# /srv — Complete Work Inventory, Ranked for Hire

**Owner:** J. Michael Duhart · j.michaelduhart@gmail.com
**Compiled:** 2026-08-27 · **28 projects**
**Target role:** Distributed Systems Engineer — Google / Spotify / financial institution
**Target comp:** $210K, fully remote

---

## How this is ranked

Every project in `/srv` is scored against what a distributed-systems hiring loop
at these three employers actually tests. Not "is it impressive" — *is it the
thing they ask about on the whiteboard, and can you say "I built that and it
runs"?*

| Weight | Signal | Why it matters to the target employers |
|---|---|---|
| ×5 | **Canonical DS primitives** — consensus, partitioning, replication, event logs, idempotency, fan-out, backpressure | This *is* the Google/Spotify systems-design interview. The whole loop. |
| ×4 | **Production evidence** — deployed, measured, has a runbook, has failure modes you can name | Separates "wrote a demo" from "carries a pager". Banks weight this highest. |
| ×4 | **Correctness under concurrency** — race conditions found, fixed, and tested for | Senior signal. The single hardest thing to fake in an interview. |
| ×3 | **Scale artifacts** — sharding keys, partition design, consumer groups, TTLs, hot-key handling | Spotify's backend and Google's SRE-adjacent roles probe this directly. |
| ×3 | **Language fit** — Go, Java, Python, C++ | Go is the lingua franca at Spotify's backend and Google Cloud. |
| ×2 | **Contract discipline** — OpenAPI/AsyncAPI/protobuf, CI-enforced | Banks require it. Google requires it culturally. |
| ×2 | **Written communication** — design docs that state trade-offs and costs | Google promo packets are made of this. |
| ×1 | Frontend / mobile / marketing | Real work, but it is not what this role hires for. |

Each project is rated 0–5 per signal. **Max score 120.** Ratings are a hiring
judgment, not a measurement — treat differences under ~5 points as ties.

---

## The ranking — all 28

### Tier S — lead with these. They *are* the interview. (95+)

| # | Score | Project | One line | Where |
|---|---|---|---|---|
| **1** | 103 | [Billboard Activity Graph](01-billboard-activity-graph.md) | Transactional outbox → Kafka → three independent consumer groups → Cassandra + Postgres + realtime. At-least-once, idempotency paid explicitly at each sink. | `app/BillboardActivityService` |
| **2** | 106 | [GlobalChat Realtime Messaging](02-globalchat-realtime-messaging.md) | 26K-line Go service: Cassandra chat, WebSocket fan-out, presence, push, calling signaling. Benchmarked and race-tested. | `app/GlobalChatService` |
| **3** | 101 | [Match Service — Distributed Ranking](03-match-service-distributed-ranking.md) | Geo-partitioned Cassandra ranking, Redis Streams consumer groups; a phantom-partition bug and a 952-message PEL leak, both fixed and written up. | `app/MatchService` |

> **The top three sit within 5 points of 120 — that is noise.** GlobalChat edges
> the rubric on production evidence and breadth. The Activity Graph is listed
> first because it leads on the axis that decides a systems-design round: it
> *is* the canonical question, with every trade-off already written down. Open
> with the Activity Graph; bring GlobalChat as proof you have carried something
> this size in production.

### Tier A — strong support. Infrastructure, ML platform, media. (75–94)

| # | Score | Project | One line | Where |
|---|---|---|---|---|
| **4** | 90 | [Solomon — Serving, Kubernetes & Autoscaling](23-solomon-serving-and-kubernetes.md) | FastAPI SSE/WS streaming + continuous batching, k3s + Helm + HPA scaled to 3 replicas, NetworkPolicy, dry-run-validated manifests. | `Solomon/k8s` |
| **5** | 89 | [Solomon — LLM Platform *(umbrella)*](04-solomon-llm-platform.md) | The whole pipeline end to end. Decomposed into the six projects below. | `Solomon/` |
| **6** | 84 | [Billboard Production Hardening](05-billboard-production-hardening.md) | 60+ commits from forgeable auth to RS256 four-tier, 9 D1 tables, resumable upload, moderation, DMCA, CI contract gates. | `app/workers/billboard_users` |
| **7** | 83 | [WebRTC Calling Plane](06-webrtc-calling-plane.md) | Signaling/media-plane audit: ICE/STUN/TURN, P2P vs orphaned SFU, a fatal concurrent-map race located. | `docs/webrtc-chat/` |
| **8** | 80 | [Media & Upload Infrastructure](26-media-and-upload-infrastructure.md) | R2 multipart ingest across five modes, `IngestDO` single-writer sessions, TUS resumability, a Go adapter bridging edge to Kafka/Redis. | `app/GlobalCloudflareAdapter` |
| **9** | 79 | [Push & Notification Pipeline](27-push-and-notification-pipeline.md) | Kafka → consumer → APNs, plus PushKit VoIP; dedupe where a duplicate is a second buzz on someone's phone. | `app/GlobalChatService` |
| **10** | 75 | [Solomon — Retrieval & Agent Tier](24-solomon-retrieval-and-agent-tier.md) | 4,757 lines of Go: chunk/embed/search/store, a bounded agent loop, a **grounding guard with its own test**, Kafka ingestion. | `Solomon/retrieval` |

### Tier B — real systems work, narrower interview surface. (60–74)

| # | Score | Project | One line | Where |
|---|---|---|---|---|
| **11** | 73 | [Platform Operations & CI/CD](28-platform-operations-and-cicd.md) | systemd units **including a restore-verify timer**, Docker Compose stacks, two CI systems, gates that encode specific past defects. | `deploy/`, `.github/` |
| **12** | 70 | [Auth & Identity Platform](09-auth-identity-platform.md) | gRPC/Connect gateway, RS256 issuance, ACL, mode-sync, 24 protobuf contracts generating Go + Swift + TS. | `app/AuthGateway` |
| **13** | 70 | [GlobalChat Messaging UI](17-globalchat-messaging-ui.md) | iOS + web realtime clients with a transport/store/runtime split — and a wiring record that retracts three of its own conclusions. | `IOS/.../GlobalChat` |
| **14** | 69 | [Realtime Gateway Trio](08-realtime-gateway-trio.md) | 48K lines of Go: three WebSocket gateways over Kafka + Cassandra, connection/session/presence separated. | `app/gateways/` |
| **15** | 68 | [Cloudflare Edge Platform](07-cloudflare-edge-platform.md) | 10 Workers over D1, R2, KV, Durable Objects, Hyperdrive — including a WASM FFT fingerprinting DO. | `app/workers/` |
| **16** | 65 | [Solomon — Evaluation Gates & Promotion](22-solomon-evaluation-gates.md) | Nine gates that can **block a release**, two of them latency and throughput; full artifact lineage to the running image. | `Solomon/solomon/evaluation` |
| **17** | 63 | [Solomon — Training & Experiment Tracking](21-solomon-training-pipeline.md) | Noam + label smoothing, checkpoint/resume, MLflow, SHA256 run manifests. Val PPL 40.0 in 3 h on CPU. | `Solomon/solomon/training` |
| **18** | 62 | [Dating Swipe Deck & Discovery UI](16-dating-swipe-and-discovery-ui.md) | The largest mode in the app — and where the phantom-partition bug became visible. 49 audited findings with `file:line`. | `IOS/TheOne/Dating` |
| **19** | 61 | [BoxOffice & the Moderator Console](15-boxoffice-and-moderator-console.md) | *"27 endpoints and curl"* → a four-route operator console where a 502 on takedown is reported as a **result**, not a failure. | `IOS/.../BoxOffice`, `/support/staff` |

### Tier C — breadth and depth-of-craft. Mention, don't lead. (<60)

| # | Score | Project | One line | Where |
|---|---|---|---|---|
| **20** | 57 | [OpenHouse Global](25-openhouse-global.md) | Real-estate service with **7 versioned forward-only CQL migrations** and a buyer journey modeled as a state machine. | `app/OpenHouseGlobal` |
| **21** | 56 | [Billboard Player — Audio UI & Engine](14-billboard-player-ui.md) | Full music player: AVPlayer behind an actor, `MTAudioProcessingTap`, live spectrum, on-device vDSP FFT fingerprinting. | `IOS/TheOne/Billboard` |
| **22** | 55 | [Palantir J8 — Exhibit Factory](10-palantir-j8-exhibit-factory.md) | Ontology-driven financial pipeline; data-driven normalizer registry; **fail-closed ingest**. | `Palantir/J8` |
| **23** | 54 | [Multiplatform Clients *(umbrella)*](11-multiplatform-clients.md) | 611K lines Swift / 13 modes, 19-module Compose port, Next.js platform. Decomposed into the five UI projects. | `IOS/`, `Android/` |
| **24** | 53 | [Solomon — The Transformer](19-solomon-transformer-model.md) | Built from the Annotated Transformer, component by component, every deviation justified in writing. KV cache **proven** equal to full recompute. | `Solomon/solomon/model` |
| **25** | 51 | [Web Platform UI](18-web-platform-ui.md) | Every product mode in one Next.js app, compiled against the same protobufs the backend serves. Playwright + vitest. | `app/web-platform` |
| **26** | 46 | [Solomon — Corpus, Tokenizer & Data Governance](20-solomon-corpus-and-tokenizer.md) | 130M tokens cleaned and deduped, SentencePiece BPE (0 UNK), data card with **contamination checks**. | `Solomon/solomon/data` |
| **27** | 39 | [Technical Documentation Corpus](12-technical-documentation.md) | Three 17–20 chapter manuals with gap registers — including a **14/52 Spotify parity analysis**. | `docs/` |
| **28** | 17 | [Portfolio & Marketing Infrastructure](13-portfolio-and-marketing.md) | Cloudflare Pages site; a DNS migration plan whose step 2 is "verify the MX records or you lose email". | `Portfolio/`, `Marketing/` |

---

## Reading paths

**Two umbrella entries decompose into the detail projects.** They are listed
once each and are not double-counted:

| Umbrella | Decomposes into |
|---|---|
| [Solomon platform](04-solomon-llm-platform.md) | [Model](19-solomon-transformer-model.md) · [Corpus](20-solomon-corpus-and-tokenizer.md) · [Training](21-solomon-training-pipeline.md) · [Eval gates](22-solomon-evaluation-gates.md) · [Serving/K8s](23-solomon-serving-and-kubernetes.md) · [Retrieval/agent](24-solomon-retrieval-and-agent-tier.md) |
| [Multiplatform clients](11-multiplatform-clients.md) | [Billboard player](14-billboard-player-ui.md) · [BoxOffice console](15-boxoffice-and-moderator-console.md) · [Dating swipe](16-dating-swipe-and-discovery-ui.md) · [Chat UI](17-globalchat-messaging-ui.md) · [Web platform](18-web-platform-ui.md) |

### If you have 20 minutes with a Google interviewer
1 → 3 → 23 → 28

### If you have 20 minutes with Spotify
1 → 14 → 26 → 5 (the parity analysis)

### If you have 20 minutes with a bank
2 → 12 → 22 → 11 (the restore-verify timer)

### The five user interfaces, as a set
[Billboard player](14-billboard-player-ui.md) ·
[BoxOffice + moderator console](15-boxoffice-and-moderator-console.md) ·
[Dating swipe deck](16-dating-swipe-and-discovery-ui.md) ·
[GlobalChat messaging](17-globalchat-messaging-ui.md) ·
[Web platform](18-web-platform-ui.md)

### The six Solomon projects, as a set
[Model](19-solomon-transformer-model.md) →
[Corpus](20-solomon-corpus-and-tokenizer.md) →
[Training](21-solomon-training-pipeline.md) →
[Eval gates](22-solomon-evaluation-gates.md) →
[Serving/K8s](23-solomon-serving-and-kubernetes.md) →
[Retrieval/agent](24-solomon-retrieval-and-agent-tier.md)

---

## Supporting documents

- **[RESUME-BULLETS.md](RESUME-BULLETS.md)** — every project reduced to resume lines, pre-sorted by employer.
- **[INTERVIEW-STORIES.md](INTERVIEW-STORIES.md)** — the eight stories worth telling, in situation/action/result form, with the follow-ups each invites.

## Infographics

Rendered, self-contained HTML in [`../infographics/`](../infographics/):

| File | What it shows |
|---|---|
| `01-portfolio-ranking.html` | All 28 projects as a scored tier board |
| `02-activity-graph.html` | The outbox → Kafka → three-consumer pipeline, drawn |
| `03-platform-map.html` | Every service in `/srv` and who calls whom |
| `04-scale-dashboard.html` | The numbers: LOC, services, datastores, tests |
| `05-skills-matrix.html` | Skills mapped to Google / Spotify / bank requirements |
| `06-solomon-pipeline.html` | Corpus → training → eval gates → promotion → k8s |

---

## The honest summary

`/srv` holds **~4.3M lines of authored code** across **13 backend services, 10
edge Workers, 3 realtime gateways, 4 datastores, and 3 client platforms**, plus
a from-scratch LLM platform and three book-length engineering manuals.

For the target role, three things carry the interview and the other twenty-five
are supporting evidence:

1. **You built a canonical event-driven fan-out pipeline** — outbox, log,
   consumer groups, idempotency — and can defend every trade-off in it.
2. **You found and fixed real distributed-systems bugs** — a phantom Cassandra
   partition, a leaking Redis consumer-group PEL, a fatal map race under
   concurrent calls — and wrote each one down.
3. **You shipped and measured it**, with runbooks, contract tests in CI, and
   named failure modes.

That is the profile. The rest is range — and there is a great deal of range.