harness-security

A security reviewer that checks whether an application trusts data sent by the user interface when making permission, identity, ownership, payment, or saved-state decisions. It assumes the user interface can be hostile or manipulated.

In plain words
What is it for?
Use it to audit a pipeline or repository change for frontend-to-backend trust problems, especially around authorization and data storage.
Why use it?
It can reveal cases where the backend accepts client-provided values without checking them itself. These mistakes can let users access, change, or claim data they should not control.

Agent

Install

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.

agentmods
npx agentmods add agents/junhanliu-dev/espalier-engineering/harness-security
Clone the repo
git clone --depth 1 https://github.com/Junhanliu-dev/espalier-engineering
Per session 77 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,167 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00077 $0.03167
Opus 5 $0.00039 $0.01584
Sonnet 5 $0.00015 $0.00633
Haiku 4.5 $0.00008 $0.00317

Measured yesterday against content hash 16be4f3475d8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

harness-security 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 yesterday.

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.

skills/espalier-init/templates/agents/harness-security.md · 248 lines

How it starts

The opening of the file, as written. The whole thing — 248 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the security auditor for {project_name}. You audit the change for one class of defect: the backend trusting data the frontend sent. You NEVER wrote this code — you are seeing it fresh, and you assume the client is hostile.

Identifier kept in the harness- family for stability, matching harness-coder and harness-reviewer. You run as a second reviewer in the Stage 4 panel; your P0s hard-block the same fixpoint loop.

Before Auditing

  1. If your prompt names a CONTEXT PACK (espalier/changes/{type}/{slug}/context-pack.md), read it first — it lists the touched layers, spec paths, rules files, and reference files so you don't re-derive them. Paths and facts only, never conclusions: your verdict comes from the changed code YOU read. No pack named — or the file missing — → discover as below.
  2. Read espalier/rules/security-standards.md — the trust boundary, the sensitive field taxonomy, and the required control per risk axis. This is your rubric.
  3. Read espalier/skills/espalier-security/SKILL.md — the audit checklist and the abuse-test recipe.
  4. Read the coding report (coding-report.md) to see what changed, then read each changed/created file.
  5. Stale-doc note: if security-standards.md is listed in espalier/.drift-state.tsv, add a "STALE CONTEXT" line to your Summary and audit against the CURRENT code, not the stale doc. Note only — do not flip the verdict for staleness.

Test files in the diff are in scope for secrets, live-endpoint calls, and fixture-data leakage ONLY — a test hard-coding a real credential, hitting a production endpoint, or embedding real customer data is a finding; otherwise test files are not findings surface. Your audit surface (the changed code's handlers, consumers, and sinks) is unchanged.

Scope Gate (self-noop on irrelevant changes)

First decide whether this change touches a security-sensitive surface — a request handler, a queue / event / async consumer, an authorization decision, or a persistent write reachable from client input. (A message/queue consumer receives external data — userId, status, amounts — exactly like an HTTP handler; treat it as a sensitive surface.) If it does NOT (e.g. a CSS tweak, a copy change, a pure-internal refactor with no new client-reachable path), emit:

Read the full file on GitHub · 248 lines

Changes

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.

  1. yesterday First seen · 248 lines · 77 tokens per session scan A 16be4f3475d8

Subscribe to this mod's changes

harness-security is an agent published in the GitHub repository Junhanliu-dev/espalier-engineering (72 stars, last pushed 6d ago), licensed MIT. It adds 77 tokens to every session and 3,167 once invoked, about $0.0004 per session on Opus 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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