A command for creating structural guard tests: automated checks that scan code for specific architecture violations. The available guards cover schemas, API boundaries, database query types, and error handling.

Adding AST-based tests that enforce architecture rules, such as matching database column and query types.

It catches certain design regressions automatically whenever the project's quality checks run.

How prebid/salesagent configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to prebid/salesagent. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/prebid/salesagent/main/.claude/skills/guard/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/prebid/salesagent

Made for: Claude Code.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/prebid/salesagent/guard/github.svg)](https://agentmods.dev/skills/prebid/salesagent/guard)

Your own site

<a href="https://agentmods.dev/skills/prebid/salesagent/guard"><img src="https://agentmods.dev/badge/skills/prebid/salesagent/guard/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/prebid/salesagent/guard"><img src="https://agentmods.dev/badge/skills/prebid/salesagent/guard.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 736 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00053	$0.00736
Opus 5.5	$0.00021	$0.00294
Sonnet 5.5	$0.00011	$0.00147
Haiku 4.5	$0.00005	$0.00074

Measured 1mo ago against content hash 3f48a1f994cd, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

guard 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.

.claude/skills/guard/SKILL.md · 88 lines

How it starts

The opening of the file, as written. The whole thing — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Structural Guard Creation

Create AST-scanning enforcement tests that catch architecture violations automatically. Each guard runs on make quality and prevents regressions.

Args

/guard <guard-name-1> [guard-name-2] ...

Guard names (space-separated). Each gets a test file at tests/unit/test_architecture_{guard_name}.py.

Available Guards

Guard	What It Enforces
schema-inheritance	Schema classes extend correct adcp library base types
boundary-completeness	MCP/A2A/REST wrappers expose all _impl parameters
query-type-safety	DB queries use column types matching the column definition
no-error-dicts	_impl functions raise exceptions, never return error dicts

Custom guard names are also supported — the research atom will determine what to enforce based on the name and #1050/#1066 principles.

Existing Structural Guards

These already exist (don't recreate):

ruff-boundary.toml (TID251) — No ToolError import anywhere under src/ but the two edge modules
test_transport_agnostic_impl.py — No transport imports in _impl
ToolImpl protocol on ToolSpec.impl (mypy) + .ast-grep/rules/impl-signature-is-request-and-identity.yml — _impl is exactly (req, identity: ResolvedIdentity)
.ast-grep/rules/resolved-identity-constructed-only-by-its-owners.yml — ResolvedIdentity constructed only by the resolver and the factory

Protocol

Step 1: Cook the molecule

python3 .claude/scripts/cook_formula.py \
  --formula .claude/formulas/structural-guard.yaml \
  --var "GUARD_NAMES={all_args}" \
  --epic-title "Guards: {all_args}"

Dry run first (recommended):

python3 .claude/scripts/cook_formula.py \
  --formula .claude/formulas/structural-guard.yaml \
  --var "GUARD_NAMES={all_args}" \
  --epic-title "Guards: {all_args}" \
  --dry-run

Step 2: Walk the molecule

bd ready → bd show <atom-id> → execute → bd close <atom-id> → repeat

Each guard goes through: research → scan → write-guard → mark-known → verify → commit.

Read the full file on GitHub · 88 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.

1mo ago Changed · +1 lines 3f48a1f994cd
1mo ago First seen · 87 lines · 53 tokens per session scan A 23a734fcb44a

Subscribe to this mod's changes

guard is a skill published in the GitHub repository prebid/salesagent (39 stars, last pushed yesterday), licensed Apache-2.0. It adds 53 tokens to every session and 736 once invoked, about $0.0002 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 2026-09-01.

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salesagent: Skill for Claude Code