Compound Engineering is a plugin that organizes software work into brainstorming, planning, implementation, review, and recording lessons for future changes. It is used with AI coding agents including Claude Code, Cursor, and Codex, and the catalogue entries provide parts of its agent, skill, command, and hook workflow.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add EveryInc/compound-engineering-plugin --skill ce-prototypegit clone --depth 1 https://github.com/EveryInc/compound-engineering-pluginWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/everyinc/compound-engineering-plugin/ce-prototype)<a href="https://agentmods.dev/skills/everyinc/compound-engineering-plugin/ce-prototype"><img src="https://agentmods.dev/badge/skills/everyinc/compound-engineering-plugin/ce-prototype/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/everyinc/compound-engineering-plugin/ce-prototype"><img src="https://agentmods.dev/badge/skills/everyinc/compound-engineering-plugin/ce-prototype.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
- Socket pass
- Snyk warn
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00069 | $0.01649 |
| Opus 5.5 | $0.00028 | $0.00660 |
| Sonnet 5.5 | $0.00014 | $0.00330 |
| Haiku 4.5 | $0.00007 | $0.00165 |
Grade A, and why
ce-prototype scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 60 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Prototype
Build a throwaway prototype at the fidelity that can answer this question, before committing an approach later work will treat as given. Then apply the decisions or hand off.
Do not fake the dimension being tested. Modality, fidelity, and medium all follow from that one rule. A question about how a flow or state model behaves is settled by driving it, so a screen that only looks like the product does not answer it. A question about how a layout or a mark reads is settled by seeing it at real finish, so a thin sketch does not answer it either. The user's own perception settles the question, never your judgment of the artifact.
Result: the user decided how the product should work or feel against a prototype that did not fake what they were deciding.
Next consumer: an existing markdown Product Contract, or ce-brainstorm / ce-plan with this session as the seed.
Done: the user settled the questions that needed an artifact, or they apply and continue into brainstorm or plan. Their choice is the settlement, not a direction you inferred.
Not: a decision a cheap sketch settles, polish, or shipping the prototype as a final product.
If there is no person to experience the prototype — mode:pipeline, a headless run, or a calling skill that reports no human is present — stop. Do not start a preview or invent how it should feel. Return that this skill needs a human. A calling skill that has a human present (an interactive lfg run, for example) is an ordinary attended run.
User-runnable invocation rendering. The attended re-run in that refusal and the next-skill recommendation when the user applies print invocation syntax. Default to /ce-prototype, /ce-brainstorm, and /ce-plan; use $ce-prototype, $ce-brainstorm, and $ce-plan only on Codex or a host that documents dollar-prefixed skill invocation. Render only the invocation as inline code; output one form only.
Scope the question
Read references/scoping.md before you ask the user anything or touch the repo. That read is not optional. It defines how the question arrives and the scoped repo read of what the question touches — do not scan the tree. It also defines narrow vs wide, sizing, the go-ahead message, and how the remaining questions change after each decision. Do not build until authorized. A request that already is to prototype a named thing is that authorization after scoping.
What ships with it
9 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago Changed de1b34ef13df
- 1mo ago Changed c8cc567bf03b
- 1mo ago Changed 5b8b4e867cf7
- 1mo ago Changed · +2 lines ea32d6ffc498
- 1mo ago First seen · 58 lines · 69 tokens per session scan A 33f4f842ea7b
ce-prototype is a skill published in the GitHub repository EveryInc/compound-engineering-plugin (25,727 stars, last pushed today), licensed MIT. It adds 69 tokens to every session and 1,649 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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