* feat: slice filtering condition for sliced scroll and deterministic sampling
Add a `slice` filter condition selecting points where
`stable_hash(point_id) % total == index`. The hash is SipHash-2-4 with a
zero key over canonical id bytes (8 LE bytes for numeric ids, 16 RFC 4122
bytes for UUIDs) — a frozen public contract, independent of the internal
resharding ring hash, reproducible by clients to predict membership.
For a fixed `total`, slices are disjoint and cover all points, enabling
parallel scroll streams (ES sliced-scroll style) and reproducible sampling
that composes with any other filter condition.
- REST: `{"slice": {"total": N, "index": R}}`; gRPC: `SliceCondition` in
the condition oneof (tag 8)
- Evaluated per point via id_tracker external-id lookup; no payload index
needed; cardinality estimated as `points / total` with no primary clause
- `total >= 1` enforced by NonZeroU32 at parse time, `index < total` by
validation in both REST and gRPC paths
- Hash contract locked by test vectors independently reproduced with a
reference SipHash-2-4 implementation
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
* tests: minimal OpenAPI test for slice filter condition
Scrolls all slices of a fixed total over numeric + UUID ids asserting
disjointness and full coverage, checks must_not inversion, and pins the
two rejection paths (422 for index >= total, 400 for total = 0). Requests
and responses are validated against the regenerated OpenAPI spec by the
test harness.
Note: the spec cannot itself reject total = 0 client-side — the Condition
anyOf falls through to the permissive Filter schema, as with any invalid
condition — so rejection is asserted via the server response.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
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