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Discord·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Jun 2026Remote

Summary

Discord SWE interview round where they pulled up PuTTY live and walked through AI-generated code I'd written earlier. Less about coding from scratch and more about defending your choices, which I was not fully prepared for.

Questions Asked (5)

Q1

Why did you write your AI prompt the way you did?

Technical Trade-offsAdaptability & Ambiguity
Author's notes

This one tripped me up more than I expected.

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AI HintsAI Generated

Suggested Approach

Walk through your prompt design as a series of deliberate engineering decisions, explaining the goal, constraints, and trade-offs you considered. Emphasize how you iterated based on results and adapted to ambiguity, showing a systematic and reflective process.

Pro tip: Frame your prompt as a prototype for a production system: discuss how you'd measure its performance and what you'd change to make it robust and scalable. This shows you think beyond the immediate task and align with Discord's engineering culture.

1. Clarify the Objective

State the specific goal you wanted the AI to achieve and why it mattered for the task or user.

2. Outline Constraints and Assumptions

Describe the technical, time, or data constraints you faced and any assumptions you made about the AI's behavior.

3. Explain Design Choices

Detail the key elements of your prompt (e.g., structure, examples, tone) and the reasoning behind each, linking to trade-offs like clarity vs. flexibility.

4. Show Iteration and Adaptation

Discuss how you tested the prompt, what you learned from failures or ambiguities, and how you refined it.

5. Connect to Engineering Principles

Relate your approach to broader software engineering practices like modularity, testing, and scalability.

Key Points to Mention

  • Trade-offs between prompt specificity and generality
  • Iterative refinement based on output quality
  • Handling ambiguity by adding constraints or examples
  • Alignment with Discord's values (e.g., user focus, scalability)
  • Potential for automation or integration into larger systems
  • Lessons learned and how you'd approach similar problems in the future

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

Q2

Are the libraries the AI selected appropriate for this use case, and why or why not?

Technical Trade-offsAPI & Integrations
Author's notes

Felt more confident here since I'd actually looked at the dependencies.

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AI HintsAI Generated

Suggested Approach

Start by restating the use case and the AI's library choices to show you understand the context. Evaluate each library against criteria like performance, scalability, and fit for Discord's real-time, high-throughput environment. Conclude with a balanced verdict, acknowledging trade-offs and suggesting alternatives if needed.

Pro tip: Mention that library appropriateness depends on specific constraints like latency, concurrency, and maintenance overhead—showing you consider non-functional requirements, not just features.

1. Clarify the use case

Summarize the problem the AI was solving, including scale, latency, and integration needs specific to Discord.

2. Identify the libraries

List the libraries the AI selected and their core purposes, noting any obvious mismatches with the use case.

3. Evaluate against criteria

Assess each library on performance, scalability, community support, security, and compatibility with Discord's tech stack.

4. Consider alternatives

Propose better-suited libraries if applicable, explaining why they would improve the solution.

5. Deliver a balanced verdict

State whether the libraries are appropriate overall, highlighting trade-offs and any conditions that would change your assessment.

Key Points to Mention

  • Performance and latency requirements for real-time messaging
  • Scalability to handle Discord's massive user base
  • Community support and long-term maintenance of the libraries
  • Security and compliance considerations
  • Integration complexity with existing systems
  • Trade-offs between using popular vs. specialized libraries

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

Q3

Is the extra functionality the AI added beyond what you asked for actually useful, or is it unnecessary?

Technical Trade-offsAdaptability & Ambiguity
Author's notes

The AI had added some error handling I didn't ask for.

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AI HintsAI Generated

Suggested Approach

Acknowledge that AI-generated extras can be valuable but must be evaluated against the original requirements and project constraints. Share a specific example where you assessed such additions, weighing usefulness against complexity, and describe how you decided to keep, modify, or discard them.

Pro tip: Emphasize that you always validate AI suggestions through code review and testing, and that you consider maintainability and team velocity—not just immediate functionality—when deciding what to keep.

1. Clarify the original goal

Restate what was actually requested and why, to establish a baseline for evaluating any extras.

2. Assess the extra functionality

Evaluate the addition on criteria like user value, alignment with product vision, and whether it solves a real problem.

3. Weigh trade-offs

Consider costs: added complexity, maintenance burden, performance impact, and potential technical debt.

4. Decide and act

Make a call—keep, adapt, or remove—and explain how you communicated the decision to stakeholders.

5. Reflect on the outcome

Share what you learned and how it improved your process for integrating AI suggestions in the future.

Key Points to Mention

  • Alignment with original requirements and user needs
  • Cost-benefit analysis including maintenance and complexity
  • Team collaboration and code review process
  • Iterative development and willingness to refactor
  • Learning from AI suggestions to improve future prompts
  • Balancing innovation with scope creep

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

Q4

How would you go about testing this code?

Technical Trade-offs
Author's notes

Standard enough question but the live PuTTY context made it feel more immediate.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the code's purpose, inputs, outputs, and dependencies to understand what needs testing. Then outline a layered testing strategy covering unit, integration, and end-to-end tests, prioritizing critical paths and edge cases. Conclude by discussing trade-offs like test coverage vs. maintenance cost and how you'd measure success.

Pro tip: Emphasize testing for failure modes and edge cases first, as they often reveal the most critical bugs. Also, mention how you'd use mocks and stubs to isolate components, especially in a microservices environment like Discord's.

1. Clarify Requirements and Scope

Ask questions to understand the code's functionality, expected behavior, and constraints. Identify what aspects are most critical to test based on business impact.

2. Design Test Strategy

Outline a testing pyramid: unit tests for individual functions, integration tests for component interactions, and end-to-end tests for user flows. Prioritize based on risk and complexity.

3. Identify Test Cases

Enumerate normal cases, edge cases, and error conditions. Consider boundary values, invalid inputs, and failure scenarios like network issues or database errors.

4. Choose Tools and Frameworks

Select appropriate testing tools (e.g., JUnit, pytest, Jest) and mocking libraries. Discuss how to automate tests and integrate with CI/CD pipelines.

5. Discuss Trade-offs and Metrics

Explain how you'd balance test coverage with development speed. Define success metrics like defect escape rate or test execution time, and how to maintain tests over time.

Key Points to Mention

  • Unit testing with mocking to isolate dependencies
  • Integration testing for API contracts and database interactions
  • End-to-end testing for critical user journeys
  • Edge cases and error handling (e.g., null inputs, timeouts)
  • Test coverage metrics and when to prioritize
  • CI/CD integration and automated regression testing

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

Q5

If you needed to add a new feature, how would you prompt the AI to write it and how would you verify the result?

System DesignTechnical Trade-offsAdaptability & Ambiguity
Author's notes

Probably the most interesting question of the whole round.

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AI HintsAI Generated

Suggested Approach

Walk through a concrete example of adding a feature, emphasizing how you craft a detailed prompt with context, constraints, and acceptance criteria, then describe a rigorous verification process that includes automated tests, manual testing, and code review. Highlight the importance of understanding the AI's limitations and iterating on both the prompt and the code.

Pro tip: Treat the AI as a junior engineer: give it clear requirements, review its work critically, and never merge without thorough testing. Also, mention that you'd version control the prompt alongside the code for reproducibility.

1. Define the feature and requirements

Clearly specify the feature's purpose, inputs, outputs, edge cases, and performance expectations. Break it down into small, testable units.

2. Craft a detailed prompt

Include context (e.g., codebase, language, frameworks), constraints (e.g., style, libraries), and examples. Ask for tests and documentation.

3. Review and iterate on the generated code

Inspect the AI's output for correctness, security, and adherence to standards. Refine the prompt or manually adjust as needed.

4. Verify with automated tests

Run unit, integration, and end-to-end tests. Ensure coverage for edge cases and performance benchmarks.

5. Conduct manual testing and code review

Manually test the feature in a realistic environment and have peers review the code for quality and maintainability.

Key Points to Mention

  • Prompt engineering techniques: providing context, examples, and constraints
  • Iterative refinement of both prompt and code
  • Automated testing: unit, integration, and end-to-end tests
  • Manual testing and edge case validation
  • Code review and pair programming with AI
  • Security and performance considerations
  • Version controlling prompts for reproducibility

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