Designs by Duhart

Designs by Duhart · work inventory

Twenty-eight projects, ranked for one job

Distributed Systems Engineer — Google / Spotify / financial institution. Scored against what those loops actually test, not against how impressive it looks.

The rubric — weight × rating, max 120

Canonical DS primitives ×5Partitioning, event logs, idempotency, fan-out, backpressure
Production evidence ×4Deployed, measured, runbooked, failure modes named
Concurrency correctness ×4Races found, fixed, and tested for
Scale artifacts ×3Shard keys, consumer groups, TTLs, hot keys
Language fit ×3Go, Java, Python, C++
Contract discipline ×2OpenAPI / AsyncAPI / protobuf, CI-enforced
Written communication ×2Design docs stating trade-offs and costs
Frontend / mobile ×1Real work; not what this role hires on

Each project is rated 0–5 per signal. Ratings are a hiring judgment, not a measurement — treat differences under about five points as ties.

Tier S

95+

Lead with these. They are the interview.

1Billboard Activity GraphGo · outbox → Kafka → three consumer groups1032GlobalChat Realtime MessagingGo · Cassandra, Redis, Kafka, WebSocket1063Match Service — Distributed RankingGo · geo-partitioned Cassandra, Redis Streams101

Within 5 points of 120 — that is noise. GlobalChat edges the rubric on production evidence and breadth. The Activity Graph leads anyway because it is the canonical systems-design question with every trade-off already written down. Open with it; bring GlobalChat as proof you have carried something this size in production.

Tier A

75–94

Strong support — infrastructure, ML platform, media.

4Solomon — Serving, Kubernetes & AutoscalingPython · k3s, Helm, HPA, continuous batching905Solomon — LLM Platform (umbrella)The whole pipeline, end to end896Billboard Production HardeningTypeScript · RS256, 9 tables, CI contract gates847WebRTC Calling PlaneGo · ICE/STUN/TURN, a fatal map race located838Media & Upload InfrastructureGo + TS · R2 multipart, IngestDO, TUS809Push & Notification PipelineGo · Kafka → APNs + PushKit VoIP7910Solomon — Retrieval & Agent TierGo · index, agent loop, grounding guard75

Tier B

60–74

Real systems work, narrower interview surface.

11Platform Operations & CI/CDsystemd, Compose, two CI systems, six gates7312Auth & Identity PlatformGo · gRPC/Connect, RS256, 24 protobufs7013GlobalChat Messaging UISwift + React · transport/store/runtime split7014Realtime Gateway TrioGo · 48,582 lines over Kafka + Cassandra6915Cloudflare Edge PlatformTypeScript · 10 Workers, D1/R2/KV/DO6816Solomon — Evaluation Gates & PromotionNine release-blocking gates6517Solomon — Training & Experiment TrackingMLflow, SHA256 manifests, val PPL 40.06318Dating Swipe Deck & Discovery UISwift · 90,161 lines; 49 audited findings6219BoxOffice & the Moderator ConsoleSwift + Next.js · statutory-deadline operator UI61

Tier C

under 60

Breadth and depth-of-craft. Mention, don’t lead.

20OpenHouse GlobalTypeScript · 7 forward-only CQL migrations5721Billboard Player — Audio UI & EngineSwift · actor-isolated AVPlayer, vDSP FFT5622Palantir J8 — Exhibit FactoryPython + React · fail-closed financial ingest5523Multiplatform Clients (umbrella)611K lines Swift, 19-module Compose port5424Solomon — The TransformerPyTorch from the paper; KV cache proven equal5325Web Platform UINext.js · every mode, generated protobuf clients5126Solomon — Corpus, Tokenizer & Data Governance130M tokens, 0 UNK, contamination checks4627Technical Documentation CorpusThree 17–20 chapter manuals with gap registers3928Portfolio & Marketing InfrastructureCloudflare Pages; a DNS plan that saves your email17

Reading paths

Google1 → 3 → 4 → 11
Spotify1 → 21 → 8 → 6
Bank2 → 12 → 16 → 11

Supporting documents

Résumé bulletsPre-sorted by employer, with quotable numbers.Interview storiesEight stories with the follow-ups each invites.The full index documentThe source inventory in long form.