# DAL Skeleton (pgvector)

## Interfaces
- `IDatabase` — connect/tx + memory ops (ensureNamespace, upsertItem/Chunks/Embeddings, searchText/searchVector).
- `PgDal` — stub implementation for now (no libpq linked).

## SQL Calls (target)
- ensureNamespace: `INSERT ... ON CONFLICT (name) DO UPDATE RETURNING id`
- upsertItem: `INSERT ... ON CONFLICT (id) DO UPDATE SET ... RETURNING id`
- upsertChunks: batch insert w/ `RETURNING id`
- upsertEmbeddings: batch insert; ensure `model, dim` set, vector column populated.
- searchText: FTS/trigram query filtered by namespace/thread/tags.
- searchVector: `ORDER BY embeddings.vector <-> $1 LIMIT k` (with filters).

## Next
- Wire `Handlers::upsert_memory` / `search_memory` to `IDatabase`.
- Add libpq (or pqxx) and parameterized statements.
- Add RLS/session GUCs & retries.