What is Workflow Config and why is it required before save?

Workflow Config (under Settings on the canvas) stores keywords and messages that control how users interact with the journey: Reset keyword (restart from start node), Cancel keyword (exit workflow), Clean localcache keyword (clear local variables), and Message for expiry (sent when the user is in a half-finished journey and the workflow expires). These are required so the execution engine knows how to handle reset, cancel, and expiry. Save is blocked until all required Workflow Config fields are filled.