---
title: "Pattern Consistency Enforcer"
description: "The only skill-scoped hook --- enforces established code patterns during review"
canonical: "https://orchestkit.yonyon.ai/docs/reference/hooks/spotlights/pattern-consistency-enforcer"
---

# Pattern Consistency Enforcer

The only skill-scoped hook --- enforces established code patterns during review

import { Callout } from "fumadocs-ui/components/callout";

<span className="badge badge-red">Blocks</span> <span className="badge badge-green">Skill-scoped</span>

> Checks written code against a project's established patterns file and blocks commits that violate architectural conventions.

## When It Fires

**Event:** PreToolUse · **Matcher:** `Write`, `Edit` · **Scope:** Skill (`code-review`)

This is OrchestKit's **only skill-scoped hook**. It activates exclusively when the `code-review` skill is loaded, adding pattern enforcement on top of the standard file guard checks.

## What It Does

When code is written or edited during a code review session, the hook reads the project's established patterns file at `.claude/context/knowledge/patterns/established.json`. If the file does not exist, the hook exits silently --- pattern enforcement is opt-in.

The hook then inspects the file content against category-specific rules based on file path and extension. Violations are classified as **errors** (blocking) or **warnings** (non-blocking, logged to stderr).

## Enforced Patterns

### Backend (Python)

| Pattern | What It Catches |
|---------|----------------|
| **Clean Architecture layers** | Router importing directly from repositories (should go through services) |
| **Circular dependencies** | Service importing from routers |
| **Async SQLAlchemy** | Using sync `Session`/`sessionmaker` instead of `AsyncSession` |
| **Pydantic v2** | Using `@validator` (v1) instead of `@field_validator` (v2) |
| **Pydantic v2** | Using `@root_validator` (v1) instead of `@model_validator` (v2) |

### Frontend (TypeScript/JavaScript)

| Pattern | What It Catches |
|---------|----------------|
| **React 19 components** | Using `React.FC<>` instead of explicit props type |
| **Zod validation** | API calls (`fetch`, `axios`) without Zod response validation |
| **React 19 forms** | Form elements without `useFormStatus`/`useActionState`/`useOptimistic` (warning only) |
| **Date formatting** | Direct `toLocaleDateString` instead of centralized `@/lib/dates` helpers |

### Testing

| Pattern | What It Catches |
|---------|----------------|
| **AAA comments** | Missing Arrange-Act-Assert comments in tests (warning only) |
| **MSW for mocking** | Using `jest.mock` for fetch instead of MSW |
| **Pytest fixtures** | Using unittest `setUp` instead of pytest fixtures |

### AI Integration

| Pattern | What It Catches |
|---------|----------------|
| **IDs in prompts** | Database IDs passed directly into LLM prompts |
| **Timeout protection** | LLM calls without `asyncio.timeout` or `Promise.race` wrapping |

## Configuration

Pattern enforcement requires an `established.json` file at `.claude/context/knowledge/patterns/established.json`. Without this file, the hook is inactive.

The patterns checked are defined in source code. To customize which patterns apply to your project, maintain the `established.json` file with your project's conventions.

## Related Hooks

- [file-guard](/docs/hooks/spotlights/file-guard) --- global file protection that runs alongside this hook
- [unified-quality-dispatcher](/docs/hooks/reference/pretool-write-edit#unified-quality-dispatcher) --- additional write quality checks