fix(persistence): bind JSONL identity before mutation

JSONL discovered a log by the requested session id but later routed repair and append from the parsed header. A log selected for session A could therefore declare session B and redirect mutation to B.

Validate the requested id and exact header-derived cwd-bucket path before returning a stored prefix, reject duplicate ids across buckets, and repeat the id/cwd guards in the coordinator before repair or state publication. Collapse the redundant loadLive hook into loadStored while retaining the existing bucket layout and one-live-writer topology, avoiding flat-layout churn and a locator generic that SQLite and test backends do not need.
This commit is contained in:
Tianyi Cui
2026-07-20 17:40:10 +08:00
parent 1a97a6b6f9
commit 73e3f658c6
11 changed files with 245 additions and 98 deletions

View File

@@ -34,14 +34,13 @@ The `PersistenceBackend<TornMarker>` hooks (the only seam between the coordinato
| Hook | Role |
|---|---|
| `name` | Backend label for the dispose-failure `AggregateError`. |
| `loadStored(id)` | Read a stored prefix by id, scanning ANY storage scope. Used by resume/load and, via `!== undefined`, the create-collision probe. Returns an opaque `tornMarker` iff a torn tail must be truncated. |
| `loadLive(id, cwd)` | Read a stored prefix SCOPED to `cwd` (HMR live-adoption must only adopt a log at the SAME cwd; a same-id log elsewhere is a collision, not a resume). A globally-unique-id backend ignores `cwd`. |
| `loadStored(id)` | Read a stored prefix by id across every storage scope. Used by resume/load, live adoption, and the create-collision probe. Returned metadata identifies `id`; an opaque `tornMarker` is present iff a torn tail must be truncated. |
| `appendBatch(meta, events, isMaterialized)` | Durably append a contiguous batch, lazily materializing ATOMICALLY when not yet materialized. |
| `commitRepair(meta, tornMarker, closers)` | Make a crash repair durable: truncate the torn tail (iff `tornMarker !== undefined` — a marker may be falsy, e.g. seq/offset `0`) and append `closers`. NOT required to be atomic. Used by load (truncate + closers) and live-adoption (truncate only). |
| `list()` | List all stored metadata. |
| `close?()` | Optional lifecycle teardown (e.g. close a db handle), awaited after the dispose drain. |
The `tornMarker` is fully OPAQUE: the coordinator only tests `!== undefined` and round-trips it to `commitRepair`, never inspecting its value (the JSONL backend uses the byte offset to truncate to, the SQLite backend the seq to delete from). The public `SessionPersistence` service shape is unchanged, so a third-party backend MAY still implement the abstract service directly without the coordinator. See [the write-coordinator Agent Note](../../../.agents/notes/implemented/architecture/2026-06-18-shared-persistence-write-coordinator.md).
The coordinator asserts the stored id and compares stored/live cwd before repair or live adoption. The `tornMarker` is fully OPAQUE: the coordinator only tests `!== undefined` and round-trips it to `commitRepair`, never inspecting its value (the JSONL backend uses the byte offset to truncate to, the SQLite backend the seq to delete from). The public `SessionPersistence` service shape is unchanged, so a third-party backend MAY still implement the abstract service directly without the coordinator. See [the write-coordinator Agent Note](../../../.agents/notes/implemented/architecture/2026-06-18-shared-persistence-write-coordinator.md).
## Testing backends