AI Engineering — from Data Platforms to Production LLM Systems

A chapter-by-chapter portfolio documenting a deliberate transition: 9 years of data platform work (churn analytics, data science, BI, data engineering) applied to AI engineering. Every chapter ships working code, reproducible measurements, an architecture decision record, and a published article on Level Up Coding.

One domain, one evolving platform. Instead of 13 disconnected demos, every chapter builds on the same customer-analytics foundation — real public data, a real data platform underneath — and ends in a capstone: a Customer Intelligence Platform.

Principles

1. Evidence over claims. Every number in every article is reproducible from experiments/ in the corresponding chapter. No hypothetical scenarios, no synthetic anecdotes.
2. Baselines first. LLM approaches are always measured against the boring classical baseline.
3. Local-first, privacy-aware. Raw LLM experiments run on local models (Ollama) — the data never leaves the machine. Frontier-model work uses the Claude Agent SDK.
4. The pipeline is the product. AI features sit on top of data engineering that is incremental, idempotent, and observable.

Data

Real, public datasets only:

• IBM Telco Customer Churn — tabular churn baseline.
• CFPB Consumer Complaint Database — millions of real customer complaint narratives, updated monthly (a genuine incremental-load problem).

Roadmap

#	Chapter	Focus	Status
0	Setup	Environment, data ingestion, access verification	✅ done
1	Baseline first	XGBoost churn model — the anchor every LLM result is measured against	✅ done
2	LLM mechanics, locally	Tokenization, sampling, structured output, quantization — measured on consumer hardware	✅ done
3	Eval harness	Golden sets, LLM-as-judge, LLM vs TF-IDF on real complaints	⏳
4	Prompt & context engineering	Few-shot / CoT / context-position effects, all measured	⏳
5	RAG through a data engineer's lens	Chunking A/B, retrieval metrics, vector store comparison	⏳
6	Production data engineering for AI	Incremental, idempotent embedding pipelines; contracts	⏳
7	Semantic layer + text-to-SQL	LLM-generated SQL scored against a golden query set	⏳
8	Tool use & the agent loop	ReAct from scratch, then the Claude Agent SDK	⏳
9	Subagents & orchestration	Orchestrator–worker, context isolation — measured	⏳
10	Automation & LLMOps	Eval gates in CI, scheduled agents, prompt versioning	⏳
11	Performance optimization	Semantic caching, model routing, quantization deep-dive	⏳
12	Observability & guardrails	Tracing, token/latency dashboards, injection defenses	⏳
13	Capstone: Customer Intelligence Platform	Everything integrated, reference architecture	⏳

Repository layout

cip/            shared platform core (data, llm, evals, observability) — grows chapter by chapter
chapters/       one directory per chapter: README (results), src, experiments
docs/adr/       architecture decision records
data/           raw data (gitignored) + small committed samples

Why cip/ and not platform/? platform is a Python standard-library module; shadowing it causes subtle import bugs. See ADR-0001.

Running anything

uv sync                          # create the environment
uv run python -m cip.data.download --dataset telco
uv run pytest                    # tests

Each chapter's README documents its own uv run experiment commands.