Expense Rule Validation Engine

Stateless rule-evaluation service that applies the expense type configuration rules (mutual-exclusivity groups, documentation requirements, amount thresholds) to a given expense or set of expense lines. Invoked server-side at submission time to prevent race conditions where rules have changed since the mobile client last cached the catalogue. Returns structured validation errors for display in the app or admin portal approval queue.

Feature: Expense Types & Requirements

expense-rule-validation-engine

• Evaluate mutual-exclusivity constraints across selected expense types
• Check whether required documentation has been attached for each type
• Validate per-type amount thresholds and flag violations
• Return structured, localised validation error messages
• Support both single-expense and batch validation modes