04 · SYSTEM DESIGN
Embeddings refresh nightly. Canary queries run after each rebuild — a small set of questions with known-good answers that must still resolve correctly. If recall drifts, the job fails loudly rather than silently serving stale context. Silent degradation is the failure mode that matters most for memory infrastructure; a stale index is worse than no index.
Ingest is deliberate. Not every file is embedded. Generated artifacts, dependency trees, and transient logs are excluded by policy. What remains is the material a senior engineer would actually consult: decisions, interfaces, constraints, and the reasoning behind them.
The retrieval path is boring by design. Query in, ranked passages out, under two seconds at the 95th percentile. No agent loop, no re-ranking service, no orchestration layer. Boring is the point. The index is consulted dozens of times a day and has to behave like a filesystem, not a product.