Walk through how you would design a scalable Apex trigger architecture for an enterprise org.

An enterprise Apex trigger architecture must be maintainable, testable, and governor-limit safe:

One Trigger per Object: Have exactly one trigger per object that handles all contexts (before insert, before update, after insert, after update, etc.). Avoids unpredictable execution order between multiple triggers on the same object.

Trigger Handler Pattern: The trigger itself contains no business logic — it delegates to a handler class:
trigger AccountTrigger on Account (before insert, after insert, before update, after update) { AccountTriggerHandler.handle(Trigger.operationType, Trigger.new, Trigger.oldMap); }

Handler Class: A switch statement routes to context-specific methods (handleBeforeInsert, handleAfterUpdate, etc.). Each method implements bulkified logic.

Service Layer: Complex business logic (reusable across triggers, Apex REST, and Batch jobs) lives in a dedicated Service class, not the handler.

Recursion prevention: Use a static Boolean or static Set of processed IDs to prevent infinite loops.

Unit testing: Test handler methods in isolation. Use test data factories for consistent, reusable test data. Aim for 85%+ code coverage with meaningful assertions.