Context glossary

Documented failure mode: content near the middle of a long context gets less attention than content near the start or end. Put critical facts at the top or bottom.

Combine vector search (semantics) with BM25/keyword (exact terms) and rerank with a cross-encoder. Standard production RAG pattern; beats either method alone.

Persistent verbatim block containing transactional data (amounts, dates, IDs) that must NEVER be summarized. Included in every prompt to prevent progressive summarization from corrupting details.

Cost pattern: cheap fast model (haiku) triages, strong model (opus/sonnet) does actual reasoning. Typical outcome: 70-80% of turns handled by cheap model.

Three valid triggers: explicit customer request, policy gap (no rule covers the case), inability to make meaningful progress. NOT sentiment or self-reported confidence.

Compaction strategy that summarizes older turns. DANGEROUS for transactional data — amounts, IDs, and dates get paraphrased into vague summaries. Use case facts block instead.