express-json-endpoint

name: express-json-endpoint description: Use this skill when adding or modifying Express JSON endpoints. Keep routing minimal, validate input, and return consistent status codes and JSON.

When implementing an Express JSON endpoint:

• Keep endpoints minimal (prefer a single route over multiple routes when feasible).
• Always add app.use(express.json()) before JSON routes.
• Validate required inputs early and return 400 with { error: string }.
• Separate concerns lightly:
  • validate inputs
  • run core logic
  • return JSON
• Status codes:
  • 200 for success
  • 400 for invalid input
  • 500 for unexpected failures
• Error payload shape:
  • { error: "Human-readable message" }
• Do not leak sensitive details to the client; log details server-side.

Output expectations:

• Provide the minimal code changes needed.
• Avoid introducing frameworks, databases, or extra layers unless asked.