What is arch-constraint-guard?

A rule checker for software architecture, meaning the boundaries between parts of a system and the contracts they must follow. It reads project rules about allowed edits, layer dependencies, service contracts, and naming.

Use it before editing files in a project with documented architectural constraints. It checks forbidden paths, layer imports, frozen APIs, owned schemas, and naming conventions.

It prevents changes that cross protected boundaries, edit generated or managed files, or violate team rules.

arch-constraint-guard — Skill for Claude Code and Codex by DVNghiem

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.

Any agent

npx skills add DVNghiem/FlowDeck --skill arch-constraint-guard

Clone the repo

git clone --depth 1 https://github.com/DVNghiem/FlowDeck

Made for: Claude Code, Codex.

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/dvnghiem/flowdeck/arch-constraint-guard.svg)](https://agentmods.dev/skills/dvnghiem/flowdeck/arch-constraint-guard)

Your own site

<a href="https://agentmods.dev/skills/dvnghiem/flowdeck/arch-constraint-guard"><img src="https://agentmods.dev/badge/skills/dvnghiem/flowdeck/arch-constraint-guard.svg" alt="Measured on agentmods" height="20"></a>

Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 531 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 warn 7 Sept 2026

SkillSpector: 2 findings, up to medium

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 →

medium Rogue Agent · line 13
Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.

Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
medium Excessive Agency · line 28
Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.

Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.

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	$0.00045	$0.00531
Opus 5	$0.00023	$0.00266
Sonnet 5	$0.00009	$0.00106
Haiku 4.5	$0.00005	$0.00053

Measured 8d ago against content hash d6f421b87286, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

arch-constraint-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 8d 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.

src/skills/arch-constraint-guard/SKILL.md · 62 lines

What it actually says

Architectural Constraint Guard

Before writing any file, check if the edit violates architectural boundaries defined in ~/.fd-plan/<slug>/.codebase/CONSTRAINTS.md. If it does, stop and explain the violation.

CONSTRAINTS.md Format

Create ~/.fd-plan/<slug>/.codebase/CONSTRAINTS.md to encode your team's architectural rules:

## Forbidden Paths
- src/core/         # do not modify core — all changes via PR with 2 approvals
- src/generated/    # auto-generated, do not edit manually
- infra/secrets/    # managed by Terraform only

## Layer Rules
- UI components MUST NOT import from services/ directly — use hooks/ or context/
- services/ MUST NOT import from routes/ — services are framework-agnostic
- domain/ MUST NOT import from infra/ — keep domain pure

## Service Contract Rules
- PaymentService API is frozen — no method signature changes without RFC
- UserSchema is owned by auth-team — no schema changes without approval

## Naming Conventions
- React components: PascalCase only
- Database tables: snake_case only
- API endpoints: kebab-case only

Workflow

For every proposed write or edit:

Read ~/.fd-plan/<slug>/.codebase/CONSTRAINTS.md
Check the target file path against ## Forbidden Paths
Check the import graph against ## Layer Rules
Check method signatures against ## Service Contract Rules
If any violation is found: STOP, report the specific rule violated, and suggest a compliant alternative

When No CONSTRAINTS.md Exists

If ~/.fd-plan/<slug>/.codebase/CONSTRAINTS.md does not exist:

Infer boundaries from ARCHITECTURE.md (layer names, service boundaries)
Apply common-sense defaults: UI does not directly query DB, domain does not call HTTP
Suggest creating CONSTRAINTS.md to codify the rules you discover

Violation Report Format

ARCH CONSTRAINT VIOLATION
Rule: [rule name from CONSTRAINTS.md]
File: [target file]
Violation: [what was attempted]
Compliant alternative: [what to do instead]

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.

8d ago First seen · 62 lines · 45 tokens per session scan A d6f421b87286

Subscribe to this mod's changes

arch-constraint-guard is a skill published in the GitHub repository DVNghiem/FlowDeck (25 stars, last pushed 19d ago), licensed MIT. It adds 45 tokens to every session and 531 once invoked, about $0.0002 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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