docs: surface MR-766 publisher OCC in storage / errors / constants

- storage.md: document the row-level CAS annotation on `__manifest.object_id`
  and the `expected_table_versions` OCC contract on `ManifestBatchPublisher::publish`.
- errors.md: list `ManifestConflictDetails` and its variants alongside `ManifestError`.
- constants.md: add `PUBLISHER_RETRY_BUDGET = 5`.

Per AGENTS.md "Maintenance contract": new schema construct, new constant, and
new typed error shape all need to ship with the source change.
This commit is contained in:
Claude 2026-04-29 07:56:18 +00:00
parent df0e158190
commit 5eb47b8c13
No known key found for this signature in database
3 changed files with 6 additions and 1 deletions

View file

@ -29,6 +29,8 @@ OmniGraph is **not** a single Lance dataset; it is a *graph* of datasets coordin
- `table_branch` is `null` for the main lineage and the branch name otherwise
- **Snapshot reconstruction**: latest visible `table_version` per `(table_key, table_branch)` minus tombstones — rows where `object_type = table_tombstone`, whose own `table_version` (acting as the tombstone version) is `>= the entry's table_version`.
- **Atomic publish**: multi-dataset commits publish via a `ManifestBatchPublisher` so a single write to `__manifest` flips all the new sub-table versions visible at once.
- **Row-level CAS on the merge-insert join key**: `object_id` carries `lance-schema:unenforced-primary-key=true` so Lance's bloom-filter conflict resolver rejects two concurrent commits that land the same `object_id` row. Without this annotation, Lance's transparent rebase would admit silent duplicates of `version:T@v=N` from racing publishers (see `.context/merge-insert-cas-granularity.md`).
- **Optimistic concurrency control on publish**: `ManifestBatchPublisher::publish` accepts a `expected_table_versions: HashMap<table_key, u64>` map. Each entry asserts the manifest's current latest non-tombstoned version for that table is exactly what the caller observed; mismatches surface as `OmniError::Manifest` with `ManifestConflictDetails::ExpectedVersionMismatch { table_key, expected, actual }`. Empty map preserves the legacy "best-effort publish" semantics. The publisher uses `conflict_retries(0)` against Lance and owns retry itself (`PUBLISHER_RETRY_BUDGET = 5`), re-running the pre-check on each iteration so concurrent advances surface as `ExpectedVersionMismatch` rather than being silently rebased through.
## URI scheme support (`storage.rs`)