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Microsoft·Software Engineer·Onsite - System Design / Architecture·Senior

Senior
Apr 2026

Summary

System design round at Microsoft for a software engineering role. The prompt was about building a re-engagement system for Copilot users, covering things like nudging inactive users and parsing reminders out of LLM conversations.

Questions Asked (1)

Q1

Design a re-engagement system for Copilot users. This includes sending notifications to users who have been inactive, as well as detecting and acting on reminders that users mention during LLM chat sessions.

System DesignAPI & IntegrationsTechnical Trade-offs
Author's notes

Two problems crammed into one prompt basically.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the scope and requirements, then design a high-level architecture that separates the notification system from the reminder detection system. Dive into each component, discussing data models, APIs, and trade-offs, and finally address scalability, privacy, and integration with existing Microsoft services.

Pro tip: Emphasize user privacy and consent, especially when processing chat content for reminders, and propose a feedback loop to continuously improve detection accuracy.

1. Clarify Requirements and Scope

Ask questions to understand what 'inactive' means, what types of notifications are acceptable, and how reminders should be detected and acted upon. Clarify integration points with existing Copilot and Microsoft services.

2. High-Level Architecture

Outline the main components: an inactivity detection service, a notification service, a reminder detection service that processes chat messages, and a reminder action service. Describe how they interact and the data flow.

3. Detailed Design of Key Components

For each component, discuss data models, APIs, and algorithms. For example, how to track user activity, how to detect reminders using NLP, and how to schedule notifications.

4. Address Trade-offs and Challenges

Discuss trade-offs such as real-time vs batch processing, accuracy vs latency in reminder detection, and privacy concerns. Propose solutions like using a message queue for scalability and encryption for privacy.

5. Scalability, Reliability, and Integration

Explain how the system scales with millions of users, ensures reliability with retries and fallbacks, and integrates with Microsoft's ecosystem (e.g., Azure services, Microsoft Graph).

Key Points to Mention

  • User activity tracking and defining inactivity thresholds
  • Notification delivery mechanisms (push, email, in-app) and user preferences
  • Natural language processing for reminder detection from chat
  • Privacy and compliance (GDPR, user consent) when processing chat data
  • Scalability using cloud services (e.g., Azure Functions, Event Hubs)
  • Feedback loops and A/B testing to improve reminder detection accuracy

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.