Hypatia May
0298f5c6f0
Reconcile the session-surface feature with master's package reorg and simplifications: - Adopt master's folded usage (assistant/message.usage; standalone `usage` event dropped) and re-attach surface metadata (surfaceOp/sourceEventSeqs). - Add surface opts to master's new max-tokens assistant/message append. - Port surface columns onto the coordinator-refactored SQLite backend at its new path; drop the dead v1->v2 migration (bump-and-reject, no migration per pre-release policy). - Move the session-surface RFC into implemented/architecture/ and refresh its stale body (no migration, SESSION_FORMAT_VERSION=0, renamed package paths). - Update the core-data-structures catalog SessionEvent blocks for the two new surface fields; regenerate the cordis catalog. - Re-harvest ACP snapshot fixtures (keyless replay) to carry surface metadata.
30 lines
5.0 KiB
Markdown
30 lines
5.0 KiB
Markdown
# @deepseek-ai/dsh-session-persistence-sqlite
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A SQLite durable session-persistence backend — a second `SessionPersistence` implementation ([session persistence](../../../docs/rfc/implemented/architecture/2026-06-14-session-persistence.md)), 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.
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> **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.
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## Storage model
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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](../../../docs/rfc/implemented/architecture/2026-06-18-session-surface.md)). 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.
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The repo targets Node ≥ 24 (the root `engines` field), which includes the stable `node:sqlite` module. The database opens with `foreign_keys = ON` (so `ON DELETE CASCADE` drops a session's events with its row) and `journal_mode = WAL`. The table-layout version is stored in `PRAGMA user_version` and checked on open: a fresh database is stamped with the current `SCHEMA_VERSION`; a database written by any other, incompatible build (a non-current `user_version`, older or newer) is rejected rather than opened against an unknown layout — there is no migration (unreleased software).
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## Contract semantics over rows
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- **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.)
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- **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).
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- **Interrupted-turn close on load.** `load()` reads every stored event ordered by `seq` and finds the longest seq-contiguous, parseable prefix — INCLUDING the real events of an interrupted final turn after the last `turn/end` (the loop only flushes at `turn/end`, so a process killed mid-turn leaves real, fully-written rows past it). A single turn can be huge in a long-horizon task, so those events are **preserved, never truncated**: `load()` CLOSES the orphaned turn by durably appending the minimal synthetic boundary events (an error `tool/result` for every assistant tool call left unanswered, a `step/end` if a step was open, then a `turn/end` carrying `{ kind: 'interrupted' }`), inside one transaction that also DELETEs any never-fully-written torn tail row. `load()` is therefore mutating — after it the stored rows are balanced and the cursor is truthful, so the next `append` continues cleanly. The boundary (last `turn/end`, torn-tail detection) is computed from the `seq`/`type` columns so a malformed `data` in a torn tail row is never parsed (discarded, not unloadable). A parse error or `seq` gap inside the committed region (at or before the last real `turn/end`) makes the session unloadable. A session whose only turn never closed keeps its metadata row and stays present in `list()` — the same as the JSONL backend, whose file likewise survives a first append that never reached `turn/end`.
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## Configuration (schemastery)
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```ts
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interface Config {
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path: string // SQLite database file path, or ':memory:' for an in-process DB
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}
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```
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## Write path
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Like the JSONL backend, the plugin also installs the `session/event` → buffer → `session/flush` drain: it snapshots each event when buffered (the live `session.events` object is mutable), 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.
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