pattern-discovery

name	pattern-discovery
description	Pattern library discovery for pattern-first development. Use BEFORE implementing any new feature, creating 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 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:

ls patterns_library/api/      # API route patterns
ls patterns_library/database/  # Database operation patterns
ls patterns_library/testing/   # Testing patterns
ls patterns_library/security/  # Security patterns
ls patterns_library/ci/        # CI/CD patterns
ls patterns_library/config/    # Configuration 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
Database	RLS Migration, SQL Transaction
Testing	API Integration Test
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
├── database/
│   ├── rls-migration.md
│   └── sql-transaction.md
├── testing/
│   └── api-integration-test.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

Archived patterns (upstream reference, not active):

• docs/archive/harness-upstream/patterns-ui/ — React/Next.js UI patterns
• docs/archive/harness-upstream/patterns-testing/e2e-user-flow.md — Playwright E2E

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
Add new table with RLS	database/rls-migration.md
Run multi-step DB operations	database/sql-transaction.md
Test API endpoints	testing/api-integration-test.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:

npm test && npm run build

Authoritative Reference

• Pattern Index: patterns_library/README.md
• RLS Patterns: See rls-patterns skill for database security