A SQLite durable session-persistence backend — a second SessionPersistence implementation (session persistence), built to validate that the abstract seam and the shared runPersistenceContract suite are genuinely backend-agnostic. It satisfies the SAME contract as dsh-session-persistence-jsonl (append-only, contiguous-seq, lazy materialization, interrupted-turn close on load), expressed over node:sqlite rows instead of file bytes.

TODO: this backend talks to node:sqlite directly. If a cordis database service (cordis/db / a @cordisjs SQL driver plugin) is adopted, route through that instead of holding a raw DatabaseSync here — the contract surface (SessionPersistence) would not change, only the storage driver.

Storage model

Each SessionEvent maps 1:1 onto a row in an events table (session_id, seq, type, time, data, source_event_seqs, surface_op) — data is the event payload as JSON text, so the row shape is the event verbatim (including assistant/chunk, keeping seq contiguous). The two TEXT columns source_event_seqs and surface_op are nullable; they store the event's optional surface-metadata fields (see session surface). Out-of-log metadata (SessionHeader) lives in a sessions row. A sessions row is written only by the first append — its existence is the lazy-materialization signal (list reports exactly the sessions that have a row), so no separate column is needed.

The repository's Node range supports unflagged node:sqlite. The database enables foreign keys and uses the configured journal mode (wal by default; use a rollback mode where WAL shared-memory files are unsuitable). PRAGMA user_version stores the table-layout version; databases with any other version are rejected because this unreleased format has no migrations.

Contract semantics over rows

Append = a transaction. append runs BEGIN/COMMIT around the batch: it materializes the sessions row (if still lazy) and INSERTs every event, asserting the contiguous-seq contract first (the first event's seq must equal the stored next-seq). A mid-batch failure (a UNIQUE violation on a duplicated seq) rolls back entirely, so the stored log and the in-memory cursor stay consistent. (load() already balanced the stored log, so append never has to repair a crash tail.)
Lazy materialization. create() records intent in memory only — no row is written until the first append. A created-but-never-appended session has no sessions row, so it is absent from list() (which reports exactly the sessions that have a row).
Interrupted-turn close on load. load() implements the shared crash-recovery contract: preserve the valid interrupted turn, append its synthetic closing events in one transaction, and remove only a torn tail row. Committed parse errors or sequence gaps make the session unloadable. Because recovery mutates stored rows, the next append starts from a balanced log and accurate cursor.

Configuration (schemastery)

interface Config {
  path: string   // SQLite database file path, or ':memory:' for an in-process DB
  journalMode?: 'wal' | 'delete' | 'truncate' | 'persist'   // journal_mode pragma; default 'wal'
}

Write path

Like the JSONL backend, the plugin also installs the session/event → buffer → session/flush drain: it copies each already-frozen event into a persistence-owned buffer, persists a fork's seed once on session/created, keeps a per-session write cursor so a resumed session never re-appends stored events, and seeds existing live sessions on apply (HMR does not replay session/created). Dispose awaits every in-flight init + final drain and then closes the database, so no write lands after teardown.