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-proofgit 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-proof)<a href="https://agentmods.dev/skills/everyinc/compound-engineering-plugin/ce-proof"><img src="https://agentmods.dev/badge/skills/everyinc/compound-engineering-plugin/ce-proof/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-proof"><img src="https://agentmods.dev/badge/skills/everyinc/compound-engineering-plugin/ce-proof.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket warn
- Snyk warn
- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Tool Misuse · line 19 Tool parameters are crafted to achieve unintended or unsafe behavior. Parameter abuse can bypass intended safety checks (e.g. shell=True, --force, dangerous glob patterns).Fix: Validate all tool parameters against an allowlist. Reject dangerous parameter values (shell=True, --force, -rf /) and use safe defaults.
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 | $0.00051 | $0.01779 |
| Opus 5.5 | $0.00020 | $0.00712 |
| Sonnet 5.5 | $0.00010 | $0.00356 |
| Haiku 4.5 | $0.00005 | $0.00178 |
Grade A, and why
ce-proof scanned grade A with 1 finding 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
**Read `references/api.md` before the first Proof read or mutation, HTTP or MCP.** It defines the endpoints: `share/markdown`, the v3 document and edit endpoints, presence, title, and `DELETE /api/documents/<slug>`. It a How it starts
The opening of the file, as written. The whole thing — 66 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Proof - Collaborative Markdown Editor
Proof is a collaborative document editor for humans and agents. It is reached through the hosted web API at https://www.proofeditor.ai, over HTTP from Bash.
Outcome: the user holds a working tokenized Proof link, or the doc carries the read, comment, suggestion, or edit they asked for.
Done: the operation is confirmed at its own level, and the user has the result plus a short summary. A create is confirmed by the tokenUrl it returned. A mutation is confirmed by ok: true; on a 202 or a partial: true response, confirm by re-reading v3/document. A pull is confirmed by the local file it wrote, and a read by the content it returned.
Read references/api.md before the first Proof read or mutation, HTTP or MCP. It defines the endpoints: share/markdown, the v3 document and edit endpoints, presence, title, and DELETE /api/documents/<slug>. It also carries the operation tables, the error and retry classes, and the curl permission hint for Claude Code.
Read references/workflows.md before reviewing a shared doc, before creating and sharing one, and before pulling a doc to a local file. Those flows have exact recipes there.
If typed proof_* MCP tools are already available in the harness (proof_share_markdown, proof_v3_document, proof_v3_edit, proof_presence, proof_document_title, proof_document_delete, proof_report_bug), prefer them. Otherwise use the HTTP recipes. In MCP mode the server injects by, X-Agent-Id, and presence identity. Pass the ?token= value from the Proof URL as shareToken for edits and presence on docs the signed-in user does not own.
Delete authority is unchanged in MCP mode. An unclaimed doc still needs its ownerSecret, and a claimed doc needs its owner's session. An editor accessToken passed as shareToken cannot delete.
Identity
Every write is attributed with both fields, and they do not vary. The machine ID is ai:compound-engineering, sent as by on every op and as the X-Agent-Id header. The display name is Compound Engineering, sent as name on POST /presence, set once per doc session so Proof binds it to that agent ID. A caller may pass a different identity pair when a distinct sub-agent should own the doc. Never improvise a variant such as ai:compound.
What ships with it
2 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 80cc09158db0
- 1mo ago First seen · 66 lines · 51 tokens per session scan A b6437e776562
ce-proof is a skill published in the GitHub repository EveryInc/compound-engineering-plugin (25,741 stars, last pushed today), licensed MIT. It adds 51 tokens to every session and 1,779 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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