Reject malformed data before it reaches your business logic by validating all incoming requests against a strict schema definition.

• Use JSON Schema or OpenAPI definitions to enforce expected types, formats, string lengths, and numeric ranges.
• Use robust validation libraries (e.g., Zod, Joi, or class-validator in Node/TypeScript).
• Fail fast and return a generic 400 Bad Request without leaking stack traces or internal structure in the error message.