command output, byte-exact recoverable
caveman browse <url> # local Chrome over a compressed a11y tree
caveman mem remember|recall # durable memory; `mem recover <handle>` = original bytes
caveman trial -- claude # A/B a real session, then `trial report`
caveman toon encode|decode # the TOON re-encoder, standalone
caveman stats # what caveman actually did, by content type
The MCP server exposes five tools to any MCP host: caveman_compress, caveman_retrieve, caveman_stats, caveman_toon_encode, caveman_toon_decode.
On browse (needs Chrome): a focused query against a 200-row operations table costs 121 tokens, 129.8× smaller than the Playwright ARIA baseline of 15,704. On a tiny checkout form Caveman is honestly larger (67 → 111 tokens) because it also returns action UIDs and a recovery handle, and the Playwright baseline carries only ARIA text, which favors Playwright. Medians over five pinned Chrome runs, inferred. Full method: browse/BENCHMARK.md.
Pixel mode
The headline trick. Text is priced per token; images are not. A dense wall of text rendered to a PNG costs a fraction as vision input, so the proxy renders big request slabs (minified JSON tool catalogs, long-line logs, old history) into glyph-rendered PNG pages.
caveman wrap --pixel claude
Real render, bundled here: 8,622 chars → one 1568×232 PNG, est. 2,597 text → 534 image tokens, inferred.
On a genuinely dense request (a 63.7k-char minified JSON tool-catalog slab plus a 93k-char long-line log, model claude-fable-5):
55,413 est. text tokens → 11,402 est. image tokens · −79% · 7 PNG pages · inferred
Originals go to CCR first; the agent pulls real bytes back via caveman_retrieve.
Important
Pixel only pays on dense, long-line content. Sparse code with short lines is honestly not profitable: the PNG carries more overhead than the text it replaces, so the profitability gate declines it and the bytes pass through untouched.
Runs only for models with measured render legibility, claude-fable-5 and gpt-5.6 by default; override with pixel_models config / CAVE_PIXEL_MODELS. Pixel ports pxpipe (MIT); font attribution in the License.
Skills as images
Full circle: the engine now compresses the thing caveman started as. Every fat skill you install re-loads its whole prompt body on every invocation, and you pay that tax forever. caveman convert renders each installed SKILL.md body to PNG pages in place. Frontmatter stays text, so discovery and triggering work exactly as before; the model reads the body as an image.
caveman convert --dry-run # every installed skill, with the token math, no writes
caveman convert --agent claude # convert the profitable ones
caveman convert --revert # byte-identical restore from SKILL.orig.md
Measured on the caveman skill itself: 1,069 → 415 est. tokens, −61%, inferred. Convert only fires when pages beat the text; any failure leaves the skill byte-identical and names the gate that said no. New skills installed through caveman skills install auto-pixel by default (--no-pixel to opt out).
The skill
The original, and still the fastest way to feel caveman. MIT forever. Works in Claude Code, Codex, Gemini, Cursor, Windsurf, Cline, Copilot, and 30+ other agents.
Type /caveman if your agent does not activate it automatically. Switch with /caveman lite|full|ultra|wenyan-lite|wenyan-full|wenyan-ultra; turn it off with /caveman off or normal mode.
One install also brings the small tools:
| Tool / command | What you get |
|---|---|
/caveman [lite|full|ultra|wenyan-lite|wenyan-full|wenyan-ultra|off] | Shorter replies at the intensity you choose. |
cavecrew-investigator, cavecrew-builder, cavecrew-reviewer | Compressed subagent presets for locating, editing, and reviewing code. |
/caveman-commit | Terse Conventional Commit messages. |
/caveman-review | One-line, actionable review findings. |
/caveman-compress <file> | Smaller Markdown memory files, with the original backed up. |
/caveman-stats | Local session token usage and estimated savings in Claude Code. |
| Task | Normal | Caveman | Saved |
|---|---|---|---|
| Explain React re-render bug | 1180 | 159 | 87% |
| Fix auth middleware token expiry | 704 | 121 | 83% |
| Set up PostgreSQL connection pool | 2347 | 380 | 84% |
| Explain git rebase vs merge | 702 | 292 | 58% |
| Refactor callback to async/await | 387 | 301 | 22% |
| Architecture: microservices vs monolith | 446 | 310 | 30% |
| Review PR for security issues | 678 | 398 | 41% |
| Docker multi-stage build | 1042 | 290 | 72% |
| Debug PostgreSQL race condition | 1200 | 232 | 81% |
| Implement React error boundary | 3454 | 456 | 87% |
| Average | 1214 | 294 | 65% |
Important
Honest number warning. The skill only shrinks output tokens. Input and reasoning tokens are untouched, and the skill itself adds ~1–1.5k input tokens per turn. Whole-session savings run smaller than the output number, and on already-terse workloads they can go net-negative. The real win is readability and speed; cost savings are the bonus. When caveman wins, when it loses, and how to measure it yourself: docs/HONEST-NUMBERS.md.
Wrap any agent
caveman <agent> wraps seven agents natively. Adding one is a data change, a single JSON profile in agents/profiles/, no code.
| Agent | Vendor | How it's wrapped |
|---|---|---|
| Claude Code | Anthropic | env vars |
| OpenAI Codex CLI | OpenAI | env vars (API key) · ephemeral CODEX_HOME (ChatGPT login) |
| Gemini CLI | env vars | |
| Aider | OpenAI/Anthropic | env vars |
| opencode | sst | inline config via env, your opencode.json untouched |
| Hermes Agent | Nous Research | --provider custom + env |
| OpenClaw | OpenClaw | ephemeral merged config, your config read-only |
Wrap never edits your own config files. Real sessions round-trip in record mode, tested against Hermes v0.18.0 and OpenClaw 2026.6.11.
Not on the list? Point any provider SDK or framework (Vercel AI SDK, LangChain, LiteLLM, OpenAI Agents, CrewAI, PydanticAI) at the local proxy with a baseURL swap: integrations/recipes/.
Note
Subscription logins work. Claude Pro/Max OAuth tokens pass through the proxy as-is, so a wrapped Claude Code on a subscription gets full compression and metering. Codex ChatGPT logins wrap too: an ephemeral CODEX_HOME (your ~/.codex is never written) points a custom provider at the proxy's /chatgpt passthrough, OAuth headers ride through byte-exact. That path is metering-only for now: honest token counts, dollars stay zero because subscription traffic has no per-token price. One exception: a provider pinned inside another agent (e.g. openai-codex inside OpenClaw) is left on its own path with a printed note instead of a broken login.
The default wrap hands the agent the whole loadout: the five caveman MCP tools, the browse MCP server when Chrome resolves, command-output shrink through a real hook on Claude, opencode, Gemini, Hermes, and OpenClaw (Codex gets an honest soft note, its runtime rejects the rewrite: openai/codex#18491), and skills-as-images on new skill installs. Turn pieces off in ~/.caveman-cloud/config.json.
The whole cave
One idea. Agent do more with less.
| Repo | What it shrinks | Status |
|---|---|---|
| caveman (you here) | What the agent says, and now what it reads | live |
| caveman-browse | What the agent sees in the browser | live |
| caveman-agent-sdk | What your production agent loads, calls, and spends | own repo · in dev |
| cavegemma | The compression baked into weights (Gemma fine-tune) | labs |
| caveman-code | The whole agent, end to end | frozen |
| cavemem | What the agent remembers, across sessions | frozen |
| cavekit | The build loop, spec-driven | frozen |
Frozen repos still install and work; they are no longer in active development. Their best ideas live on here: cavemem's compressed-memory core ships inside caveman, and caveman-code's lesson became caveman wrap. Make the agent you already use cheaper instead of replacing it.
From inferred to verified
Caveman make token small. Caveman Cloud make it provable.
Local runtime results report inferred; controlled benchmark results report benchmark_counterfactual. Neither is a provider invoice. Caveman Cloud is where qualifying live evidence can become verified: baseline in record mode, changes behind eval gates, rollback on quality loss, savings from real traffic with signed receipts. Offline caveman never says verified.
Join the waitlist → caveman.so
Privacy
Your agent still talks to the provider you chose. Local compression needs no Caveman account. The caveman CLI sends anonymous usage stats by default: which commands ran, plus token counts through and cut. Never your prompts, code, or file paths. It says so on first run, and one command turns it off forever: caveman telemetry off (or DO_NOT_TRACK=1). Skill and hooks run locally; the proxy forwards provider traffic; CCR stays in a SQLite file on your disk. Exact network, telemetry, and storage boundaries: SECURITY.md.
License
Split license. Skill and adoption surfaces are MIT. Engine-linked runtime is BSL-1.1 source-available, not OSI Open Source before Change Date.
MIT — the skill, Agent SDK and initializer, the CLI, both client SDKs (TS + Python), kit, evals/graders, contracts, provider catalog, the extension shell, and the thin cavemem clients.
BSL-1.1 — Engine, Proxy, Cache Engine, rewriter, Browse, MCP server, shrink, cavemem Go core, and shared Go platform. New Engine-linked runtime modules default to BSL-1.1. Source-available: read it, fork it, self-host it for your own first-party traffic free, production included. Every BSL version auto-converts to Apache-2.0 on the earlier of 2030-06-21 or four years after that version first ships. Third-party hosted, managed, or embedded service use needs commercial license. BSL text and per-directory map ship with source.
engine/pixel embeds pxpipe (MIT) plus glyph atlases derived from Spleen 5×8 (BSD-2-Clause) and GNU Unifont (dual OFL-1.1 / GPLv2-with-font-exception); its NOTICE travels with that source.
"Caveman" and the rock logo are trademarks of Julius Brussee. "Powered by Caveman" is fine when true.
Sponsors
Caveman free forever. Sponsors keep the rock sharp.
Atlas Cloud — full-modal AI inference platform, one API.
Want your rock here? → Sponsor caveman
Star this repo
Caveman save you token, save you money. Star cost zero. Fair trade. ⭐
Docs: Technical manual · Install matrix · Honest numbers · License · Contributing · Maintainer guide · Issues
MIT skill · BSL-1.1 engine — few token. no lie.
