Design a Rules Engine for Corporate Card Expenses

Context

You are building an expense policy engine for a corporate credit-card system. Managers define policies (rules) that must be evaluated against expense transactions. Each expense is represented as a dictionary/map with string keys and string values.

Task

Design and describe an implementation for:

• A rule representation that supports at least the four sample policies below and scales to hundreds of rules.
• A function: evaluateRules(rules: list <rule> , expenses: list <expense> ) -> ?
• Define what the function should return as an API response that downstream services and UIs can consume.
• Explain conflict handling and precedence, auditing/explanations, performance and scalability, and how managers select and manage rules.
• State assumptions and product clarifications you would ask before coding.

Given Policies (minimum support)

1. No restaurant expense over $75.
2. No airfare expenses.
3. No entertainment expenses.
4. No expense over $250.

The system must flag violating expenses.