Kysely queries

Read src/db/types.ts, client.ts, dialect.ts, helpers.ts, dialects/, and the affected file under src/db/queries/. Reference paths in this paragraph after the first are relative to src/db/. Consult Kysely documentation for the installed API.

• Query functions accept the database/transaction argument. Pass the same transaction through all related writes; do not accidentally use the global connection inside a transaction.
• Keep the project's snake_case schema and explicit result mappings. A TypeScript generic on sql<T> does not convert runtime strings, bigints, booleans or binary data.
• Reuse supportsReturning() and existing insert/update helpers. The MySQL adapter takes the fallback path; do not add unconditional .returning()/.onConflict() from a PostgreSQL example.
• Use toBinaryData()/fromBinaryData() for Yjs updates and snapshots. mysql2 requires Buffer handling; preserve typed-array offsets when converting results.
• Preserve ownership/collaborator and status filters. Projects use active/archived/inactive states; do not invent a universal deleted_at rule. Keep denied mutations side-effect free.
• Parameterize values. Dynamic identifiers need the existing validated identifier path; never interpolate user text into sql.raw. Builder queries are immutable: retain the returned query when adding filters.
• Prefer queries that fetch only needed data and avoid repeated per-row work, but do not impose a new domain-object or {data} envelope architecture on existing functions.

Run the colocated query tests and relevant helpers.spec.ts/dialect tests. Include empty results, unauthorized access, rollback and dialect result conversions when affected. For schema changes, also load database-migration; SQLite-only success is not evidence of all-driver compatibility.