/pattern-discovery

name: pattern-discovery
description: Pattern library discovery for pattern-first development. Use BEFORE implementing any new feature, creating components, writing API routes, or adding database operations. Ensures existing patterns are checked first before writing new code.
context: fork
agent: Explore
allowed-tools: Read, Grep, Glob

Pattern Discovery Skill

Purpose

Enforce pattern-first development by checking the Pattern library before implementing new functionality. This reduces code duplication, ensures consistency, and leverages battle-tested solutions.

When to Use

Invoke this skill when:

• About to create a new API route
• About to create a new UI component
• About to add database operations
• About to write integration tests
• User asks "how do I implement..." or "how should I build..."
• Starting work on any feature implementation

Pattern Discovery Protocol

**ALWAYS follow this sequence before writing new code:**

Step 1: Check Pattern Library

Search `patterns_library/` for existing patterns:

# Find patterns by category
ls patterns_library/api/      # API route patterns
ls patterns_library/ui/       # UI component patterns
ls patterns_library/database/ # Database operation patterns
ls patterns_library/testing/  # Testing patterns

Step 2: Review Pattern Index

Check `patterns_library/README.md` for the complete pattern index:

| Category | Patterns Available | | -------- | --------------------------------------------------------------------------- | | API | User Context, Admin Context, Webhook Handler, Zod Validation, Bonus Content | | UI | Authenticated Page, Form with Validation, Data Table, Marketing Page | | Database | RLS Migration, Prisma Transaction, Server Component Access | | Testing | API Integration Test, E2E User Flow | | Security | Input Sanitization, Rate Limiting, Secrets Management | | CI | GitHub Actions Workflow, Deployment Pipeline | | Config | Environment Config, Structured Logging |

Step 3: Apply or Escalate

**If pattern exists:**

1. Read the pattern file 2. Copy the code pattern 3. Follow the customization guide 4. Run validation commands

**If pattern is missing:**

1. Search codebase for similar implementations 2. If found, consider extracting as new pattern (BSA/ARCHitect only) 3. If not found, implement from scratch following existing conventions 4. Report pattern gap to BSA for future extraction

Pattern Library Structure

patterns_library/
├── README.md           # Pattern index and usage guide
├── api/
│   ├── user-context-api.md
│   ├── admin-context-api.md
│   ├── webhook-handler.md
│   ├── zod-validation-api.md
│   └── bonus-content-delivery.md
├── ui/
│   ├── authenticated-page.md
│   ├── form-with-validation.md
│   ├── data-table.md
│   └── marketing-page.md
├── database/
│   ├── rls-migration.md
│   ├── prisma-transaction.md
│   └── server-component-direct-access.md
├── testing/
│   ├── api-integration-test.md
│   └── e2e-user-flow.md
├── security/
│   ├── input-sanitization.md
│   ├── rate-limiting.md
│   └── secrets-management.md
├── ci/
│   ├── github-actions-workflow.md
│   └── deployment-pipeline.md
└── config/
    ├── environment-config.md
    └── structured-logging.md

Pattern Matching Guide

| If you need to... | Use this pattern | | ---------------------------------- | --------------------------------- | | Create authenticated API endpoint | `api/user-context-api.md` | | Create admin-only API endpoint | `api/admin-context-api.md` | | Handle external webhooks | `api/webhook-handler.md` | | Validate API input with Zod | `api/zod-validation-api.md` | | Serve private downloadable content | `api/bonus-content-delivery.md` | | Create protected page | `ui/authenticated-page.md` | | Build form with validation | `ui/form-with-validation.md` | | Display paginated data | `ui/data-table.md` | | Create marketing/landing page | `ui/marketing-page.md` | | Add new table with RLS | `database/rls-migration.md` | | Run multi-step DB operations | `database/prisma-transaction.md` | | Test API endpoints | `testing/api-integration-test.md` | | Write E2E user flow tests | `testing/e2e-user-flow.md` | | Sanitize user input | `security/input-sanitization.md` | | Add API rate limiting | `security/rate-limiting.md` | | Manage secrets/env vars | `security/secrets-management.md` | | Set up CI/CD pipeline | `ci/github-actions-workflow.md` | | Configure deployment stages | `ci/deployment-pipeline.md` | | Load environment configuration | `config/environment-config.md` | | Add structured logging | `config/structured-logging.md` |

Security Requirements

All patterns enforce:

• **RLS Context** - Database operations use `withUserContext`, `withAdminContext`, or `withSystemContext`
• **Authentication** - Protected routes verify auth before processing
• **Input Validation** - All inputs validated with Zod schemas
• **Error Handling** - Comprehensive error handling with proper status codes

Validation Commands

After applying a pattern, run:

yarn lint && yarn type-check  # All patterns
yarn test:integration         # API patterns
yarn test:e2e                 # UI patterns

Authoritative Reference

• **Pattern Index**: `patterns_library/README.md`
• **RLS Patterns**: See `rls-patterns` skill for database security
• **Frontend Patterns**: See `frontend-patterns` skill for UI conventions