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tmac33/README.md

Hi, I'm Cosmo 👋

Senior Backend Engineer · Go · Distributed Systems · LLM Applications 📍 Auckland, New Zealand · 🌐 tmac33.top · ✉️ therealtmac33@gmail.com


I build backend platforms that orchestrate complex, multi-party systems — telecom provisioning, number portability, wholesale APIs. 10+ years of experience, currently focused on Go, gRPC, and GCP-native architectures, with a parallel track in LLM-powered tooling and agent orchestration.

🛠️ What I work with daily

  • Languages: Go, Python, TypeScript, Rust (learning), C#
  • APIs & RPC: gRPC, Protocol Buffers, grpc-gateway, REST, SOAP/WSDL, TMF Open APIs
  • Cloud: GCP (Cloud Run, BigTable, Pub/Sub, Firestore, BigQuery), Docker, Terraform
  • Databases: PostgreSQL, MySQL, BigTable, Firestore — and pgvector / LanceDB for embeddings
  • Observability: Datadog, Jaeger, OpenTelemetry, Prometheus, Sentry, OpenCensus
  • Patterns: Microservices, event-driven, saga / compensating transactions, state machines, multi-tenancy

🤖 LLM & agent work

I treat LLM systems with the same rigour as any other production backend — typed contracts, graceful degradation, observability, cost control. Things I've built or shipped:

  • Agent skill systems — maintain 90+ reusable skills across two frameworks (Hermes, OpenClaw); designed the on-disk skill layout and Git-sync workflow so agents and humans share the same source of truth.
  • Multi-agent orchestration — LangGraph / CrewAI workflows for content pipelines (research → draft → review → publish) with deterministic step boundaries instead of free-form planning loops.
  • MCP servers & Claude Skills SDK — built tools that agents call directly; clean tool schemas, idempotent side effects, structured errors.
  • Retrieval — pgvector for transactional metadata-adjacent search; LanceDB for local, file-backed embedding stores; hybrid retrieval (BM25 + vector) where pure semantic search underperforms.
  • Production LLM hygiene — prompt caching / system-instruction reuse, 429-rate-limit fallbacks to local templates (real users never see a 500), function calling with strict JSON schemas, streaming responses with per-call token accounting for cost monitoring.

📦 Open source

  • go-saga — Tiny generic synchronous saga library for Go. Deterministic rollback, survives client disconnect via context.WithoutCancel, ~150 LOC, zero deps, 97% test coverage. Abstracts the pattern I've shipped to production several times for telecom provisioning.
  • goauth-demo — Production-shaped JWT auth service. Single-use refresh-token rotation via atomic UPDATE ... RETURNING, bcrypt, Postgres, Prometheus + OpenTelemetry, k6 load tests with p95/p99 thresholds.

🚀 Backend systems I've shipped

Most of my production work lives in private repos, so here are the systems I've designed and led:

  • UFB Product Service (One New Zealand, 2024–present) — Tech lead for the central orchestration layer for Ultra-Fast Broadband provisioning on One NZ's wholesale NaaS platform. End-to-end provisioning across 7 microservices and 4 LFC operators (Chorus, Enable, Northpower, UFF), serving ~40 RSPs nationally. Synchronous saga with defer-based deterministic rollback across 5+ downstream gRPC services.

  • NZ Mobile Number Portability (Vodafone NZ, 2022–2024) — Implemented the full NZ TCF LMNP protocol as a dual-interface gRPC server. 13 port scenarios, characteristic-based state machine, two-phase inter-carrier activation with atomic MSISDN cutover at RFS. Replaced two legacy porting platforms.

  • Mobile Postpay & FWA Product Services — Distributed saga provisioning for multi-resource allocation (MSISDN, OCS, Cellular, IPv4, SIM) with cascaded compensating transactions across 17 downstream gRPC integrations. context.WithoutCancel rollback ensures cleanup after client disconnect.

🔭 Currently exploring

  • Authentication protocols (OAuth, OIDC, SAML) and identity at scale
  • Postgres operational concerns — schema migrations, multi-tenant patterns, pgvector tuning
  • Rust for systems-level work
  • Where the line should sit between deterministic workflows and agent autonomy

📫 Get in touch

Open to senior backend / staff engineer roles, especially fully-remote teams working on developer infrastructure, identity, distributed systems, or AI-product platforms.

LinkedIn · Blog · therealtmac33@gmail.com

Pinned Loading

  1. goauth-demo goauth-demo Public

    Production-shaped Go JWT auth service — bcrypt, refresh-token rotation, Postgres, Prometheus + OpenTelemetry

    Go

  2. go-saga go-saga Public

    Tiny generic synchronous saga library for Go — deterministic rollback, survives client disconnect, ~150 LOC, no deps

    Go

  3. agent-rag-learning agent-rag-learning Public

    16-week structured curriculum for going from "I called the LLM API" to shipping production-grade Agentic RAG. Go + Python, ~80 hours total.

    Python 1 1