euthyna

euthyna

εὔθυνα — in classical Athens, the audit every outgoing official had to submit. You did not get to simply walk away from office. You handed over your accounts and they were examined. Pass, and you left with your standing intact. Fail, and you faced trial.

euthyna is a code security audit framework for AI coding agents. It is not another scanner. It does two things: it produces the facts an agent cannot compute by reading code, and it forces every security claim the agent makes through gates before it counts as a finding.

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📖 The problem, in plain words

When an AI coding agent touches security, it fails in two specific ways:

1. It reports things that are not real. Code that looks dangerous gets called a vulnerability, without tracing the data. In validation runs on real codebases — a JavaScript one and a Python one — the pattern-matched "vulnerabilities" were mostly false: 5 out of 5 refuted at the gates on the first run; 2 out of 3 refuted, the third unresolved (INCONCLUSIVE, supply-chain-dependent) on the second. See the case studies (Python/crewAI, JavaScript/axe-core).
2. Its reassurances cannot be checked. "I'm done." "The tests cover this." "It's safe now." These are assertions. You cannot tell a done-claim from a done-deal.

Neither is fixed by telling the agent to be more careful. euthyna changes the handshake between you and the agent:

The agent saying "I'm done" does not count. The accounts get handed over, and the gates decide.

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⚖️ The two things it does

1. It measures what a model cannot

Three fact producers — a zero-dependency Node CLI:

• history — for every line a change deletes, it attributes the line to a commit and classifies that commit from its message, its own diff, and the deleted line's content (a deleted if (!authorized) is flagged even under a "tweaks" subject). By default the attribution is blame's "last touched"; --origins digs for the commit that first introduced the content with git log -S. If the deleted code came from a security fix, that is flagged. This is git archaeology no model can do from reading a diff.
• coverage — was this symbol ever actually invoked by a test? It has exactly two answers: never invoked (established), or entered but that proves nothing about any specific call site (unknown). It never reports "executed" — V8 coverage marks unreachable code as covered, and "line covered → call ran" is wrong in exactly the direction an audit cannot afford. The reasoning is in docs/fact-contract.md §6.2.
• deps — what version is a dependency actually pinned to? It reads the lockfile (package-lock.json / Cargo.lock / go.mod) and reports the resolved versions, or that a dependency is absent from the tree entirely. This is the fact that resolves supply-chain claims ("the app uses a vulnerable version of X"): the version-to-CVE mapping is left to the adjudication layer, exactly as the fact contract requires. See docs/fact-contract.md §6.3.

2. It gates what the agent claims

The skill is the audit discipline itself, as loadable Markdown. Every security claim must pass six gates — reachability, trust boundary, real impact, and their counterparts. A claim that cannot produce evidence is downgraded to an observation, not reported as a finding. "I'm done" becomes a package: claims, evidence, and the commands that reproduce both.

The gates are not only prose. euthyna gate <report> reads an adjudication report and mechanically checks every finding against its verdict — evidence down to path:L123, a reproduce command, an impact statement, consistent gate statuses — and downgrades whatever does not measure up. --verify re-runs the reproduce commands: git commands by default, interpreter commands (node/npm/python) only with the explicit --allow-exec, because an interpreter command from a report is arbitrary code and the flag is the caller vouching for that report.

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🖥️ Which tools it works in, and how to install

Prerequisite for everything: Node >= 20 and git. There is nothing else to install — the project is deliberately zero-dependency.

Host	The skill (audit discipline)	The CLI (fact producers)
DSH	dsh plugin --profile web add euthyna — the npm package mounts its own skill; or copy .agents/skills/euthyna/ into ~/.agents/skills/ (user-wide) or <project>/.agents/skills/. Markdown hot-reloads; no restart needed.	npm install -g euthyna — runs in any terminal
Claude Code	/plugin marketplace add slow-stack/euthyna then /plugin install euthyna@euthyna, or copy .agents/skills/euthyna/ into ~/.claude/skills/	Same
Codex	The same Markdown layer works; packaging goes through Codex's plugin/marketplace format	Same
Hermes	Copy the same folder into ~/.hermes/skills/ under a category folder, or install from a repo with hermes skills install — and for the slash command, install the repo as a plugin (see below)	Same
OpenCode	Copy the same folder into ~/.agents/skills/ or ~/.config/opencode/skills/ (OpenCode loads both; unknown frontmatter fields are ignored)	Same
Any terminal	—	npm install -g euthyna, then euthyna …

The skill ships in two languages. The directory above is the Chinese original (euthyna); an English mirror lives at .agents/skills/euthyna-en/ (skill name euthyna-en) — install that one for an English-speaking agent, or translate the folder yourself. Both define the same discipline, and euthyna gate accepts report markers in either language.

Two honest notes:

• The skill is the instructions; the CLI is the measurement. The skill directory does not contain the CLI. Install the CLI from npm (npm install -g euthyna) or keep this repository checked out; on a host without the CLI, the skill requires the unmeasurable criteria to be recorded as not evaluated rather than guessed at — that fallback is the design, not a gap.
• The CLI speaks Chinese by default, English on request. Output is Chinese unless you pass --lang en (any command) or set EUTHYNA_LANG=en; the default never changes for existing users. The skill text and the CLI's reports exist in both languages — the English reader should expect Chinese only from a run that did not ask for English.

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🎯 First use

euthyna is user-invoked, not auto-triggering. The skill declares disable-model-invocation: true, so the model will not load it on its own — you have to ask for the audit explicitly. That is also how you tell it apart from other security skills you may have installed: if you did not name it, it did not run.

Triggering the audit

Say it plainly in conversation:

「用 euthyna 审计一下 D:\some-project，审完再交付」

The agent then loads the skill and runs the audit discipline: it produces the deterministic facts (history / coverage / deps) first, walks every suspect through the six gates, and writes a report file instead of only replying in chat.

Slash commands

Host	Command	Setup
Claude Code	/euthyna <path>	copy .claude/commands/euthyna.md from the package into ~/.claude/commands/ (user-wide) or .claude/commands/ (project)
Codex	—	Codex's custom-prompt slash commands (~/.codex/prompts/) are deprecated upstream; the same Markdown can still be placed there manually
DSH	/euthyna	installed with the plugin; after a restart the command prints the usage manual (DSH slash commands run without reaching the model)
Hermes	/euthyna <subcommand> <args…>	install this repository as a Hermes plugin: hermes plugins install slow-stack/euthyna then hermes plugins enable euthyna (needs Node >= 20 on PATH; the repo root carries plugin.yaml + __init__.py). The command forwards to the CLI and prints its output without reaching the model. The skill itself can still be installed separately with hermes skills install slow-stack/euthyna/.agents/skills/euthyna

How to tell it was euthyna that audited

• the report filename is <PROJECT>_EUTHYNA_AUDIT_<YYYY-MM-DD>.md
• verdicts use the three-state shape BUG #N TRUE POSITIVE / FALSE POSITIVE / INCONCLUSIVE
• every claim cites path:L123 evidence and a reproduce command
• missing data is recorded as not evaluated, never as "clean"

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🚀 Quick start

npm install -g euthyna
euthyna history --repo <path> --base main --head HEAD          # add --origins to chase the first introducer
euthyna coverage --coverage coverage/coverage-final.json --symbol <name>
euthyna deps --repo <path> --dep <name>
euthyna gate <adjudication-report.md> --verify --cwd <repo>    # mechanically check the six gates

Or without a global install: npx euthyna history --repo <path> --base main.

From a checkout instead (development):

git clone https://github.com/slow-stack/euthyna
cd euthyna && npm test                                 # 178 tests; no install step exists
node bin/euthyna.js history --repo <path> --base main --head HEAD

What history reports looks like this:

已确证 (7)
  • 本次变更删除了 4 行来自提交 ab877f9d70 的代码，分布在 2 个文件。
    提交信息："fix(link-in-text-block): don't match style or script text (#3775)"，分类：fix
      证据: lib/checks/color/link-in-text-block-evaluate.js (ab877f9d70)
      复现: git blame --porcelain -L 104,104 -L 114,114 <base> -- lib/checks/.../evaluate.js

Every deleted line is blamed back to a commit, and the 复现 (Reproduce) command lets you re-derive the claim yourself without trusting the report. Add --json for the structured fact report, --pickaxe to detect lines that were removed and are now being added back, and --origins to attribute deleted lines to the commit that first introduced their content rather than to blame's last modifier.

Exit codes are part of the contract

Surveying eight measurement plugins in this ecosystem found none of them publishes a process exit code, which makes their output unusable as a CI gate. This one does:

Code	Meaning
0	Measured; nothing security-classified found — or a gate report fully passes
10	Measured; at least one security-classified fact exists — or a gate report has findings downgraded to observations
1	Usage error
2	Could not measure at all — must not be read as clean (also: a gate report that cannot be read or has no findings)

2 being distinct from 0 is the whole point: failing to measure and measuring and finding nothing are different things.

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🧱 What is actually built

Piece	What it is	Status
Fact producers	A zero-dependency Node CLI that answers three questions deterministically	Working, tested
The skill	The audit discipline itself, as loadable Markdown	Working, loadable
The benchmark	A blind recall measurement for the adjudication layer	Four rounds complete; the loop is one command (bench/adjudicate.js), with a deterministic golden round on CI

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✅ What has been verified, and what has not

This project tries to be explicit about the difference. Current state:

Verified

• history attribution against real repositories — in two languages. Run against axe-core (JavaScript) and crewAI (Python); deleted lines attributed to the commits that introduced them, then checked by hand against git blame. The checks developed for that comparison now run as regression tests in the suite.
• coverage on real output in three formats — c8/V8 JSON, classic istanbul (jest/nyc, same fnMap/f shape) and coverage.py JSON (format 3) — distinguishing all three states correctly, and refusing anything that is not a recognizable coverage report instead of answering "symbol not located" against it.
• deps against a real lockfile — resolved versions reported with a line-level evidence pointer into the lockfile, and absent dependencies reported as established absences rather than silent skips. Verified against a populated npm v3 lockfile and fixture lockfiles for Cargo.lock and go.mod.
• Adjudication recall and specificity, measured blind: 10/10 cases, 4 real vulnerabilities all caught, 6 non-vulnerabilities all correctly cleared, no abstentions. Round 2 repeated every case three times — 30 adjudications, zero flips, four of them on a different model. Round 3 expanded the set to 18 cases (8 real, 10 not) and reshuffled the blind ids every round: 54 adjudications, 24/24 real-bug claims caught with no misses and no abstentions, 29/30 non-vulnerabilities correctly cleared — and the single "false alarm" was the round's finding, not noise: the adjudicator caught a defect in a fixture's guard, confirmed by reproduction and fixed. Every case is a near-neighbour pair — same pattern, one guard apart — so the verdicts had to come from reading the guard rather than recognising the shape. Round 4 re-ran the full set under fresh id shuffles, with the twice-defeated guard — rebuilt as a bare-name allow-list — facing its first blind adjudication: 54/54 correct, all 8 pairs separated, and a third run on a second model family agreed with the first two on every case. See bench/RESULTS.md, bench/RESULTS-round2.md, bench/RESULTS-round3.md, and bench/RESULTS-round4.md.
• The delivery-gate mechanism, by running the real host plugin: blocking works, and the two documented ways of getting it wrong do not. See docs/dsh-stop-gate.md.
• The gate discipline, mechanically. euthyna gate is not a claim in prose: the suite pins the contract per verdict (a TRUE POSITIVE without path:L123 evidence, a reproduce command or all six gates passing is downgraded; a FALSE POSITIVE needs a failing gate with a reason), and --verify is tested to not execute an interpreter command without --allow-exec. test/skill.test.js fails CI if the skill text stops declaring the six gates, the three verdicts, or the command that enforces them.
• The adjudication loop, end to end and on CI. bench/adjudicate.js runs a whole round — blind tree, one adjudicator process per case, machine-validated reports, scoring — and a deterministic golden round runs on every push, so the pipeline (and score.js going red on a wrong verdict) is checked without a model.

Not verified

• Whether the method finds vulnerabilities in real code. The benchmark measures whether the discipline reaches the right verdict on a claim. It does not measure whether the claims would be found in the first place. The cases are deliberately constructed. The crewAI case study surfaced one INCONCLUSIVE (pickle deserialization, supply-chain-dependent) and refuted the rest — a directional signal, not a rate.
• Recall in the field. The benchmark's real-bug cases are constructed; whether the discipline helps on code nobody staged for it is unmeasured.
• Source maps, bundlers, monorepos for the coverage producer. Untested.
• A real model round on CI. The golden round is deterministic plumbing, not an adjudication: it writes the ground truth into the reports by design. A model round needs credentials and is non-deterministic by nature, so it stays a local/manual step (bench/README.md documents the command) rather than a CI gate that could flake.
• --verify as a sandbox. It is not one, and does not claim to be: it executes the report's commands with your privileges, git only unless --allow-exec is passed.
• deps beyond three formats and version facts only. pnpm/yarn/poetry lockfiles are detected but not parsed (reported as not evaluated, never guessed at); go.mod reports the declared requirement, not the resolved build version; and the producer never maps a version to a CVE — that mapping is deliberately left to the adjudication layer.
• Anything about the case-study targets' security — the runs found nothing to endorse or condemn; that is not a statement about either project. See docs/case-study-crewai.md and docs/case-study-axe-core.md.

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📂 Repository layout

euthyna/
├── bin/  src/  test/        Fact producers (zero dependencies, Node >= 20)
├── .agents/skills/euthyna/  The audit discipline, as a portable skill
├── plugin.yaml  __init__.py  Hermes plugin: the /euthyna slash command
├── bench/                   Blind recall benchmark + results
├── docs/                    Design notes and case studies (English and Chinese)
├── tools/                   Research and verification scripts
└── data/                    DSH plugin catalog snapshot

tools/fetch-references.js downloads the upstream sources this project reads into .refs/ (gitignored). No third-party files are distributed in this repository — see NOTICE.md for why, and for what is owed to whom.

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🧭 Status

Early, and honest about it. Working: the two fact producers, the skill, the benchmark harness. Not yet built: wiring the skill to the CLI so an agent uses them without being told, and the git-history / coverage work needed to close the remaining recall gap.

The design notes are available in English and Chinese; the -zh files are the originals.

🤝 Contributing

Read CONTRIBUTING.md. The short version: no AI attribution in commits, one change per commit, and do not claim something works until you have run it.

🔒 Security

The fact producers execute git and parse coverage output; their integrity is the product. What is in scope, and how to report privately: SECURITY.md. Note that the benchmark fixtures in bench/cases/ are vulnerable by construction and are not vulnerabilities.

📜 License

Apache License 2.0 — see LICENSE.