Feature: Add configurable request-body validation to the Webhook node

Feature request Add optional request-body validation to the built-in Webhook node. Problem The Webhook node is commonly used to expose HTTP API endpoints. It currently accepts the incoming request and starts the workflow, but validating the request shape requires building validation logic manually inside the workflow. For a production API endpoint, users often need to validate: • Required properties • Property types • Nested objects and arrays • Allowed values • String, number, and array constraints • Additional properties • Default values or type coercion • A consistent HTTP 400 response for invalid requests At the moment, users need to implement this with expressions, Set nodes, If nodes, or Code nodes. This makes validation repetitive and makes it harder to return a consistent error contract before the workflow starts. Existing prototype We have built and published a prototype community node: • Repository: • Pack…