n8n Sub-workflows Sub-workflows are reusable functions. The declares input parameters, the body does work, the last node returns output. Callers invoke it like any other node. That framing opens up the function-shaped wins: encapsulation, reuse, testability, replaceability. It's the primary reuse mechanism in n8n, and unfortunately underused. Without sub-workflows, the same logic gets duplicated across workflows. Bug fixes happen in multiple places, one gets missed, and "identical" copies drift. Non-negotiables 1. Search before you build. Before writing logic that handles a generic problem, c…