system-designEASYSYSTEM DESIGN MINI
Warm up with cache invalidation plan
Easy System Design arena: TTL choices, write-through versus cache-aside, and stale-read risk
XP reward
90
Coins
8
Target time
12m
A profile service serves stale account data after users update privacy settings. You are working inside a system design review board, and the arena only clears when the result is safe, deterministic, and explainable.
Learning objective
Learn to apply TTL choices, write-through versus cache-aside, and stale-read risk in a system design review board while explaining the invariant, safety constraints, and hidden edge cases.
Mission order
Clients read profiles through an API gateway, Redis cache, and Postgres source of truth. Implement the direct solution first, then document the one edge case that can break it. Submit the solution plus enough reasoning to pass hidden edge cases.Visible checks
selects the safest option
Expected: B
includes justification
Expected: mentions correctness or risk
Clear requirements
- Demonstrates TTL choices, write-through versus cache-aside, and stale-read risk
- Handles the visible sample and hidden edge cases
- Keeps output deterministic and explainable
- Avoids unsafe dynamic execution
Secure validation contract
Judge type
SYSTEM DESIGN MINI
Complexity target
Architecture answer names constraints, tradeoffs, and failure modes
Workspace
Reasoning panel
Test Results
Run the visible checks when your first pass is ready.
Clear Protocol
1Read the scenario and restate the expected output shape.
2Run visible checks before chasing hidden edge cases.
3Use Genie for one nudge if stuck, then explain the invariant.
4Submit only when the result is deterministic and safe.
Rewards
XP
90
Coins
8
Mission Route
Hints
Hints are metered and logged for No Hint Hero runs.
Genie Mentor Core
Hint protocol / contextual guardrails active
Progressive hints
Failed-test aware
Solution guarded
Mission: system-design-easy-cache-invalidation0 attempts0 failed tests0 hints used
Progressive hint depth
Genie: Genie online. I use your mission, attempts, failed tests, hints, and path context to coach the next rep without dumping answers first.