caveman
Caveman encoding for SPEC.md and spec-adjacent writes. Loaded by /spec, /build, /check. Cuts tokens 75% vs prose while staying precise. Triggers on any write to SPEC.md or when user says "caveman", "compress this", "be brief".
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/juliusbrussee/cavekit --skill caveman- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads caveman automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
caveman — spec encoding
Applies to SPEC.md writes, spec-referencing prose, backprop entries. Does NOT apply to code, error strings, commit messages, PR descriptions.
GRAMMAR
- Drop articles (a, an, the).
- Drop filler (just, really, basically, simply, actually).
- Drop aux verbs where fragment works (is, are, was, were, being).
- Drop pleasantries.
- No hedging (skip "might", "perhaps", "could be worth").
- Fragments fine.
- Short synonyms: fix > implement, big > extensive, run > execute.
SYMBOLS
Prefer over words:
→ leads to / becomes / on <x>
∴ therefore / fix
∀ for all / every
∃ exists / some
! must / required
? may / optional / unknown
⊥ never / forbidden / nil
≠ not equal
∈ in
∉ not in
≤ at most
≥ at least
& and
| or
§ section reference
PRESERVE VERBATIM
Never compress:
- Code blocks, snippets, one-liners with backticks.
- Paths:
src/auth/mw.go. - URLs.
- Identifiers: function names, variable names, env vars.
- Numbers and versions.
- Error message strings.
- SQL, regex, JSON, YAML.
- Quoted strings.
SHAPES
Invariant:
V<n>: <subject> <relation> <condition>
V1: ∀ req → auth check before handler
V2: token expiry ≤ current_time → reject
Bug row (pipe table under §B):
id|date|cause|fix
B1|2026-04-20|token `<` not `≤`|V2
Task row (pipe table under §T):
id|status|task|cites
T3|x|add auth mw|V1,I.api
Status: x done, ~ wip, . todo. Escape literal | as \|.
Interface:
<kind>: <name> → <shape>
api: POST /x → 200 {id:string}
cmd: `foo bar <arg>` → stdout JSON
env: FOO_KEY ! set
EXAMPLES
Bad:
The system should ensure that every incoming request is properly authenticated before being forwarded to its corresponding handler function.
Good:
V1: ∀ req → auth check before handler
Bad:
We discovered that the token expiration check in the middleware was using a strict less-than comparison operator, which meant tokens were being rejected at the exact moment of their expiry.
Good:
B1: token
<not≤→ reject @ expiry boundary.
Bad:
The POST endpoint at /x accepts a JSON body and returns a 200 response with an object containing the created id.
Good:
api: POST /x → 200 {id}
BOUNDARIES
- User asks for prose explanation → switch to normal English.
- Spec documents for external review (RFC, pitch) → normal English.
- Commit message → normal English (git readers expect it).
- Diff comment in code → normal English.
WHEN UNSURE
If cutting a word loses a fact, keep it. Caveman is compression, not amputation.
FAQ
What does the caveman skill do?
Caveman encoding for SPEC.md and spec-adjacent writes. Loaded by /spec, /build, /check. Cuts tokens 75% vs prose while staying precise. Triggers on any write to SPEC.md or when user says "caveman", "compress this", "be brief".
How do I install caveman?
Run npx skills add https://github.com/juliusbrussee/cavekit --skill caveman in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/caveman/ (personal) or .claude/skills/caveman/ (project).
Which AI agents can use caveman?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is caveman safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains caveman?
It is published by juliusbrussee in juliusbrussee/cavekit. It has 2,803 recorded installs.
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Plan-then-execute implementation against SPEC.md. Native single-thread loop, no sub-agents. On test or build failure, auto-invokes the backprop skill before retrying — a failed verification always considers whether a new §V invariant would prevent recurrence. Triggers when the user asks to build, implement, execute the spec, or tackle a specific §T task (build §T.3, build --next, implement next task, run the build). Expects SPEC.md to exist; if not, defers to the spec skill.
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