Add cross-property BM25 And operator

[amourao]

Exposes the OPERATOR_AND_CROSS search operator (Weaviate 1.39.0, backported to 1.37.15 and 1.38.8) as BM25Operator.and_cross(), available wherever a BM25 operator is accepted: query.bm25, query.hybrid, the generative-query equivalents, and aggregate.hybrid.

Unlike and_(), which requires every query token to occur within a single property, and_cross() lets a token be matched by any of the searched properties as long as each token is matched by at least one. All searched properties must share the same tokenization and analyzer settings — the server rejects the query otherwise.

collection.query.bm25("banana split", operator=wvc.query.BM25Operator.and_cross())

Changes

• BM25OperatorAndCross + BM25Operator.and_cross() in weaviate/collections/classes/grpc.py.
• The duplicated SearchOperatorOptions construction in the bm25 and hybrid paths is folded into _BaseGRPC._bm25_operator_to_grpc(), so the version gate covers every caller. Using and_cross() against an older server raises WeaviateUnsupportedFeatureError rather than sending an enum value the server does not understand.
• _ServerVersion.is_at_least_any() expresses a minimum that was backported across several release branches (a 1.38.x server needs 1.38.8, a 1.37.x server needs 1.37.15).
• Regenerated protos for the OPERATOR_AND_CROSS enum value.
• CI's 1.39 image bumped to 1.39.0-rc.1-89299a5 — the first RC carrying the operator.

Tests

• test/collection/test_bm25_operator.py — and_cross() maps to OPERATOR_AND_CROSS on the bm25 and hybrid requests, and is rejected on servers that predate it.
• test/test_server_version.py — is_at_least_any() around each branch boundary.
• integration/test_collection.py — one cross-property match against a live server, version-gated with a skip.

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Secrets	0   0   0   0	View in Orca

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.00000% with 1 line in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (dev/1.39@ae327ca). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
integration/test_collection.py	90.00%	1 Missing ⚠️

Additional details and impacted files

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##             dev/1.39    #2114   +/-   ##
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[dirkkul]

BM25OperatorAndCross (weaviate/collections/classes/grpc.py:676) isn't exported from weaviate/outputs/query.py, but its two siblings are: BM25OperatorAnd and BM25OperatorOr appear both in the import block (outputs/query.py:11-12) and in __all__ (:64-65).

That leaves the public surface asymmetric for no reason — users who want to isinstance-check or type-annotate against the new operator can't import it from the public namespace the way they can for the other two. One line in each spot:

from weaviate.collections.classes.grpc import (
    MMR,
    BM25OperatorAnd,
    BM25OperatorAndCross,
    BM25OperatorOr,
    ...
)

__all__ = [
    ...
    "BM25OperatorAnd",
    "BM25OperatorAndCross",
    "BM25OperatorOr",
    ...
]