AI Eng Prep — Batch 03: Retrieval

[MHHamdan]

Delivers the retrieval half of Path 03 of the AI-Engineering-Preparation sub-repo.

Adds:

• six concept notes: RAG end-to-end, chunking and retrieval, reranking and citation, similarity and ANN, HNSW, IVF and quantization
• a runnable offline lab: minimal RAG with TF-IDF retrieval, grounded answer, citation, abstention, and exact-vs-IVF nearest-neighbor tradeoff study
• lab scaffold and solution notebooks
• a math page for nearest-neighbor search
• a diagram for the RAG pipeline
• navigation, glossary, and counts updates

Verification:

• rag.py --self-test passes
• ann.py --self-test passes
• notebooks are valid JSON
• internal links resolve
• ruff check passes

Memory and context engineering complete Path 03 next. Applies on top of Batch 02. All content is original; technical claims cite canonical sources.