code-explainer

Expected outcome:

• Overview: The service validates an order, charges the payment method, records success, and sends a receipt.
• Key risks: Duplicate charges, client-controlled amounts, and email failures need explicit handling.
• Learning prompt: Ask the reader where retry logic should live.

Expected outcome:

• Flow: Logging runs first, authentication verifies identity, authorization checks access, then the route handles the request.
• Common mistake: Running authorization before authentication leaves the user context unavailable.
• Diagram suggestion: Show each middleware as a checkpoint in request order.

Expected outcome:

• Issue explained: The function may return before asynchronous work finishes.
• Fix direction: Use a collection method that waits for all requested records.
• Audience note: For beginners, explain promises before discussing concurrency.