1. Feature Flags advanced

    A feature flag controls a pricing rule. Finance asks who changed it, when, what the previous value was, and which orders were priced under the new value. Walk me through what that requirement does to the design of your flag system.

    3 min answer feature flagsconfigurationauditpricing
  2. Hexagonal Architecture advanced

    A communications platform integrates many external providers. How does a ports-and-adapters structure help, and what is the design mistake that negates it?

    2 min answer hexagonalports-adaptersanti-corruptionproviders
  3. Microservices advanced

    A platform adopts microservices and now needs service discovery, distributed tracing, multiple pipelines, a message broker and complex local development. Which of these costs are inherent and which indicate a boundary problem?

    2 min answer microservicescomplexityboundariesdistributed-monolith
  4. Microservices advanced

    A team adopted microservices and now every feature touches five services, five pipelines and a distributed debugging session. Which boundaries were justified, and when is consolidation the improvement?

    2 min answer meeshomicroservicesconsolidationboundaries
  5. Microservices advanced

    An organisation cites Netflix as justification for adopting microservices. What is missing from the comparison?

    2 min answer microservicesplatformnetflixprerequisites
  6. Microservices advanced

    Your organisation has grown to 2,000 microservices. Teams report that understanding and changing the system is now harder than before decomposition. What do you do?

    2 min answer uberdomaboundariesgovernance
  7. Modular Monolith advanced

    A productivity app keeps a full local database on each client and syncs deltas with the server. Why would a small team choose this over conventional REST, and how are optimistic updates, conflicts, permission changes and client schema migrations handled?

    3 min answer linearsync-engineoffline-firstoptimistic-updates
  8. Refactoring advanced

    An enterprise software vendor of SAP's shape must replace a logging call used at 2,400 sites across 1,100 files owned by 40 teams. The codemod itself takes an afternoon to write. Sequence the change so it lands once and stays landed.

    3 min answer codemodmechanical changebranchinglint
  9. Refactoring advanced

    Figma's database stack grew roughly 100x between 2020 and 2024. Rather than rewriting the application to be shard-aware in one step, the team vertically partitioned first, then introduced logical sharding, where queries still ran against a single database but were routed as if it were already sharded. Why is that intermediate step worth its cost, and what does it find that a cutover cannot?

    3 min answer figmapostgresshardingrefactoring
  10. Release Strategies advanced

    A brokerage must deploy without disrupting customers who may be mid-transaction. Which release strategy fits, and what does it require?

    2 min answer growwreleasecanarydraining
  11. Release Strategies advanced

    A collaborative product with long-lived client connections needs zero-downtime releases. How do rolling, blue-green and canary differ here?

    2 min answer releasestatefulconnectionscanary
  12. Release Strategies advanced

    A regulated business releases every two weeks through a change advisory board. Engineering wants continuous deployment. The control is real: an auditor tests that every production change was authorised, risk-assessed, tested and reversible. Sequence the migration.

    3 min answer continuous deploymentchange managementauditstandard change