Layer cake
Locked decisions
Section titled “Locked decisions”| # | Decision | Choice |
|---|---|---|
| 1 | Agent loop substrate | Vercel AI SDK v6 (ai ≥ 6.0, @ai-sdk/mcp for MCP client) |
| 2 | Persistence | PGLite single store (knowledge + conversations) |
| 3 | ORM | Drizzle (schema-as-TS, auto-generated migrations) |
| 4 | Embedding model | OpenAI text-embedding-3-small (1536-dim) |
| 5 | Retrieval | Hybrid: pgvector (HNSW) + tsvector (GIN) |
| 6 | Cross-thread recall | Adaptive: cosine ≥ 0.78, top-3, always-search |
| 7 | Summarization trigger | Turn count: every 20 runs |
| 8 | LLM call style | streamText everywhere |
| 9 | KeeperHub default | Audit-by-default — undeclared tools routed |
For the full design — schemas, event taxonomy, retrieval strategy, daemon lifecycle, audit-by-default contract — see docs/architecture.md in the repo.