Senior Engineer Approach Review
A staff-level second opinion on an implementation approach: codebase fit, failure modes, ownership cost, and one clear pick.
Before & after
Same prompt, same agent — the only difference is the skill.
This looks like a reasonable approach. You've thought through the main components and how they'll interact. One thing to consider is whether this will scale if traffic increases, and whether you have fallback options if something breaks. You might also want to think about monitoring and alerting so you know if something goes wrong. The design seems solid, and I think it should work well for your use case. If you want to discuss any specific concerns or edge cases, I'm happy to dig deeper into those areas.
ARCHITECTURE REVIEW: SENIOR ENGINEER ASSESSMENT DESIGN SUMMARY (3-tier) • Read path: Web → CDN → Origin (database direct) • Write path: Web → API → Queue → Worker → Database • Assumption: separation improves write throughput (worker async) SCRUTINY (Deep dive) ✗ ISSUE 1: No backpressure on queue • Problem: If workers slow (database contention), queue grows unbounded → memory leak • Risk level: HIGH (could lose messages after 7-day retention) • Fix: Add circuit breaker (stop accepting writes if queue depth > 100k) • Estimate: 2-4 hours (add monitoring + handler) ✗ ISSUE 2: CDN cache invalidation not defined • Problem: How long do reads stay cached? What triggers purge on write? • Risk level: MEDIUM (data freshness gaps possible) • Fix: Define TTL (60s for user-specific data; 1h for public data) + purge on write • Estimate: 1-2 hours (cache headers + invalidation webhook) ✓ GOOD: Database connection pooling mentioned • Evidence: Uses PgBouncer; avoids connection exhaustion (solid) ✓ GOOD: Separation of concerns (read vs write) • Benefit: Allows independent scaling; read replicas can be added later FAILURE MODES ANALYSIS 1. Database down → Reads fail (expected); writes queue → acceptable 2. Queue worker down → Backlog accumulates → triggers circuit breaker → acceptable 3. CDN down → Origin traffic spikes 10x → may overload → ADD fallback (cache on origin) RECOMMENDATION Ship with circuit breaker + cache invalidation strategy. Monitor queue depth + p99 write latency for first 2 weeks. If CDN failure tests show origin saturation, add origin cache layer (Redis 10GB, ~$500/mo). CONFIDENCE: 7/10 (solid foundation; 2 gaps need filling before 9/10)
About this skill
Before you build it, get the second opinion a staff engineer would give: is this the right shape of solution for this codebase, and what will it cost to own? It judges the approach rather than line-level style, and it always commits to one recommendation.
What it does
- Compares implementation options (A vs B, build vs reuse) and picks one, with the condition that would flip it
- Searches for existing abstractions the change duplicates, the most common hidden cost
- Checks partial failure, retries and idempotency, concurrency, timeouts, and edge inputs
- Names the concrete future cost of each weakness and separates MUST from SHOULD from taste
- Flags overengineering as readily as underengineering
What you get
A short answer for quick A-or-B questions, or a full review with recommendation, confidence, MUST and SHOULD findings, an options table, assumptions, and the first step.
Best for
Engineers and tech leads choosing between approaches or sanity-checking a design before investing in it. For merge-readiness of a specific diff, pair it with a layer-specific PR review.
SKILL.md preview
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name: senior-engineer-approach-review
description: Give a senior engineer's second opinion on an implementation approach or design choice - does it fit the existing codebase, what does it cost to own for the next year, what breaks under load, retries, or partial failure, and is it reversible - ending in one committed recommendation. Layer-agnostic; judges the approach, not line-level style. Use when the user asks "is this the right approach?", "option A or option B?", "should we build this or reuse X?", "sanity-check this design before I build it", "would a senior engineer sign off on this?", "is this overengineered?", or "review how I solved this, not the syntax".
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