# DAL Skeleton (pgvector)

## Interfaces
- `IDatabase` — connect/tx + memory ops (ensureNamespace, upsertItem/Chunks/Embeddings, searchText/searchVector).
- `PgDal` — Qt6/QSql-based implementation with in-memory fallback.

## 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`.
- Harden SQL with RLS/session GUCs & retries.
- Expand hybrid search scoring (RRF weights, secret filters).

## Implementation Checklist (2025-10-15)
- Require Qt6::Sql (`QPSQL` driver) at configure time; bail out early when unavailable.
- During `PgDal::connect`, parse DSNs with `QUrl`, open `QSqlDatabase`, and retain in-memory fallback for `stub://`.
- Use `QSqlQuery` with `INSERT ... RETURNING` for namespace/item/chunk/embedding operations.
- Derive DSNs from `kompanionrc` (KConfig) or CLI wizard, and surface informative `std::runtime_error` messages when QSql operations fail.