My first instinct was to just patch the user object when I hit a change date, but that blew up the structure I'd built in the previous part.
Start by clarifying the data model and requirements, then propose an event-driven approach where plan changes are processed as events that update the user's current plan and trigger an 'Updated' email. For scheduling future emails, ensure the email generation logic always references the user's current plan at the time of sending, rather than precomputing plan names.
Pro tip: Emphasize idempotency and ordering: plan changes might be processed out of order or duplicated, so use a version or timestamp to ensure the correct plan is applied and emails are sent exactly once. Also, consider time zones and the exact moment of plan change to avoid off-by-one-day errors.
Ask questions to understand the structure of user plans, plan changes, and existing email scheduling logic. Confirm edge cases like multiple changes on the same day, backdated changes, and time zone handling.
Propose an event-driven system where each plan change is an event that updates the user's current plan and triggers an 'Updated' email on the effective date. Ensure events are processed in order and idempotently.
Change the email generation logic to fetch the user's current plan at the time of sending, rather than precomputing plan names. This ensures all future emails reference the correct plan.
Use a scheduler or queue to process plan changes on their effective date, sending the 'Updated' email and updating the user's plan. For other emails, schedule them to be generated dynamically at send time.
Discuss how to handle large volumes, failures, retries, and consistency. Consider using a database transaction to update plan and enqueue email atomically, and a dead-letter queue for failures.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.