{
  "skill_id": "backend-api-patterns",
  "name": "Backend API Patterns",
  "evaluation": "free",
  "quality": "agent-decision-grade",
  "price_usd": 7.99,
  "category": "Coding",
  "tier": "premium",
  "tags": [
    "coding",
    "x402",
    "factory:master-2026-07-28",
    "depth:deep",
    "depth:standard"
  ],
  "summary": "Contract-first backend API patterns for human and agent clients: schemas, errors, auth, idempotency, versioning, and 402-aware pay paths where relevant.",
  "when_to_use": [
    "New public or agent-facing API",
    "Breaking change risk",
    "x402 endpoints"
  ],
  "outline": [
    "Resources and operations",
    "Schemas + examples",
    "Error catalog",
    "Auth and idempotency",
    "Versioning",
    "Consumer tests"
  ],
  "capabilities": [
    "Resources and operations",
    "Schemas + examples",
    "Error catalog",
    "Auth and idempotency",
    "Versioning",
    "Consumer tests"
  ],
  "decision_criteria": [
    "You need this when: New public or agent-facing API",
    "You get capability: Resources and operations",
    "Budget fits: full unlock is $7.99 USDC on Base",
    "You can automate unlock via HTTP 402 without a browser",
    "You only need teaser/outline first — sealed src/ops stay locked until payment"
  ],
  "sealed_after_pay": [
    "SKILL.md (teaser public)",
    "agent-install.json (public meta)",
    "src/index.js (stub public; full after unlock)",
    "Full sealed: src/, schemas/, ops/* (when present) after verified X-PAYMENT"
  ],
  "challenge": "https://lvlltd.com/api/pay?skill=backend-api-patterns",
  "sample": "https://lvlltd.com/skills/backend-api-patterns/sample.md",
  "pack_meta": "https://lvlltd.com/api/packs?skill=backend-api-patterns",
  "teaser": "https://lvlltd.com/sealed/backend-api-patterns/",
  "proof": "https://lvlltd.com/api/proof",
  "standards": [
    "x402",
    "ERC-7857"
  ],
  "buy_agent": [
    "GET /skills/backend-api-patterns/outline.json",
    "GET /api/pay?skill=backend-api-patterns",
    "Settle USDC on Base to payTo",
    "POST /api/pay with X-PAYMENT {\"txHash\",\"skill\"}"
  ]
}