AI Engineer
Build the retrieval, prompting, and evaluation machinery that turns a model into a product.
Who this is for
Engineers shipping LLM and RAG features that other people depend on.
What you should be able to do
Ship a retrieval pipeline with evaluation, structured outputs, and a rollback path.
Career ladder
The titles this track maps onto. Levels differ between companies. The useful part is the direction, and what each step adds to the one before it.
- AI Developer
- AI Engineer
- Senior AI Engineer
- Principal AI Engineer
- Distinguished Engineer
Tech stack
What the work is actually done with. Grouped by the job each tool does, so the list reads as a system rather than a pile of names.
- Language
- PythonTypeScript
- Serving
- FastAPIRay Serve
- Orchestration
- LangChainLangGraphMCP
- Models
- ClaudeGPTGeminiBedrockAzure OpenAIOllama
- Retrieval
- pgvectorPineconeWeaviateQdrant
The delivery flow
The order the work actually happens in. Each step is where a decision gets made and written down, not a chapter heading.
- Requirement
- Data ingestion
- Chunking + embedding
- Vector store
- Retrieval + rerank
- Prompt + structured output
- Evaluation harness
- Deploy + observe
Reference repository structure
A starting layout for this track. The directories are the ones that get added late and hurt. Decisions, evals, policy, lineage. Promoted to the top level where they are visible.
ai-service/ ├── app/ │ ├── api/ # FastAPI routers, request/response models │ ├── chains/ # retrieval + generation composition │ ├── prompts/ # versioned, one file per prompt │ └── schemas/ # structured output contracts ├── ingestion/ │ ├── loaders/ # source connectors │ ├── chunking/ # strategy per document type │ └── embed.py ├── evals/ # golden set, metrics, regression gate ├── infra/ # terraform, docker, k8s manifests └── tests/
Reading path
12 published guides on this track. Every one is a live page on this site. Nothing here is a placeholder.
- Building Production RAG Pipelines with LangChain & Claude
- How to Build a Production RAG Pipeline on AWS Bedrock in 2026
- RAG vs Fine-Tuning: Which Should Enterprises Use? [2026]
- Vector Databases for RAG: pgvector, Pinecone, Weaviate & Milvus
- AI Engineering Course: LLMs, RAG, Agents [2026]
- Building Production RAG Pipelines: A Senior Engineer's Guide
- Building Production RAG Pipelines: Engineer's Guide
- How to Build a DevSecOps Pipeline from Scratch [2026 Guide]
- How to Build a DevSecOps Pipeline from Scratch: A Step-by-Step Guide for 2026
- RAG Pipeline in Production: From Prototype to Enterprise-Grade in 2026
- LangChain vs LlamaIndex vs AutoGen: Which AI Framework for Enterprise in 2026
- LangChain vs LlamaIndex vs AutoGen: Which AI Framework? [2026]
Reference implementations
Citadel’s open-source repositories for this track. Terraform modules, MCP servers, and reference architectures you can read, fork, and run. Apache/MIT licensed; check each repository for its terms.
- GitHub ★ 1rag-pipeline-hallucination-mitigationProduction RAG with 5-layer hallucination mitigation. Hybrid retrieval (RRF), cross-encoder reranking, NLI validation. 94.3% faithfulness. Python + Azure AI Search.rag-pipeline-hallucination-mitigation on github.com (external site, opens in a new tab)
- GitHub ★ 1langchain-multi-agent-frameworkMulti-agent framework with LangGraph orchestrator, supervisor routing, shared memory, and tool integrationlangchain-multi-agent-framework on github.com (external site, opens in a new tab)
- GitHubmulti-industry-ai-assistantHIPAA/SOX/OSHA AI assistant for Healthcare, Finance, Oil & Gas. Plugin architecture, PII detection, NLI faithfulness validation, audit logging. FastAPI + Python.multi-industry-ai-assistant on github.com (external site, opens in a new tab)
- GitHubmcp-server-vector-dbMCP server for vector database operations - Pinecone, Weaviate, Qdrant, and ChromaDBmcp-server-vector-db on github.com (external site, opens in a new tab)
Primary sources
The standards, framework documents, and vendor references this track is built against. Go here when you need the authoritative wording rather than a summary. In a security review or an audit, the source is what counts.
- Model Context Protocol specification (external site, opens in a new tab)
- Anthropic developer documentation (external site, opens in a new tab)
- OpenAI API reference (external site, opens in a new tab)
- LangGraph documentation (external site, opens in a new tab)
- FastAPI documentation (external site, opens in a new tab)
- Amazon Bedrock user guide (external site, opens in a new tab)
- Hugging Face documentation (external site, opens in a new tab)